DIY Balanced Power project

[ThomasW]

Secrets of Home Theater has 'arranged' with Plitron Transformers to offer one of their balanced power transformers for a fairly low price, $250ea+ shipping.

Jon and I have ordered 2 transformers, unfortunately they're on back order and won't be shipping until 4-6 weeks. :cry:

We'll be documentating the design and construction of a multi-outlet, multi-purpose device. There will be ~3 outlets, each with separate isolation for driving individual pieces of front end gear. There will also be a single outlet with no extra filtration, that will be suitable for driving a single large power amp (up to 2000va of draw). One must choose how the device will be used. The transformer isn't large enough to power both a large power amp and the front end gear. So wiring it the manner described will allow the greatest flexibility for the user

Since I have a gaggle of various balanced power devices from www.B-P-T.com, we'll be able to do a performance shootout between the factory built BPT units and our DIY project.

Given the delay in getting the transformers I decided to start this thread so that people could give feedback and make requests for 'features' they would like to see incorporated into the project.

Let the games begin........ arty:




theAudioWorx
Klone-Audio

[ThomasW]

We're going to use a chassis (p/n 14-19103x) from Par-Metal



Here's a pic of the transformer



Here are a couple of links to tech papers detailing balanced power for those interested

http://www.equitech.com/articles/origin.html

http://www.equitech.com/articles/widescreen.html

theAudioWorx
Klone-Audio

[Andrew Pratt]

Hopefully the results aren't too shocking

[PMazz]

I know nothing about this subject. ops:

What is the difference in these xformers to the PE Avel jobs? Apples and oranges or Ferrari and Chevy?

Pete

[ThomasW]

Pete,

I know nothing about this subject.

Check out the Equi-Tech links, the principles of balanced power are easy to understand. The result is CLEAN electricity = blacker blacks, so to speak

The Arvel 60V+60V will provide 800va of balanced power. But it doesn't have a shield circuit like the Plitron. This means it will be susceptible to electrical noise. Also Avel transformers have a history of mechanical hummmmmm.....




theAudioWorx
Klone-Audio

[Pat]

Very interesting to say the least.

How would one determine if they would benefit from a device like this?




Pat's Page

[JonMarsh]

A "properly" implemented balanced power system conveys some of the same benefits as balanced signal systems- improved common mode isolation, lower system noise, reduced effects from ground loops at low and high frequencies. The latter seems to account for the improvemetns some claim for projectors put on this type of system.

There are some details requiring attention, including filtering to eliminate DC in the transformer primary (many systems due to unequal load sharing on the distribution transformer phases have small net DC offset on neutral line), HF filtering, etc.

In some regards, this is one of those things that a conventional engineering approach might say isn't "cost effective"; if things were always done 100% right in the equipment itself, and in the power source, and in the signal source equipment (including cable system) their wouldn't be any net improvement by using a balanced power source, or very little. But in the real world, it's not the case, and there seem to be significant benefits to taking the time and trouble if you can afford the expense.

We thought this would be a somewhat newer and intersting DIY area, not requiring quite the level of technical expertise that a speaker or electronics project would, but admittedly, requiring good mechanical work and soldering skills.

Let us know what you guys think.

Best regards,

Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Bent]

Will a ballanced power supply not result in the components in the AV system possibly having their chasis grounds (cases?) at an elevated potential as well?

I'm sure there is something I'm missing here, but I had to ask.

I guarantee you'll feel a 60 volt poke if what I'm thinking could happen does happen.

Anybody?

[ThomasW]

ABent

Using a balanced power device has no impact on the grounding system. The transformer isn't 'lifiting' the grounds of items that are plugged into it.

If you look at the transformer's .pdf file from the Plitron site you'll see there's a green/yellow electrostatic 'ground' grid wire on the transformer. That supplies the 'ground' for everything plugged into the device. The AC receptacles we're going to use are hospital grade with isolated grounds.



If it will make people happy a GFCI/GFI can be placed in the chassis




theAudioWorx
Klone-Audio

[Bent]

Please don't get me wrong, I'm not trying to say anyody is bending/breaking any code rules here, I am just missing something that is likely really obvious,
I'm thinking along the lines that a a20 volt components chasis, box, case, whatever could likely be tied to the electrical ground, and if you isolate the ground on the supply side would you not wind up with the case being at an elevated potential?

This has obviously been done and the success of those who have done it warrants some definate credibility, I'm merely wondering if there is a chance that it could enrgize the components case as I am imagining.

(like I said, there is very likely something that I have missed, I just need to be pointed in the right direction.)

Ben.

[JonMarsh]

Actually, conventional components and connections DO energize the component case, because differential EMI filtering uses equal value Y caps to ground (normally connected to chasis, except when double insulated), but the ground current isn't balanced, because the normal neutral should have NO AC voltage on it (though you'll often see a small level due to the afore mentioned distribution transformer phase imbalance), while the hot side of the AC line has 110-120 VAC. This is one of the reason that Y caps have to be limited in size, in order to limit the ground current to the regulatory level.

Now, in the case of a balanced system, the transformer has two output windings, configured as a Center tapped push pull. The safety/chasis ground is connected to the center tap, and the hot and neutral connections are now balanced push pull. As a result, with whatever Y caps are used on the line, the low frequency current through the cap is balanced and cancels nearly perfectly at the chasis ground (center tap).

If this description isn't clear, see below.




Best regards,

Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[PMazz]

In my reading so far I get the impression that certain types of equipment shouldn't be plugged in to a balanced power circuit? Potential damage?

I hate to ask this......but do you have any idea of projected cost? No need to be exact, just ballpark?

OT: PE has a sale on the M8a drivers for any that's interested.

Pete

[ThomasW]

Pete,

The only things I'm aware of that shouldn't be plugged into balanced power are any kind of incandescent light bulb or halogen lamp.

Note that it's fine to plug CRT/LCD video projectors/TV's/RPTV's/etc, into them.

Cost:
Transformer = $250+ shipping
Chassis = let's say $150 for a primo unit
Hosp grade AC plugs = $18ea @ Evil Orange
Mil spec wire = $.25/ft for the primo stuff
Power cord = anywhere from $3.50 to $350 your choice
Power switch and EMI/RFI filters ????? we haven't gotten pricing on those yet.

So let's say ~$550 for a REALLY nice version. This would retail for almost triple the DIY cost

Understand that one could go low ball; knock together a MDF box with a single outlet, then plug a $10 outlet strip into it, use a stock hard wired Belden power cord, forget the power switch, forgo the EMI/RFI filters and get by for under $300.




theAudioWorx
Klone-Audio

[Dennis H]

It seems like with many "modern" components, with digital circuits and switching power supplies, the biggest problem is often one component polluting another, rather than bad stuff coming in from outside. I'll be interested to see how you poobahs address that.

[JonMarsh]

with digital circuits and switching power supplies, the biggest problem is often one component polluting another

That's a potential problem, for certain, though that's the point behind EMI filtering requirements, of course, reducing these effects.

My preference is to use an oversized individual EMI filter on each outlet type intended to feed a "low level" component such as preamp or CD player. The reason it generally must be oversized is so that the line impedance seen by the component isn't seriously altered (i.e., it has to remain reasonably low), lest there be interactions with the power supply of the DUT. This is especially important when SMPS supplies are used in cable boxes, DVD players, and the like, becuase the loop stability is partly dependent on the source impedance of the AC line.

~Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Hank]

Well, I hate to say it again, but that's still big bucks to me, even if only at 1/3 retail. I think I'd lean towards some increased EMI/RFI filtering rather than the basic A/C, BUT that's because I'm thinking budget and saving money for that "ultimate line source speaker project. I have Brick Wall ( and the company that BW licensed the circuitry from) filtering that even though I haven't A/B'd its effect on audio and video, I like the engineering behind it and will stick to it for taming the A/C.

Ahh, the challenge of budget apportionment with a daughter at TCU and a son at UT. :cry:

[ThomasW]

Hank

I think we've had this discussion before

Yes the Brickwall devices are very good at surge protection and filtering

Balanced power devices are a different kind of animal as compared to the units made by Brickwall.

Although not using balanced power, users on other forums are liking the effects they get from isolation transformers. If people want to inexpensively dabble with isolation transformers then there are deals available Here and Here are some examples.




theAudioWorx
Klone-Audio

[Hank]

I think we've had this discussion before

Uh-oh, the exact same discussion? If so, I apologize - older memory you know. Yes, they're different things, I was just saying that for the A/C, I've spent my budget on the BW protection/filtering for now. Maybe in the future, my ultimate A/C tweak might be balanced power. Anyway, forget my temporary $$limitations, let's get some comparison reviews up here. I'd love to see some comparative photos of video differences posted or at least verbalized. Since front projection is in my future, I could be persuaded.

[ThomasW]

Hank

I'll try to post some before and after pics of what the BPT device does for my Toshiba 32"CRT. It's more evident with it and probably can be captured with a digital camera.

As for the sonic improvement, when I was younger I used to do a lot of listening into the early hours of the morning. I noticed that the audio sounded better/cleaner/more accurate then, compared to other times of the day. Balanced power creates those effects 24/7. What's happening is that it's lowering the overall noise floor of the AC. That to my ears has a positive impact on the sound quality




theAudioWorx
Klone-Audio

[JonMarsh]

Now if only there were some other ways that Balanced Power could make us feel younger 24/7!

Merry Christmas to all.


~Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[ThomasW]

We're still waiting on Plitron, but have been ordering the other stuff needed for the project. Here's a break down.

Chassis Par-Metal #14-19103C $112.80. Clear anodized, not as cool looking as black but hides dust well , (important priority for bachelor living ). For those wanting a lower buck option, PE has a same sized chassis that lists for $77 p/n 262-434. This has thinner metal than the Par-Metal chassis. If one goes with the PE chassis then plan on reinforcing the bottom with a layer of Masonite to support the weight of the transformer.

Below are the Mouser.com items we ordered. The 693....... is the Mouser part number

First item below is a 20 amp on/off switch, second item is a 20amp IEC 'power entry module'. That means an IEC AC inlet combined with a high current RFI filter. Using this eliminates the need for a shielded power cable.

693-ABDBL200C0 Schurter TA45 BLK ROCKER 20A $15.41
693-C20F.0001 Schurter FRONT SCREW MT 20A $26.39

These are the 2 values of EMI/RFI filters. The smaller amperage is for front end gear, pre-amps, CDP's etc. The larger 20 amp filter is for higher draw devices like projectors, power amps, receivers. etc.

693-5500.2041 Schurter 1-STAGE STD 6A FMW $ 9.58
693-5500.2047 Schurter 1-STAGE STD 20A FMW2 $ 17.58

The following power cord part was ordered from BrigarElectronics.com

H320C Hubbell 20 amp IEC Female connector $6.95

The actual power cord wire was ordered from PE it's the Carol 12 gauge. PE p/n 100-577 $11.60/25 ft

We've nixed the idea of a 'soft start' device. Smaller transformers let's say 1000va, can be powered up using a simple thermistor. But using one of these isn't a good idea for larger transformers. The reason being that once on they stay on until cooled down. As a result if there's a temporary power loss the Thermistor doesn't have time to cool down and reset. We could use a relay circuit, but that in our opinion will add needless cost and complexity to the design.

To be continued.....




theAudioWorx
Klone-Audio

[ThomasW]

Just a quick update.

In the 'slow work takes time' world, I finally received an order confirmation from Plitron. Note this isn't a shipping confirmation. They must send out an order confirmation notice when the shop starts processing the order to wind the transformers. The expected shipping date is 1/16/04 (slow winding obviously takes time... ) . Given clearing customs and the shipping distance to Denver, it's going to be the end of January before they arrive. :roll:

Well at least I'll have all the other construction aspects of the project completed when the transformers arrive......

PS: all the parts ordered from Mouser arrived monday




theAudioWorx
Klone-Audio

[brucek]

if things were always done 100% right in the equipment itself, and in the power source, and in the signal source equipment (including cable system) their wouldn't be any net improvement by using a balanced power source, or very little.

Also Avel transformers have a history of mechanical hummmmmm

Let us know what you guys think

Interesting project. Actually, I'm kind of ambivalent about these devices. On one hand (as Jon alluded to in the quote), I feel if you have your electrical house in order with proper dedicated circuit(s) and ground systems, that the benefit will be negligible, if not non-existent.
On the other hand, if you don't, you'll likely experience a much improved noise floor at a cost for the balanced unit that is likely greater than the cost to clean up your act.

I'm aware that balanced power has merit in the correct application, particularly in somewhat reducing reactive currents, but I feel standard residential power gets an undeserved bad rap and doesn't really benefit from being converted to common mode as much as using sensible electrical practices in wiring and grounding an audio system.

I've seen too many poorly wired and grounded systems that produce a ridiculous amount of hum that the owners believe that throwing a balanced power or line conditioner at will solve - and sometimes it does, at a high price.

I feel power manipulation of any kind is the 'fun' that comes after we have our systems as silent as they can be, while using standard residential differential power. The idea that there is always something fundamentally flawed with power from the wall is silly. Most AC power is fairly well regulated and generally free from noise. It can benefit from some surge protection and some RFI/EMI filtering.

The power supplies in our equipment will filter any small noise spikes and bypass most RFI to ground. The power supply regulators will make up for small line voltage changes. In fact, the noise rejection from power cord to DC at the chip in any piece of equipment today is extremely high and doesn't need any help.

If you feel that the AC power in your home is causing some problems with your system, then those problems should be tracked down to the source before resorting to converting all your AC to balanced mode.
If you're experiencing some sort of ground loop hum or noise in your system, perhaps you could isolate this problem and correct it before spending money on something you don't actually need.

Certainly one of the better things you can do for a system is to install one or two dedicated AC circuits ensuring they're on the same leg of your loadcenter. I don't think a dedicated circuit is a panacea, but I think in a lot of cases it can help. You avoid a lot of problems and eliminate any questions about your circuits quality. It's a great starting point. The benefits of a dedicated circuit are many. I highly recommend it.

Although there's nothing magic about dedicated circuits, it ensures a single run of cable from your power panel to a wall receptacle, with no interconnections between and nothing else plugged into the circuit except your system.

Consider non-dedicated circuits. The AC wall receptacles in a room may have up to 12 lights and receptacles on the same circuit. At each receptacle box that the wiring runs through, there is a set of twisted connections inside connected with marrettes (wire nuts) that may be presenting a small resistance. The more of these connections, the more possibilities of poor, high resistive joints before the circuit reaches the AC receptacle that you are using for your system. These connections can become highly resistive.
In addition, there are a myriad of things like motors, fluorescent lamps, and computers that may also be plugged into this same circuit shared with your system.
There's also a good possibility that if you are using more than one receptacle in your HT room, that they may be on a different leg of the loadcenter.
All this can result in a loss of power and increased noise at the receptacle(s) you're using for your system.

When you use a dedicated circuit, and noise is introduced on a different circuit in the house, even though they return to a common point at the loadcentre, this noise tends not to travel down your dedicated circuit because of the extremely low source impedance of the mains at the panel .This noise induced on other circuits is "sunk" once it arrives back at the loadcenter and is not passed to the dedicated circuit. It acts like a pass filter to this induced noise. The noise rejection is quite high. This is one major advantage of a dedicated circuit. You know that there are no other noisy devices plugged into this circuit.
Some whole-house or local surge protection is also a good idea to try and help protect that expensive equipment. Beyond that, not much else is necessary as far as AC power is concerned.

If I use my own system as an example. I have two identical dedicated 20 amp circuits feeding my system. I don't have any noise making refrigerators or fluorescence or anything but my system plugged into them. I only use some simple whole-house surge protection. I have ensured my safety grounds are installed from my loadcenter properly and are properly bonded to neutral.
I have to press my ear up against my speakers to hear even the slightest thermal hiss. There is zero hum at full volume on my preamp. Maybe I'm just lucky. But, what is a balanced power unit going to do to my system? If you have a hum coming from your speakers, find the fault before purchasing anything else.

I think that once you're satisfied that your power for your system is in good order, the addition of a balanced power unit may be an interesting test. A balanced power unit is basically a very high quality isolation transformer with a center tapped low impedance secondary. So instead of a hot of 120 volts and neutral return, you have two 60 volt lines with a center tapped ground. Across the 60 volt lines which are 180 degrees out of phase you have 120 volts, with each 60 volt lead referenced to the ground at the center tap. There are a lot of benefits in this configuration. Any reactive currents developed in the load arrive at the common center tap and are cancelled. Any noise or voltage that would normally travel on the AC safety ground are cancelled at the center tap. The ground is basically re-defined and becomes very close to a true zero reference. This does a good job in helping to reduce ground loop currents which can cause hum. There's not much chance of a ground loop. The other benefit can be a lower noise floor under certain conditions, but this is traded off against the possible mechanical hum that the toroidal transformer itself may create, so the electrical noise you're trying to reduce is substituted by a mechanical noise from the unit itself. I suppose you could hide the box so you can't hear it.

Large current balanced power units aren't cheap, although the ones offered by B-P-T are fairly reasonable and a DIY cheaper still. The trade off you have to accept is that a 20 amp wall plug can supply approximately 2400 VA's and this available power will be reduced by the size of the balanced power unit you choose. If you get units that supply this and can afford it, that's good, and you'll also realize the benefit of the EMI/RFI filtering the unit provides. Of course on the down side, you've just added another device (transformer) in the chain. Generally power amps aren't as sensitive to voltage and don't benefit from balanced power as much as a source devices might. In fact, there's anecdotal evidence of perceived loss of soundstage when power amps are plugged into balanced power units. I wouldn't plug my power amps into one, but I'd be interested to see what benefit I would realize with my CD player.

Anyway, those are few thoughts on it - comments? :roll:

brucek

[ThomasW]

Holy cow Bruce, that's what I call a power post. 8O

I find balanced power an interesting commodity...........

My system, like yours, has whole house surge protection, dedicated 20 amp lines for the equipment, and virtually no 'noise' when the pedal is to the metal......

But.......Part I

Quite a while back I was offered an amazing deal on a salesman's Tice Titan/Power Block II combo (note these are 2-66lb isolation transformers not the stuff Tice sold in later years). Being one of those "what the hell" sort of characters at the time, I bought them. There was a nice improvement in the system. Now we're not talking about massive overall change, but more improvement than could be purchased in any single component, given the price I paid for the transformers.

But .....Part II

True to my namesake, I am truly a 'doubting Thomas'. So when first offered a B-P-T device for evalution I balked. What could it do that the Tice transformers didn't do? A few weeks later the offer was "we'll send one out no charge. Try it for as long as you want, if you don't like what it does just box it up and send it back".......So how could I refuse?

Well it was pretty damn weird, but anywhere I put the device there was improvement. On the video equipment, CRT or LCD projector the color saturation was deeper and there was less video noise. On any audio playback device, it was like a layer of 'grunge' had been removed. And the effects were oddly enough cummulative....... The greater the number of devices plugged in the better the sound.

Now that's a pretty 'heady' statement and I could understand if I had crappy AC power and a ton of mid-fi gear with wimpy power supplies. However most of my gear is considered 'high-end' Most weighs in at 70-80+ lbs per device (note that this includes CDP's). So we know balanced power isn't 'fixing' problems inherent in the equipment....

Lest people think I'm a sucker for any 'tweak' that comes my way, nope not the case. No funny little black 'dot's on my gear. No cable lifters, no CyroTx'ed AC outlets, etc, etc........ It's pretty easy to separate the items that actually work, from those who's only function is to lighten one's wallet..... 8)

Since I'm not an engineer or scientist I can't comment as to what's actually going on with these transformers. But having been around state-of-the-art high-end A/V gear for some 30+yrs, it's pretty obvious when something impacts the playback quality as much as balanced power transformers do.....

I now consider balanced power a 'must have' in any system I own. So on this particular topic, Bruce and I will agree to disagree....... :W




theAudioWorx
Klone-Audio

[Brandon B]

but more improvement than could be purchased in any single component

OK, that hooks me. Gotta stop reading this subforum.

Some questions. If I were to apply this to the music portion of my audio system, would the following factors negate any of the benefit?

CD/SACD deck hooks to 2 ch preamp - hooks to 3 ch Marchand active XO hooks to 3 ch amp for front 3 speakers and 2 large amps for woofers. 2 ch preamp has pass through from HT pre/pro for R/L mains.

If I were to only use this for the CD deck, the preamp, the Marchand, and 3 ch amp for the high end of the front 3 speakers, does their audio connection to the other components introduce any noise back in that negates some of the benefit?

Would one of these run all of the above (amp is an Odyssey HT3, 3 channels at ~150 watts each. One power cord but split inside to a 1 channel amp on 1 transformer/PS, and 2 on the other). If that this is overloading it a bit, if I built 2 of the balanced power units, can they share a rack case, or does that raise noise issues? They could have 2 separate power cords and switching and everything, just be in one box. My 7 foot tall audio rack is very close to full and there is nowhere else for me to go, so if they can be combined, I am much better off. Also, does your part number refer to the 1 rack space enclosure in the picture (I hope, not the giant one), or is the toroid too tall for that?

Thanks.

BB

[ThomasW]

We charge $10 for each question we answer.....

The answer to you questions are yes, but it depends .....

Usually only a power amp or receiver can be used with each device. This is of course dependent on the rating of the unit in va. The Plitron transformer we're using for this DIY thread is rated to a total of 2000va. So one can't exceed that power rating with number of devices that are plugged into it.

As was already discussed above, yes digital components can dump 'noise' back into the AC line. That's why we're using the Schuter 6 and 10 amp EMI/RFI filters, also discussed above.

The chassis we're using is 5-1/4" tall. That's just slightly taller than the transformer.

There are no problems having some components plugged into a balanced unit and others into a normal outlet.

I have my whole system on multiple B-P-T units. Smaller ones (1000va) power the front end gear and bigger ones (2500va) power a couple of Aragon 8008's each.

Best bang for the buck is putting the all the front end gear (meaning no power amps or receivers) on one unit.




theAudioWorx
Klone-Audio

[Brandon B]

Thanks. Guess I will maybe go for 1 unit and put everything but the amps into it (don't have a receiver).

So . . . the links aren't real clear about ordering the plitron. It seems to suggest getting a powerbuy going in order to achieve that price. Did I miss where someone noted a group purchase that is presently open to orders? Or were we planning one here?

5+ inches, sounds like a 3 rack space chassis. Guess I'll either have to lose my pullout drawer in my rack, or go with a 3 space high chassis but half width case with a built in shelf or something, and put on of my skinny components next to it or something.

More bottom weight to keep my rack from tipping in an earthquake, maybe my homeowners insurance will lower my rates for installing this.

BB

[ThomasW]

No there is no current group buy. People can create a group buy if they want. It's frequently problematic to deal with the logistics involved in those.......

In this thread Jon and I are detailing the design and construction of a pair of transformers we're customizing to our wants and needs. In certain areas we are giving info about lower cost alternative parts to those we're using. Obviously there are countless other variants that can be implimented.

I seriously doubt that a DIY power conditioner will qualify one for lower cost home owner's insurance. I'd be inclined to keep quiet since these devices won't have UL or CE approval.




theAudioWorx
Klone-Audio

[Brandon B]

Actually, the insurance thing was 100% joke. Was implying adding a heavy component to the bottom of the rack would reduce the likelihood of it toppling in an earthquake, so they'd lower my premium.

Since I bailed on the earthquake insurance when it went well over $1000 a year with a $45K deductible, not really relevant anyway.

So I guess I just order the unit straight from plitron? Make sense to do it now, to better follow along with you guys, or wait until you are into it and then follow your lessons learned?

BB

[JonMarsh]

Yeah, you could just wait and see how it all turns out. Sort of like watching one of those "reality" TV shows.

Now, I wonder how that would do, having a reality TV show based on a couple of teams of guys and gals doing DIY audio projects, with the studio/view audience voting on which one they thought did the best job on each project in putting together an HT or home music system- Tribe Alpha does a great job on the sub, but Tribe Beta cleans their clock on the power amp and the dipole speakers. And the losing team has to vote off a member, which of course reduces the design and engineering resources available to that tribe, further raising the stress levels and degree of challenge....


Man, I gotta get a real life!

~Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[ThomasW]

Brandon,

You call 1-800-Plitron, ask to speak with Helen Chen. Tell her you want to order part #8575-X0-02. She'll tell you that they don't stock the part, they custom wind all transformers to order. She'll take your CC number and ask for an email addy. In about 4 weeks you'll get an email with billing info and an expected ship date. Then you wait and wait and wait for it to arrive .......

Note that they are a Canadian company. My shipping cost to Denver is $30/transformer. I imagine that the trip to LA will cost more.

While waiting there's plenty of time to ponder and order the rest of the parts. Understand it's a given that these things work. The only variable is how many extra bells and whistles you want to add.

If you want to play with a lower cost but lower output device Transcendent Sound has a fairly nice kit. This kit has only a one duplex receptacle and no dedicated RMI/EFI filters.. For comparison here is the pricing from B-P-T.com. Note that Chris Hoff provides are 30day money back policy. Balanced power from the 'big guys' (Furman and Equ=Tech ) is really spendy! But from time to time Equi=Tech has closeout sales

There are always a ton of devices at AudioGon. Unfortunately used pricing isn't all that great.




theAudioWorx
Klone-Audio

[Brandon B]

I'd watch that show. At least for one season. About the only reality show I've watched is "Rough Science" on BBC, which is kinda cool.

Thanks for all the info. And actually, I pretty much believe any project you and Jon embark on is guaranteed to work. Far and away two of the most objective guys I've seen slinging audio advice.

Thanks for answering all my questions.

BB

[ThomasW]

Transformers finally arrived................

I'd take a picture but it would look identical to the one in my first post 8)

Now that all the parts are here, and if Jon ever stops traveling, the construction can begin.




theAudioWorx
Klone-Audio

[Brandon B]

Well, my big copper donut is on order. 4 weeks to ship.

BB

[ThomasW]

Well, my big copper donut is on order. 4 weeks to ship.

Cool ...............Your UPS guy will give you a funny look when he delivers the relatively small box that weighs a ton

Interesting thing, the transformer itself is only 3.5" high, but the in/output wiring adds another 1/2"+ to the height. So our 3U rack chassis are a bit too tall; but using the next size down would put a pretty sharp bend in the wiring. Also the AC receptacles would need to be mounted horizontally if a shorter chassis were used.

The transformer is so compact and heavy, I'm seriously thinking about putting a layer of 3/4" ply on the inside bottom of the chassis. That will spread out the load and decrease the potential for the chassis to flex. Since the transformer is grounded by a wire and it's not an issue to have it sitting on a wooden platform.......




theAudioWorx
Klone-Audio

[Brandon B]

http://www.sescom.com/enclosures/heavy_duty_rack_chassis.html

Bit beefier chassis, but a bit more $. With the extra height, could accept an interior panel which would better support the transformer.

I am going to make my own I think. Amongst our building's equipment is a large industrial metal shop.

BB

[ThomasW]

The issue is the concentration of mass, and having only one attachment point for the transformer. Given the nature of the construction of a torriod, they can't be 'torqued down' to add strength to the chassis. Doing that can damage the windings.

I think it would take 1/4" thick plate bottom to avoid flexing. So it seems that the easiest solution is to simply reinforce the bottom of a standard chassis.




theAudioWorx
Klone-Audio

[Brandon B]

OK a magnetic/noise question. I have torn apart my audio rack to rearrange it to make room for both the upcoming balanced power unit and a second satellite tuner. I am tying to group the components to prevent any induced noise in one from the other.

You may remember some time back Jon helped me eliminate a hum from my sub channel by moving my Symmetrix 551 equalizer away from the 3 large crown macrotech amps which run my sub and woofers, as the large toroidal transformers in those give off a pretty good field.

Will this plitron do the same thing? If so, or even if not, should it be separated from the crowns or the other sensitive components? I am sort of limited here as ALL components must go in the rack, and it is getting close to full. I think I need to move the crowns to the bottom of the rack, but the outlets for them presently prevent this (I will probably make extender cords to remedy this shortly).

Anyway, basic question is can this thing pick up nose from the big amps' toroids, and also, will it put out noise like they do? Former seems unlikely given is raison d'etre is prevention of this, but what about the latter?

BB

BB

[ThomasW]

Don't know yet about this particular transformer, but the Plitron transformers in my B-P-T devices all emit a low level mechanical hum. I have no problems with them in close placement to other components. Some are sitting on top of or immediately next to some very high power amps.

Went to the surplus store and found a piece of 1/8" alu plate 74"X10" for $18. That's big enough that we can cut 2 plates each to stiffen the bottoms of both chassis. So no need for plywood...........




theAudioWorx
Klone-Audio

[JonMarsh]

Mechanical hum from transformers can be due to several factors, but often a small (100-200mV) DC bias in the neutral to hot AC line is a contributing factor. Because of the low impedance of toroids (regarding DCR), and the smaller cores compared with EI transformers of the same power handling and regulation, they're more susceptible to "humming" from DC flux offset.

For this reason, I'm planning on building in a DC blocking filter on the primary, though it may not be completed initially.

The other potential issue when stacking power amps with anything else electronic is stray magentic field; actually, it's the high harmonics which get coupled more easily, due to the short conduction time of rectifiers into caps in the power amps at the peak of the AC waveform. A reasonable setup would probably be puting the BPU (Balanced Power Unit) at the bottom, power amps next, and other gear above? especiall since the BPU won't be generating heat to rise into the other electronics.

Regards,

Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Brandon B]

Thanks guys. Turns out shuffling everything in a 7' tall rack with about 250 pounds of amps and another 150 lbs of other components is a pretty decent workout. Whoof.

BB

[JonMarsh]

well, at least you won't have to worry about the expense of renewing your gym membership! And you can apply the money you save to more audio goodies!

~Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Brandon B]

Rouding up some parts for order, couple of questions -

On the milspec wire - what gauge should we be buying? 10 or 12 or ? I note the leads on the plitron are only 12 so any reason to go with 10?

Should the outlets be isolated ground HG or will standard hospital grade be fine (I see both and the isolated ones seem to be more $$).

Also, what/where is evil orange (or is this a nickname for Home Depot)?


Are you guys putting 20 amp rated plugs on the wall end of the power cord, given that 2000VA is a little past 15 amps? I can as I have all 20 amp circuits and commercial grade outlets in my AV closet that accept the little sideways blade from a 5-20P plug, but was curious what you guys were doing.

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[ThomasW]

On the milspec wire - what gauge should we be buying? 10 or 12 or ? I note the leads on the plitron are only 12 so any reason to go with 10?

We're using 12 gauge mil spec. I posted a link to our supplier toward the beginning of the thread.

Should the outlets be isolated ground HG or will standard hospital grade be fine (I see both and the isolated ones seem to be more $$).

Yeap we're using spec grade and hospital grade, all are isolated ground. You can certainly use standard receptacles if you want. Get the Pass & Seymour brand they have the highest clamping pressure and all brass construction.

Also, what/where is evil orange (or is this a nickname for Home Depot)?

Yeap it's our nickname for HD

Are you guys putting 20 amp rated plugs on the wall end of the power cord, given that 2000VA is a little past 15 amps?

This hasn't been discussed, I tend to use the 20 receptacles, but not the 20 amp AC plugs. That way the devices are compatible with everyone's wiring




theAudioWorx
Klone-Audio

[Brandon B]

We're using 12 gauge mil spec. I posted a link to our supplier toward the beginning of the thread.

Yeah, noted that. They are actually about a 10 minute side trip for me from work, so I'm probably gonna will-call my stuff from them.

Also, got my email from Plitron, shipping is about US$38 to SoCal (and no tax on the xformer!), so given Toronto is east coast Canada, shouldn't be any more than that for anyone else in the 48.

BB