Dumble Bargain

[Suckseeder]

https://reverb.com/item/51444840-dumble ... p1nWxQp0W4

[talbany]

OHH!! This is COOL! (Caps say 1976)

Oddessey.jpg

klfdgxk4sndtg0h8rhsx.jpg

d6uwpk4jjt3tzcmgebuq.jpg

Tony

[martin manning]

Very cool indeed! thanks for posting!

[Suckseeder]

regarding the Phoenix Preamp,there‘s a control labeled ˋ Taper‘ ,any ideas what it does?

[martin manning]

The term taper has been used for a high frequency cut (treble bleed, post-OD. Its location on the panel would support that.

[Suckseeder]

thank you,that makes sense

[Mr. dB]

Too bad there's no gut shot of the preamp.

[wokkel]

Here is the link to the 'scrapbook' the reverb ad mentions, with extra information from the owner

https://myalbum.com/album/5WtZHuNfc8pUWk/

[Max]

The term taper has been used for a high frequency cut (treble bleed, post-OD. ...

Correct: " ... Overdrive Controls: level, ratio, with internal trigger & h.f. taper ..."

source:

4th generation classic ODS 100W data sheet.jpg

Here's another example (ODS150W #0121) of those four overdrive controls on the front panel: trigger (silver ring in the "level" location), taper (Marshall-like knob in the "level" location), level (silver ring in the "ratio" location), and ratio (Marshall-like knob in the "ratio" location)

ODS 150W #121 - with 4 OD controls.jpg

[pottedplant]

10.jpg

Interesting that the tube pairs are oriented in this manner, I tried to double check by looking at the internal view wiring but it's kinda hard to see. Did Dumble wire this amp to be paired as such or did the owner misunderstand Dumble's instruction when pulling 2 tubes for half power?

[ijedouglas]

I doesn't matter, as long as you don't pull V4 + V5 or V6 + V7

[martin manning]

Any combination with one tube on each half of the OT primary should be equivalent:

[pompeiisneaks]

and the basic rule is this:

you have two halves of the push pull amplifier. Both sides need one tube to operate. You do adjust the plate impedance when you do so, but it will still function without any negative impact to the circuit or tubes, it will just not sound the same.

If you leave one half without tubes it's bad juju.

~Phil

[Max]

... (Caps say 1976) ...

To be exact (from left to right): 2 x MIEC 200uF/300V without a visible date - 2 x TVA 20uF/500V 1975 - 1 x TVA 20uF/500V 1976

[talbany]

... (Caps say 1976) ...

To be exact (from left to right): 2 x MIEC 200uF/300V without a visible date - 2 x TVA 20uF/500V 1975 - 1 x TVA 20uF/500V 1976

To be even more exact?
I wasn't dating the caps? I was dating the amp (using the most recent cap date as a reference)

Tony