Questions about "Final ODS-101 Schematics" post

[ic-racer]

First off, thanks for posting these schematics, they are 'enjoyable reading.'

First, for the 3 schematics, am I correct that the one "ODS-101" contains all the info for both HRM and NON-HRM? Is that why there are 3 schematics?

Second, where is the input jack? Is there another schematic for this part of the amp?

Third, is there a thread that explains the genesis of this schematic (or should I not ask)? Has anyone ever heard an amp made with this 'exact' schematic or is it a new recent creation? Historically, where would this schematic fall. ie Jackson Brown 70s, Stevie Ray 80s, 'Talk To Your Daughter' Robbin Ford 90s, or modern Santana/Carlton etc?

Fourth, what are the 3 little round symbols near the output tubes?

Again, good work!

[Fischerman]

Yes, the ODS-101 covers both HRM and non-HRM in one schemo. The other two are just the individual HRM and non-HRM schemos. They are supposedly some of the more accurate schemos around here to 'real things' but I have nothing to back that up other than hearsay.

Input jack is up at the top left it's just not shown. The 22K grid stopper and 1M ground reference are shown. Standard input jack stuff.

Can't help with the history except to say that SRV's amp was a Steel String Singer which isn't quite like an ODS. More of a high-powered clean amp.

The round symbols near the power tubes are just bias test points if you choose to have them. They're all the rage these days.

[ic-racer]

Input jack is up at the top left it's just not shown. The 22K grid stopper and 1M ground reference are shown. Standard input jack stuff.

I was curious about the "FET" input, or is that essentially useless for solidbody guitars?

[Structo]

I believe Alexander included the FET input for acoustic guitar.
Rumor has it that Robben Ford put a piece of tape over this jack to prevent his tech from accidentally plugging into it.

[ampdork]

Kimock uses it with his cripes guitar because the PU are out of phase with the rest of his guitars. This keeps the output phase relationship the same at the speaker.
This all leads back the debate about imaging and usch in regards to phasing. It has been done to death at TGP and here as well I think. While not everyone feels it is important there are a number of well respected player for whom it does make a difference.
So while acoustic instruments is what it was made for it can have other uses.

[Bob-I]

HiGain did an amazing job on these schematics. They're not intended to be an accurate Dumble, but a compilation of ideas shared on this forum around making a good sounding Dumble inspired amp. In fact everything I've read about Dumble leads me to believe that every amp he makes is unique.

The real key to making a great sounding amp is to let it speak to you, and make adjustments accordingly. Often a simple change in lead dress will change the amp dramatically. Look at the pictures posted and follow your ears.

[ic-racer]

HiGain did an amazing job on these schematics.

Agree; I have noticed how the tidbits of expert info can be spread out over hundreds of posts. Its great to have all the good ideas in a single schematic.

On a more pragmatic level, which is better starting strategy:

A)Start project as Final ODS-101 or
B)Start with 124 and if it needs tweaking, use ideas in Final ODS-101 as needed?
C) other??

[mlp-mx6]

Better for achieving what? Have you read the descriptions of #124 and the attempts to recreate it?

I would recommend the 101 schem - but pick either HRM or Non-HRM, they're a little easier to read.

[ic-racer]

Better for achieving what? Have you read the descriptions of #124 and the attempts to recreate it?

I would recommend the 101 schem - but pick either HRM or Non-HRM, they're a little easier to read.

I am still figuring all this out, but I thought I read that #124 was a good sounding amp (some post by Gil I believe) and read a post by someone else that started something like "I built a copy of #124..."

In terms of 101, I have not seen any post of anyone who built one or a description of what it sounds llike.

I must be missing something if you are recommending building 101. Is there a thread you can point me to on whats wrong with 124? I did a search on 124 one day but there were so many hits I don't think I read them all.

[mlp-mx6]

"Conventional wisdom" is that the 100K/1.5K makes for nicer clean tones, but not as rich in the OD department.

ODS-101 still has nice cleans (though perhaps not as nice as 124) but smoother OD.

Either will be nice.

My point is that 124 is one specific Dumble (realizing that all of them are tweaked, likely no two exactly the same) whereas the ODS-101 values have come from much tweaking by many folks.

Also - realize that you will likely be tweaking at the end of the build, regardless of which schematic you choose to follow. Good luck!

[ic-racer]

Either will be nice.

Thank you, I wanted to make shure I wasn't making a mistake by going the 124 route.

My background in tube amps comes more from 'fixing' and 'repairing' rather than 'modding' so my mindset has always been that of trying to maintain original specs on my previous projects.

From what I have read, I am shure a lot of people on this board can improve 124 just by looking at the schematic. For me, part of the entertainment value of this project (this is just a hobby) is 're-inventing the wheel'. Like, I have 10 amps, I really don't need any more but I don't know what changing resistors to 100K will sound like so it will be a learning experience.

I just ordered my first parts today; once I get something to take a picture of I'll probably start a new build thread.

[ryanf]

As long as we are on the subject of the ODS 101 Schematic, is the wire with the 22 M resistors meant to "jump" or connect with the wires going from the top and middle of the bass pot? I'm having trouble visualising everything.
Thanks in advance!

[ic-racer]

As long as we are on the subject of the ODS 101 Schematic, is the wire with the 22 M resistors meant to "jump" or connect with the wires going from the top and middle of the bass pot? I'm having trouble visualising everything.
Thanks in advance!

I believe there IS a connection at those two crossing points. Check out the "#124 schematic rev 2" for another view of the same (though that schematic has a somewhat confusing line indicating the two poles of the DPDT jazz/rock switch). Also check out the Ceriatone Overtone layout. They all show the same connections in their own way.

[ryanf]

Do you happen to have the link for #124? I cant seem to find it.

[dobbhill]

Try this:
https://tubeamparchive.com/viewtopic.ph ... hlight=124