what kind of amp should I build with this transformer set

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
User avatar
Curranproducer
Posts: 285
Joined: Sun Oct 16, 2011 4:58 pm
Location: Akron, Ohio

what kind of amp should I build with this transformer set

Post by Curranproducer »

OK- I have a few sets of these transformers! I want to build an amp around them BUT I am still a novice in this area and would like some help in figuring out HOW to deduce what components I need to use to get these transformers to work in a "new" build, not a clone. I know I can run (2)KT88/KT66/6L6/EL34's and (8)12ax7's off of the power tranny. I have the 3hy choke, 8k JTM45 style OT, and 40-18024PT. these are all from triode electronics and are great trannies!!!

So................. after skulking and posting and searching I am hoping you guys can help me with some easy tutorial info for laying out the power section. I am wanting to build a two channel(foot switchable) 50 watt amp loaded with KT88's. two 12ax7's for a vox inspired clean, and (2) 12ax7 lead channel with a super saturated death metal type of tone, a tube FX loop in parallel, and of cousre a PPIMV. I was going to use the london power switching PCB that they offer. independant eq's of course.

I have built about (5) DIY amps from kits and raw turret board build with wonderful success. So this feel like the next fun trip!
You do not have the required permissions to view the files attached to this post.
Curran

Owner of Custom Audio Mutation Recording Studio, Guitar/Amp/Pedal Repair, and Mod center in Akron Ohio
Devout Distortion Worshipper and fan of warm hugs
234-788-6141
tictac
Posts: 617
Joined: Fri Mar 31, 2006 4:42 am

Re: what kind of amp should I build with this transformer set

Post by tictac »

An 8K transformer does not match up well with a pair of KT88's

Why not just use a pair of KT66's which would be ideal and they sound great...

TT
vibratoking
Posts: 2640
Joined: Tue Nov 10, 2009 9:55 pm
Location: Colorado Springs, CO

Re: what kind of amp should I build with this transformer set

Post by vibratoking »

+1 on tictac's comment, although you could run KT88s push-pull Class AB1 with cathode bias and get a decent good match with that transformer. Not sure if would get you death metal tones, but I am also not sure what death metal tones are TBH.
User avatar
NickC
Posts: 1814
Joined: Fri May 14, 2010 1:05 pm
Location: Upstate New York

Re: what kind of amp should I build with this transformer set

Post by NickC »

I built a JTM45 running KT66's. Love it. Not a death-metal type amp though, unless you run a pedal(s) in front. Mine takes pedals very well.
User avatar
Meat&Beer
Posts: 243
Joined: Fri Jun 07, 2013 5:37 pm
Location: Coldest tip of NY woods

Re: what kind of amp should I build with this transformer set

Post by Meat&Beer »

If you've truly got enough grunt from that PT to run 8 12A_7's, (2 for "Vox", 1 for PI, 1/2 for FX loop, and 2 for "Metal") why only run 5 1/2? I'm thinking if you really want a ripping metal channel, you'll need more than two tubes for it.

I'd be lying if I said it can't be done with just two, but you're not working with the limitation to only be able to use two tubes for it. Three of 'em (or so) will get you a smoother more refined sound. I'd look at something like an Engl schematic to get you ideas for this channel. (I own a Savage, it's very nice to me. )

Engl generally does plate driven everything, so it depends on if you want a CF in there, etc, so that's why I said "for ideas".

Kudos to you, for wanting to stray off the clone path! :) It's very rewarding. (Not that a clone isn't, mind you.)
User avatar
Phil_S
Posts: 6048
Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: what kind of amp should I build with this transformer set

Post by Phil_S »

I suspect you'll need to get your metal sound out of the preamp. Your power amp choice is going to be confined by the 8K primary.

The good news is that you have 6.3V @ 7A. With a pair of KT66, you'll still have plenty reserved for quite a few preamp tubes.

Maybe you should consider holding the choke for another time. It is rated for 250mA, which means you can use a choke input. That will give you lower plate voltage and I don't think that's what you are after. A big choke like that seems wasted if you put it between the plates and the screens.
User avatar
Curranproducer
Posts: 285
Joined: Sun Oct 16, 2011 4:58 pm
Location: Akron, Ohio

Re: what kind of amp should I build with this transformer set

Post by Curranproducer »

I can add up to 8 tubes, I was just spit balling the preamp layout with two tubes for each section of the amp. and KT88's are real tight and clanky for the newer JDENT thing that is going on in the world of 8 string metal guitar playing. Not really looking to saturate the power section at all, I can of course use Kt66's I could really care less, I just dig the look of the KT88's in the back of an amp
Curran

Owner of Custom Audio Mutation Recording Studio, Guitar/Amp/Pedal Repair, and Mod center in Akron Ohio
Devout Distortion Worshipper and fan of warm hugs
234-788-6141
User avatar
Colossal
Posts: 5205
Joined: Sat Oct 20, 2007 9:04 pm
Location: Moving through Kashmir

Re: what kind of amp should I build with this transformer set

Post by Colossal »

vibratoking wrote:Not sure if would get you death metal tones, but I am also not sure what death metal tones are TBH.
Cascade four to six preamp stages together, scoop the mids, and keep the power amp tight.
User avatar
Curranproducer
Posts: 285
Joined: Sun Oct 16, 2011 4:58 pm
Location: Akron, Ohio

Re: what kind of amp should I build with this transformer set

Post by Curranproducer »

OK SO i am going to roll with KT66's per the suggestions from this thread. so NOW where do I turn to know what kind of filter caps and such for the power section and getting the voltage to the correct amounts
Curran

Owner of Custom Audio Mutation Recording Studio, Guitar/Amp/Pedal Repair, and Mod center in Akron Ohio
Devout Distortion Worshipper and fan of warm hugs
234-788-6141
User avatar
Curranproducer
Posts: 285
Joined: Sun Oct 16, 2011 4:58 pm
Location: Akron, Ohio

Re: what kind of amp should I build with this transformer set

Post by Curranproducer »

ok I am looking at the triode electronics pages and the PT is going to be all good for a 100 JCM800, BUT I still want to use the JTM45 OT with it, will this cause any problems? AND if so how can I start to figure this out for myself!
Curran

Owner of Custom Audio Mutation Recording Studio, Guitar/Amp/Pedal Repair, and Mod center in Akron Ohio
Devout Distortion Worshipper and fan of warm hugs
234-788-6141
User avatar
lord preset
Posts: 447
Joined: Tue Aug 27, 2013 3:06 am
Location: San Diego

Re: what kind of amp should I build with this transformer set

Post by lord preset »

Curranproducer wrote:ok I am looking at the triode electronics pages and the PT is going to be all good for a 100 JCM800, BUT I still want to use the JTM45 OT with it, will this cause any problems? AND if so how can I start to figure this out for myself!
Using a 100 watt PS for a 50 watt amp will not cause problems just a bit of overkill. A very useful site for figuring these things out is - http://www.valvewizard.co.uk/index.html
User avatar
JazzGuitarGimp
Posts: 2357
Joined: Mon Jul 23, 2012 4:54 pm
Location: Northern CA

Re: what kind of amp should I build with this transformer set

Post by JazzGuitarGimp »

If a 4k load is more appropriate for KT88's, then you could re-label the 4R, 8R, and 16R outputs to 2R, 4R, and 8R. That will give you a 4K primary. Just keep in mind the OT is rated for 45 watts - you could probably push that a bit, maybe to 55 to 60 watts.... Just thinking out loud.
Lou Rossi Designs
Printed Circuit Design & Layout,
and Schematic Capture
User avatar
Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: what kind of amp should I build with this transformer set

Post by Structo »

I agree, you are pushing it for more than 50 watts or so since the OT is not rated for 50 clean power + distortion at full tilt.

Z out for AB1 PP KT66 is about 5K.

KT88 are usually ran in ultra linear mode but not etched into stone.

Of course it does depend on the power supply and the plate voltage and current available to the power tubes.
Tom

Don't let that smoke out!
Post Reply