Low volume/gain/loose bass? Try changing your H11F1s

[ramalhais]

Hi,
I have a second hand Ultra XL module which had problems:
- almost no distortion even at full gain
- if i strummed real hard on the guitar i could hear some weird and loud distortion/clipping. This was more noticeable at low gain.

I thought that if the clipping is happening even at low gain levels it must be happening in the circuit, before the gain control.
Tried measuring and resoldering all of the resistors. Also tried to change the anode capacitor on the first gain stage with no results.
Then i changed the input H11F1 (OP1) and behold! Beatifull and powerfull UltraXL sound!

After this i thought, well let's try it on the SL+ and sure enough, i now have a lot of gain and the module sounds more open and with great attack/aggressiveness. Also, the bass is now very tight/focused.

So, if you think your module has low volume/gain and seems like it has a blanket over, try changing the H11F1.
The ones i bought were from china:
http://www.ebay.com/itm/10-PCS-H11F...397806?hash=item56669795ee:g:Dw4AAOxyUylTWGPo
6.68EUR for 10 pieces.

Now for the reason i can only speculate: maybe the H11F1s get tired with age and start having a bigger resistance (typical should be around 100/200Ohm) when they're conducting.

Anyone got a better explanation?

 

[galao]

Bem-vindo, Ramalhais!

Optocouplers can get old and disfunctional. I had a simililar issue with an ADA MP-1 preamp. The old optocoupler added some fizzy distortion and the overall volume was reduced.

I also made the experience that two stock modules of the same type can sound completely different. Maybe this is also influenced by old optocouplers.

 

[ramalhais]

Oi!

That's called Mojo, lol!
Components drifting from their orifinal specs, and producing special sounds. In both our experiences it was not that special

 

[galao]

Unfortunately this effect is difficult to measure. Maybe you can detect a signal drop or added noise if you use an oscilloscope. But this would at first require to disassemble the amp completely.

P.S. estava na costa da caparica em Outubro. E mesmo uma paisagem maravilhosa, particularmente no outono quando todas as turistas desapareceram