102 v 124 v 183 v 3rd Gen differences

[Lycoming360]

Greetings Masters of the Overdrive!

I've been an amp builder for the past 5 years, mostly building Fender type circuits, but now "need" to venture into Dumble territory.

aaelectronics has a board that allows the builder to construct a 102, 124, 183, or 3rd Gen amp. So which one to build? This being the pre-eminent forum for constructing HAD inspired amps, I thought I'd ask:

What are the sonic differences between these pre-amp circuits? My guess is the differences will be subtle. Is there one of the above that is more versatile? One to avoid?

How useful is the JFET input?

In all likelihood, I will use a low power PA section, with either 2x5881 or 2x6V6 (I just don't need or want the power beyond that).

All opinions / thoughts welcome. Part of the reason I want to do this is for the challenge -- these are really complex amps.

[fred.violleau]

Welcome to the forum Lycoming360,

There are numerous posts about the different ODS and I suppose listening to the artists that have recorded with those amps would be a great way for you start and forge an opinion on what you would prefer and why.

As always with a switching channel ODS, there will be compromises between the clean and the mean channel, as they usually (HRM excluded) share the same EQ.

Here is Tony Albany's thoughts (and experience) with some of the amps you asked about :
"The closest you will get to an AB-763 Blackface Clean sound and feel would be a Low Plate Classic (wDeep switch)
This will give you that classic scooped low plate 100k slope .047 mid cap Fender tone
If you want more mids (500Hz)push I would go Low Plate Skyliner (124)

High Plate Skyliners 102/183 amps seem to have a flatter Treble control heavier bass response and different gain structure and so it will sound and feel different than your Typical Blackface Fender. 183 has has a more Marshall style output section..
I do however prefer the OD of a high plate w/ thicker mids but this is personal
The 2nd and 3rd Gen amps are also Fender like but are again more mid heavy (.01 Mid cap /250k Mid pot) and a bit more raw sounding OD.

A few other thoughts would be to put the NFB on V1 (ala #102) on a switch to disengage it, if it gets in your way and remember your tone will change given your parts selection so there is always that

BTW. Which is Better?...All the amps listed are legit and are designed for different sounds and applications or guitars. The 102 amp is popular amp here and a bit more forgiving but doesn't really remind me of a typical Fender BF type amp (like a Classic) "

Here is the link to the thread:
https://ampgarage.com/forum/viewtopic.php?t=33795

#102 is refered to as a "bright amp" compared to 124 or 183, it has snubbers on V2 and uses 6L6s but 183 (has snubbers on V2 as well) uses EL34

You should study the schematics and simulate the EQ response in the Duncan simulator. It may help you decide between those 3. And again, every amp was tailored for a player and his instrument in mind, so there differences (LNFB on V1 for #102 as an example).

Then using 6V6 is possible and there again numerous layouts in the file section for that. It seems thought that part of the charm of the ODS is its strong punchy and clean output section, so you can push the preamp into compression and distortion while maintaining a clear output section, probably to keep the subtle overtones and not squash everything on the output stage.

The master volume works great on those amps, but IMO you need to play a decent volume (above bedroom level) to get a good tone. So if you plan on using the amp at home 6V6 is probably a nice option. If you plan to use it live, it may come short without a PA.

My 2 cents here!

Have fun on your journey!

Fred.

[Lycoming360]

Thank you for the reply. Exactly what I needed! If nothing else, the nomenclature (eg, 124=Low Plate Skyliner) is incredibly helpful.

I've been over the schematics, and haven't decided between Skyliner or 3rd Gen.

[romberg]

How useful is the JFET input?

I find the FET input very useful. I have guitars with both high output hum-buckers, P90s etc and lower output single coils. If you set things up to sound good gain wise with the higher output pickups then the lower output ones don't cut it. But I've been able to dial in the FET gain to make my single coils hit the first tube gain stage about the same as the higher output pickups.

Of course you could do this all with a clean boost in front of the amp. But then you have to mess around with all the extra hassle pedals involve. Nice to have it built right in.

Mike

[pfarrell]

@Lycoming360

Did you decide on what to build?

I too have @frusciante89's Dumble board on order...mostly because it's something different and offers some simplicity factors. I'd like to build an EL34 based amp—having scratch built 5 other Fender designs....#183 for me I think in Dumble land...

Thank you Fred for the rundown—very helpful.

[Guy77]

The Low plate classic with the Deep switch is my favorite. Can't go wrong with this one!
I actually find the Deep switch more useful than the Rock/Jazz switch. I always keep the switch in Rock mode but with the Deep switch I find I enjoy both settings.


Cheers
Guy

[Lycoming360]

Did you decide on what to build?

I decided to build a "hybrid" of #124 pre-amp, coupled with a "low power" 6V6 output section (using the "3rd Gen" circuit). I may have to dial down the volts later in the build, we'll see.

Frusciante89's schematics and layouts are well done, and the schematics allowed me to easily compare the different circuits. His PCB is well done.

I've been working on the chassis, getting holes drilled, and am about to do the PT cutout.

[chaccmgr]

Hi Lycoming360,

did you finish your project? I'm considering to build a similar one to the one you described,,,
I am curious about the outcome, esp. the 6V6 power amp.

BR
Robert