Precision Power Supply Question

[jelle]

Does anyone know when the transition was made from 'original' power supply to precision power supply?

My guess would be around 1987.

[talbany]

Fascinating discussion guys.

I have experimented with adding lots of capacitance on the power tube filters and it does change the "feel" of the amp.

Over filtered amps seem to be sort of less lively or bloomy. (if that's a word)
One author described the power supply of a tube amp as the heart and soul of the amp.
Probably because we are taking that current and voltage and amplifying it with a modulated signal riding on top of it.

Goes to show that there are a lot of opinions on ratings, ESR and voltage.

Perhaps the current data on E caps does not correspond well with tube amps since most solid state devices don't develop a lot of heat, with the exception of power devices such as power amps.
Although there are series of capacitors that are made to withstand higher temperatures.

As Aluminum Electrolytic capacitors age, heat and ripple current, the ESR (Equivalent Series Resistance) increases.

The higher the ESR gets, the higher the temperature generated inside the capacitor.
This is why we use balancing resistors on capacitors connected in series.
This helps equalize the voltage and leakage current through the resistors.

Capacitors have a lot of properties most of us gloss over.
At high enough frequencies, the capacitor will actually start looking like an inductor.
The frequency at which the capacitor transitions from looking capacitive to inductive is called the self resonant frequency.

Here is an interesting paper about it.

Something else to consider with respect to filtering..
a difference in AC line frequency
(60Hz in the US and 50Hz in Europe, for example) also has an
important impact. Converting between 120 and 230 volts is not difficult.
Converting between 50 and 60 Hertz to achieve a particular tone
dynamic is a whole different story!

So trying to get that JTM 45/Clapton tone out of a 45 plugged into an outlet in the US would not sound the same..

I never cared for the PPS either..
Tony
_________________

[David Root]

Looks like I will keep the PPS for a 183 build, I think, and build a classic PS for this 102. Thanx to all for your advice and comments.

[Structo]

Thanks Tony!

I think a lot of us that don't do this stuff for a living don't realize how important the power supply is for a good sounding amp.

It can and certainly does affect the way an amp feels and sounds.

[talbany]

Thanks Tony!

I think a lot of us that don't do this stuff for a living don't realize how important the power supply is for a good sounding amp.

It can and certainly does affect the way an amp feels and sounds.

Tom
Your welcome!!

Check out this cool experiment done on an old Bassman!!

The trick is to filter the amp just enough to eliminate hum and ghost notes and leave the harmonic content and touch sensativity or sag be.. (Marshall knew this early on)
This could partly be the reason why some people prefer the Fender clean over the Dumble clean..(A little to stiff/sterile)more than double the filtering (over kill in my opinion) Although the balanced PI helps retain Bloom/feedback!!
Dumble obviously does this to keep the amp tighter (in OD) at high volumes, I would think..



Tony

[vibratoking]

Thanks for posting that Tony. I haven't seen that before. Very interesting experiment. Thanks, now I must go rip out my PPS and put in a saggy, ripply replacement. And all this time I thought it was the grill cloth. I guess my next product is a 60 to 50 Hz line frequency converter.

[talbany]

Thanks for posting that Tony. I haven't seen that before. Very interesting experiment. Thanks, now I must go rip out my PPS and put in a saggy, ripply replacement. And all this time I thought it was the grill cloth. I guess my next product is a 60 to 50 Hz line frequency converter.

I guess my next product is a 60 to 50 Hz line frequency converter.

Your worse off than me.

Tony

[Structo]

Cool article

Conclusion:

The WILDCAT team concludes that AC ripple present in the power
stage represents much more than just noise. Its modulation of the
output appears to have a significant effect on the Bassman's sonic
character.
As important as this result is in itself, the team goes on to conclude that
if ripple is tonally significant, then a difference in AC line frequency
(60Hz in the US and 50Hz in Europe, for example) also has an
important impact. Converting between 120 and 230 volts is not difficult.
Converting between 50 and 60 Hertz to achieve a particular tone
dynamic is a whole different story!

[rogb]

Hopefully I'll be building in some character next week sometime. Thanks for the info guys.

[talbany]

I suppose one could look at filter voicing similar to that of Global NFB.. (harmonic content,flatter response,tighter..etc)

Note to self..Hi/ low power filter switch..

Tony

[67plexi]

Tony, Thank you that would explain why My #183 builds sound so good Marshall plexi values
on the filter supply. Time will tell with this SSS #001 build 50uf-50uf filters.

Best regards, Steve.

[talbany]

Tony, Thank you that would explain why My #183 builds sound so good Marshall plexi values
on the filter supply. Time will tell with this SSS #001 build 50uf-50uf filters.

Best regards, Steve.

Probably that and those nice radial caps you have on the screens and Pre..I think that is a part of the problem with the PPS..Using those cheap radial's (especially those Xicons) I don't care for at all!!
Also you know how to build an Amp..

Time will tell with this SSS #001 build 50uf-50uf filters.

I wouldn't worry about it..How many 100w Twins that sound and feel great have 40uf..A loud clean bright amp your going to welcome some give..

Tony

[Structo]

That looks great Steve!

[ic-racer]

Check out this cool experiment done on an old Bassman!!


Tony

Great post Tony. I'll have to read it through a few more times. Any more info on the circuit they used.

Of course the Manzamp is a Bassman + Precision Power Supply project and this weekend I'm planning on testing out some different dropping strings. After reading that I'm also going to check how much AC ripple I have at each stage.

[LeftyStrat]

The only disappointment for me with that study is why they didn't take the next step and try to re-inject synthesized ripple, both at 50Hz, 60Hz as well as other frequencies to see how it affected the amp.

What would be the result of having the ripple be at a multiplier of standard tuning, say 55Hz?