Express problem?

[Ukko75]

Hi everyone!
I just made an express clone and i am wondering, is that normal that when you got guitar volume at 10 and you turn up the amplifier volume it distorts the sound allmoust immediatly. Volume as you increase it volume level dont rise almoust at all. It just get thicker and more compressed. Is this normal or is something wrong? And if the amp volume is in about half way you get cleantones only when you guitarvolume is less than 2 (espected that fullvolume is 10)

Can enyone help me!
Sorry the bad language i am from finland.

[amplifiednation]

Yeah that sounds about right! You might want to check the taper of those guitar pots. The Express should have decent headroom with the volume rolled back, but anywhere on the amps volume above 9 o'clock with Max guitar volume is balls to the walls!! The volume control acts more like a saturation control than a typical volume control on other amps.

You might want to try lower gain preamp tubes to kill the gain a bit if you want more headroom.

[Ukko75]

Thank you for the answer!
I will try different tubes on V1, it might also lower the high squeel when volume treble and precense is all the way up.

[M Fowler]

Did you use a 33k grid on pin 7 V1 from input jack?

Also, an 820R grid from volume pot wiper to pin 2 V1?

Those help with stability.

Mark

[amplifiednation]

Try what Mark suggested, also you might want to post some pics of your preamp wiring and also the bright switch. There might be an adjustment to lead dress that can help

[M Fowler]

Also use shielded wire for those two grid resistors.

[Ukko75]

Thanks for advises! I will try them today. Here is couple of pictures at preamp and pots.

[geetarpicker]

The best cleans with these amps is with the guitar backed off IMHO, and the amp cranked. With the right pots and pickups you shouldn't have to dumb down the gain with alternate tube types though that is an option.

Pot taper makes all the difference in these amps and the guitars you play through them. As far as guitar pots many 250k pots are ok these days, 500ks are much trickier. For 500ks the latest era Gibson Historic series 500k pots are excellent, and even come on a tad more slowly than the original 50s Centralabs. The only downside is they run low (which can make some pickups muddy) as it's hard to find historic pots that are close to 500k let alone perhaps a little higher which would be typical in an old LP. That said with these pots you should be able to play a PAF type pickup up to about 3-5 (with the amp cranked a bit) and still get a nice clean tone. 50s wiring also helps, and with that wiring if you back off the tones along with the volumes you get an additional volume cut and mild mid scoop which also helps the cleans on a wreck.

For pots in the amp it's also worth seeking out a slow rising 1meg for the volume if you can find one. That said the pots in my recently acquired '85 Express are quite an amazing match to the circuit, and are even nicer taper than what Ken put in my later '89 wreck. They come on so slowly the amp is quite clean up to about 4 (even with a LP) and it takes about 1-2pm to really get to the dirt. Even then going from 3/4 to full up there is still noticably more gain. In my latest Youtube video a few of the clips with my '85 were with the amp close to 3/4 on the volume and it still wasn't too gainy. It seems on the earlier wrecks Ken found pots that had tapers that were had a very VERY slow rise to them, and sadly I have yet to find any modern pots that truly match them. It's another reason that many original wrecks sound great with all the knobs on 1/2 or 1pm, but many clones often require the treble, mids, and even volume backed off quite a bit less then 1/2 to find the sweet spot.

[eazilyled]

It sounds like your amp could be behaving normally.

I had the same problem with guitar pot clean up until I switched to the Gibson Historic Series and 50s wiring (used to have modern wiring with treble bleeds). I had to dial down down to 1-2 previously to get clean, now it's more like 6 for clean and perhaps 7 for a hairy clean. These pots really are great for this amp. If you buy pots for all of the controls on your guitar, you could pick the ones with the highest resistance value for the volume(s). I bought four and two of them were 500K+, so I used the lower ones for the tones. I used the highest value for the neck vol to brighten it up a bit. I have Gibson Classic 57 PAF type pickups btw.

Also it's true what GK said about using the tone pot as a secondary volume with 50s wiring. In fact I've started keeping my tone at 7 and EQ'ing the amp to compensate so I get a better clean up with the volume pot.

Also the shielding chassis cover is pretty much essential to avoid unwanted noise etc.

Regarding tube swaps in V1, I was playing with a Mullard 12AU7 in that position just last night. It makes for a more traditional amp setup where you get crunch with the guitar volume at 10, and a pristine beautiful clean with the guitar volume rolled down. You could also throw in a boost for leads with this setup.

[Ukko75]

Thanks for advices!
Where can i found that 50s wiring?

[dorrisant]

Thanks for advices!
Where can i found that 50s wiring?

http://www.dominocs.com/AshBassGuitar/W ... ibson.html

[Ukko75]

Thanks a lot!
I put 1,5k resistor on V1 pin 7, that helped oskillation, now i can turn up all the knobs an there is no squeeling.

I still have a hiss problem. I tried shielded gabels on V1 7 and V1 2 , but that was no help. also tried 1,5k resistor on V1 pin 2, but nothing seems to help. Amp is dead quiet when i take of first pre amp tube.

Is there something that could do?

[geetarpicker]

These amps hiss even if built properly, it's just the nature of this much gain and a wide open non-master output stage. I find a TW usually is actually quieter noise wise than say most other amps with a boost pedal set to simulate the same amount of gain. That said with most channel switchers one kicks off the gain channel when they want less noise, and with a overdrive pedal one usually turns that off when going for clean. However with the wreck you are wide open ALL the time. Try a power attenuator, really! Keep in mind the amp probably puts out close to 115-120 db when fully cranked into a healty cabinet, so even a little hiss will be audible if you are playing that loud. Around the house if you back things down with a power attenuator the noise floor will really be lowered too. That said, the TW amp with all knobs around 1/2 should hiss a bit less than say a fully dimed 4 input style lead spec Marshall 50 or 100...just for comparison. Also you might experiment with different preamp tubes, as these amps are not tolerant of a noisy tube especially in V1.

[Ukko75]

Ok! That comforts me, that it is normal. Amp works just great! Now I can play whit my Strato as well. Whit my first build amp Plexi it sounds too thin, but with this it sounds great.
Thanks to eweryone who had helped me!
This is so good forum to get information to build an amp!

[Reeltarded]

Aha.. I just realized I mostly come here for the good news. These are the best of times.