Power Supply Caps Question

[wattsup]

I've noticed that the different style of Dumble amp all have different values on the two entrance caps on the power supply, ranging from 100uf to 300uf. Why the different values and such a wide spread of them and how does that affect the tone of the amp? Did HAD just use what he could get at the time, or are the values critical to each design?

[wattsup]

No one?

[ToneMerc]

I've noticed that the different style of Dumble amp all have different values on the two entrance caps on the power supply, ranging from 100uf to 300uf. Why the different values and such a wide spread of them and how does that affect the tone of the amp? Did HAD just use what he could get at the time, or are the values critical to each design?

Only HAD knows why he did what he did with the mains filters. I've always felt it was a little bit of both, but at the same time I don't think he picked many values by accident. The 50W's usually are found with 40-50uF or so, you will see 110uF and 160uF on the ODS 100W. Although some 4 output tube amps with MusicMan HV supplies can be found with only 50uF on the mains.

My 183 only has around 115uF and I don't think it gives up anything.

TM

[wattsup]

So best guess as far as HAD is concerned, the values are more likely tone related as opposed to a practical application then.

[ToneMerc]

So best guess as far as HAD is concerned, the values are more likely tone related as opposed to a practical application then.

The feel of the amp might be slightly different depending upon one's style and how the amp is setup, but in the grand scheme of voicing the amp, there are other things I would chase before sweating over an extra 50uF of filtering on the front end, particularly if the amp already has 110uF of filtering.

TM

[wattsup]

The feel of the amp might be slightly different depending upon one's style and how the amp is setup, but in the grand scheme of voicing the amp, there are other things I would chase before sweating over an extra 50uF of filtering on the front end, particularly if the amp already has 110uF of filtering.

TM

Ok thanks ToneMerc. That helps a lot. I was looking at Antique Electronic Supply and trying to determine what size caps to get for PS filtering on the front end. They have Sprague Atoms but only up to 100uf. There are also the F&T that go up to the 230uf and I think the JJ's go up to 230uf as well, but the Atom's seem to be more highly recommended.

[Max]

... but in the grand scheme of voicing the amp, there are other things I would chase before sweating over an extra 50uF of filtering on the front end, particularly if the amp already has 110uF of filtering.

AFAIK different opinons in regard to the effects of power supply performance on timbre have been published, too. Some examples:

"The timbre of a sound is also greatly affected by the following aspects of its envelope: attack time and characteristics, decay, sustain, release (ADSR envelope) and transients."

Source: http://en.wikipedia.org/wiki/Timbre

"Starting transients

A very important part of time are the starting transients: the short-lived sounds at the start of a note. These often contain substantial components that are not harmonics of the note. Broad band noise may be present, and the fundamental may be relatively slow to start. Without the starting (and sometimes finishing) transients, it is very difficult to recognise different musical instruments."

Source: http://www.animations.physics.unsw.edu. ... velope.htm

"The signal/spectral parameters related to timbral similarity/difference, as identified in a series of studies (Plomp, 1970 & 1976, Grey & Gordon, 1978; Kendall & Carterette studies in Hajda et all, 1997; etc.), have been described as:

a. signal time variance (envelope)
b. degree of attack and decay synchrony of the sine components;
c. presence or absence of high-frequency inharmonic energy in the attack portion of a signal;
d. spectral energy distribution (frequency, amplitude and phase values of the sine components of a complex signal - may change with changes in intensity and register, even for a given instrument); and
e. spectral energy distribution time-variance (spectral flux or "jitter")."

Source: http://acousticslab.org/psychoacoustics ... dule06.htm

Cheers,

Max

[hitchcaster]

I've noticed smaller values sound good with amp on low.... crank it and they sound like shit compared to bigger values... it just depends on the circuit and what your doing, and 50 vs 100w. stick with stock values on what your doing to be safe

[wattsup]

I've noticed smaller values sound good with amp on low.... crank it and they sound like shit compared to bigger values... it just depends on the circuit and what your doing, and 50 vs 100w. stick with stock values on what your doing to be safe

Thanks that's a good thing to know also. I guess it makes sense too though.

[talbany]

I've noticed smaller values sound good with amp on low.... crank it and they sound like shit compared to bigger values... it just depends on the circuit and what your doing, and 50 vs 100w. stick with stock values on what your doing to be safe

I too agree with this as well.. The amp overall seems to breath a bit more and feels loose .. Some notes/cords seem to want to hang and doesn't feel quite as choked at lower volumes with lower filtering on the plates.. At much higher volumes when the you start to tax the PS and sag begins to happen I prefer more filtering to keep things tighter (especially in OD)..Naturally the louder you play the greater the chance of acoustic coupling and therefore more sustain and feedback, but the amp stays tight..Dumbles were designed to be run at high volumes so there is no right or wrong,personal preference IMO!..My fave ODS is a 102 and has 50uf on the plates and is a 100 watts.. My master hardly ever get's to noon..

Tony

[Mark]

I think you also have to ask yourself questions about the pwr txer too. What can it deliver, can it handle the ripple current etc.

I think people notice the effect of power supply to a point.

[bluesfendermanblues]

I've noticed smaller values sound good with amp on low.... crank it and they sound like shit compared to bigger values... it just depends on the circuit and what your doing, and 50 vs 100w. stick with stock values on what your doing to be safe

I too agree with this as well.. The amp overall seems to breath a bit more and feels loose .. Some notes/cords seem to want to hang and doesn't feel quite as choked at lower volumes with lower filtering on the plates.. At much higher volumes when the you start to tax the PS and sag begins to happen I prefer more filtering to keep things tighter (especially in OD)..Naturally the louder you play the greater the chance of acoustic coupling and therefore more sustain and feedback, but the amp stays tight..Dumbles were designed to be run at high volumes so there is no right or wrong,personal preference IMO!..My fave ODS is a 102 and has 50uf on the plates and is a 100 watts.. My master hardly ever get's to noon..

Tony

...and since Dumble amps are supposed to be biased at 50% a pair of 6L6 will deliver (max per pair is 55-60W) only 25-30watt (plentyfull for most applications) and won't stress the PSU (and caps) as much as a higher biasing point.