KT88 push pull noob questions (sry)

[Baronty]

HI there - im really interested in building myself some valve amplification

I have had quite a lot of experience of electronic construction circuit layout soldering before in a previous job.

BUT - im not as confident in my abilities to design an amp from scratch.

I was looking - (possibly a little ambitiously) to build a pre + pair of Mono blocks - most likely KT88 push pull mono blocks i think

Now i came accross this nice looking design for a universial amp by Pete Millett:

http://www.pmillett.addr.com/push-pull_kt88_class_a_amp_with_universal_driver_pcb.htm

Has anyone on here built this from his schematics???

if so what are the reactions?

Are there any other designs i should be considering for my first real build? Words of warning and general advice greatfully accepted.

Also a suitable pre amp design suggestion would be useful

I may be a noob to all this and i know its a lot of questions but i am reasonably intelligent (honest)
and i have read quite a lot of liturature and have a couple of texts on the way. I have sooo much time on my hands and this is something ive been wanting to do for years!

Also friend of mine works in a company dealing with electronic construction so help will be availiable and i can get brushed steel plates made and drilled there too if i ask nicely.

If you think im getting myself in to deep please say - i respect your words of wisdom.

Cheers

 

[Brett]

I've built a couple of similar amps, and some of Pete's other work has influenced some of my designs, so that Universal amp will likely sound good. If you can layout a circuit, as you've said you can, it would be an easy build. IIRC he may even sell PCBs, but a point to point shouldn't be too hard. Would make a good project for a first tube build, for someone with electronics experience, and give you the opportunity to try some different valve types relatively easily to build up your experience with different types.
Whatever amp you build, buy decent output transformers.

The amp has plenty of gain, and I doubt you actually need a preamp beyond a switch and a pot.

Go for it, and post further questions here if you need to.
I'd build it on a piece of scrap wood, to get the layout right, then, get your friend to build and drill the enclosure.

 

[Baronty]

As a follow on ive been looking at out put transformers and chokes and now im even more confused as what i require for this project.

found this PP output transformer - although im not sure if this is what i need

U069 PP Output for KT88 Cathode bias

http://www.sowter.co.uk/acatalog/SOWTER_PUSH_PULL_OUTPUT_12.html

and i thought xover design was complex lol..............

Comment suggestions cyanide........

 

[Brett]

As a follow on ive been looking at out put transformers and chokes and now im even more confused as what i require for this project.

found this PP output transformer - although im not sure if this is what i need

U069 PP Output for KT88 Cathode bias

http://www.sowter.co.uk/acatalog/SOWTER_PUSH_PULL_OUTPUT_12.html

and i thought xover design was complex lol..............

Comment suggestions cyanide........

The Sowter would be fine, as would a Lundahl LL1663 (triode or UL) or 1620 (my choice for triode only, no UL taps)), but I don't know pricing in the UK. There are also (no doubt) other UK/Euro options I'm not aware of.

Pete also uses an input transformer to split, but I'd say you could use a CCS in the tail of the first pair if you didn't want the expense and were happy to add in a small negative supply. I'd use a Lundahl LL1676 myself, as I use one to split in my current amp.

The circuit isn't difficult, and you have the option of having PCB's made, which is a great idea for a first build, to greatly increase the chances it will work properly first time.

For PS chokes, any of the Sowter, Lundahl or Hammond ones would work fine.