Re: Class D amp - modifications

jtsnead · « **Reply #60 on:** 30 Jun 2010, 03:49 am »

Ok to clarify I bought the 80 volt x 10000 supply

Let it play for nine hours, initial thoughts are not a big
difference, I do notice a stronger pop or transient responce
when a vocalist sings to close to the mic, vocals do seem smoother
with less sibilance. The cd I was listening to before and after
is Valarie Joyce on Chesky

I will have to try some rock or electronic stuff to see if the supply
makes a difference on that type of music.

20 minutes later,

Well I went and listened to Nils Lofgren Acoustice Live
on Keith Dont G sound does seem to have quicker responce on the guitar
strings with better dynamic swings on his voice. Piano tone
on Big Tears Fall seems to have a truer tone.

I imagine the board does have to burn in and things might get
a little better.

Might try some Acme silver fuses in the supply next.

Overall I feel it was worth the $60

wushuliu · « **Reply #61 on:** 30 Jun 2010, 04:39 am »

Yes to the Acme silver fuses. Yes, yes, yes.

mintzar · « **Reply #62 on:** 5 Jul 2010, 06:40 pm »

I started building these amps for a few people a while back. I have now totally revamped the design using my own power supply.

I use Jensen 4-pole capacitors ($90 each) and BYV-27s to make the rectifier. The power supply alone costs me over $1000. Pure copper binding posts, cryo-treated XLR inputs, A star grounding system using Goertz Boa wire, internal wiring is Goertz and the same wire used in Mojo Audio power cords for power signals. I also use an anti-resonant shrink fabric over all the cabling to minimize distortion caused by resonance. I then shield and damp the entire chassis.

The normal class D amps are great. This "upgrade" to the kit makes the amp competitive with just about anything on the market. I recently sold this amp to a gentleman and he replaced a Gryphon dual mono amp.

So there's A LOT of performance to be had out of these suckers!

wushuliu · « **Reply #63 on:** 5 Jul 2010, 07:08 pm »

Quote from: mintzar on 5 Jul 2010, 06:40 pm

I started building these amps for a few people a while back. I have now totally revamped the design using my own power supply.

I use Jensen 4-pole capacitors ($90 each) and BYV-27s to make the rectifier. The power supply alone costs me over $1000. Pure copper binding posts, cryo-treated XLR inputs, A star grounding system using Goertz Boa wire, internal wiring is Goertz and the same wire used in Mojo Audio power cords for power signals. I also use an anti-resonant shrink fabric over all the cabling to minimize distortion caused by resonance. I then shield and damp the entire chassis.

The normal class D amps are great. This "upgrade" to the kit makes the amp competitive with just about anything on the market. I recently sold this amp to a gentleman and he replaced a Gryphon dual mono amp.

So there's A LOT of performance to be had out of these suckers!

Hay-sus Christmas!

Where do you get anti-resonant heat shrink?

mintzar · « **Reply #64 on:** 5 Jul 2010, 07:29 pm »

I bought it through Ben at Mojo Audio. WOWZA does this stuff work well! It was about $55 for 30' of the stuff. Totally worth it. I am building speakers and am using this same stuff on my speaker cables. I have become obsessed with it. I 'think' buyheatshrink.com has it. But Ben tends to buy them out of all their stock O.o

I'm drooling over this amp right now. The better caps in the power supply (even over a bigger supply like the 60kuF supplies you guys are building) makes a HUGE difference. I built a bigger supply first using those same caps and an IXYS regulator and it was a really nice upgrade. But these jensen caps are in a totally different league. Granted, they had BETTER be at $90 each.

Nick77 · « **Reply #65 on:** 5 Jul 2010, 07:57 pm »

I am running 40kuf panasonics tsha's with stock ps and bridge. I am thinking about the ixys fred bridge, but didnt know if it was a worth while upgrade??
I also have 2 open slots on the ps for more caps but wasnt sure if more than 40k was worthwhile but you say even above 60k yields results?

mintzar · « **Reply #66 on:** 5 Jul 2010, 08:03 pm »

40kuF is plenty for these amps. Bigger, Better power supplies always are... well, better. If I had the budget I'd double my jensen PSU and see where that takes me.

The IXYS rectifier is worthwhile IMO. More speed = more texture, accuracy and neutrality.

On another note...

Has anyone tried using a circuit breaker instead of a fuse? What rating did you use?

wushuliu · « **Reply #67 on:** 5 Jul 2010, 08:32 pm »

Quote from: mintzar on 5 Jul 2010, 08:03 pm

40kuF is plenty for these amps. Bigger, Better power supplies always are... well, better. If I had the budget I'd double my jensen PSU and see where that takes me.

The IXYS rectifier is worthwhile IMO. More speed = more texture, accuracy and neutrality.

On another note...

Has anyone tried using a circuit breaker instead of a fuse? What rating did you use?

I would have liked to have tried the IXYS but if I recall they are not swappable with the stock rectifier.

I would love if someone walked through how to build your own PS (in terms of actual construction materials needed, like bread/perf board(?), etc.)

avionic · « **Reply #68 on:** 5 Jul 2010, 08:51 pm »

I would love if someone walked through how to build your own PS (in terms of actual construction materials needed, like bread/perf board(?), etc.)
[/quote]

x2 I would be all over this project just not quite sure how.

mintzar · « **Reply #69 on:** 5 Jul 2010, 08:54 pm »

You can clip the middle pin on the IXYS to use on the stock PSU board.

DIY PSU:

This is relatively new to me, I've only built two from-scratch supplies.

Ready go:

You need a TX first rated at the proper voltage.

For instance, if the amp board requires a +/- 35V PSU you would want something like a 25V TX.

What happens is the voltage from the TX is multiplied by the square root of 2 or 1.41. 25*1.41 gives you just under 35V.

Then all you need is a rectifier and caps. The rectifier gives you DC. The Caps will give you the B+ and B- rails which output to the amp board. To test voltage you connect the multimeter between B+ and ground or B- and Ground.

I wouldn't recommend connecting the ground between the amp board and the PSU either. What I would recommend is doing a star ground style setup. Pick a place on your chassis (usually away from components, but the shortest run of wire possible) and run all of your ground wires to that central point -- should have one from the amp board and one from the PSU, since you drilled a hole into the chassis for the ground lug (found at home depot -- pure copper is best) the ground terminal is already connected to chassis ground to help shield the chassis. Then from that point run wire to the mains ground. Makes a very big difference. You can do that with the stock amp too.

Not much info, but at least it's something to get you started.

jtsnead · « **Reply #70 on:** 17 Jul 2010, 01:13 pm »

Ok I thought I would do a follow up on the power supply
board change. I had not listened to any music for a while
w/ graduation parties, 4th of July etc.

Listening last night I feel the ps supply board upgrade was
well worth it, maybe because the amp has been on for a couple
weeks and the caps settled in some more but the soundstage
is better in regrads to clarity of voices and instrument locations
in the soundfield. On the new She & Him album track 2 Zoey Deschanel
is front and center with back up vocals rear left and right, this track
shows how well the ps supply board improved the clarity of the
soundstage. This is a great recording if you like the whimiscal sound
of her voice, also has alot of instruments in different locations.

wushuliu · « **Reply #71 on:** 18 Jul 2010, 02:02 am »

Quote from: jtsnead on 17 Jul 2010, 01:13 pm

Ok I thought I would do a follow up on the power supply
board change. I had not listened to any music for a while
w/ graduation parties, 4th of July etc.

Listening last night I feel the ps supply board upgrade was
well worth it, maybe because the amp has been on for a couple
weeks and the caps settled in some more but the soundstage
is better in regrads to clarity of voices and instrument locations
in the soundfield. On the new She & Him album track 2 Zoey Deschanel
is front and center with back up vocals rear left and right, this track
shows how well the ps supply board improved the clarity of the
soundstage. This is a great recording if you like the whimiscal sound
of her voice, also has alot of instruments in different locations.

Happy to hear this as this was my impression of the 90k version as well, though I think this may be more due to the design of the PS w/ bypass caps, etc., not increase in capacitance.

HiroPro · « **Reply #72 on:** 20 Jul 2010, 12:58 am »

By 90k version you mean the SDS-254 "Kits" etc that come with the DC board from classdaudio?

What is the difference between the SDS-254 and SDS-258?

wushuliu · « **Reply #73 on:** 20 Jul 2010, 01:11 am »

Quote from: HiroPro on 20 Jul 2010, 12:58 am

By 90k version you mean the SDS-254 "Kits" etc that come with the DC board from classdaudio?

What is the difference between the SDS-254 and SDS-258?

90k refers to the connexelectric PS I had briefly, mentioned earlier in this thread.

The difference between the two amps are the 254 is spec'd for 4 ohms, the 258, 8 ohms. That's as much as I know; you may want to check the website or the main amp thread for more info.

HiroPro · « **Reply #74 on:** 20 Jul 2010, 01:36 am »

I'm sorry but what thread are you referring to?

Curious as to what PSU your using now?

Barry_NJ · « **Reply #75 on:** 20 Jul 2010, 02:02 am »

Quote from: HiroPro on 20 Jul 2010, 01:36 am

I'm sorry but what thread are you referring to?

Pretty sure it's this one...

http://www.audiocircle.com/index.php?topic=76400.0

Barry_NJ · « **Reply #76 on:** 14 Sep 2010, 03:02 am »

I've got a bunch of different capacitors lying around...

Twelve, Mallory 75-VDC, 12000 uF.
Eight, Phillips 100-VDC, 15000 uF.
Two Mallory 80-VDC 15000 uF.

Can I use any of these in Tom's PS to up the capacitance in his supply, or maybe even build my own?

FWIW, I'm interested in the SDS-258 board.

Thanks, Barry

wushuliu · « **Reply #77 on:** 14 Sep 2010, 03:13 am »

Quote from: Barry_NJ on 14 Sep 2010, 03:02 am

I've got a bunch of different capacitors lying around...

Twelve, Mallory 75-VDC, 12000 uF.
Eight, Phillips 100-VDC, 15000 uF.
Two Mallory 80-VDC 15000 uF.

Can I use any of these in Tom's PS to up the capacitance in his supply, or maybe even build my own?

FWIW, I'm interested in the SDS-258 board.

Thanks, Barry

The caps need 10mm lead spacing (.394") for the PS board.

Barry_NJ · « **Reply #78 on:** 14 Sep 2010, 03:30 am »

Quote from: wushuliu on 14 Sep 2010, 03:13 am

The caps need 10mm lead spacing (.394") for the PS board.

The caps have screw terminals. Could I run leads from the terminals to the board?

wushuliu · « **Reply #79 on:** 14 Sep 2010, 03:36 am »

Quote from: Barry_NJ on 14 Sep 2010, 03:30 am

The caps have screw terminals. Could I run leads from the terminals to the board?

Mmmm, not sure I would recommend that.