More uf = better sound

rgrayton · 22nd December 2005, 03:58 PM

I don't really mean that, but adding 16.4Kuf/ch to a "Brian Board LM4780 PS" made a very positive and noticible difference to both the detail and transients. For a reference, the power output capacity jumped from around 89W to 116W with the change. Also, I did add in a little more PS filtering and reduced the grounds from the PS to the amp boards to a single wire. CDs auditioned were "Money for Nothing" (loud) and Rebecca Pigeon's Spanish Harlem on the Ultimate Demo Disc. Everything got better and now sounds discenable better, imaging, resolution, detail..., than my $2800 Yamaha DSP A1 (or whatever it is called). Just though I would throw that out there.
-BG

jaudio · 23rd December 2005, 05:05 PM

What was the capacitance before? I added 15,000uf per rail(up from 220uf,that I used while testing) to my amp and everything balanced out. It also helped stabilized the voltage from the power supply. I did the 1000uf thing first and decided to keep the 15Kuf caps in.

Cortez · 23rd December 2005, 07:57 PM

> ... and reduced the grounds from the PS to the amp boards to a single wire.
What do you mean on reducing ? Shorter GND wires between the PS and the amp ?

rgrayton · 24th December 2005, 12:50 PM

Quote:

What was the capacitance before?

The kit comes with 1500 on the rectifier board. I think it is generally a great kit, but requires much more uf, especially for the LM4780 4ohm parallel kit.

Quote:

What do you mean on reducing ?

The kit comes with 2 ground terminals per ch, so 4 for a 2ch. These terminals are on both the PS boards and also on the amp boards. That means 4 grounds from the 2 PS boards to the amp boards. This having been my first amp, I had a lot to learn. I also thought it important from a learning standpoint to start with the designed kit as a reference. Under these conditions, I had a ground loop between the two channels -- 4 ground wires, about 1 ft, from the 2 PS boards to the 2 amp boards. I tied the 4 together, equidistant, close to the PSs at one point, and the same on the other side near the amp boards. Then one wire between the two "stars"
-BG

jaudio · 24th December 2005, 01:27 PM

Will you post pictures?

zenon · 24th December 2005, 06:42 PM

please do post some type of picture or schematic. There are others "hovering"

safetyman · 25th December 2005, 03:01 AM

Quote:

Originally posted by rgrayton

The kit comes with 1500 on the rectifier board. I think it is generally a great kit, but requires much more uf, especially for the LM4780 4ohm parallel kit.

I just ordered a set of these LM4780 boards from Peter (Audiosector). Just to confirm, you like it better with the snubber PSU with the 10,000uf and above caps?

Would powering both the dual mono boards of a single transformer with 22-0-22 secondaries work and where would the sero tap be connected to? Is there a gound on the PSU board? I am planning to use this in a bridged cinfiguration. Sorry, noob here, but thanks for any advise given.

Merry Christmas.

zenon · 25th December 2005, 05:35 AM

safetyman,

From what I've read in these forums using one transformer is fine, you just wire both power supplies in parallel up to it. The thing you have to make sure of is that the total power (VA) the transformer can output will meet the needs of both amplifiers.

Also from what I've read, for those boards you need 300VA for ?each amp?
ie: for a pair of these boards you need 600VA total, correct?

safetyman · 25th December 2005, 03:09 PM

Quote:

Originally posted by zenon
safetyman,

From what I've read in these forums using one transformer is fine, you just wire both power supplies in parallel up to it. The thing you have to make sure of is that the total power (VA) the transformer can output will meet the needs of both amplifiers.

Also from what I've read, for those boards you need 300VA for ?each amp?
ie: for a pair of these boards you need 600VA total, correct?

zenon, thanks for the tip. An EI 600VAC transformer should not be too much of a problem. I can get one custom wound to that, in fact I am thinking of doing a 700 or 800VAC, but the 1500uf caps I mentioned earlier are the ones to upgrade to >10,000uf caps?

h_andree · 25th December 2005, 04:08 PM

I've added 132,000uF per rail (Cheap from apexjr.com) to
my BPA. When I tried this on a single chip it also helps compared
to 1000-2000uF/rail. I'm using a 625 Va transformer.

22nd December 2005, 03:58 PM	#1
rgrayton diyAudio Member Join Date: May 2003 Location: MA	More uf = better sound I don't really mean that, but adding 16.4Kuf/ch to a "Brian Board LM4780 PS" made a very positive and noticible difference to both the detail and transients. For a reference, the power output capacity jumped from around 89W to 116W with the change. Also, I did add in a little more PS filtering and reduced the grounds from the PS to the amp boards to a single wire. CDs auditioned were "Money for Nothing" (loud) and Rebecca Pigeon's Spanish Harlem on the Ultimate Demo Disc. Everything got better and now sounds discenable better, imaging, resolution, detail..., than my $2800 Yamaha DSP A1 (or whatever it is called). Just though I would throw that out there. -BG

25th December 2005, 04:08 PM	#10
h_andree diyAudio Member Join Date: Apr 2003 Location: New York	Agree I've added 132,000uF per rail (Cheap from apexjr.com) to my BPA. When I tried this on a single chip it also helps compared to 1000-2000uF/rail. I'm using a 625 Va transformer.

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23rd December 2005, 05:05 PM	#2
jaudio diyAudio Member Join Date: Oct 2004	What was the capacitance before? I added 15,000uf per rail(up from 220uf,that I used while testing) to my amp and everything balanced out. It also helped stabilized the voltage from the power supply. I did the 1000uf thing first and decided to keep the 15Kuf caps in.

23rd December 2005, 07:57 PM	#3
Cortez diyAudio Member Join Date: Dec 2002 Location: Hungary	> ... and reduced the grounds from the PS to the amp boards to a single wire. What do you mean on reducing ? Shorter GND wires between the PS and the amp ?

24th December 2005, 01:27 PM	#5
jaudio diyAudio Member Join Date: Oct 2004	Will you post pictures?

24th December 2005, 06:42 PM	#6
zenon diyAudio Member Join Date: Nov 2004 Location: here	please do post some type of picture or schematic. There are others "hovering"

25th December 2005, 05:35 AM	#8
zenon diyAudio Member Join Date: Nov 2004 Location: here	safetyman, From what I've read in these forums using one transformer is fine, you just wire both power supplies in parallel up to it. The thing you have to make sure of is that the total power (VA) the transformer can output will meet the needs of both amplifiers. Also from what I've read, for those boards you need 300VA for ?each amp? ie: for a pair of these boards you need 600VA total, correct?

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