Tweaking a Fuchs ODS50

[vibratoking]

I have a Fuchs ODS50 combo with single 12" Sugarcone. I like the amp alot, but I feel like someting is missing. It doesn't have any of the shimnmer on the clean channel that I have heard in some of the posted clips. In OD mode, it doesn't have much bloom unless I crank it to ear splitting volume. I have put in several brands of power tubes and tried different bias current values. I have gotten an improvement in the amp's sound, but it still needs tweaking to my ear.
Question 1 - do other D-style amps bloom at reasonable volumes or are the amps cranked hard in the clips I am hearing?

Question 2 - do any of you experienced guys think this is a good platform to tweak? If so, does anyone have any hints on where to start? I haven't opened the amp to trace a schematic. If I did, it would be used exclusively be me.

Also, I am aware that Andy offers a HT service and I don't want to step into a political pile of dung by asking these questions. I am just more of a DIYer and would like to work on this myself so that I can learn a few things as a precursor to some future amp builds. Perhaps I should just ask Andy directly how he feels about this, or he maye he will just reply here.

I have tried other speakers - Eminence Delta Pro, Mesa labeled EV12L, and Tonker. I don't believe the speaker is the issue.

Thanks in advance for any comments or recomendations.

[jelle]

Maybe shoot Andy a PM?

Or gut it and put in a Ceriatone board.

[Structo]

If your amp has a balance trimmer between the phase inverter plate resistors, I found after some encouragement here, that that does indeed add that note bloom and harmonics that can blend into musical feedback.

If you don't want to get into that, try several different tubes in the PI position to see if that will help it.

On my D'Lite has a 100K/ 110K and 10k trimmer currently on the phase inverter.

After I mess around with mine I can get it to bloom really well at high bedroom levels.

Another ingredient that seems to make a difference is that the amp has to be very well warmed up, like more than 1/2 hour of playing time.
I think that is because once the amp is warmed up well, it stabilizes and gets more musical.

Looks like you are aware that Andy posts here, maybe he'll throw you a bone and help you out.

[vibratoking]

Jelle - thanks for the 'gut it out' suggestion, but I like the Fuchs. It is still by far the best amp in my moderate stable -and I have some good amps. I value the Fuchs too much to violate it in that way. I would probably start a new build before I trashed the Fuchs. If I start a new build, I will still be left with the Fuchs which I feel could be improved. Whether it can be or not is another question.

Structo - thanks for the ideas. This is what I was looking for. Ideas based on the previous experiences of other amp gurus. I am hoping to put together a list of possibilities, proiritize them and then start the experiments.

Thanks again guys

[jelle]

I was not quite serious about gutting it....my bad.

Seriously, I would contact Andy and ask for his input. He knows his products best.

[vibratoking]

Whoosh... the sarcasm went right over my head. I'm a new guy here, so I am not familiar with the personalities...yet

[kingsxman]

Is this a newer ODS (i.e. SLX) or an older model? I had a similiar issue with mine not having much of a clean sound with the rock switch on. I did end up sending mine to Andy and it came back much better. Its not cheap though...

Have you tried preamp tubes?

[vibratoking]

This is a pre SLX. I have tried several preamp tubes without much success - JJ, Telefunken, and some vintage RCAs.

Andy's upgrades are a little pricey and I won't gain much knowledge about tweaking if I send it to him. Good to know that you got nice results from his tweak though.

[vibratoking]

This is a pre SLX. I have tried several preamp tubes without much success - JJ, Telefunken, and some vintage RCAs.

Andy's upgrades are a little pricey and I won't gain much knowledge about tweaking if I send it to him. Good to know that you got nice results from his tweak though.

sorry 2x post by hitting the refresh key i think

[kingsxman]

This is a pre SLX. I have tried several preamp tubes without much success - JJ, Telefunken, and some vintage RCAs.

Andy's upgrades are a little pricey and I won't gain much knowledge about tweaking if I send it to him. Good to know that you got nice results from his tweak though.

Mine had other issues also...so I was kind of in "must send" mode.
Mine is pre-slx also. I debated on just getting the slx mod done..but couldnt swing it at this time.

[glasman]

Send Dogears a PM, he has been in and tweaked a lot of Fuchs.

Mr SLX himself

Gary

[bluesfendermanblues]

My amp did not really bloom before I installed JJ ECC83S in all preamp and PI tube positions.

Have you tried to adjust the internal gain trimmer, down to around 9 'oclock?

[bluesfendermanblues]

My amp did not really bloom before I installed JJ ECC83S in all preamp and PI tube positions.

Have you tried to adjust the internal gain trimmer, down to around 9 'oclock?

[vibratoking]

Blues - thanks for the tips.

I have adjusted the internal trimmers. 9 o'clock is about where I have them, but pot values vary alot. Have you ever measured the resistance at the 9 o'clock pot setting? I tend to run the gain on the low side because I like the OD smoothness and the tone is better to my ear.

I haven't conducted a full test of V1, V2, and PI tubes. I'll try JJs as you suggest - also some others based on some threads that I read here regarding the more Dumble-like circuits. Did you finally arrive at a tone that you are happy with or are you still wanting more?

Also, I notice that there is zero bloom in the jazz setting. The only hints of bloom in my amp are in the rock setting. Is that your experience?

[bluesfendermanblues]

Blues - thanks for the tips.
I have adjusted the internal trimmers. 9 o'clock is about where I have them, but pot values vary alot. Have you ever measured the resistance at the 9 o'clock pot setting? I tend to run the gain on the low side because I like the OD smoothness and the tone is better to my ear.

I think my OD trimmer, at 9 o'clock, is 23k mesured from ground to center viper.

Blues - thanks for the tips.
Did you finally arrive at a tone that you are happy with or are you still wanting more?

Yes, my amp is a 50w, #124 design with JJ preamp tubes and its has a nice bloom in OD mode - both with and without the PAB boost engaged.
I'm mainly a tele/strat player and use a 1x12 Thiele cabinet with a EV12L.

Also, I notice that there is zero bloom in the jazz setting. The only hints of bloom in my amp are in the rock setting. Is that your experience?

IMHO the jazz setting sucks I never heard of anybody who used the Jazz setting and I think most (pro)builders put it on their amps, because Dumble did. And its got the be there in order for the amp to be reconised as a 'real' dumble amp.