Power Supply Cap Banks

[kt88pppamp]

Anyone notice that if more capacitance is added in the power supply a greater bass definition is attained? The drawback, the highs and mids are muddled.

My amps with tube rectifiers all sound sweeter because you are forced to use less capacity in the filtering. They lack that powerful earth shaking bass effect though.

What are all you thoughts and feelings on this?

[kheper]

I think it becomes a matter of diminishing returns as regards to larger and larger capacitance and bass response. At some point, adding more just saps you wallet. Large filter capacitance can make your amp quite vulnerable to a voltage doubling effect, if the amp is switched off and on before the caps can drain. Below is an equation for the recommended minimum amount of capacitance,

http://tubes.nekhbet.com/power.shtml#fil

[kt88pppamp]

According to that equation, I am using two 68uF caps in series for the 5AR4 (34uF) and an 80uF and a 40uF after the choke. So there is 153uF. The equation says I need somewhere in the ballpark of 260uF of capacitance. Would that be too much for a 5AR4?

[kheper]

According to that equation, I am using two 68uF caps in series for the 5AR4 (34uF) and an 80uF and a 40uF after the choke. So there is 153uF. The equation says I need somewhere in the ballpark of 260uF of capacitance. Would that be too much for a 5AR4?

As long as the first cap off the rectifier is no larger than 60uf, 260uf in total is fine.

http://tdsl.duncanamps.com/show.php?des=5AR4

Cout = 60

[kt88pppamp]

Will change out that can cap for a cap board of some kind. Having minor ground loop issues with it anyways in one of the blocks. Good to hear.

[soundbrigade]

I built myself a pair of small horns using Sonido's 5" fullragers, while my friend used the 6 1/2" drivers. Comparing our speakers gave me a hint that mine lacked a bit in the low end, while my friend's spekaers lacked mid and high end. The explanation from Sonido was that the extended freq range sort of "masked" the mid/high range.
I guess that's the same with the cap mystery. The more lows you get the more you feel that you loose the mids and highs. But I am convinced that they are still tehre but as I wrote, you hear the low notes and thing you have lost the top.

[kt88pppamp]

So you believe that if you are feeling the bass more it distracts you from enjoying the mids/highs. The only way I could verify that is a a bi-amp system where each range can be controlled.

[soundbrigade]

That's my belief. I see reason why a bigger cap bank would affect the mids and highs. Why not set up a microphone and a frequency analyzer.

[Geek]

What's affected is supply impedance. The same reason different rectifiers have their own sound.

If you want great mids, IME, use a 5U4-G with traditional C-L-C (say 47uF, 10H, 47uF).

With tube amps, IMO, it's best to leave caps low (47uF or less) and play with grievous amounds of choke
(scientifically, the end result is the same and LOTS easier on the rectifier)

Cheers!

[20to20]

I think the goal is to make something that is small, ...bigger.

If the power transformer doesn't provide the requested (power to the outputs) because the driver signal is too big for its rating, then no amount of added filtering is going to improve the quality of the output signal. The transformer is underrated and can't provide the power, period.

If the power transformer can supply all the needs because it is rated large enough, then if adding more first filter capacity improves the sound quality, that indicates that there wasn't enough filtering there in the original design. Sound quality improvement defined by how much closer the output wave form shape is to the original input wave form. If your drive signal asks for more power than the filter can supply, then you need more filter, or less input. No mystery.

If you ask the rectifier to carry more current than it is rated for (capable of providing), then your output wave form will suffer. No amount of added filtering will compenste for that either.

Each amp's qualities are a case by case situation. If the small thing we want larger looks like crap, it's because the power supply design was lacking in the first place.

Saying that any particular rectifier sounds better than any other, is just more phoolery that doesn't keep the bigger picture in proper perspective.

20

[Geek]

If the power transformer doesn't provide the requested (power to the outputs) because the driver signal is too big for its rating, then no amount of added filtering is going to improve the quality of the output signal. The transformer is underrated and can't provide the power, period.

Yep!

There's no free lunch. If you need more current, you'll have to sacrifice voltage (think choke-input filter). Conversely, if you need voltage, you'll sacrifice current.

Best way to calculate it is VA rather then voltage, etc.

Saying that any particular rectifier sounds better than any other, is just more phoolery that doesn't keep the bigger picture in proper perspective.

Supply impedance is a measurable phenomenon and does affect sound

Cheers!

[20to20]

Saying that any particular rectifier sounds better than any other, is just more phoolery that doesn't keep the bigger picture in proper perspective.

Supply impedance is a measurable phenomenon and does affect sound

Cheers!

Geek,

The way I see the load on the rectifier contributing some unwanted influence on the output signal is if the load is pushing the rectifier to its limit and filtering is just adequate. If the load is under that then the filtering will "cover" any rectifier signiture. The first cap will always provide the filtered power and any rectifier impedance is no longer a "signiture" in the output. The filter "blinds" the output circuit to the rectifier no matter what its impedance is.

Go Hawks

EDIT...

So if a rectifier change does actually "improve" the sound, (once again defined as an output wave that more closely matches the shape of the input wave) because the new rectifier provides more power throughput without strain, then that indicates the original design was marginal, power demanded vs. power supplied. Anyone can ask their amp to do too much, if they've never done the figuring... then take a potshot tube roll and suddenly find the magic pill that "sounds much better than tube X in the "mids and highs or tightens up a muddy bottom..."

[Geek]

Improve the sound? No, no, no... just different.

And have you tried it? The sonic difference on say a ST-70 is noticeable.

I was like you, shouted it down... then I tried it and nearly crapped myself

Cheers!

[DeathRex]

Well then would a 5U4 with more resistance and drop, sound better or worse than a 5AR4?
It seems with a loud volume a 5U4 will drop B+ and lower the signal or round the peaks, kinda a compression effect.

[Geek]

Swap and try, all I can say.