ODS #020 for sale on Reverb

[dbharris]

Happy Thanksgiving y'all!

ODS #020 showed up for sale again on Reverb here 1980s Dumble Overdrive Special https:// ... t=76212312

Tony previously posted a gut shot of this amp on page 2 of this thread https://ampgarage.com/forum/viewtopic.p ... lit=%23020 and posted below for ease of reference.

Dumble.jpg

This amp is also in the Dumble Book. All of the places mention that it has a built in effects loop and that of the original controls (later updated by HAD it appears), some were moved but the circuit was not changed. It is unclear if HAD or someone else did that work (changing and moving the switches, pots, and on/standby/off etc.).

Mid and Deep switches are interesting. Is the midcut the presence control or a vox style cut? If not, is the mid switch the accent? Would volume 2 be the traditional Master and Level is the output of the loop?

Where is the 4th noval tube? Or is this a solid state loop?

Is this the stiffest filtering in a documented amp...550uf?

Anyone have more information on this amp?

By the way, this amp is documented in the online archive with a loop, but perhaps without some of the other mods and before the new (non-HAD cabinets) and faceplates.

https://thesubjectmatter.com/dumblearchive.html

-Dan

[jabguit]

I think it would have 275uF filtering as they're series wired.

cheers,

[dbharris]

I think it would have 275uF filtering as they're series wired.

cheers,

Yes, that is correct. I was referring to the value of each cap and should've been more clear.

My thought was that a 100W ODS would usually be seen with 2x 220u or 2x 330u in series. I am sure there are amps that deviate, but 2x 550u is quite a bit more filtering. Just seemed like an interesting detail.

-Dan

[ijedouglas]

I think it would have 275uF filtering as they're series wired.

cheers,

Yes, that is correct. I was referring to the value of each cap and should've been more clear.

My thought was that a 100W ODS would usually be seen with 2x 220u or 2x 330u in series. I am sure there are amps that deviate, but 2x 550u is quite a bit more filtering. Just seemed like an interesting detail.

-Dan

The caps look replaced so maybe the tech didn't have the correct values???

[Guy77]

I noticed original Reverb link that was posted wasn't working so I posted this one below.

https://reverb.com/item/76212312-1980s- ... ve-special

Cheers
G

[beasleybodyshop]

I see zero dumbelator in that amp. no extra tube, no controls.

Listing claims it has a built in dumbleator....

hmm.....

[martin manning]

And what's up with the plastic plate covering most of the back panel?

[beasleybodyshop]

Seems like at some point they had a new rear plate made to cover up a bunch of holes and other things that were changed around.

[martin manning]

Originally a 50W combo, now a 100W head. Possibly a mix of old and new photos gut shot, Dumble book, pre/post conversion(s). https://www.dreamguitars.com/shop/uncat ... -50w-0020/

[dbharris]

I noticed original Reverb link that was posted wasn't working so I posted this one below.

https://reverb.com/item/76212312-1980s- ... ve-special

Cheers
G

Thanks Guy!

[dbharris]

If you look at the picture of the back of the amp in the online archive before it was updated to it's current format, you can see two small black and green knobs for the dumbleator where the loop jacks are. You can also see what looks like 4 octal tubes and 3 noval tubes in the normal places. Maybe HAD only had a chassis on hand with 50W screen printing on it or customer changed their mind.

I am still not sure where the loop tube was hiding back then and it does appear to be removed now. Very strange that they would advertise a $200K amp and get basic info like that so wrong.

-Dan

[beasleybodyshop]

To be charitable, my guess is the current seller has very little clue, and is taking information from the previous owner. Why would they know? This group here knows more than anyone how these amps work and should look. Based on the gut shot of the chassis above it doesn't have a loop, unless someone can show me where it's hiding lol.

[jelle]

3 preamp tubes: this means either no: Cleans, OD, PI or loop. Take your pick, lol

[beasleybodyshop]

For what its worth, I asked the seller to clarify the loop situation. This was their response:

"Based on the info we have from previous owners, there was a dumbleator installed. I was skeptical of this, and tested the preamp out, and sure enough its a buffered effects loop. There are a few articles out there that mention this amp having it as well. Albeit a bit vague and veiled in mystery as per the usual Dumble Mojo."

I don't think they actually know.

[GAStan]

For what its worth, I asked the seller to clarify the loop situation. This was their response:

"Based on the info we have from previous owners, there was a dumbleator installed. I was skeptical of this, and tested the preamp out, and sure enough its a buffered effects loop. There are a few articles out there that mention this amp having it as well. Albeit a bit vague and veiled in mystery as per the usual Dumble Mojo."

I don't think they actually know.

A very diplomatic (non)answer