DIY mono amp for the Wavecor Ardents

[TEK]

Unknown performance and some odd choices at a premium price vs known outstanding performance at a significantly lower price. I know which way I'd go.

Yeah, that's my conclusion as well.8)

[JonMarsh]

Mine, too, for the most part. Unless I have solid information from a trusted source....

[oneplustwo]

I'm going to give this a try. Seems so easy with the enclosures and the lack of heat sinking required. Almost feels like I'm cheating compared to the Class A Pass amps I've built.

[TEK]

Oneplustwo: agree, it's to easy so I'm planning on adding some extra compexity by applying Jon's transformer tweek as well as bridging two nc400
My choice stand between the Jensen 6110 as Jon first suggested, or a different one that does not require me to change the resistor on the nc400 module (and therby void warranty)
Hoping Jon comes up with an alternativ transformator 8)

At the same time I'm doing a small check to see if it is possible to become a OEM, and thus getting access to those nc1200 modules... I dont have high hopes regarding that, but we'll see. That would for sure affect this project.

So, something completly else while my monoblock project is awaiting some decitions...
I'm preparing for future projects after this is done (going to be a challange to run this orojects in serie, but I guess that if I buy components for the next project at the end of the previous project I should be OK)

My next project will be a DIY DAC to feed from the HTPC.
This one have come up as a candidate: http://dddac.com/dddac1794.html
It looks like they have done a lot of work on designing it, but I do note the there seems to be very little measuring (obective) testing, and much listening (subjective). Anyone have comments on this DAC, or maybe suggestions of other DIY DAC's?

[TEK]

http://www.6moons.com/audioreviews2/henry/1.html

This norwegian dac would be around 200 usd. The dddac around 1000 usd. Is it likely to be that much better?

[Leeuwarden]

I'm using the Holton NXV500r2. Before that I had a Pass Aleph 5 and a couple of versions of the Hypex UCD 400. The Holton is by far, and I really mean by far, the best power amp I ever had.
The DDDAC is nice but you need to modify the PSU's to get it to sound musical. I would not recommend it. I'm using a www.twistedpearaudio.com Buffalo BIIISE with the appropriate Placid PSU's, IVY or Legato (I have both) output stages and I just upgraded it with a Cronus/Hermes/Amanero stack. I will never ever buy another dac again :-)

Rest of my system is a Mac Mini with Audirvana (Soon to be replaced by a Auralic Aries Mini), Relaixed II pre amp (http://www.vaneijndhoven.net/jos/relaixed2/index.html) , Bi amping with Holton NXV 500r2 amps and Troels Gravesen Jenzen Next speakers.

[oneplustwo]

If you're not familiar, I would recommend on reading up on amb's offerings. He's just wrapping up the latest DAC, an all out desktop DAC he's called the gamma 3.

http://www.amb.org/audio/gamma3/

Lots of measurements, great track record, and tons of support on his own forum. I've built a couple DAC's, headphone amps, and preamps from him. I have zero hesitation recommending any of his products.

[Horio]

If you're not familiar, I would recommend on reading up on amb's offerings. He's just wrapping up the latest DAC, an all out desktop DAC he's called the gamma 3.

http://www.amb.org/audio/gamma3/

Lots of measurements, great track record, and tons of support on his own forum. I've built a couple DAC's, headphone amps, and preamps from him. I have zero hesitation recommending any of his products.

I would second AMB's gamma3 in a heartbeat. It's not the simplest of builds, but circuit boards will be available and the design is very much high end. I believe it uses the same Wolfson chips (on per channel) found in the PS Audio Perfectwave DACs. The DAC is in its final stages of development and testing, and should be published soon. I know AMB from when I lived in the Bay Area, and he's a great guy who designs some really great stuff for the DIY community. I've built a few of his designs and just finished a balanced preamp using a bunch of his various modules (here's a thread with photos). There is great documentation on the website and AMB along with others give great build support on the forum over there.

Definitely worth checking out.

[TEK]

...
If you have a preamp that can't output 8VRMS, then you need to change the value of the Rg gain resistor R141 on the NC400, if you change it from 680 ohms from the original 1200 ohms, then in concert with the feedback resistors, (which are balanced) the net gain increase is 12 dB. You could also go for something intermediate.
...

Jon, you are referring to a given resistor on the NC400 board, the "Rg gain resistor R141".
Either there are some generic design principles causing a "Rg gain resistor R141" to always be mounted on amplifiers, OR you have access to a schematic that I'm unable to find.
How do you know about the "Rg gain resitor R141"? Is the schematic available for us other mortals?

[JonMarsh]

It's in documentation from Hypex, available to anyone checking their site online- do you have the NC400 data sheet, manual, and gain app note? If not, PM me your email address, and I'll send them to you.

[JonMarsh]

If you're not familiar, I would recommend on reading up on amb's offerings. He's just wrapping up the latest DAC, an all out desktop DAC he's called the gamma 3.

http://www.amb.org/audio/gamma3/

Lots of measurements, great track record, and tons of support on his own forum. I've built a couple DAC's, headphone amps, and preamps from him. I have zero hesitation recommending any of his products.

That just linked to what he calls a place holder page with an outline of topics.

[oneplustwo]

That just linked to what he calls a place holder page with an outline of topics.

Yes, the link on the bottom of that page to the forum discussion is where the meat is: http://www.amb.org/forum/gamma3-high...ent-t2656.html

[TEK]

Yes, the link on the bottom of that page to the forum discussion is where the meat is: http://www.amb.org/forum/gamma3-high...ent-t2656.html

I did not find any reasonable efficient way of finding out what price range this DAC will be in. Does anyone have a ballpark number about the build cost?
The reference DAC looked awesome, but I have to say I'm a bit supriced that a DAC would need to be build in not one bug TWO full size chassies.





For me, one of the features I'm planning on taking advantages of if/when I build a DIY DAC is that I can simplify it to only suite my needs. That will mean that I will only need one single input/output (SPDIF or USB).
But from what I can tell by the pictures, that would not affect the build much - probably because it's just different plugs that all handles signals that have to be handled the same way anyway.

Also, if I read the spec correct, this is not just a DAC - but also a pre-amplifier as it's currently suggested. Is that correct?

[oneplustwo]

Yes, that's the analog output stage. It's all modular though so you can decide not to use it if you choose. And yes, two chassis, because you always need to separate out the power supplies, right?!

[TEK]

OK, going to jump of the DAC track for a while and move focus back to the amplifier track.

There has been some changes in the outer condition of my build situation here.
It seems like I might get access to some NC500 modules...

If we look at just the power rating it's quite much difference in how they behave.
NC400: 580W@2ohm/400W@4ohm/200W@8ohm, THD+N 0.0007 % 20Hz, SNR 125, Power supply voltage +/- 75V
NC500: 550W@2ohm/700W@4ohm/400W@8ohm, THD+N 0.001 % 20Hz, SNR 135, Power supply voltage +/- 100V
NC1200:1200W@2ohm/700W@4ohm/400W@8ohm, THD+N 0.004 % 20Hz, SNR 137 or 124, Power supply voltage +/- 105V

Datasheets:

http://www.hypexpro.com/wp-content/uploads/2015/03/NC500-OEM-datasheet-R4.pdf

http://www.hypex.nl/component/weblin...c400-datasheet.

Anyone want to comment on how to understand the difference between the NC400 and NC500?

Edit: For example, the NC500 actually drops in watt from 4ohm to 2 ohm. What is that about?
Edit 2: One major (for me) difference is this: "Unlike in many other Hypex products, no input buffer is present as manufacturers of audiophile equipment tend to bypass it anyway and design their own"

Starting to look like a real DIY build if I build something based on the NC500 ;-)

[oneplustwo]

I have a some modules in the mail to me. 4 amp modules and 2 PSUs. (I'll likely have two extra NC400's since I'll probably go two monoblocks vs. two stereo units if you're interested.) I also ordered the Ghent enclosures so this may be the fastest build ever! Will likely wait on the transformer upgrade that Jon recommended for now.

The other question for me on the difference is in the THD. Is that because of the lack of input buffer? Or the higher power rating?

[TEK]

oneplustwo - I'm not sure about the difference in THD.
I'm quite a bit curious about what it means that the NC500 is delivering 400W@8ohm vs. NC400 that "only" delivers 200W@8ohm.
The NC500 is also a lot more at 4ohm (700 vs 400), but at 2 ohm the NC400 and the NC500 is almost the same.

If going for NC500 I have to say that I do not feel the same urge to use two NC500 for one mono block as one singel already delivers 400W@8ohm.
I'm also wondering about this 400W@8ohm vs. RMS of 400@ohm

[JonMarsh]

Recommended reading for anyone pondering DACs, or a DAC purchase.

http://www.computeraudiophile.com/content/670-schiit-audio-yggdrasil-multibit-dac-review/

A number of things these guys are doing right, especially their up sampling methodology, and you can't argue with the value proposition.

[oneplustwo]

Recommended reading for anyone pondering DACs, or a DAC purchase.

http://www.computeraudiophile.com/content/670-schiit-audio-yggdrasil-multibit-dac-review/

A number of things these guys are doing right, especially their up sampling methodology, and you can't argue with the value proposition.

What's the consensus on whether you need a preamp between your DAC and your power amp? Is it a matter of impedance matching? Perhaps voltage swing of your source vs the input range? The specs on the volume control and output stage of your DAC?

[TEK]

Isn't a preamp there to increse the signal so that it's high enough for the amp to reinforce it to the wanted level - and the output from the source/dac is typically not powerful enough?
You do have passive volume regulators in some products that only pull down the signal level.
Just thoughts with little knowledge behind...

[TEK]

Anyone know of a good tool to create (draw, not produce) circut boards?
New territories about to be explored :-D

[TEK]

OK, going to jump of the DAC track for a while and move focus back to the amplifier track.

There has been some changes in the outer condition of my build situation here.
It seems like I might get access to some NC500 modules...

If we look at just the power rating it's quite much difference in how they behave.
NC400: 580W@2ohm/400W@4ohm/200W@8ohm, THD+N 0.0007 % 20Hz, SNR 125, Power supply voltage +/- 75V
NC500: 550W@2ohm/700W@4ohm/400W@8ohm, THD+N 0.001 % 20Hz, SNR 135, Power supply voltage +/- 100V
NC1200:1200W@2ohm/700W@4ohm/400W@8ohm, THD+N 0.004 % 20Hz, SNR 137 or 124, Power supply voltage +/- 105V

Datasheets:

http://www.hypexpro.com/wp-content/uploads/2015/03/NC500-OEM-datasheet-R4.pdf

http://www.hypex.nl/component/weblin...c400-datasheet.

Anyone want to comment on how to understand the difference between the NC400 and NC500?

Edit: For example, the NC500 actually drops in watt from 4ohm to 2 ohm. What is that about?
Edit 2: One major (for me) difference is this: "Unlike in many other Hypex products, no input buffer is present as manufacturers of audiophile equipment tend to bypass it anyway and design their own"

Starting to look like a real DIY build if I build something based on the NC500 ;-)

Got this reply over at a different forum (as it was quite silent here...)

The nc500 is designed for a higher supply voltage (and thus also higher output voltage), so it can deliver a higher power into a higher-impedance load (where the power is limited by voltage). They both have roughly similar current capability, so the nc500 drops down to the same power level as the nc400 when driving a low-impedance load (where the power is limited by current capability).

I think that sounds resonable.
That means that for me, that have quite high impedance speakers (Wavecor Ardentsmyou know ;-)) the nc500 would be quite an improvement compared to nc400 (or at least have a lot more headroom).
I was origianally thinking about bridging two nc400 modules (using a SMPS1200A400 as power), but it seems as one nc500 with a SMPS1200A700 would do almost just as well with fewer components.
Seems like santa came early this year

[oneplustwo]

How about the distortion? Is the difference meaningful and if so, is it more important than headroom?

[TEK]

How about the distortion? Is the difference meaningful and if so, is it more important than headroom?

From what I have heard the nc1200 based amp's are getting very good reviews, and those have more distortion than the nc400. Also, the difference is only 0.0003 %. I think you will have some problems hearing that. I also notice that the SNR is higher, 135 vs. 125.
I would think that the added headroom would be more important than the small change in distortion.

[JonMarsh]

What's the consensus on whether you need a preamp between your DAC and your power amp? Is it a matter of impedance matching? Perhaps voltage swing of your source vs the input range? The specs on the volume control and output stage of your DAC?

A couple of sites have addressed this topic directly, looking at the effective bit resolution using an internal volume control (in DAC's like my BADA, M51, TotalDAC-D1) versus running the DAC full tilt and using a high grade preamplifier.

This is a data set calculated and posted on the six moons review of the AURALiC Vega, which uses the SABRE DAC and it's high resolution volume control capability.



My own experience and that of my Munich colleague (who has the only other fairly high end system that I'm quite familiar with - don't know any locals) is that at moderate and lower listening levels, it's best whether with 16 bit or 24 bit sources to have a high grade analog preamp (120 to 130 dB dynamic range) than to use the DAC volume control (the only exception being the Metric Halo ULN8, who's volume control is not digital, but actually a built in analog preamp stage). Otherwise, tonality and imaging drops off at the lower playback volumes.

The best "cheap" preamp I've found so far, with the requisite I/O for my needs, is the Cambridge Audio 851e; 0.0005% THD, 8VRMS single ended/16VRMS balanced output, a very clever multiplying DAC volume control with excellent tracking, and plenty of balanced I/O.

I'm also considering checking out the AURALiC Taurus Pre, which takes the output headroom to 12VRMS/24VRMS (useful for the Benchmark AHB2 amplifiers, with their variable gain structure) and with 130 dB dynamic range. It would be a good match to my Vega for the "portable" system.

BTW, I may have a pair of the AHB2's to audition in a couple of weeks; I've sent on the data and reviews to my Munich friend/colleague, and he's quite interested, as he has spent a lot of time optimizing the dynamic range and low level clarity of his system, and we are agreed this amp my likely be a new benchmark overall, for the right system configurations. He's going to be here on the 9th of December, we're seeing if we can arrange for getting a pair of amps to evaluate and deliver to him to take back (wide range input AC power is standard for these).

I'm planning to order a pair regardless in December, unless we hear or encounter something unexpected with this first set. If nothing else, they will be something of a reference for a number of characteristics. Vis a vis the NAD M22, to put it in perspective, the AHB2's at the same power level do cost 2X the money. From what I hear, sonically an nC1200 setup should give them a good run, with greater output power, but then the question becomes, just how much is enough? For me, I doubt the difference between 400W and 500W, for example, has any meaning.

As to my M22, they can go in to the 2.1 system I'm putting together for the man cave, anyway...

This all gives me more motivation to finish tweaking up the original Isiris, as well as getting the Model One monitor's built and tested....

[JonMarsh]

Anyone know of a good tool to create (draw, not produce) circut boards?
New territories about to be explored :-D

My recommendation would be Eagle PCB; it covers hobbyist through fairly professional requirements, with different configurations and cost points. Available for PC and Mac. I have the Pro version on my Mac, use it for my hobbyist stuff and some work stuff, as some of our internal groups use it, and most of our external design companies, like FinePower, use it.

http://www.cadsoftusa.com

My long term package is Altium Designer, formerly Protel; I have a large library of custom symbols and footprints for it, and my work projects are usually done with that. Much more expensive, though, and not available in hobbyist versions, to my knowledge.

[JonMarsh]

Got this reply over at a different forum (as it was quite silent here...)

I think that sounds resonable.
That means that for me, that have quite high impedance speakers (Wavecor Ardentsmyou know ;-)) the nc500 would be quite an improvement compared to nc400 (or at least have a lot more headroom).
I was origianally thinking about bridging two nc400 modules (using a SMPS1200A400 as power), but it seems as one nc500 with a SMPS1200A700 would do almost just as well with fewer components.
Seems like santa came early this year

That would be cool if you can get some NC500 modules. I'm curious as to how; PM me if you're willing to share the story, not that I'll likely be trying to do the same thing. Just curiosity for now.

[JonMarsh]

To clarify what the NAD M22 seems to use, let's revisit this picture I posted in Audio hideout, taken of the unit I bought earlier this year:



Note the upper center area: this is an NC400OEM module, which as far as I know is based on the nCore 400 DIY circuits, but in an OEM format without the input stage and with more bypass capacitance and an interface header quite similar (perhaps identical?) to the NC500. This module is not listed on the HypexPro web site, and may in fact be a precursor to what is now the NC500, as this has been out for a while. Note that NAD adds quite a bit of additional supply capacitance immediately adjacent to the module; this is a good thing, in my opinion.

Note also the copper bus wrapped around the module; my first suspicion is that this is a low impedance ground connection, though Cambridge does some similar things that are actually power bus connection.

I think I'll need to spend some time with this on the bench with my new scope in December... :W :B

[TEK]

I thing you are right about the NC400OEM being the forerunner to the NC500. I do also notice that it's version 0.1, so it's seems to be a quite early edition.
My first thought about the copper was that it was to isolate noise from the amp module.

Below is a picture from "the net".
I assume the part in the lower left corner is a SMPS power supply. Do you know if they are using a SMPS1200 or another one?
But it seems like there is another, smaller powersupply, up in the upper left corner. Any idea about why that is? The SMPS1200 have other output powers that should be able to power "different" stuff, is they do not have any very special needs. I also notice that there is a wall between the power supplies and the amplifier modules. I assume that mainly is to limit noise from the powersupply to reach the amplifier modules?

[oneplustwo]

I got the ghent enclosures today. The quality is quite good and I think it's a good value given the fit and finish. The hardware provided looks good too and the machining is clean. Assuming everything fits together fine, I will be very happy with the purchase. Only minor complaint is the anodizing on the inside surface has some flaws, but you won't see it when assembled obviously.

I'm amazed how small they are. I knew class D amps were quite efficient in this regard, but it was still a surprise to me.

A couple pics of the package contents and the anodizing flaw.

[TEK]

Always fun when stuff starts coming into the door :-)
When do you expect to get your amp modules?

[oneplustwo]

Apparently they're in customs at the moment. So hopefully in the next couple days. Unfortunately, I don't have any of my nice speakers anymore. I've been selling or loaning everything in prep for the house remodel. And I'm considering not assembling these until the house is done as well. But since they're so small and the build should be so straight forward, I might just go ahead and get it done.

[JonMarsh]

I thing you are right about the NC400OEM being the forerunner to the NC500. I do also notice that it's version 0.1, so it's seems to be a quite early edition.
My first thought about the copper was that it was to isolate noise from the amp module.

Below is a picture from "the net".
I assume the part in the lower left corner is a SMPS power supply. Do you know if they are using a SMPS1200 or another one?
But it seems like there is another, smaller powersupply, up in the upper left corner. Any idea about why that is? The SMPS1200 have other output powers that should be able to power "different" stuff, is they do not have any very special needs. I also notice that there is a wall between the power supplies and the amplifier modules. I assume that mainly is to limit noise from the powersupply to reach the amplifier modules?

The part in the upper left corner is the EMC/EMI input filter, between the line and the SMPS. As far as I know, the power supply is proprietary to NAD for this application. They're not using a Hypex module, and you may note that there are 6 instead of 4 of the line filter caps (usually 250V ones connected in series; 250V caps have much nicer figure of merit than 450V, even when you factor in working voltage to the calculation). (I'll post some foils about this from a recent training I gave to illustrate). Like Hypex, they use EP or ETD style cores, which are not, in my experience, an optimal choice for volume and shielding or efficiency, but they are less expensive, because they are cheaper to manufacture and gap accurately than PQ cores (my normal form factor preference, developed for high density SMPS).

[oneplustwo]

Got my amp modules today and did some basic assembly. Which means they're about 90% done. Just need to wire up the mains, solder the input and output connections and wire up the LED. So easy!







I have two extra amp modules and may get the SMPS1200 along with the stereo case to put one more together since it was so easy!

[TEK]

Sweet :-)
I see that you are going only balanced in, what is your source?
And what is that cable for?

[JonMarsh]

Yeah, it's pretty much a walk in the park. With an SMPS1200A700, I believe you'll have to modify the cables to make the right connections, as the supply and control connections are a bit different. The SMPS600 and NC400 are plug and play. Happy listening!

[oneplustwo]

Sweet :-)
I see that you are going only balanced in, what is your source?
And what is that cable for?

Source will be a balanced miniDSP. That will likely be fed by an Emotiva XDA-2 or some TBD AVR.

That cable is the connection between the XLR jack and the module. It carries the three pins of the XLR plus a shield. Pretty nice cable with a plug on one end and bare wire to solder to the jack on the other. That's another great thing about these... The cables that you can buy with them make the wire management very clean and easy.

[dar47]

Boy at this price for NC500's with a small up cost for changeable imput buffers, i would jump on this if I had the spare shillings!

http://www.iqspeakers.co.uk/#!product-page/onbar/1bcd21a6-e0fa-10ad-b63b-73f0a3425241

[TEK]

Boy at this price for NC500's with a small up cost for changeable imput buffers, i would jump on this if I had the spare shillings!

http://www.iqspeakers.co.uk/#!produc...b-73f0a3425241

The case he is using is from Modushop.biz (or at least they sell that typenof case).
I have two monoblock cases from them that I'm going to fill with some stuff, it's a very nice case with good build quality.

However, I have followed this a bit, and if you look at the pictures you should note that there are no CE mark on it.
The theoretical consequenced of this is that the supplier probably are not allowed to sell this product in the EU.
The practical consequence of this is that the supplier does not self claim to have verified that all safety regulations has been followed and may not know how to verify that the product is safe.
Buying this I would look at it as buying a diy product.
On the practical side, the construction is pritty straight forward and is probably/hopefully safe - also in case of some electrical failure.

https://www.gov.uk/guidance/ce-marking

(as CE mark is a label put on by the supplier there is no garanti even with it on, but then at least the supplier tells you "yes I know there are a lot of stuff to consider and I have considered it". Formally there are several regulations that have to be followed before a CE mark can be applied.

[dar47]

I was looking at this to move everything to my own case later but what's got me interested is you can try different input buffers and it's NC500 with a little more head room for the same price as nc400 to Canada.

[Alaric]

Boy at this price for NC500's with a small up cost for changeable imput buffers, i would jump on this if I had the spare shillings!

http://www.iqspeakers.co.uk/#!produc...b-73f0a3425241

I followed the link and they are now on my Favorites list. You guys are killing me! So many "wants" and so little money! LOL

[oneplustwo]

That looks nice! If it wasn't for enjoying DIY, they would be a good option for a reasonable premium over my nc400 build.