did i get it right?

[drewl]

Well, i built my 18watter using the trannies and chassis from a crappy Gibson Super medalist.
I only built the normal channel. The amp sounds great, nice full sound, with light breakup, so here's the questions.

Does the trem channel have more gain?
Do yours/originals have alot of gain/distortion?
How active is the tones control?
do they sound like any other marshalls?

Using a boost or distortion in front really makes this baby sing!
go easy I'm fairly new here......
thanks!

[Tony]

FYI My homebrew 18watt has a lot of gain. With an unboosted single coil I am getting more distortion than on my 100w JTM lead. The trem channel has indeed somewhat more gain but sounds a bit thinner when maxed, but not much. With a one channel version you should be able to get even more gain out of it compared to the regular two channel amp since you don't have any signal losses in the mixer. With help of other members of this forum you should be able to get more out of it if you can give some more information on your amp (measured voltages, any deviations from the original circuit (layout, component values), high/low gain inputs etc.). Also, are you sure that the tubes are still OK?

good luck,
Tony

[zaphod_phil]

If you've only built one channel, hopefully, you've paralleled the two halves of the 12AX7 together, as in Mark Huss' Lite II. That will get you some more gain, if you haven't already done so.

[drewl]

Well, i have another tube and a half to play with, so i was thinking of adding reverb. (only 1 input so far).
is there a difference in ch1 hi & lo?
The thing sounds so sweet, but I have never heard the marshall 18w, so I have nothing to compare it to.
There's probably sound clips here i can compare it to.
the circuit variations are as follows:

It's SS rectified.
Filter caps C20 A&B are 22uf
C2 is also 22uf
Bias C3 is 47uf, R20 is 100 ohm
C5 is .0047
pots are 1Meg.
R21 & 22 are 4.7k

I tried a crossline master volume, but it thins the tone considerably when turned down, lowering gain and increasing treble.
I thought of using a dual 500k MV pot in place of the 470k resistors to ground.

thanks for the replies.

[SteveinTempe]

I would like to design in reverb I also have an amp with
a tube and 1/2 left..
Any Ideas on how to mix in the verb with a minimum of knobs..
I was thinking single channel ..? as far as input
then I guess some kind of mixer..
I guess you could also use the reverb return 1/2 triode for
a really hot channel most likely too hot..
?

[zaphod_phil]

ON the AX84 BBS some of the guys have been playing with a simplified reverb circuit also found in one of Kevin O'Connor's TUT books, sometimes refered to as a "backwash" reverb. It takes some signal from the amp's OT to drive the reverb tank, and then only needs a single triode for the recovery. The beauty of this scheme is that it reverbs the amp's full overdriven sound, rather than just a signal from the preamp. However, it's a litlle more tricky to get tweaked right, so that the tone sounds good, while avoiding feedback. instability

[loverocker]

I guess that if you have only used one channel then you could avoid having to use the typical mixing resistors to recombine dry and wet signals. Instead you could feed the reverb signal back into the other side of the PI (i.e. where the Trem channel input would have been on a two channel 18Wer).

Have to say though that I've never heard any internal reverb that sounded musical when the amp is being cranked. Post-reverb overdrive sounds nasty - or is it just me?

[Graydon]

That reminds me of something I tried a while back. On my 18Ws that have a MASS, I add a lineout. So, I took the lineout to a small reverb box (in this case it was a Lexico LXP-1, the older half rack unit) and fed the output back to the unused channel input. It worked pretty well although I had to be very careful with the levels as it is a feedback loop. Also with a delay, multiple repeats got really nasty sounding. The first repeat sounded OK though. This also had the advantage of effecting the entire amp's signal, preamp through poweramp.

[drewl]

okay, after reading another post on input jacks, i realize the hi hits both halves of V1.
I'll fix this tonight.
FWIW i listened to some 18w sound samples, and mine is pretty much dead on!