Laney AOR OT shrill? Effects of Trannies on tone?

[Kapo_Polenton]

Ok, back to my Laney 6 knobber AOR. I had tried a PTP in this thing and had problems so i put my PCB back in. Cut the push/pull knobbies from the circuitry and it is a straight up JCM800 now (checked schematic side by side when i was rewiring). Anyway, powered this thing up and man alive is it thin and shrill! Tubes biased properly at around 42 mA (397 plate voltage). I seem to remember this was the original issue i had with the amp. I thought it shrill, tight, a bit fizzy. Best tone i could get was bass boost pulled but set at zero. Anyone else find that or is it just my OT? I actually thought the OT was burned a few weeks back so i picked up one of those classictone OT's that have been getting good reviews. I'm starting to think Laney cheaped out on the transformers in this thing. Anyone else? The OT must really make that much of a difference. I've read that before about SLO's and the cost of their iron and i'm starting to believe it if this is the case. Discuss!

 

[chumbucket]

Sounds like something else is wrong. They're not excessively bright. The classictone OT sounded better to me than the stock OT as well.

 

[1big1]

my nine knob combo is pretty much stock. i wouldn't describe it as thin or shrill. one thing i have discovered is that aor's are pretty picky about the pre amp tubes you put in them.. though since you've changed it over to pretty much a jcm 800 it's hard to say if that will make a difference. the combo also comes stock with a 70 watt fane. perhaps speakers could also make a difference.
now that i think about it when i first got it it sounded somewhat like you describe. took it to a tech and he found that several of the push pull pots needed to removed.. cleaned and re-tensioned.

 

[Kapo_Polenton]

Well not sure what could be wrong component wise as i have been through this thing part by part with the schematic in hand but the only thing I can think of right this second is that I put in a bright cap. That can usually bring the crunch and high end in unless turned wayyyy up.

 

[1big1]

chop stick test?

 

[Kapo_Polenton]

Got it! 500pf bright cap I had put in.. didn't think it would make that much diff.. it does. Now I have the opposite, everything is balanced except the low end which is a tad flubby. I'm thinking coming in with a 50 pf might do the trick to tighten up that bass a tad. We'll see, this is my experimentation circuit.

 

[1big1]

excellent!

 

[TrueTone500]

Try replacing the V1a 10k cathode resistor with a 4.7k resistor for a nice kick to the gain. There's no bypass cap at the V1a cathode resistor, so it won't change the tone at all. Also try changing the 33k slope resistor to a 47k resistor. This will notch the tone curve into Soldano SLO territory.

 

[Kapo_Polenton]

Good tips truetone.. I was thinking of just going with a bypass cap on V2B as I preferred that in my JCM800 to dropping the 10k to 4.7k..i found that can get a tad buzzy. That said, no point in having two the same so maybe i'll see what i can do to bring out some different tones from this thing. Any other suggestions to notch this further into SLO territory? Might be time to bust out some preamp schematics.

 

[TrueTone500]

If your circuit is a JCM 2203/2204 type, the 4.7k cathode mod should be done at V1a.

 

[bravedude2]

funny, you hacked it up and it's laneys' fault it sounds thin...

 

[Kapo_Polenton]

funny, you hacked it up and it's laneys' fault it sounds thin...

Did you wake up on the wrong side of the bed this morning or jam your nuts on a rail?? Clearly my question was to check whether or not anyone else had perceived this with theirs. Furthermore, it may be "hacked up" but I can read a schematic and am going off that. Finally, I have recorded clips of what it sounded like before and it was either on the thin side or woofy and fizzy. So yeah, hacked up for a good reason. Might have been the transformer on it's way out at that time.. I don't know, that's why I posted. Rig talk remember?

 

[bravedude2]

bitter

 

[Kapo_Polenton]

Pointless post. The amp sounds great with the master at 4 onward but as most people know, it's loud as f_ck so no bright cap it sounds a bit mush lower volumes, bright cap in, sounds too hasrh buzzy.

 

[TrueTone500]

Pointless post. The amp sounds great with the master at 4 onward but as most people know, it's loud as f_ck so no bright cap it sounds a bit mush lower volumes, bright cap in, sounds too hasrh buzzy.

What value cap are you using?

 

[Kapo_Polenton]

500pf... wouldn't think it that drastic. Am going to try a 50 or 100pf ceramic I think.

 

[Kapo_Polenton]

50pf seems to be working right now. Usable at lower volume levels, opens up nicely higher up. Also not sure i subscribe to the idea that the bright cap is totally out of the circuit as you turn it up. At least not to 6 on the master. I was able to connect and disconnect one leg of the 500pf cap and listen to the difference. The bright cap just gives you that bit more defintion and sparkle on top and helps the bass sound more pronounced/clearer. A lot of gain mods i think also work better with that bright cap on. It can all get a bit woofy

 

[TrueTone500]

You can boost the bottom-end by replacing the .022 output coupler (if that's what is there now) to a higher value without adding 'flub' to the preamp.

 

[Kapo_Polenton]

Thanks for the tip.. to be honest, I think the key with this is that it needs volume. My 82 800 seems better at lower volumes. Trannies, components, a few mods i made? Not sure, it just has the mojo. This one sucks at lower volumes. Master from 4 onward to around 7 though, it's the goods. I think the key with any JMP or 800 circuit is not only boosting, but i think a higher output pup as well. Running an Air Zone right now, think i will drop the super distortion in there. More and more i gravitate towards higher output pups. I do love the alnico II's though. But for anything not GnR', they don't give the goods for lead work.