Preamp Tubes in 1974x clone

[jimijames]

So, I had mentioned earlier that I had modified slightly my Epi Valve Jr. (basically some higher value caps in the power filtering stage) and after doing said modifications it wouldn't start up.

I toyed around with it for a while in an effort to revive the beast, and then came across some information on the 18w 'baby will' lite iib build designed by Mr. Terry Stinger (RIP): http://guitaramplifierpcbs.com/liteiib.html

So I got all the parts for it. I'll post up some photos of the build, which will be interesting because I don't have a drill press or anything - just a hand drill. So it will be all kinds of backyard ghetto fabulous.

The 1974x circuit which this is based on begins to break up very early from what I've heard (and seen on demos) - and I'd like just a wee bit more clean headroom. I've heard you can do this by using lower gain preamp tubes.

I've got two JAN 5751s but I was wondering about other combinations of preamp tubes - specifically the 12at7/12au7/12ay7 in combination with one of the 5751s. I saw someone post on here that the 12at7 and the 5751 worked well together?

At any rate I was curious if anybody had tried different preamp tubes in the marshall 1974x 18w circuit. If not, no biggie - it will be a good opportunity to experiment some.

 

[jimijames]

Re: Preamp Tubes in 1974x clone

So, I tried out various combinations of the following tubes:

5751 - maybe my favorite sounding tube of the bunch. Sensitive attack - you can play chord melodies very smoothly with this one, or dig in for more 'pop'. SRV style ballads like lenny, little wing, riveria paradise, etc. all sound spot on with this tube. If anybody has ever put corn starch in water to make a non-newtonian fluid, that's what the attack on these tubes is like. Firms up when you dig into it.
12at7 - Very very transparent tube. Powerful and 'stiff' feeling. Can be kind of harsh sometimes, but with a 5751 in v1 sounds just fine.
12ay7 - My 2nd favorite. Does well a lot of the things the 5751 does but is more transparent sounding like the 12at7 IMO/IME. The 12xx7's all have a similar sound and eq.
12ax7 - Most gain out of all the tubes. Sounds good, but I prefer most of my distortion to come from the power amp and with the gain this thing has the amp starts compressing and distorting pretty early on. The sound I like but the 12ay7 sounds close enough with a lot less gain so I went with that.

I settled on the 5751 in v1 and the 12ay7 in v2. With that tube combination the Baby Will has about my favorite clean sound of any marshall I've played, and at full tilt it has less distortion than you might otherwise get - but I prefer it that way as most of the distortion comes from the power tubes and once those el84s get cooking it's a fantastic noise. Played my tele with a rio grande dirty harry bridge pickup and there are shades of Billy Gibbons and AC/DC.

For some reason I want to say it was loudest with the 5751 and 12at7 though. Either it's less loud or I'm getting used to the volume more with what I got in there now.

Anybody who wants a cheap alternative to one of those expensive marshall 1974x reissues should give the baby will a long hard look. Lots of great sounds with just a guitar, cable, and amp.

 

[Gearjoneser]

Re: Preamp Tubes in 1974x clone

Every time I think in terms of knocking the gain down, using 5751's and 12AT7's, I feel that it cuts some of the nuts off the amp's potential. I'm not saying it won't give you the desired lower level of gain though.

I just usually like throwing a high quality set of tubes in there, that are rated for high gain, fat tone, and the least noise, and then get the amp's controls set right. Then, it's putting out all it's capable of, and the amp and guitar controls can be used to keep the gain under control.

That's just my opinion in general, not necessarily commenting on your particular model.