Discussion in 'Tube Audio' started by ferninando, Mar 26, 2015.
whats the diff between a DPA30 and DPA 20 Packead Bell consol amp?
I have seen them both but can't remember which is which. I think one runs four 6BQ5 tubes push/pull each channel, and the other one runs only two 6BQ5's single ended each channel.
Don't quote me on that 'cause now I'm going to have to look them up.
its 10 better obviously
honestly, don't know.
The DPA 20 & 30 have the same tube line-up. Four 6BQ5 tubes, two for each channel in push pull. I own the DPA 20 and it has the tuner preamp which has to be powered from the power amplifier via umbilical connection.
Both pics are from e-bay. No affiliation!
First pic shows the DPA 30. It looks to be the same as the DPA 20 but has a different power transformer. Possibly this model didn't come with a tuner/preamp.
2nd pic is the DPA 20. Not my pic but I have the exact same amplifier.
one is ultralinear the other is not, is all I know. What makes it ultralinear.?
If you are referring to the amps on the bay, the one listed as ultralinea is actually not ultralinear. The guy probably doesn't know what he's talking about so be aware. You can look at the underside pics and see that it uses regular push/pull, plate to plate with center tap output transformers.
Packard Bell never made an ultralinear amplifier that I am aware of.
From Wikipedai. No affiliation!
"A pentode or tetrode vacuum-tube (valve) configured as a common-cathode amplifier (where the output signal appears on the plate) may be operated as:
a pentode or tetrode, in which the screen-grid is connected to a stable DC voltage so there are no signal variations on the screen-grid (i.e. the screen-grid has 0% of the plate's output signal impressed on it), or
a triode, in which the screen-grid is connected to the plate (i.e. the screen-grid has 100% of the plate's output signal voltage impressed on it), or
a blend of triode and pentode, in which the screen-grid has a percentage (between 0% and 100%) of the plate's output signal impressed on it. This is the basis of the distributed load circuit, and is usually achieved by incorporating a suitable "tap" on the primary winding of the output transformer that the vacuum-tube (valve) is connected to.
The impression of any portion of the output signal onto the screen-grid can be seen as a form of feedback, which alters the behaviour of the electron stream passing from cathode to anode".
yes cadman, those are the ones. only visable diff is the pwr trannys.
Thanks for clearing that up.
As long as we're on the subject, has anyone deciphered Bob Carver's mod on these that makes them $uper good?
I have a friend who has one , will try to get info from his.
Those look like Mullard output tubes, with very low hours. Not much nickel on the glass yet, just enough to tell the tale.
Have you or anyone else done anymore digging into the DPA-20, the DPA-30, or the Baby Silver Seven?
I have read the thread on "DC restoration" and it kind goes all over.... without a conclusion.....
Bump I am curious about these...
I have been learning alot... I have 4 of these, and I have a pair that have potted transformers that are a delight! I have only got them "limping along" but they sound as good as the Dennis Had amps I've owned...
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