Cheap DIY balanced power device

[brucek]

Yep, OK Thomas.... sorry, I hadn't read the web site yet, but it looks like you took the words right out of my mouth - and better said too....

in part:

(11) low mfd, high voltage non-polarized film caps. The value of these caps isn't critical, but they should be relatively small (less than 1 mfd, bigger in this case isn't better). The cap's power handling however should be adequate to the task (600V min). On hand I had some .22 mfd 1200V GE caps purchased at Madisound. One cap is used as a differential noise blocking cap for each AC outlet used. Note; the industry 'standard' is to use what are called X2 caps on AC outlets. If one uses the non-X2 caps; and if the unit passes a high voltage transient the caps will fuse (short), and need to be replaced. Unlike X2 caps these regular caps aren't 'self-clearing'.

From just reading the thread it looked like safety was getting a bit loosy-goosey and I thought I'd throw in my two cents, but what you have posted on the web site is great......

brucek

[ThomasW]

Hey,

We're always "a bit loosy-goosey", but never where safety is concerned .. :T

[David Meek]

Set-up And Initial Impressions

Since I'm the first to get a crack at the Cheapskate, I thought I'd post my impressions as I go along. Just to be thorough, here's the complete equipment list involved in the tests - I've included links where available. The units that will be plugged into the Cheapskate for testing are:

the CD transport:
Yamaha CDR-S1000

the DAC:
Musical Fidelity AC3.24

the turntable and cartridge:
Nottingham Analog Horizon w/Rega RB250 tonearm
Grado Reference Sonata cartridge

the phono stage:
Musical Fidelity X-LPS vII

the DVD:
Panasonic DVD-RP91K

the RPTV:
Pioneer Pro Elite 610, 58", 16:9

Items that will be static, ie. no configuration change (not plugged into the Cheapskate) during my tests are:

the receiver - yes a receiver,but it's a good one as far as receivers go:
Yamaha RX-V1

the speakers:
Aerial Acoustics 7Bs

the speaker cables:
MIT Terminator 4s in a bi-wire configuration

the interconnects:
CATCables SilverCats - DAC to receiver
CATCables SilverCoax - CD to DAC
CATCables SilverCoax - DVD to receiver
CATCables Tigress component video - DVD to RPTV

the surge protector/filter:
VansEvers Model 100/14

The CD transport sits on a glass sheet which in turn rests on 6 Vibra-Pod isolation devices. The turntable sits on a Symposium Svelte Shelf isolation platform. All components (except the RPTV) sit on a Lovan Classic II equipment rack which has all legs filled with steel shot. Both Aerial speakers sit on Sound Design isolation stands.

I'm still not sure about plugging the RPTV into the Cheapskate as I haven't found the service manual yet. Once I find it, I'll know if it's too much of a draw or not. More later. . . .

I'm doing my own power cable switching at this time. Later, I'll have Aaron or Jen do the switching for me in a blind set-up. Again, more later. . . .

I'm using music that I'm VERY familiar with. The CD's are
Fleetwood Mac, Tusk
- Sisters Of The Moon
- Beautiful Child
Fleetwood Mac, The Dance
- Landslide
- Silver Springs
Vaughan Williams
- Symphony #7, Synfonia Antarctica

Okay, that's all out of the way. So here we go.

First off, it's a solid little bugger! Twenty pounds sounds like a moderate amount of weight, but when you stuff it in an 8" x 8" box with no give or play noticable in any of the parts, it's impressive. I know it's a purely subjective POV, but if it's heavy/solid/inflexible in build, that's a big plus for me. This little guy qualifies all the way around. I'm testing my CD and DAC first. I've had the Cheapskate plugged in for 24 hours and have had music playing through the system for a couple of hours to make sure everything is running at a stable operating temperature. The differences so far are, in general, small with one exception. The detail is enhanced in most instrumental passages. The tiny background guitar picks in the first minute of Beautiful Child become very distinct, clearly highlighting the "bend" that Lindsey Buckingham puts in them. This bend was almost unoticable before. Strings in the Antarctica Symphony have a more palpable and in-the-room-with-you feel to them. Stevie Nicks' vocals are a touch more "solid". Mick Fleetwood's drums have a touch more strength to them on the front of the strike and a longer decay on the back side. Cymbals have a tiny bit more detail to them which adds a more natural feel to them. I know that I'm using a lot of minimalist words and feely concepts, but that's how I'm perceiving the changes I'm hearing. The ones listed ARE all small and detail-oriented, but they ARE changes, and changes for the better. The one large thing I mentioned earlier is more of a composite of all the small changes than anything. It amounts to a lack of noise, or a better way to put it is a quieter background that allows you to hear further into the musical detail. You hear a minute amount more of each note, starting a fraction earlier and lasting a fraction longer which mimics more fully the actual sound you would be hearing if the instruments were themselves played in front of you.

Enough for now. I'll be back. . . . :later:

[brucek]

david,

Could you perform a small test for me?

With the CD transport and DAC powered up and plugged into the BPU, and the receiver switched to CD (and no CD playing), what differences do you hear from your mains speakers when the receiver volume control is full up - compared to performing the same test with the CD and DAC plugged into your regular power controller.

Perhaps you can comment on any changes to the level and quality of hiss/hum from woofers, mids, tweeters..... Presumably, the BPU will lower your noise floor - does it?

brucek

[David Meek]

Bruce,

Jen is currently watching a movie, but as soon as she's finished I'll give it a try. That'll be an interesting test. Tell you what - I'll get the SPL meter out and see if that shows any difference also.

[Cowanrg]

David,

about current draw, most electronics have a little tag by the power cord or iec that has all those safety warnings and such, and a little UL listed thing... many of these tags have power consumption right on there. i know almost ALL my stuff does. typically power consumption on a tv will be around 280 watts (for a 36" tube), to around 400 or so watts for a bigger tv. you SHOULD be fine, but check first.

[Cowanrg]

i did a quick search and found that a 51" sony RPTV (crt based) uses about 280W when its on. if you can tell me your model, it can be found pretty quick online.

i would suggest that the DVD player and TV could probably both be operated at the same time with the BPU.

[David Meek]

I found the manual(s). The Pioneer draws 325W or 600VA. The Panasonic draws 16W so I'll be able to run both through the Cheapskate. Thanks though.

[David Meek]

Noise Floor Readings

Here ya go Bruce,

I set the Radio Shack analog SPL meter to slow response, c-weighted, and used the 60 dB setting (most sensitive). I set the meter on a tripod that left the sensor 3 inches from the face of the tweeter. I made absolutely sure there was no disc in the CD transport, and then turned the volume on the RX-V1 up to 0 (full tilt boogie ). With the CD and DAC off the Cheapskate, I got a -9 dB reading. IOW, the needle barely moved off the -10 dB setting on the far left of the dial - but it did move and it was constant. I plugged both components into the Cheapskate and repeated the operation. The needle never moved off the -10 dB setting. Nothing. Nada. Zip. So, there is at least a one decibel difference between the Cheapskate and my standard surge-protected house-power. It might be more, but the meter wouldn't read any lower. I tried the meter on both channels and got the same reading from both. I tried this on the mid-range and then the bass drivers and got zero from the Cheapskate powered run, and as close to zero from the non-Cheapskate run as to not matter.

The old "ear" test was simpler. With the components run off my standard setup, I could barely hear a hiss with my ear about 3 inches from the tweeter face. Very quiet, very innocuous. Not a harsh sounding noise, just a very mild hiss. With the components run off the Cheapskate there was nothing audible. Period.

Just out of curiousity, I'm going to do this again, but with the CD and DAC plugged straight into a wall outlet instead of the VansEvers surge protector/filter.

[ThomasW]

May I assume we have a convert? :wink:

[brucek]

Thanks for the results david - smart to test with the instrument and the ears - their results supported each other.

I think you certainly proved the BPU is beneficial, specifically for your sources where it really counts.
That lowered noise floor is increasing your system S/N ratio and your dynamic range. :T

I guess the only other question I would have is if you hear any audible hum coming from the BPU itself. If so, would you characterize it as a problem.

You best hold onto this unit and tell the other guys to build their own........ 8O

brucek

[David Meek]

May I assume we have a convert? :wink:

Oh, I've always been "in camp" Thomas. This is just icing on the cake! :T

I guess the only other question I would have is if you hear any audible hum coming from the BPU itself. If so, would you characterize it as a problem.

Nothing audible from the Cheapskate that I remember. I didn't really check it too closely, so all I can say is that with it in the equipment area there wasn't anything noticable. I'll check in detail tonight.

You best hold onto this unit and tell the other guys to build their own........ 8O

Nah, it's tempting, but I'm gonna build a super-mondo-oh-baby unit that I can run all my non-dynamic components off of. Heehee, thanks for the thought tho'.

[ThomasW]

The Avel Lindberg transformer in "The Cheapskate", is quieter than any of the Plitron transformers in my $$$$ B-P-T devices. If you press your ear firmly to the chassis, you can hear a VERY slight mechanical hum. It's so much lower than the ambient noise level in any room where I've used them, that for all practical purposes it's nonexistant.

Other than the supplied neoprene gasket between the transformer and the bottom of the chassis, there were no attempts to further mechanically isolate the transformer. Nor was any dampening material added to the chassis itself. (note that chassis damping is standard issue on the high-end BP devices)

[Cowanrg]

Thomas,

ive had a few avels that had a slight hum. when you start really loading them they can get a little noise out of them.

if anyone is interested in building one of these and wants it dead silent, i suggest this... i do this for my amps and pre-amps, or anything that will have an xformer in it. i use a 1/4" thick sheet of rubber that i get at the local hardware store. its just a few dollars. i cut a disc out of it, and use two in conjunction with the supplied neoprene washers. the washers touch the transformer, and the rubber pads touch the bottom of the chassis, and the top plate. this works REALLY well. you might need a slightly longer center bolt though. but even when fully loaded, mine are now SILENT, where before they had hum.

its a cheap and easy fix. maybe adds $5 to a dual xformer device.

[David Meek]

I've finished up with the Cheapskate. Who's next on the list? Anyone in Houston interested in trying it before it heads to parts unknown?

I'll be posting more thoughts on it once I have a bit more time available.

[ThomasW]

David,

Cam McFarland was interested. He's in the greater Houston area and wanted you to PM/email him when you were finished.

Also would you copy your review posts to the newly renamed "Tour and Review" thread? This particular thread is getting so big and running so far a field, anyone coming in 'new' and trying to read it would be completely lost.

I'll delete the old posts once they're copied to the "Tour and Review" thread

Thanks
Thomas

[Eric S]

Hey Guys,

Been watching this thread for a while and I just have to say this is great stuff! Now it looks like there is a new project to build - what fun!

[robertwb70]

I have many pieces of equipment that run off "wall wart" power supplies-would one of these units do any good for those too?

the stuff with wal warts
-scott nixon DAC
-creek OBH-12 pre-amp(passive)-really doubt it on this one
-paradigm X-30 crossover

jeez-other than that the only stuff I'd worry about is the transport and amps

couldn't we do a 2 transformers in parallel version for 1600VA-for amps?

[ThomasW]

Hi Robert,

One can put 2 transformers in a single case, that's what the 'big unit' is. But as far as I know, two small transformers can't be wired together to allow a single device (receiver/power amp) pull 1.6kVa. If one wants a higher rated device the best bet is buy the 2kVa transformer from Plitron (# 8575-X0-02) . That transformer runs approx $300 delivered to the USA. It has no problem powering a receiver or power amps

[Glen B]

As you know the "Cheapskate" versions were minimalist by design.

So unlike those designs, this one's going to have some bells and whistles. It won't be all that expensive. Probably $300-$350, for a unit with 2 transformers (1600VA total), 8 individually RFI/EMI filtered outlets, RFI/EMI input filter, individual illuminated power switches, and 6 rubber feet ........ :wink:

I have spent the past couple of months breaking in and tweaking my own DIY balanced power unit and have an issue with the EMI/RFI filters. Quite by "accident" [a too-long story that is not necessary to relate here] I discovered that the EMI/RFI filters I was using on the inputs of the transformers in my project were having a negative effect on my system.

With the filters in place, I noted a slight loss of high frequency and upper midrange detail as if a blanket was thrown over the speakers. Listening to a couple of excellent recordings of solo acoustic guitar and vocals accompanied by acoustic guitar for example, it was as if the leading edge of each pick of the guitar strings was dulled. I tried both Qualtek and Corcom filters, which are both very good products, so I don't think its a question of filter quality. In fact, one manufacturer of balanced power conditioners whose flagship product has received good reviews, uses the same Qualtek high-current filter in their unit. I wonder how much better their unit might perform with that filter removed.

These EMI/RFI filters are supposed to remove additional noise but at what cost to the music ? IMO, the tradeoff in my system is not worth it. Just my two cents.

[brucek]

I'm not questioning what you hear Glen, but I can't imagine what negative effect an RFI/EMI filter could have on your system.

The insertion loss is negligible below 100KHz, and is esscentially out of the circuit at 60Hz.

In fact the IEC type filters will have smaller inductors in them, and as such offer less impedance at 60Hz than a larger 'can' type. A typical IEC type might have an inductor of 0.18mH which translates to an impedance of 0.07ohms at 60Hz. A typical inductor in a can RFI filter would be around 0.7mH, so then at 60Hz it offers an impedance of 0.26ohms. Even so, this is not worth considering.

What are your ideas on this (other than listening tests)?

[Glen B]

I'm not questioning what you hear Glen, but I can't imagine what negative effect an RFI/EMI filter could have on your system.

The insertion loss is negligible below 100KHz, and is essentially out of the circuit at 60Hz.

In fact the IEC type filters will have smaller inductors in them, and as such offer less impedance at 60Hz than a larger 'can' type. A typical IEC type might have an inductor of 0.18mH which translates to an impedance of 0.07ohms at 60Hz. A typical inductor in a can RFI filter would be around 0.7mH, so then at 60Hz it offers an impedance of 0.26ohms. Even so, this is not worth considering.

What are your ideas on this (other than listening tests)?

I am aware that these filters should not have an effect on the audio band. I installed them initially and did not imagine they would be a problem. I was very surprised myself to discover that they had a negative effect in my application. :E

How this came about was that the original 2kVA tranny I was using buzzed loudly when certain appliances in the home were running. I contacted the manufacturer, Toroid Corp. and they recommended I try a number of solutions, one of which was to disconnect the EMI/RFI pre-filter. It was only after I disconnected the filter and starting doing some listening, that I immediately realized the sound was better. Several rounds of listening with the filter in and out of the circuit confirmed this difference.

I ended up replacing the noisy transformer with a "Q" type piece from Equi=Tech which is absolutely silent. I discussed the negative effect of the filter I observed with the folks at Equi=Tech and was told they do not recommend the use of EMI/RFI pre-filters because they "choke the sound" and that with their transformers, such pre-filtration is "not necessary." Their transformer has two electrostatic shields.

Equi=Tech said they have found Corcom filters to be sonically acceptable and use them for isolation of digital outlets in their products. I tried a Corcom filter on the just the primary of the 250VA digital transformer and found that while the negative effect was less than with a Qualtek brand filter, it was still apparent. I did not try these filters on the secondary for digital isolation and cannot comment on their effect in such an application.

One thing I notice is that the high-current Corcom filter BPT advertises as an option in their product is listed at $150.00. Just about every filter Corcom makes is available at Digi-Key and Mouser. No filter either one carries costs anywhere close to $150 or $75 for that matter. This makes me wonder if the Corcom piece that BPT uses is not a custom unit.

[ThomasW]

This makes me wonder if the Corcom piece that BPT uses is not a custom unit.

I doubt it.

It's been a couple of years since I last spoke with Chris Hoff. I used to buy his products at wholesale. BPT is a VERY small one man evenings/weekend company. His bread and butter is his fulltime job at GMAC as I recall.

The $150 certainly isn't his actual cost, it's just how much he charges the customer.

I stopped doing business with him since he went tweak crazy, in an attempt to pad the bottom line. The markup on things like Z-sleeve, cryo-outlets, ERS cloth, Bybee, etc, etc, is a crime.

[Glen B]

I doubt it.

It's been a couple of years since I last spoke with Chris Hoff. I used to buy his products at wholesale. BPT is a VERY small one man evenings/weekend company. His bread and butter is his fulltime job at GMAC as I recall.

The $150 certainly isn't his actual cost, it's just how much he charges the customer.

I stopped doing business with him since he went tweak crazy, in an attempt to pad the bottom line. The markup on things like Z-sleeve, cryo-outlets, ERS cloth, Bybee, etc, etc, is a crime.

Wow, then that's some markup on the Corcom filters.

[ThomasW]

Just figure out which Corcom filter is this big, and you're good to go. (note it's probably the biggest one they make, used primarily for it's looks)

Image not available

For comparison the chassis excluding the front panel is 11" OD

[brucek]

A standard CORCOM VK-series 30 amp line filter Part # 30VK6 here:

http://www.cor.com/results.asp?Catalog=30VK6

http://www.cor.com/catalog/filters/Khigh/specifications.htm

Shows a cost of $55.70 using a Digi-Key search of 30VK6 here:

http://www.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch

http://dkc3.digikey.com/PDF/T043/0802.pdf

brucek

[Glen B]

Just figure out which Corcom filter is this big, and you're good to go. (note it's probably the biggest one they make, used primarily for it's looks)


For comparison the chassis excluding the front panel is 11" OD

Been there, done that a long time ago. The filter in the BPT unit appears to be slightly more than twice as long as it is wide. I could find no Corcom filter of that size and shape in their catalog.

[Ten 99]

It almost looks like there's some kinda funky foil cover on that picture Thomas posted above. Could there be two of those corcom filters underneath that filter, run in series? I have no idea if you can even do this, that's why I'm asking. Just thought I'd take a slash in the dark at it, in case it proves useful?

[Glen B]

It almost looks like there's some kinda funky foil cover on that picture Thomas posted above. Could there be two of those corcom filters underneath that filter, run in series? I have no idea if you can even do this, that's why I'm asking. Just thought I'd take a slash in the dark at it, in case it proves useful?

It looks like it could be mu-metal foil. The same material appears to be lining the bottom and front panels. Below is a pic of the model BP-2+ where you can see the filter is a single unit.

[ThomasW]

Chris,

The pale gray stuff you're looking at is called ERS cloth. It's an adhesive backed matt made primarily from randon carbon fiber stands with some added things like nickle, etc.

He also uses fairly thick foil backed bituminous damping pads to mass load the chassis.

Glen

I don't think he's using Mu-metal. If he was, it's use would be hyped.

Yea the filter is one piece. It may come from a supplier other than Corcom

[Glen B]

Glen

I don't think he's using Mu-metal. If he was, it's use would be hyped.

That's what I figured that he would likely hype the use of Mu-Metal. Just making a wild guess.