Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Satellite^Guy on December 06, 2010, 12:24:20 am
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First, the disclaimer:
I've never built an amp, and I probably won't become a hobby builder, so I want this one to count.
I do have some basic knowledge of electronics; Ohm's law... capacitors hold a charge and can kill if you're not careful... the voltage out of a transformer is just as deadly... that sort of thing.
now, to the list:
Combo amp
15-20 watts
pre-post
bmt stack
tube-driven reverb
footswitch to select driven and clean
running a 15" JBL
As far as tone goes, I want something that plays beautifully clean, but also does some great blues-rock tone. I'm thinking Colin James, or Jeff Healey type tone. I'll probably be playing a Yamaha SBG 200 -- somewhat of an SG clone, twin-humbucker; in case that makes a difference.
What would be your recommendation for an amp design?
Of course, from an asthetics standpoint, I'd love to do a Fender Tweed style amp, with white chickenheads on a gold faceplate. :D
So, hit me up with your suggestions and recommendations! :)
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This would be my attempt based on your requirements.
However, you might find it challenging for a first build. But your requirements make it a challenging amp.
You'd need relay switching on the DPDT to have it footswitchable.
With respect, Tubenit
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I don't think you'll get a Jeff Healy tone with that guitar and a 15" speaker.
So right off the bat you want an amp to do 2 different things, get a totally clean jazzy sound and then go into complete overdrive and make a Gibson based guitar sound like a strat. I hate to burst your bubble in anyway but IMO by trying to do both you'll get neither.
I think you might want to rethink your direction with this whole one amp does it all. Not to mention the speaker. Going from a clean JBL 15 sound into a more 12" celestion type sound is impossible.
You might want to do a BFDR type amp head with one channel being for overdrive and 2 separate cabinets. One with the open back 15 JBL D130 or similar speaker and one with a pair of Celestion greenbacks. The difference alone with the speakers is 2 ends of the spectrum. This will allow you to more easily use the same amp without having it complex with 2 completely different channels. That would make for a very difficult amp to design and build especially for a novice. It's as much about working out the bugs of a design like that then building it. If you do not have extensive experience working out experimental and complex amps you will have a lot of issues.
My advice to you would be to build a Weber BFDR clone kit and use the two different cabs. Then as you learn more about amps tweak the Weber until you dial in both channels the way you want to. As for reverb with a distorted Jeff Healy type tone, it is not necessary, the reverb washes out. A clean sound with reverb sounds nice. So one channel can be for clean with the reverb and the other a higher gain. You don't need extra gain stages to get high gain from a 12AX7, if you know how there is plenty of gain there and driving a pair of greenbacks is going to really send it home for that sound. You could also go with a pair of 10" greenbacks or the less expensive but great Emi ramrods.
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Actually, I was just tooling around on the site, listening to various recordings of amps, and came across CraigB's recordings of the HoSo56, and realized that it's about as versatile as anyone could need! It sounds sweet!
I'm going to have to revisit the threads on that one :)
bigdaddy, I realize that my twin-hummer will sound different from a strat, but I'm not looking for an exact sound, but more an amp that's versatile, capable of clean cleans (I've heard some amps that their proclaimed clean channel isn't very), and a versatile OD sound. I just happen to love the bluesy rock OD sound like those guitarists... I'm sure my guitar would sound just as sweet, if a little different... :)
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"I'm sure my guitar would sound just as sweet, if a little different"
Yes, it will, but keep in mind that humbuckers are easier to overdrive and harder to keep clean. You have an advantage, though, with that SG200. Those early Yamaha pickups are the sweetest I've ever heard. They go against accepted knowledge but so what? They're lower output but very sweet and warm sounding. I bought an SHB400 on a whim. I've sold all my Gibsons (except the Firebird) and Guilds and now have 3 SHB's. I had an SG2000 but as my back got worse, it got heavier. It's my son's main guitar now.
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Now versatile is a different animal then what you described. Versatile is doable but as soon as you add a JBL 15" speaker that goes out the window IMO. Although a JBL can be overdriven and sounds great overdriven they can get real loud. I had a BF bassman with a SUNN bass cab and a D130 that kept up with a Marshall 100 watt half stack. It was loud because of the SPL of that speaker. So to overdrive it you need to push it.
One thing goes against the other and you end up with a headache from it all. So now you have to drive the JBL to distort and make sure the Fender type amp doesn't get farty so you have to add more filtering and use the master volume if you want one. A master volume on a 20 watt amp is weird to me. It's also very hard to get a really clean low wattage amp, you need headroom and that takes a clean power supply without sag so if it is a BFDR type amp it should be SS rectified and with either JJ 6V6 or a pair of 6L6GCs but with a lower voltage maybe. So that means you might need a different PT like the Allen PT replacement for a Princeton/champ. They can run a pair of 6L6Gcs very well and are not higher voltage epically with a SS rec. I did an amp just like that using that PT and it did have a lot more clean headroom then using the 6V6 but wasn't much louder.
And so on and so on. Add a good OD pedal like a bluesdriver and you might make it all work.