#54 (photos)

[Charlie Wilson]

Here are some photos of a nice 70s amp I had the chance to visit with for a while(this was a few years ago).
CW

[Structo]

Cool!

Any history with this amp?

Maybe there should be a Dumble registry with serial numbers.

[ToneMerc]

CW, thanks for sharing! I see a couple of things that I had not seen before.

TM

[Deric]

Thanks for sharing.

[Luthierwnc]

Again, the EVM12S comes up.

[ToneMerc]

The longer I stare at it, the more I think it deserves it's own a layout.

Thanks again CW

TM

[Aaron]

Cool!

Any history with this amp?

Maybe there should be a Dumble registry with serial numbers.

I started one a couple of years ago. I never received any other info on amps that I already had.

http://ampgarage.com/forum/viewtopic.ph ... ight=aaron

And thanks for these Charlie. All your pics have been great.

Aaron

[dcribbs1412]

Very cool
Thanks Charlie



Agree with TM
a few different changes from the original layouts from Tony
FET board looks like it says 1972?

D

[Charlie Wilson]

Hello, this amp was brought to me for a new set of power tubes to be biased and a footswitch to be made. The owner told me he purchased the amp from kind of a hippy guy and they did the transaction on the side of the road half way to Northern California. I don't have any info about the original owner. At the time I took these photos(about 6 years ago) I didn't know much about Dumble amps but I thought I may regret not having photos one day, so I took some shots. I wish I had done a layout but that's ancient history now. I have a few more shots I could post, I didn't want to bog down the server. Oh yeah, that EVM12S speaker is not original. It had an Altec in it but the owner did not like the sound of it. The amp sounded great. I turned the knobs trying to get a harsh sound out of it but I couldn't.
Nice and chimey with a nice medium gain warm sounding overdrive.
CW

[Max]

I see a couple of things that I had not seen before.

Of course: different serial number = very high probability for a (more or less) different circuit. At least up to now I personally don't know of two Dumble amps with completely identical circuits.

FET board looks like it says 1972?

AFAIU "1972" next to a copyright symbol (C in the middle of a circle) on one of the (usually: preamp) boards of an ODS amp doesn't mean "this specimen of an ODS amp was built in 1972" but means: "the more general architecture of this kind of circuit was 'invented' and 'copyrighted' in 1972".

Cheers,

Max

[martin manning]

I have a few more shots I could post, I didn't want to bog down the server.

Don't be silly! I'm sure there is plenty of space available for such things.

[marcos]

Very cool, Charlie,
thanks for sharing. The amp looks very familiar to me,
typical 3rd generation amp with "fiunky od entrance". Right away,
I noticed some differences: LNFB loop on V1b, balance trimmer in the PI
section, tone stack might be 250k /250k / 1 M (T/M/B).I
will dig deepeer into this when time allows

Marcos

[marcos]

Sorry, I was wrong about the LNFB,
looks like the orange drops on V1b and V2 bypass the grid stoppers.
I was unable to decipher the values, anyway, something I have not seen before, wonder if this is original. Also, obviously, original e-caps
were replaced .
Looking forward to your contributions, I am in a hurry now,
see you later

Marcos

[Tubetastic]

You're a very cool dude charlie.

[UltraHookedOnPhonix]

Cool shots, thanks Charlie!

Those three 68K/.005uF "treble-peakers" (break freq 468Hz) on grids of CL2, OD1 and OD2 should carve out plenty of bass. I've only seen this type of HPF setup in one other amp.

Slightly unusual to see these earlier OD Specials in a 100W config no?

Also, nice to see it's been very well-maintained by previous owners. Clean as a whistle.