Prototype monoblock (NC500OEM/Converter board/SMPS1200)

[TEK]

OK, not going to repeat it all here - but as you all know I'm building two protoyp monoblocks to test the most basic setup possible with the NC500OEM modules - and at the same time get myself a couple of monoblocks to complete my audio/HT setup.

I find that there is a lot of very small parts and details that I had not thought about before that influence the build, both when it comes to time used and to parts I have to get hold on. As this is one of my first amp builds (I have built a bottlehead tube kit many years ago, but that does not count) there are some stuff I have not done before and some parts that you folks probably just have laying around that I have to get my hands on.

This goes for:
- plugs and pins for the OEM adapter board
- fastons
- spacers and screws to mount everything to the amp
And some of these are only sold in 100's, for example the pins for the P6 plug...

I think most of what I need is one the way now.
As I'm going to cut out the back plate myself to get the power-plug installed I will probably go out and get myself a small dremel. I do not have one from before - and I have wondered about getting one several times.

I will add some assembly questions/notes as I go along here.

Note to myself:
Led is 3.0V, 20mA, 1000mcd, Ultra Blue
Resistor is 3300 ohm

[TEK]

I think I will expand the spec with a small detail.
It will be nice if the av-processor could turn the amp on/off. So I will add a 12v standby input.
As far as I can tell that should be possible to do by mounting a mini-jack on the back of the chassie and connect the mini-jack to the SMPS1200 J5 : Pin 1 and J5 : Pin 5 (ground).


Jon: You noted in a email that I should connect the led to a 12V output with a 820ohm resistor between.
What 12V output are you thinking about? The J5 on the SMPS have 21V output. J4 has a 12V output, but that is already used by the OEM board.

Another detail I see that apply to both the minijack plug and the led is how to mount them.
Right now I'm looking at a min-jack plug like this:
But that will leave a mut on the outside of the chassie, so ideally this should be fastened on the inside of the chassie so that only the plug hole was visible on the outside. But to do that you would have some way of mounting the jack at the inside fo the cabinet.

The same detail goes for a led. If you are to mount a led you have to have something to mount the led to.
What do you usually use for that? My first idea is a mini pcb-board with two holes and the led soldered onto the pc-board and then the pdb board fastened to the chassie. Have some other boxes here. Guess I will have to open them up to see what is done.

[JonMarsh]

I was using 12V just as an example for how to calculate the current limiting resistor if you know the desired LED current in mA.

With regards to LED mounting, this really depends on how the specific part you get is designed. There are "raw" LED's with wires, which you could use with a small hole drilled in the front panel, and tack soldering some wires to the LED pins and covering with heat shrink tube. There are LED's in complete socket/fixture assemblies, which may mount through the panel from in front and have a nut to secure in the back. I recall that Ben documented his build and how he added details like that. If you check the PDF I sent you, you can see how it was done by the supplier of that chassis, they actually had a small metal fixture mounting a PCB and a three position switch through the bottom of the chassis to control the brightness of the LED.

Go have a look at this page on Ghent Audio- their "mono" chassis is adaptable to a lot of configurations, including NC500 modules and SMPS1200 as well as SMPS600.

http://www.ghentaudio.com/kit/ncore-mx.html

In the USA we'd just use Digikey or Mouser or a similar distributor to look for a suitable part. Yes, it's a bit tedious- one reason why I latched on to this guy for chassis work. Seems to do the basics OK. Of course, there are others, too.

[TEK]

Thanks Jon.
From the image you posted I see that ghentaudio is using the one I identified as a candidate, pin j5 pin 3 (Positive Unregulated Auxiliary Output Voltage (+21V)) and pin 5 (ground).
So I will need to take the led down from 21V.
For the 12V standby trigger I will have to split pin 5 (ground) so I can have one wire to the led (in front) and one to the standby jack (in the back).
And I have to figure out some way of mounting both of them.
I see now that a large part of amp building will be searching for and finding suited parts, just need to embrace that - and do a bit more work to figure out all that up-front as there are a bit of a cost penalty pr. order in freight and handling cost (if the order is small).

[TEK]

Got my connector stuff and plugget the adaptor board, the NC500 and the SMPS togheter yesterday - just to check.
Got a overcurrent led lit up (not supriced, had seen that on the net already).

Input from Hypex was as follows:
This is normal. J12 pin 9 on the adaptor board is permanently connected to ground on the SMPS, thus pulling the pin low. If you disconnect this pin from the ribbon cable the indicator should function normally.

[JonMarsh]

That's an important errata to track - maybe we should have another doc for doing that?

in other news, the order with cashiers check went out to day, will be at Beaverton Monday AM, and the Northern CA guy is tracking stuff and got me the name of the relevant sales person to send this to in Beaverton. Waiting for feedback on lead-time.

[TEK]

I tought that since this apply to the adaptor board (which will not be a part of the system board) that I should include it in the prototype build description together with the other information about how these could be wired together.

My solution to this is that I removed pin 9 from the J4 connector at the adaptor board (I did not want to destroy the cable as I was not sure if I might need it to connect the SMPS to the system board.
I also think it should be ok to remount it if nessesarly.

[TEK]

Planned backplate. The plate is in 3mm aluminium. I will have to do the cutouts myself. I'm a bit unsure about the connector. i see now that having the fuse, switch and plug in one snap-in module might not be the best idea when it comes to how this affect the strength of the backplate. I'm a bit worried that it will twist when I make that large hole in it.


And I will also need a 23,5mm drill as well as a 11mm drill. 11 should be no problem (I hope), but I will guess the 23.5 will have to be a 24mm. Will have to go out looking for those later today.

[TEK]

Blue led prototyping...

Jon's input was:

With regards to the power on LED, thing to remember is the need for a current limiting resistor- most LED’s are in the 3V range, except blue, which are around 4V; run it off 12V, and you need to have a series resistor to limit the current to the preferred range (5-10mA or so), so if it is a 12V source, then 12V - 4V = 8V, 8V/0.01=800 ohms, nearest standard value would be 820. There might be LED assemblies with a built in resistor

In my case I have a 21V source. The led are 3V/20mA.
That should mean that to run them on 10mA on a 21V source line I would need a 1800 ohms resistor (21V-3V = 18V, 18V/0.01 = 1800 ohms)
I guess I could regulate it up to 20mA if I would like a stronger light by using a 900 ohms resistor instead (21V-3V = 18V, 18V/0.02 = 900 ohms).
I guess I also could have two resistors with a switch to select which one to use, but I think I will start out with just one at 1800 ohms. After all it's just a prototype.
And guess what, I actually had a 1800 ohms resistor laying around :-)

[JonMarsh]

Serendipity? But is it the preferred brightness for you? Often it may be too bright, in which case doubling the resistor value may do the trick.

BTW, you wouldn't believe how many circuits I put together and tested on protoboards like that back in the 70's. No SPICE, no computers, it was the only way to try things out...

[JonMarsh]

Planned backplate. The plate is in 3mm aluminium. I will have to do the cutouts myself. I'm a bit unsure about the connector. i see now that having the fuse, switch and plug in one snap-in module might not be the best idea when it comes to how this affect the strength of the backplate. I'm a bit worried that it will twist when I make that large hole in it.
[ATTACH=CONFIG]25008[/ATTACH]

And I will also need a 23,5mm drill as well as a 11mm drill. 11 should be no problem (I hope), but I will guess the 23.5 will have to be a 24mm. Will have to go out looking for those later today.

Can you get hole punches? That would be a better way to do the large holes. I was using Greenlee punches back in the 60's when I was a kid working on amateur radio stuff- never used anything else since then.

http://www.all-spec.com/products/Gre...FUhcfgod7vcKSg

[TEK]

I had actually not heard about hole puncher for metal. Had to go over to You tube to find some diff
However, since this is just a prototype build I will use my dremel as well as drills to make the holes that I need.
Later on I will plan ahead and make sure that any holes needed is added when the case is ordered.

About the led, I'm not sure. I will make the led so that it points down to the ground, so no direct light will be visible when looking at the amp. That may cause me to need a bit more light then other equipment. So I will build a small board for mounting as it is now, and then I will consider it then.

Getting closer to getting these into some real testing

[dar47]

Ah, blinky blink. You have that bread board and Nano just play with a Arduino sketch till you like then try and match a resister. I'm getting antsy seeing that stuff on the table. I have to do a bathroom reno right away then I can focus on this which will give Jon some playing time. Have fun guys.

[TEK]

When you mention the Arduino (not directly related to the previous post).
An Arduino nano runs on 7-12v unregulate. It can draw up to 40mA pr. IO pin (there are 14 pins).
Ref https://www.arduino.cc/en/Main/ArduinoBoardNano

I expect a resonable assumption is to power the nano from the +21 source, for example to drive your led strips, select color and so on (ps: I still think arduino is a bit overkill for this usage but it's easy to program and it should work just fine, and you get it for approx 5usd...).
What should be done to pull down the voltage to 7-12V so that it could be used to power the Arduino?

Sorry to hear about the bathroom reno. Not sure if I'm right, but from your text I got the impression that something unexpected has happend and caused the need for the reno?

[TEK]

OK, it's getting somewhere now. I have made all the holes and both the SMPS, the NC500 and the adaptor board is now mounted to the chassie. Also the power plug/on-off switch/fuse is mounted(dont have the right fuse yet, so that is bypassed... ouch) as well as the XLR input and speaker output terminals.
XLR input and speaker output terminals are not connected yet. Also the blue led is mounted.

I do however have a issue. Please give me any input if you have, if not I will probably have to run this trough hypex.
When I power up the amp the first time it powers up just fine. It takes about 2-4 seconds from I turn the power switch to on before a relay clicks, the led turns on and it all looks OK. It can stand on for several minutes and everything continue to look the same.
However, if I turn it off, just waits a couple of seconds and then turn it back on it takes 2-4 seconds and the relay clicks, the led turns on and then after a short time (maybe 1/4 to 1 second) the relay clicks again and all leds goes off, indicating that the SMPS shuts down.
If I then wait for some minutes before I turn the power on again it will start normally again.

So, it seems like if I turn it back on again a short time after turning it off - it will shut down by some reason that I do not understand. That does not seem OK.

Oh, and another question. As you can see I have mounted the SMPS with the heat sink against the front plate. On some other builds, for example the one posted by Jon earlier in this thread, they have placed the heat sink between the SMPS and the NC500.
Is there anything that would cause one to be preferred over another? (My reason for mounting it up against the thick front panel would in effect cause the whole front panel to act as a heat sink).

[JonMarsh]

That is somewhat odd behavior- without having it on the bench, would be hard to say- my NC400 stuff is on the way to Steve Manning, along with the cases I have. (not the OEM stuff- and I have a new set of cases in route from China to here).

The delay on the start up for the relay is the soft start charge bypass for the primary side capacitors- the circuit will be using a relay to bypass the resistor that limits the inrush current charging those caps. Maybe it doesn't like having a module connected that is not pulling any load current or discharging the caps? I don't know- most of the protection control is by internal firmware. We'll have to look at the flow chart for startup and protection.

Mounting the heatsink up against the front panel is something I'd think carefully about- it depends on the isolation of the power switches from the heatsink. Usually I'd say that should be floating relative to the chassis, as part of the safety isolation considerations. I'll dig into my packed up stuff tomorrow and look at how that is put together (the SMPS supply and heatsink construction).

[TEK]

And there is sound...
Test setup (did not want to risk blowing up the ardents on my first attempt...).
Dragged out a old tupe preamp and are using my phone as a source. For a long time I did not get ANY respons - until I figured oit that I had forgot to insert the plug from the xlr connection into the adaptor module ops:

I have more info on the shutdown issue as well as some comments on the heatsink. More details and question about the prototype will come as well before I build the the next one.
Now this will get a try in the real setup 8O

[dar47]

That's great, should be fun when you get to speaks.

I think I would orientate more like the Ghent case example, power in on one side and output on the other. Make output cables as short as possible with nice tight twisted cables, although the Ghent cable looks like it could be done nicer. Not sure on twisting that ribbon cable. Is there an alternative to even using that ribbon, seems most computer setups do away with ribbon now.

[TEK]

Ai, ai, ai...
I had a very low hum in the test setup - probably from the tube amp.
Just to test I tried to disconnect safety earth to see if that had an effect on the background noice.

Holy shit - that was noicy!
It seems like I was able to disconnect the element fast enough - it does at least still play.
What happens is that when I disconnect safty earth I get over 70V out of the speaker terminals. The terminals is isolated from the chassie, so this must mean that it is the amp that deliver this.
And that happends, for some reason, when safty earth is disconnected.

So, anyone has a glue about what might be going on?
I have the following ground connections in the amp:
- from xlr input pin 1 and the chassie
- from xlr internal cables screen to the chassie via the ground connector on the xlr socket
- from the gnd faston plug on the adaptor board to ground via on of the connectors.
- the screen on the internal cable is connecred to fnd on the connector board (through the 4-pins input connector).
- from earth safty ground (power) to the chassie

I'll attach some photos. Hopefully someone is able to see where I have done something wrong?

[JonMarsh]

It's likely a common mode problem- that is, a common signal voltage that appears relative to the amplifier signal ground to both input, because the ground is lifted when you disconnect the safety ground. An active balanced input can only reject so much, until the inputs of the op amp clips-

This is the sort of thing I would normally trouble shoot using a scope and looking for a floating voltage. you may have current leakage from that heatsink assembly touching the chassis. Anodized aluminum is nominally an insulator, but it takes the right processing to make it a good insulator. One scratch, you get leakage current path.

The insulation on the heatsink for the semiconductors looks quite well done. And the main metal bracket and heatsink of the SMPS1200 provide the necessary isolation for safety. BUT, I"m wondering about your tube preamp? For example, I would suggest doing another test using an inherently floating piece of gear (like an iPod, iPad, iPhone) as an audio source, and see if this works without issues. Then I would use a DVM or scope to look at the possible difference in ground potential between the tube preamp and the power amp with safety ground CONNECTED, nothing powered up. Your amp could be providing the path to ground when it has the safety ground connected, for leakage current in the ground path of the preamp. This has to be ruled out.

Note, I don't usually directly connect pin one to chassis, but run it through a 50 ohm resistor and a 1 to 10nF high voltage cap. This provides RF shielding just find, but prevents low frequency AC current from flowing through the shield.

Back in the 70's I did some jobs re-wiring studios and audio shops- it's amazing what kind of problems you can uncover with different equipment. Much better to put a higher impedance test load (such as 16 ohms or more) and always a meter or scope to monitor).

It might be worthwhile for you guys to consider an inexpensive scope- there are some decent ones from China these days, they'll never put Tektronix or Teledyne-Leroy out of business, but it's amazing how well they work for what they cost.

http://www.amazon.com/Rigol-DS1054Z-Digital-Oscilloscopes-Bandwidth/dp/B012938E76/ref=sr_1_1?s=industrial&ie=UTF8&qid=1452568368&sr= 1-1&keywords=rigol+oscilloscopes

Mind you, they make more expensive ones, too, but 50MHz bandwidth would be fine for Audio trouble shooting.

In case you think it isn't, then something like this might do... :W



http://www.amazon.com/Rigol-DS4054-Digital-Oscilloscope-channels/dp/B00J7XJKVQ/ref=sr_1_7?s=industrial&ie=UTF8&qid=1452568368&sr= 1-7&keywords=rigol+oscilloscopes

[TEK]

Thanks a lot Jon.
Seems we are looking at the same ideas - with your input I might be able to track it down.

I will do some testing later tonight or tomorrow (have some work deliverable's that might have to take presences).
Guess I also have to start reading about this: https://learn.sparkfun.com/tutorials...n-oscilloscope
Always wanted a scope, but never quite found out what they are about ;-)

[JonMarsh]

I hear you about the work deliverables- got the same situation by COB tonight- review of a paper from one of the European team that needs a lot of review and additional support. Worked most of Sunday on that, just to get a head start, because I didn't figure two regular work days would be enough. Made good progress Sunday and yesterday, but it will still be a long day today.

Scopes are something I find indispensable - got my first one when I was 11, government surplus, paid for by Christmas & Birthday money, and a lot of saving allowance and chores money. Next was a HeathKit.

Another thing to check is the actual grounds being made to the chassis- anodized aluminum has to be complete sanded off so that a solid electrical connection is made. Some of the chassis vendors go to specific trouble to prepare ground points with screw holes and anodizing masking, but it's still a good idea to use a little sand paper and check connectivity with a DVM (ohmmeter mode). The photo of your pin one connection to the chassis is very suspect- all I see is black anodizing under the terminal lug.

[TEK]

...
Another thing to check is the actual grounds being made to the chassis- anodized aluminum has to be complete sanded off so that a solid electrical connection is made. Some of the chassis vendors go to specific trouble to prepare ground points with screw holes and anodizing masking, but it's still a good idea to use a little sand paper and check connectivity with a DVM (ohmmeter mode). The photo of your pin one connection to the chassis is very suspect- all I see is black anodizing under the terminal lug.

What you do not see from the picture is that the holes has been drilled by me and that I have made recess for the screw head, so right benith the connector is bare aluminium.
Anyway, I took your advice and used the multimeter to check the ohm between all ground connections and the chassie. All resultet in 0 ohm resistance, so the impression is that the connection is ok.

OK, today I have tested quite a bit more. And I'm kindof lost. I'm actually unable to reproduce the issue today. I have tried about everything, but it's working just fine both on and off earth.
I have tested with and without safty earth connected, not connected, driven from the tube amp and from the phoe. I'm noticing the following:
- It works flawless with both solutions in all cases
- The background hum I mentioned before is a attribute of the tube amp. It's unrelated to safty earth beeing connected or not (it's also only noticable if you are a few cm from the speaker element)

For now I have 3 hypoteses for what might have caused the behaviour I observed yesterday.
1) During testing today I did notice that if I turn off the tube preamp while the amp is still on I get some very high pop's (and I can see the element beeing pulled all the way down).
So the hypothese is that I might have experienced something related to on/off attributes with the preamp.
I do not have mutch belife in this hypothese as I mean the length of the observed period the problem occured was mutch longer.
2) I had a temporary ugly fix where I used a thin wire instead of a fuse (I have got a real fuse now, 2.5A, slow). If that wire, after the power plug was moved around because I removed the safty earth, touched the chassie there would be a connection between safty earth and one pole. This would have made a extra connection between one of the pole and other earth that again may have caused very strange results. Any action of inserting/removing the power plug, connecting/disconnecting safty earth might have affected this and would explain that the error could have disappared today.
3) There is some bad connection or errornous connection in the amp (other than 2) that occures or does not occure and that caused the issue. If this is the case that would mean that the issue might reoccure at any given time, probably blowing out any connected speakers.


Hmm, I actually just now discovered something. If the amp is on, the balanced input cable is connected to the amp but not to anything else.
Then I will hear noice from the speaker. Kindof a even pulse. If I move the cable around the noice differences in loudness from barly noticable to very easy to hear.
Unblugging the cable from the amp or plugging it into the pre-amp causes the sound to disappare.
The sound I got from the speaker yesterday was the same kind of pulse - just extremly mutch higher.
That is just an observation, I actually have no idea what or even if, that means.

My problem right now is that the amp seems to be working great. However, when that incident occure, there was a very unwanted signals going out of the speaker terminals. If that happends when there are permanently connected speakers to the amp - the result might be that the speaker will be destroyed.
And as I'm unable to reproduce the issue, I'm also unable to say for sure that the issue will not reocurre. This makes me quite worried about starting to use the amp.

Not sure what to do now...

* There is a earthing error in my area of the grid. This means that between earth and left power pin there is 7V. Between earth and right powe pin there is 223V. I'm not sure if that might have some kind of effect.

[JonMarsh]

I'll review this in detail soon- I've been tied up with this work paper review, which has actually turned in to making major contributions to some sections of the paper, to supplant the inadequate materials and support in the original. This mentoring other people and teams stuff can really take up a lot of time... Even in the evenings with deadlines for review to address.

[TEK]

Yeah, it's not always what you think should take time that actually does take time. I'm writing up on a concept document over here, but a lot of the time that was supposed to be used on that is instead used on hunting down and making sure other, unrelated, issues are being handled.

I had the amp playing all evening, mostly everything is looking very good. Except now recently when I was turning on the preamp first, then the amp right afterwards.
That caused there to be some really load sounds from the speaker. Almost like fireworks. Turned the amp off and on again and everything was fine.
From what I can understand this must be the pre-amp that passes on some very nasty signals when it's powering up. And because I powered up the amp very close to the pre-amp, those was passed on into the amp.
I guess I should be able to use a oscilloscope to monitor what the pre-amp is passing on the the amp during power up/down and that very verify if something fishy is going on with the pre-amp.
Maybe I should up the stake a bit and take out the AV8801 and let that drive the amp for some testing. If it's behaving nicely there should be no bad behaviour when using a decent pre.
This might be soly pre-amp related.

BTW, there is a Tektronix 2213 for sale here is norway for very little (around 50usd). Will that do as a start, or should I just beet the bullet and get a new digital one if I'm going to get a scope??

[JonMarsh]

Vacuum tube preamps are a bit notorious for start up issues; depends a lot on the design. Usually it's best to turn one on a few minutes before turning on the connected power amp.

Your new Marantz is a much safer bet for initial testing without drama, IMO.

A working 2213 for $50 would be a great deal- 2 channel, 60MHz bandwidth, and good input sensitivity. You would normally pay more than that for a good 10x scope probe.

[TEK]

It's without probes, so I will have to figure oit how to get those and what they cost.
I'll fire up the Marantz for further test sessions. If stuff looks ok I will build the other one and get the hole system set up.

There is one thing with the design that I do not cuite get.
According to the Hypex drawings, the recommended solution is to connect pin 1 to the chassie.
Also, the screen of the cable going from the xlr side of the wire to the amp is supposed to be connected to the chassie - but at a different location. Then the amp side of the screen is also connected to ground.
Why two different connections to ground at the xlr plug?
Why is not the screen of the internal cable just connected to pin 1 on the xlr connector?
Why at all have a ground connection at the xlr connection point instead of just at the end? Is it because signals might be picked up between the input and output of the xlr connection?
I get the need for balanced cable, the thinking about hot/cold as the differential, but this several earth when going into the chassie I don't get yet. Maybe I have to read the documents again with this as a focus area.
The balanced inpu

[JonMarsh]

Reasons: Redundancy, and start grounds. If one connection fails, the other is still there. The ground connections wind up going back to the same point on the system board. If they were daisy chained, in a conventional amplifier, any current flowing through the ground resistance would create a voltage potential between the two grounds; this is an example of how problems occur with single ended setups. Recall some of the papers I sent you about grounding in audio systems. A long read, but a necessary overview if you go working on this yourself.

I've still been short of free time because of work, but one of the issues you noticed with the inputs of the OEM module when they aren't connected is quite easy to explain, it's what I consider the one issue or vulnerability of how Hypex implements the input configuration.

Look at the circuit- the type of balanced instrumentation amplifier Hypex uses is largely immune to source impedance imbalance causing a deterioration in common mode rejection because there is no input resistor network as for a conventional balanced bridge single amplifier- there is instead just a high value input impedance. High input impedance if NOT connected to a preamplifier means "noise". There is intrinsic noise to all circuits which is just due to the resistance; the higher the resistance, the more. With the input not terminated, the input sensitivity even to electrostatic effects due to handling the input cable becomes apparent. With the input terminated by a low output impedance preamp, no noise. BTW, tube preamp output stages have much higher impedance than typical solid state, and yes,, that means more noise.

This is part of why I have a different preferred input stage configuration in mind, using transformer coupling and a well defined input impedance whether a preamp is connected or not. This has many advantages, including this aspect; but it costs more- it will have similar semiconductor costs, but also incur the transformer cost. I bought them at a good price because of getting 20+. But consider, if for a conventional product material cost is $30, one normally multiplies that by a minimum factor of 5 and a maximum factor of up to 8-10 to determine the impact on product retail price- this means adding the transformer concept would increase the system resale price by between 125 and $250, depending on what the actual BOM cost was.

Monday is a holiday for us in the USA and I'll be working on the front end stage design schematics and documentation, so I can share this in more detail.

Also, those documents I sent to you, I will load to my public folder in DropBox and post links so Ben and Darrel can have easy access also.

[TEK]

Thanks Jon!.
Just so you know it, the documents are already available here, together with all the hypex documents I have gathered. You all have full access to the area.
But better to have it many places than few ;-)

Today I moved the prototype into the home theater and connected one of the Ardents to it. First of all, no problems with on/off pops or cracks - so that part absolutly seems to be related to the tube preamp (as expected).
I have been listening to it for a short while now, and have made some observations. You all will have to consider carefully that I have put this together myself, so my objectivity is very questionable.

As mentioned I have one speaker connected. The other speaker is powered by the thule AV350B (350W, balanced input, A/B).
- The impression is that it produces a higher output than the thule does. It is however hard to evaluate this as I'm not sure that what I hear is caused by "louder" (see next point). I have tried to adjusted the speaker levels to match, but ...
- The sound is "clearer". This is easily noticed by the following factors: I hear the difference between different types of drums. The drum beats are better separated. The bass is a lot "fuller". As you probably know, my normal setup is to use the Ardent + 3 subs, the fronts as small, crossed over at 40hz. That does not feel like it's necessarily with the NCore 500 prototype connected (to one speaker!). So I will say that there is a significant improvement in the bass area. In the same way does the mid-tone seems clearer. Something that causes the voice to feel shifted against the speaker with the ncore amp. I first thought that was a leveling issue, but after drying different level adjustments it's quite clear that the voices are just clearer on that speaker. The treble I'm a bit more unsure about - but I do believe that voices are "softer/clearer/less sharp/less stingy" in the upper frequence area. However, that change is more subtil. It is in the the mid and bass area the largest improvements are.

And connecting safety earth is not a good idea - so this, the next one and future builds will be build as non-earthed double insulated amp.
After the amp was connected I god high frequency noise in all speakers, no matter if they played anything or not.
I disconnected safety earth - and all noise was gone. I checked the Marantz SR7005, and found that it is build as unearthed and double isolated (it has the double square symbol). I could probably worked around it by adding resistor and stuff like Jon have mentioned before. And I guess I should do that to the input screen anyway - but when it comes to safety earth I will go for double isolation instead.
I guess I should not have a earthed connection plug on the amp if the amp itself is not earthed, so that should most likely be replaced with a non-earthed power plug. Guess these prototypes will just have to live with that - but it will influence the component selection for "the real deal".

Learnings so far:
- double isolated, not saefty earth (yeah Jon, I know you told me so - but you know, the lessons you learn by yourself is much easy to remembered ;-)
- remember that the case has wall (I have positioned the amp/adaptor board to close to the edge, about 3mm, should have been at least 6mm)¨
- i will probably turn the power supply around - even if I'm not quite sure why - but it seems to be the most used setup so I'll guess someone have done some thinking about that before ;-)

[dar47]

Well that sounds very positive, it sure making me full of anticipation.

I have heard the NC400 on my friends set up and I noticed clear differences over his Emotive mono amps, he has gains across the board but a lot more puncher base. His are ported towers with the Scan 7" Illuminators (like Jons 2nd version Ardent's) with the same mid as ours and the 6620 tweet which I don't like especially over the 6600. His have the biggest improvement in the highs (made that tweet clear) and I would (want to), put a sock in his port maybe cause I like sealed base way more, haha. I'm running the XPA-2 so there should be some improvement. I still haven't pick his amp up to try so maybe tomorrow. I think the Ardent's are good as gold and the better you give them the more they resolve for you! Interesting that your crossing at 40 and you don't think that is to low, it will be cool to see what they do on mine with the 2 18's in the IB setup. I'm at 60hrz now so I'll have to play with that but when listening to just music I don't always turn the subs on. Mine and Ben's thoughts were the IB just kind of shows up in and out at 60db or higher but doesn't have much of a presence at low listening levels unless it's crossed higher. (very low distortion base). If I felt I didn't need the IB I could just go straight to the dac and skip the pre-amp for music although I have felt the pre-amp doesn't degrade anything and is nice for the times your watching movie after music, (HT bypass).

I think it was wise of you to try the grounding options as you now have a great understanding and comfort level with your design choices. It will be interesting to see if you feel there is more improvement with both amps on both Ardents.:T I think it's hard to evaluate in mono unless you have spent a lot time listening like that. No problem for a guy like Jon who has done a million designs starting with mono but find it to point source like a clock radio. I tried 2 different amps same manufacture before and I felt it muck the imaging giving you a feeling of no coherence, maybe just me. So even with this your hearing solid improvement, which is great.

[TEK]

In my experience it is VERY hard to hear improvements. Not that hard to hear difference, but to know if they area an improvement or not is often much harder.
That is much of the story when it comes to using sub's or not. Sometime I think it's heaven, and sometimes it's more like hell - that balance between the accurate and good bass that is just enought and that overloaded bass that is way to mutch is hard to find in my experience.
However, i'm quite familiar with my current setup - and I feel confident to say - even with just one speaker - that the lower mid and bass is at a different level with the ncore500 than with the Thule AV350. With the ncore500 I'm mutch more in doubt if using the subs for regular music content actually is nessesarly - but that is something I will have to test a lot more when I have both amps up and running. When it comes to the mid and tweeter I think there is a lot of improvements, but as I'm having only one amp it's hard to say what is due to leveling issues and what is actually differences because when I level them equally the other speaker will affect the sound as well and when listening to both I'm not sure if I'm able to say what (regarding clarity) is coming from what speaker.
And in all that it is of course the physiologic effect - I have put this together myself, based on a amp I have heard a lot about. That is not a good starting point for doing a objective comparison. But what the heck - I like it better, and that is for real no matter what ;-)

Now, I have a question.
As you can see form the picture below, Hypex and Marantz have different opiniums on what is hot and cold in the XLR connections.
Wikipedia is siding with Marantz. https://en.wikipedia.org/wiki/XLR_co...ee_pin_-_audio

Does this make a difference? I'm not that familiar with balanced signals, but as far as I know the point with the hot/cold is to get the difference between the signals - and in such what is hot or cold should not make a difference, as the delta is the same.
Or will this work as with speaker cables, so that you will shift the phase of the speakers by swapping this channels?
If it makes a difference I assume that it is important to select what is closed to the "industry standard" (I assume there is none as Marantz is typing what hot/cold/ground is on all balanced equipment) as possible.
Are there a "industry standard" for what the different pins mean?
Does it make a difference if you swap hot and cold?

The answare to these questions might both affect how I connect the amp internal as well as how I will connect the cables I make.
(I think I will wire the amp to be according to Marantz so that I can use standard cables if I like to)

[dar47]

Hum never seen it different before always 1 ground 2 pos and 3 neg but the cable ends are positioned different between male and female ends. That's just to line the pins up. When wiring from the inside of your case just match the pins on your connector.

[TEK]

Hmm, I should have read the wiki page better. It explains it.

"EIA Standard RS-297-A describes the use of the XLR3 for balanced audio signal level applications"
(Picture of connections)
"Prior to the introduction of this standard, the wiring of pins 2 and 3 varied. The pin 2 "hot" and pin 3 "cold" convention was typically used by European and Japanese equipment manufacturers, but American companies used pin 3 "hot" and pin 2 "cold". This caused problems when interconnecting equipment with unbalanced connections. The pin 3 "hot" convention is now obsolete but is still found on vintage equipment"

[dar47]

Well I have my buddies Ncore 400 for three days! initial thought tighter base compared to the xpa-2 but the xpa-2 does 350watts so it's no slouch in the base department. Mids and high are cleaner and it is defiantly blacker background very quite. Seem to have a bigger effective base with no change crossing to the sub. I should measure to see my 30 to 35hrz null moved up that I'm eqing for. Maybe better response in that range and I'm hearing it?

[JonMarsh]

that may say cold blue wire, but the way it is wired, the blue wire is actually hot, and connected to the center tip of the RCA connector.

[TEK]

that may say cold blue wire, but the way it is wired, the blue wire is actually hot, and connected to the center tip of the RCA connector.

Yes, I also notice that I have done it according to standar inside the casing.
I think I was looking at the hypex wiring app note when I connected the internal socket to the chassie xlr, and there they refer to pin 2 as hot.
In other documents they are more referring to non-inverting audio input and inverting audio input, where non-inverting is hot and inverting is cold.

So, probably just a typo regarding naming in the nc400 datasheet then.

[TEK]

OK, then some progress again.
I have tried to focus a bit this weekend to get some of my project done. The In-Kahn-Neatos for the living room is waiting to be completed, but I have decided that the they (and the livingroom) will inherit the old receiver.
So, due to that I will have to install the new AV8801 before there is any point in finishing the In-Kahn-Neatos, and before I can install the new AV8801 I have to have some amps for my Ardent's. And that's the prototype monoblocks...

OK, anyway, I have build the second one now. It was quite a bit more work than I had believed, and at the same time is it incredible how much faster things is done the second time around. Not having to figure out stuff, not having to buy new parts and so on makes the process a lot more efficient.
I need to make a couple of longer balanced cables to get them and the AV8801 installed - and that (both making cables and install the AV8801) will take some time so I'm considering if I should do it tonight or wait.
But the week to come at work will involve a lot of overtime and extra work due to a delivery this Thursday, so if I do not install it tonight I will probably not be able to do it before next weekend. And then I will not be able to enjoy it when I'm tiered after work... :unsure:

Anyway, as I mentioned, the second one is done.
I have turned around the SMPS1200 so it's the other way around (I have done that to the first monoblock as well). I have also moved the adaptor board a bit more away from the sides of the case. I have also moved the balanced input a bit more towards the center (the back panel drawing is updated) to make more room between the balanced input and the speaker cables. During testing of the first it felt a bit "tight" around the speaker terminals. And I have used a 3300 resistor for the led instead of the 1800 I used on the first. I will live it like that for now and compare them when they are in use to figure out what I like best.









Really looking forward to get the setup updated arty:

[dar47]

Nice! That looks sorted now turning the power supply around. Those cases are well done with venting on the bottom and top with the thick simple fronts. I think your going to love all the channels you have planned.

These little amps are a game changers after spending a least 8 hrs with my friends nc400's this would be my take on them in my room. Not much of a change through the AV7005 for movies or music, they are held back by the pre section of the pre pro. You do get that very quite background though.

1. Damping factor deep controlled base best on the ardents, as good as a Bryston 4BSST2 and Moon neoM400 mono's I have tried on lone in my room.
2. Comparing M51 through just the amps or through my XSP-1 I hear no difference which is a relief, the dual differential balanced right through on the XSP-1 is a help I guess. I'm glad I didn't want to upgrade my pre-amp if it was holding things back and the theater bypass is nice. I could add a TT later if I got stupid going back there, haha.
3. Mids and highs are improved on any 16bit recordings and the well recorded ones are way better, 10% improvement.
4. Mids and highs on 24bit are the most improved it's weird like listening to a whole new setup. Separation depth and mid and tweet clarity are improved even at low levels. These amps removed the bottle neck for me.

My Ardents measure a DB down at 15k hrz through 20 with the grills on and taking them off makes a difference with these amps I found myself wanting them off when all was quite and no one home. Wonder what the padding change on the tweeter would be to bring them up 1 db? Anyways they are not fatiguing never felt like getting up as I would with the emo xpa-2 amp. I think the Ardents whispered to me last night and said you treat me I'll treat you, haha. Ben and I treated this room well and these amps take advantage better. My youngest set down closed his eyes for a couple of tunes and said dad that's really clear and the instruments seem spread out. He not in to audio and being a stand up comedian there was no jock and that was rare.

[JonMarsh]

OK, then some progress again.
I have tried to focus a bit this weekend to get some of my project done. The In-Kahn-Neatos for the living room is waiting to be completed, but I have decided that the they (and the livingroom) will inherit the old receiver.
So, due to that I will have to install the new AV8801 before there is any point in finishing the In-Kahn-Neatos, and before I can install the new AV8801 I have to have some amps for my Ardent's. And that's the prototype monoblocks...

OK, anyway, I have build the second one now. It was quite a bit more work than I had believed, and at the same time is it incredible how much faster things is done the second time around. Not having to figure out stuff, not having to buy new parts and so on makes the process a lot more efficient.
I need to make a couple of longer balanced cables to get them and the AV8801 installed - and that (both making cables and install the AV8801) will take some time so I'm considering if I should do it tonight or wait.
But the week to come at work will involve a lot of overtime and extra work due to a delivery this Thursday, so if I do not install it tonight I will probably not be able to do it before next weekend. And then I will not be able to enjoy it when I'm tiered after work... :unsure:

Anyway, as I mentioned, the second one is done.
I have turned around the SMPS1200 so it's the other way around (I have done that to the first monoblock as well). I have also moved the adaptor board a bit more away from the sides of the case. I have also moved the balanced input a bit more towards the center (the back panel drawing is updated) to make more room between the balanced input and the speaker cables. During testing of the first it felt a bit "tight" around the speaker terminals. And I have used a 3300 resistor for the led instead of the 1800 I used on the first. I will live it like that for now and compare them when they are in use to figure out what I like best.

[ATTACH=CONFIG]25041[/ATTACH]

[ATTACH=CONFIG]25042[/ATTACH]

[ATTACH=CONFIG]25043[/ATTACH]

[ATTACH=CONFIG]25044[/ATTACH]

Really looking forward to get the setup updated arty:

This is what we call iterative development... :W :T

[JonMarsh]

Nice! That looks sorted now turning the power supply around. Those cases are well done with venting on the bottom and top with the thick simple fronts. I think your going to love all the channels you have planned.

These little amps are a game changers after spending a least 8 hrs with my friends nc400's this would be my take on them in my room. Not much of a change through the AV7005 for movies or music, they are held back by the pre section of the pre pro. You do get that very quite background though.

1. Damping factor deep controlled base best on the ardents, as good as a Bryston 4BSST2 and Moon neoM400 mono's I have tried on lone in my room.
2. Comparing M51 through just the amps or through my XSP-1 I hear no difference which is a relief, the dual differential balanced right through on the XSP-1 is a help I guess. I'm glad I didn't want to upgrade my pre-amp if it was holding things back and the theater bypass is nice. I could add a TT later if I got stupid going back there, haha.
3. Mids and highs are improved on any 16bit recordings and the well recorded ones are way better, 10% improvement.
4. Mids and highs on 24bit are the most improved it's weird like listening to a whole new setup. Separation depth and mid and tweet clarity are improved even at low levels. These amps removed the bottle neck for me.

My Ardents measure a DB down at 15k hrz through 20 with the grills on and taking them off makes a difference with these amps I found myself wanting them off when all was quite and no one home. Wonder what the padding change on the tweeter would be to bring them up 1 db? Anyways they are not fatiguing never felt like getting up as I would with the emo xpa-2 amp. I think the Ardents whispered to me last night and said you treat me I'll treat you, haha. Ben and I treated this room well and these amps take advantage better. My youngest set down closed his eyes for a couple of tunes and said dad that's really clear and the instruments seem spread out. He not in to audio and being a stand up comedian there was no jock and that was rare.

Not too surprised to hear what you are reporting, but it's good that you perceive the value proposition is there...

[TEK]

Hi

Got it all setup yesterday. My experience is much like Darwell's.

Not sure if it's wise to start listening to them right away - or if they should be allowed to be "burn in" first.

The NCore has very good control of the speakers.
I would also say that the mid is clearer than it was before.
In my opinion it is much better than before.

I do however suspect that there is something more to gain in the upper mid or tweeter area. Especially if I turn the volume up a bit, I'm wondering if it is "something" up there that could been better. I suspect it to be related to the prototype board not quite keeping up all over the frequency range. This depends on the music - it's especially noticeable on newer music - so it might be related to the heavy use if vibrators in new music.
I'm looking forward to jon get his prototype assembled - will be interesting what his more trained ears might think about it. Or maybe his new scope might measure ;-)

[dar47]

Tek, not sure on burn in as the ones I had were left on all the time as there is no on off switch. He has them in an old receiver case for now till he chooses a case. If you want to see them at their best feed straight from a dac through nothing else this will tell you if anything is down grading them. In my case I started with just the M51 feeding them. My pre has a resister ladder volume control and is deferentially balanced right through and didn't seem to add anything I could hear. Yes It's going to be cool if Jon can find some gains on these tiny gems, as I would not spend $8000. a pair on some Moon Neo M400's or $4000. for the Bryston even with the 20 warranty. Now the only thing is how long will these modules hold up as they only been out a short while and not much has been said in terms of part quality?

[TEK]

I have a setup so that power to all amplifiers and subs are controlled by a light switch that I turn off when I leve the room - so it will take quite some time then ;-)
Quality wise I cannot say, but these have been out quite some year noe - and hypex is quite experiended by now. I have however heard runers about there beeing some rma's - but I think those are mostly off the the factory. But this is just rumors with little substance.

Remember that I have a prototype board for a input stage - I'm not sure if that will match the input stage if the nc400.
That's why it would be interesting ti here jon's take on it since he might have the option ti compere those two.

[JonMarsh]

The OEM adapter prototype board is pretty similar to whats in the OEM NC400- TI LM4562 in an instrumentation balanced input configuration.

[TEK]

Hi

I must admit that I had a period when I was not quite happy with the sound. The bass was a huge improvement, but in the upper midtone and treble area it was not very relaxing to listening. I experienced the sound as a bit "pushy" or "messy". I mentioned that in a previous post as well.
That was resolved the other day when I did a new setup on the AV8801 - and it told me that the left speaker was out of phase. First I thought it was kidding me, but sure enough - after checking the cables I realized I had actually swapped +/- on that speaker.

I have been a bit pre-occupied so I have not have much time for critical listening (neither before or after that). The listening sessions I have done have mostly been when I have been quite tiered just before bedtime and so on.
However, from the little listening I have done I think the sound is very good and a good step up from the 350W Thule running in A/B mode.
Bass is a lot better and the mid-tone is clearer, and after fixing the phase the treble is as good or better.

The OEM adapter prototype board is pretty similar to whats in the OEM NC400- TI LM4562 in an instrumentation balanced input configuration.

I'm a bit surprised to hear that - mostly based on the difference in the form factor (have not checked the technical details), but also the price. That means that the total for a NC500 with the adaptor board is about 110 usd vs. the 380 usd for the NC400, and according to spec I would say that the NC500 is a better amp than the NC400.