Anyone build a DIY tube amp/

[yabba]

Re: Anyone build a DIY tube amp/

here's doug hammond's (it's his design) page with some info and schematics (I think all revisions are there): http://home.cfl.rr.com/dbhammond/ff.htm

someone else's documented build: http://www.firebottle.com/ampage/hom...6726808cSGgrKj

yet another: http://www.maizingrayz.com/firefly.htm

very cool little amp [img]/images/graemlins/smile.gif[/img]

[cruster]

Re: Anyone build a DIY tube amp/

Thanks for the links to the firefly. I decided, after much thought and many days (paid! Man I have a great job<G>) of poring over schematics, design docs and layouts that I'm going to build the AX84 P1-eXtreme, although slightly modified with a 3-pos speaker switch (16, 8, 4 ohm) and a 'clean/dirty' switch.

I ordered everything but the trannies, chassis and tubes today and spent a whopping $119.14. The trannies are going to run me another $60 or so, and the chassis looks to be about $20-25, depending on where I source it. Of course, I'm going to have build an enclosure. I'm not sure if I should go 'head' and just run it through the 15" EV cab, or if I should go combo and pick up a nice greenback or something similar.

[Twisteramps]

Re: Anyone build a DIY tube amp/

I've built about a dozen amps - from scratchbuilds of my own design to ones that were documented (like ax84s) to finding schematics and building one of those. It's all good, it's all fun, just be careful.

Measure twice, cut once is something to remember. Well, something like that... [img]/images/graemlins/smile.gif[/img]

Pete

[cruster]

Re: Anyone build a DIY tube amp/

Yeah, when I installed the new hardwood floor (now, *that* is a story...) and then the baseboard/shoe molding, I went the other way. Even when I cut three times, it was still too short. [img]/images/graemlins/laugh.gif[/img]

[mrr3000gt]

Re: Anyone build a DIY tube amp/

I do lots of work covering different areas: I have two pro reverbs Im building. Most of my building experience is 1959 bassmans and model 1987/JCM 800 Marshall clones in 50 watts.
On my pathetic 'solo artist' page, I used amps I built for multi-track recordings:

http://www.soundclick.com/bands/4/melanogaster.htm

[MetalMan]

Re: Anyone build a DIY tube amp/

I am wanting to build me an amp from scratch. Slowly getting into it. I have built a SS 1/2 watt tiny little amp.
And am currently modding my Electar tube 10 from some info i found on the net years ago. Slow going on that. haha
Adding a preamp tube and if that works out(crosses fingers) i want to build a new enclosure for it and add a 12 inch speaker. Got the amp apart and drained the caps and gave it all a look. Learning the schematic and figuring out what parts i need.

[mrr3000gt]

Re: Anyone build a DIY tube amp/

The schemo is the easy part in a tube amp: the hard part is the layout of the parts and components (tubes, transformers). The board layout will make or break a tube amp.

My best advise on DIYers is to buy books on the topic of tube amp building, and do your Internet research. Unfortunately, just relying on the Internet will not totally help you. Nobody is giving the important secrets away for free.

The best book I found for exaplaining a tube amp in laymans terms is INSIDE TUBE AMPS by Dan Torres. If you have to get ONE book, this has to be it.

This book exaplains preamps, power sections, rectifiers, biasing, modifications, and even has a simple tube amp project in it to tie up everything you learned. It has bias tables that I do use on occasion, and offers the reader some of the theory behind the practical knowledge if they want to read it. It is an easy reading book, and not like reading a manual for a F-16.

Again, I have found no better book for the absolute beginner in tube amp buuilding. The book is only around 20.00, and you get it signed by Dan Torres himself (a lesser known Ceasar Diaz-type in southern calli).

(this is recommendation is unsolicited, as it is too good of a book not to have!)

[Twisteramps]

Re: Anyone build a DIY tube amp/

Torres has a really bad rep for his service and mods... do a deja.com search on him. His book has some good info for the beginner, but if you really want to go in depth, check out the Kevin O'Connor books. One of the O'Connor books spends about 80 pages just on channel switching [img]/images/graemlins/smile.gif[/img] However, it is a much harder read than the Torres book.

Oh, and if you do want the 'secrets' for free - go to ax84.com in particular and read the theory document behind the P1. They also have a great on topic bulletin board too.

Pete

[cruster]

Re: Anyone build a DIY tube amp/

+1 on ax84.com. In fact, that's where I got my schematic and layout from. I went through the P1 stuff first, so that I could follow along with the 'theory' document, the schem and the layout...to put it all together sort of (virtually, anyway). I've decided to build the P1x, though, as it doesn't appear that much more difficult.

Luckily, I've made the acquaintance of an honest-to-ghod amp dude who is willing to share his knowledge...he's already straightened me out on a couple of things, and I haven't even started building yet. [img]/images/graemlins/wink.gif[/img]

[mrr3000gt]

Re: Anyone build a DIY tube amp/

I have heard Dan Torres rep also. When you are on the front line, not everyone gets what they want (unfortunately). I do only a limited amount of repairs and do not take on more than a 1 week backlog. There is another guy in my area that has a 6 month backlog and a similar reputation to Torres. But, like Dan, he is good, but over burdened.

The Torres book is the best book for beginners hands down. The AX84 theory document is good for the intermediate builder who needs some further understanding. I particularly like the emphasis on the tone stack pricipals the document covers.

The AX84 site is a good beginner site, and the P1 and Hi Octane are nice little project amps, but they are hardly professional quality (in spite of the fact Randall Aiken - a real whos who in the builder world - helped in the design of the P1). The goal of the P1 was to give the world a sort of 'open source' amplifier, and to help spread the knowledge of tube amplifier building to all. I watched the website develop into a springboard for Doberman Amplifiers. I think the P1 is the best sounding amplifier you can build for less than 250.00. In fact, I have played 1000.00 amps that did not have the tone the P1 has: just build one and you will be blown away. What IS true that it is NOT like a 18 watt Marshall, JCM 800 clone, or a Bassman clone. The AX84 site can help you, but it will not provide one of the most important aspects of tube amp building: the layout. You have to go to the Houseofjim.com website to get layouts of some of the AX84 amps.

I can attest that without a real production layout, and DIY amp will be nothing more than a novelty you break out and play when you are in the mood to ignore hum, squeals, and other unpredictable behaviors from improperly implemented tube amp designs. It took me a junk heap full of $500.00 near-misses (about $20K in builds and projects) to get to the point I was able to build amplifiers that sell for 1500.00+ dollars. The difference between a professional amplifier and a DIY amounts to the workmanship and performance.

My best advice to the budding tube techie is to send Chris of Doberman the 200.00 bucks or so and build a P1 (with the Houseofjim turretboard layout). Then, when you are ready, buy a JTM45 or 5F6 kit from Mojo or other vendor and build a real guitar amp you will use on gigs. Understand how and why the kit works, then graduate to building yourseld a custom amp and ask questions until you are chrystal clear.

I used a clone of a early 1970s non-master volume Marshall 50 watter I built from scratch (no kit) to record the tune 'trojan hearse' on this site:
http://www.soundclick.com/bands/4/melanogaster.htm

That amp was the first 'real' amp I built (perhaps the 20th build I did). Its not that I was slow in learning, as any fool can slap parts together because tube amp tech dates back to the world of line workers with 6th grade educations. The trick is to build one QUIET that performs uniformly across the board at all volumes and settings.

[Twisteramps]

Re: Anyone build a DIY tube amp/

Well... you're comparing Class A single ended amps with push/pull A/B amps. Apples and Oranges. Here are a few clips of amps I've built:

http://mothrastewart.com/peteclips.htm

I gotta disagree with the '6th grade education' thing too... there's a lot of math in scratch building an amp.
I sure as hell couldn't have done it in 6th grade!

BTW, single ended amps are inherently noisier than push-pulls, but that doesn't mean they are inferior, it's just part of how they work.

One thing that is nice about the Torres book is that you can use it to mod your preamp to some extent, but you won't get into any real crazy/interesting stuff until you hit the O'Connor books.

Pete

[mrr3000gt]

Re: Anyone build a DIY tube amp/

Twister:
Yer right about that: class A and AB are different. I know enough about the two to know that class A is not my sound.

As far as the 6th grade thing, I meant that line workers assembling TVs and radios in the 40s and 50s were not the engineers that designed the devices they were assembling :-).

The clips sound great! Its cool to not only build amps, but to really be able to demo them well (as you do).

The O'Conner books are the way once you have the basics (like the Gerald Weber books).

[cruster]

Re: Anyone build a DIY tube amp/

Well, the p1x build is under way. I've put up a blog about it at:

http://www.shermonster.org/blog/

Tonight I'm pretty unhappy. Not a good amp building day. I need a drink. Or maybe 'drinks.'

[dd3keegs]

Re: Anyone build a DIY tube amp/

Cheers...I'm drilling holes in my chassis tonite. Gotta love stepper bits. [img]/images/graemlins/toast.gif[/img]

[cruster]

Re: Anyone build a DIY tube amp/

Forum necromancy! (well, almost, I guess three weeks isn't really dead<G>)

The chassis buildout is done (http://www.shermonster.org/blog/) and it sounds fantastic. I've spent so much time playing it that I haven't the motivation to build the enclsoure. [img]/images/graemlins/smile.gif[/img] Just kidding...I need to get the cherry finished then dovetailed.

At any rate, regarding mrr3000gt's earlier post about squealing and oscillations and noise...didn't have those problems at all (and I even screwed up my chassis, so my leads are longer than I would like). In fact, this thing has less 'buzz' than my commercial solid state amps. Go figure.

I think the next build is going to be a 5F4-A or maybe a Dual Showman type thing. I'll not be drilling my own chassis again, however. [img]/images/graemlins/wink.gif[/img]