F4 power amplifier

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hershann

Member
Joined 2007
I'm intending to use the Panasonic TSHA series 33000uF / 25V (x4) on Peter's PSU board. Any comments on this choice?

http://www.panasonic.com/industrial/components/pdf/pic_ts-ha_dne.pdf

What will the effect be if I populate another PSU board with another 4 of these capacitors (i.e. from transformer -> rectifiers -> PSU1 -> PSU2 ->F4 boards) will that be detrimental to the sound - due to increased lead length and inductance? Or might it improve the power reserve?

thanks

her shann
 
B

Blitz

Member
Joined 2002
I guess it depends on your setup. With two monos I would expect "only" a tighter bass. In Stereo, you would see a better holographic 3D-presentation due to better channel separation and as well a tighter bass.

The Panasonics are as well fine...but as Peter is pointing me to Jensens I will try to get those. I recall Peter's monster Boards with many, many smaller caps in Parallel, I am thinking about such a setup with some Silmics or Cerafines as well...would still be cheaper than using BlackGates as PSU-Caps.

Anyhow, I plan as well to use a choke, I guess the optimal setup is a small C-big L- gib C, so that you stress the transformer and the choke not to much, basically a mixture of a classical pi-filter and a choke-input-Supply.

Which kind of chokes / inductance are you guys using ?
 
H

hershann

Member
Joined 2007
hershann said:
I'm intending to use the Panasonic TSHA series 33000uF / 25V (x4) on Peter's PSU board. Any comments on this choice?

http://www.panasonic.com/industrial/components/pdf/pic_ts-ha_dne.pdf

What will the effect be if I populate another PSU board with another 4 of these capacitors (i.e. from transformer -> rectifiers -> PSU1 -> PSU2 ->F4 boards) will that be detrimental to the sound - due to increased lead length and inductance? Or might it improve the power reserve?

thanks

her shann
Click to expand...


Blitz said:
I guess it depends on your setup. With two monos I would expect "only" a tighter bass. In Stereo, you would see a better holographic 3D-presentation due to better channel separation and as well a tighter bass.

The Panasonics are as well fine...but as Peter is pointing me to Jensens I will try to get those. I recall Peter's monster Boards with many, many smaller caps in Parallel, I am thinking about such a setup with some Silmics or Cerafines as well...would still be cheaper than using BlackGates as PSU-Caps.

Anyhow, I plan as well to use a choke, I guess the optimal setup is a small C-big L- gib C, so that you stress the transformer and the choke not to much, basically a mixture of a classical pi-filter and a choke-input-Supply.

Which kind of chokes / inductance are you guys using ?
Click to expand...


I am talking about wiring the 2 PS boards in series to feed the stereo F4, not monoblocks. I guess the ideal is to have 2 transformer, 2 PS boards for seperate supply to each F4 board - but space is always a premium.

But i guess I can go the dual transformer route if there is a noticeable improvement - comments? [Of course then the two 400VA transformers will really be an huge overkill]

her shann
 
Peter Daniel

Peter Daniel

Member
Joined 2002
audiosector.com
Paid Member
hershann said:

I am talking about wiring the 2 PS boards in series to feed the stereo F4, not monoblocks. I guess the ideal is to have 2 transformer, 2 PS boards for seperate supply to each F4 board - but space is always a premium.

But i guess I can go the dual transformer route if there is a noticeable improvement - comments? [Of course then the two 400VA transformers will really be an huge overkill]
Click to expand...

If you use a single chassis, I would use a single transformer (2 PS boards with separate caps for each channel may be a good idea though).

If you have enough space in your chassis, you can alsways add second transformer later.
 
B

Blitz

Member
Joined 2002
If you want to go into the theory of PSU-Design, here is a nice tool:

http://www.duncanamps.com/

It is nice to see how bad the current peaks are, which stress the transformer. That plus the inner lower resisants plus some other parameters in theory should make an amp sounding better with a transformer being oversized at least by the factor 2-3x...a theory with which NAIM at least is charging their customers thousands of $$$ for a simple transformer upgrade with cist maybe small hundred $$$...
 
H

hershann

Member
Joined 2007
Peter Daniel said:


If you use a single chassis, I would use a single transformer (2 PS boards with separate caps for each channel may be a good idea though).

If you have enough space in your chassis, you can alsways add second transformer later.
Click to expand...

So that means - after the 2 bridge rectifiers I split the wires to supply 2 PS boards, each supplying a F4 board (i.e. parallel supply)

thanks

her shann
 
B

Blitz

Member
Joined 2002
OK, Here is a question to Mr. Nelson Pass:

Why is the current value 150R for the "grid stoppers" / Series resistors ?

I think there was as well a version with 100R and I think we have as well other designs from you with 221R ? So any reason to exactly use this one or would 100 R or 221 R as well fine ?

Best Regards
 
MikeW

MikeW

Member
Joined 2002
GRollins said:
Mike,
My brain has been eaten by the Cold Germs From Hell...there's something else that I should have mentioned above: Power supply.
Are the two amps running on more or less equivalent power supplies? It's not always easy to compare, especially if you're using different transformers, etc., but when in doubt throw another couple zillion uF into the filter. If can have a profound effect on the perceived bass response.
The Threshold S-500 came stock with 4 big computer grade caps, something on the order of 30000uF ea. Sounds like a lot. Worked pretty well. Then I got a wild hair and roughly doubled it to around a quarter-Farad per chassis. Improved the bass considerably. Just something to ponder as you're listening.

Grey
Click to expand...


They both have a 750 VA transformer and at least 60,000 uf per rail. I still have another 600,000 uf of caps hanging around. I guess I could put some more in.:smash:
 
apassgear

apassgear

Member
Joined 2002
GRollins said:
Mike,

The Threshold S-500 came stock with 4 big computer grade caps, something on the order of 30000uF ea. Sounds like a lot. Worked pretty well. Then I got a wild hair and roughly doubled it to around a quarter-Farad per chassis. Improved the bass considerably. Just something to ponder as you're listening.

Grey
Click to expand...

Farads are good up to a point, depending on the amp bias of course, but more interesting is cap quality, I do bypass the amps PSU with some oiled polyprops cans on the 40 to 80 uf range which are usually rated @ 370 VAC used for motor runs / power factor correction, besides that you may add some small film caps. I also use these caps for lineamps some 25uf bypassed also with small film caps (0.1uf) with outstanding results. YMMV, but I suggest you try them and have your ears be the judge.

:)
 
MikeW

MikeW

Member
Joined 2002
mpmarino said:
Mike,

Elementary question I know.....

Are they biased heavily enough for the load?

also. could it have to do with differing input impedances(etc) with respect to the preamp? just a thought...


(I haven't had the time to come close to completion on the '4' myself, waaayyy too much going on)
Click to expand...


Plenty of bias.
There are some bypass caps. I think I will add some more cap and re-evaluate.
I am not saying I don't like the F4, It just different from the ZV9.
The ZV9 may be the best Pass labs amp I have heard.

Mark, if you want to listen to either amp come and take them for a couple of weeks.
 
Babowana

Babowana

Formerly "jh6you". R.I.P.
Joined 2006
aheadamp.com
MikeW said:
I finished my F4 this week. I have been listen to it for a couple of days. It is being driven by my Aikido tube pre-amp. I switch in my ZV9 tonight and it has more bass. Do I need a different pre-amp to get more bass out of the F4?
Click to expand...


More bass . . . ?
What about the quality?

I also driving F4 with a tube pre (20dB).
I'm really satisfied with the bass quality.
(I don't have ZV9 to compare, tho . . .)



:darkside:
 
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