This was going to be so simple… Then I came across this foru

[Taylor2011]

Hi, I just wanted to say Hi, and thank you all for such a wonderful resource.

Around 2001-2002 I built a single ended 6V6/6L6 amp from a kit, but it never quite hit the mark tone wise, so I redeveloped it into something a little more to my liking, nothing fancy, actually it brought it back inline with more conventional designs. It’s probably got one gain stage too many, and I should really sort that out, but it sounds okay at the moment running a 6L6 thorough a 9dB bridged T attenuator I made and then into a Celestion G10 - I can get pleasing tones at comfortable volumes.

This little foray into amp building got a little side tracked for many years when I took up the saxophone, that was until just recently when I suddenly had the urge to pick up the guitar again. Just before the saxophone interlude I was getting the parts together for a 5E8A build, I’ve got the chassis, tubes, pots, capacitors etc but not the transformers. Having got back into the guitar I thought it’s be nice to have an amp building project on the side, and so the dream to build the 5E8A began to take seed again, then I realised a 50W Fender was overkill, so it scaled down via a 5F4 to a 5E3 in my head, I was all sorted and very grateful I hadn’t invest in the transformers…

Having been out of touch with what was going on on the web, I revisited a lot of my old bookmarks only to find forum communities and various websites have moved on or vanished, and that’s when I discovered this place, and that’s also when the simple idea to build a 5E3 became derailed. I discovered ‘Trainwreck’ amps, I’d not come across them before and I was liking what I was reading, touch sensitive response, chiming clean tones, works well with a rolled back guitar volume to clean it up.

I want a simple to use single channel amp that responds to my playing, no reverb, no vibrato and no multiple voices. Essentially I want a simple circuit that doesn’t get in the way of the player. I’ve been reading for hours over the last week the various posts and followed with great admiration the builds people have documented, and I’m really quite excited to roll up my sleeves and get the soldering iron out.

I feel at the moment I could take so many paths with my next project, I’ve not built a Push Pull power amp stage and I’d like to try that. I play mostly clean to bluesy to a bit of crunch but sustaining saturated overdrive - which is lovely - is not really me. So I feel I’m falling on the ‘Rocket’ and ‘Rockster’ side of the Train-tracks. The ‘Rockster’ is really quite appealing due to the tube swapping possibilities, but a quad of El84 - that’s appealing as well! I guess my requirements in an amp are covered by most models, so it’s also what would be a pleasure to build and tweak to perfection.

One thing with the Rocket schematic that I wonder about is the 80uf first filter stage, isn’t a GZ34 only designed for a maximum of 60uf? Saying that I’ve not read anything in the forum of people with Rectifier tube issues, except a dodgy batch from JJ - I think it was a JJ rectifier.

Sorry this was far longer than I intended.

Best wishes,

Chris

[paulster]

Hi Chris

First, let's just establish something about the Rocket before you decide to proceed.

In case you don't know it's an AC30 Top Boost channel stripped down to its bare minimum and given a couple of tiny tweaks. But other than that it's straight out of an AC30.

So before diving in to a Rocket (or derivative) build I'd just consider whether this is particularly the tone you're looking for.

The Trainwrecks that really have their own unique voice (and in particular the control from the guitar) are the Liverpool and Express, which are original designs.

Don't get me wrong, I love the Rocket, but it is essentially a clone of another amp because it was Ken Fischer's favourite amp. It's so much better than the equivalent channel on an AC30 though; don't underestimate the effects of stripping it down, simplifying it and refining it, but it's still undeniably AC30.

It's a great platform though, and can be tweaked pretty easily for the octal output stage as you've already discovered, and reverb can be added quite easily too, so you might find it's the ideal platform for you.

Also, with no global negative feedback, it's quite a good candidate for a post-PI master volume, which sounds like something that would interest you if you're already attenuating the single-ended amp.

You are correct in that the 80uF filter cap exceeds the data sheet specifications for GZ34s but it sounds good that way, and if you get a good GZ34 it'll be able to deal with it.

They are expensive but you really can't beat a Mullard GZ34 in here, and even better, a yellow print one which are the screened and selected military-spec ones.

Paul

[Taylor2011]

Hi Paul,

Thank you for your comments, I was aware of the Rockets homage to the AC30, although for a little while I was confused thinking it was the Liverpool. I was looking at the schematics and figuring I must be missing something because the Liverpool and Express have very similar pre-amps, where as the cathode follower in the Rocket seemed in keeping with the AC30. Unfortunately I was jumping to conclusions based on the amps names!

You are right about considering the tone I’m looking for, not always an easy thing to pin down, but a singing sustaining lead tone is probably not what I’d be looking for first and foremost in an amp. If there were only the Express and Liverpool I’d be interested, but I would probably pass on having a go making one. It’s the idea that a classic and effective circuit has been reinterpreted to get the most out of it that really appeals, and tone wise from the clips I’ve heard, it has got a very desirable voice.

Thanks for confirming my thoughts on the rectifier. I’ll keep my eyes peeled for the Mullard GZ34.

I have at least come to one decision today, and that is to build a head cabinet for my single-ended amp and also a speaker cabinet. I was originally going to house it in a combo but if I’m going to get into building amps, a speaker cabinet and amp heads makes a lot more sense. Now... do I go for 1x12, 2x10 or 2x12 I wonder if anyone has put two Celestion G10 Gold’s in a Cab? Off to do a search…

Thanks again,

Chris