barrymclark Posted July 19, 2012 Posted July 19, 2012 Since affording a KBP build (as reasonably priced as they are) is likely out of the question, I may be going back to the DIY approach just for something to do. Also, since the Starlite will never be the production model that it was intended to be, I am stripping it down to the amp initially invision... plus a little more stripping down. I am looking at the Fender Champ as a basis. It is simple... and if it sounds like crap... that is because either you, your guitar or both... sound like crap (this being relative of course). Here is the question: Can I take, say, a Champ kit sans the tubes and transformers and replace them with beefier counterparts such as EF86 instead of the 12ax7, KT88 instead of the 6v6 and beef up the iron to put out 25w-30w and have a solid state rectifier? ...or due to the power bump is there a serious redesign necessary? There will only be a volume knob. I'd like it to feed an internal speaker and one extension ultimately. Thanks!
DetroitBlues Posted July 19, 2012 Posted July 19, 2012 My thought is the components have to match what you're putting in it. The exact values should be left to people with experience. Perhaps KBP or Bigbob may be able to help you.
barrymclark Posted July 19, 2012 Author Posted July 19, 2012 My thought is the components have to match what you're putting in it. The exact values should be left to people with experience. Perhaps KBP or Bigbob may be able to help you. I know they do... just how much of a complete redesign is necessary? Does a larger chassis have to be ordered for the leads? That sort of stuff.
DetroitBlues Posted July 19, 2012 Posted July 19, 2012 I know they do... just how much of a complete redesign is necessary? Does a larger chassis have to be ordered for the leads? That sort of stuff. No, its the components that make the difference. They have to be able to handle the load. Since its not a KBP Starlite, its now the Starlite Homebrew?
barrymclark Posted July 19, 2012 Author Posted July 19, 2012 No, its the components that make the difference. They have to be able to handle the load. Since its not a KBP Starlite, its now the Starlite Homebrew? Well, if I could swing it... it would still be a KBP Starlite.... but since that isn't likely... it would be just a, I don't know, Barritone Starlite. haha. Kinda what figured on the components... but I just wanted to be sure that there wasn't. Well, I certainly hope to lean on Brian and Lance. Brian seems busy these days. Hit and miss on PM responses. Don't wanna bug him too much. Once I am ready to order parts... I may ask him what he'd charge for the world's angriest Champ in a chassis. But... that is a couple months off. I wanna get the next semester of school going first and my daughter's 18th birthday out of the way. ...so I won't be doing anything until at least after October 4th. Maybe December if my school load is just silly.
barrymclark Posted July 19, 2012 Author Posted July 19, 2012 I see what you were getting at DB. Sorry, I know my initial post was an oversimplification. Just trying to think of the way to word it all. Hopefully Brian or Lance will chime in.
Hfan Posted July 19, 2012 Posted July 19, 2012 didn't Bigbob just post a bunch of stuff on a Champ build?
barrymclark Posted July 19, 2012 Author Posted July 19, 2012 didn't Bigbob just post a bunch of stuff on a Champ build? He did. This one would probably be more than double the output power and a very different preamp tube.
Gitfiddler Posted July 19, 2012 Posted July 19, 2012 Wouldn't it be easier and possibly cheaper to look for an 80's Rivera-era Champ II or Silverface Princeton? SF Princetons (sans reverb) can still be good deals if you look hard enough. And the tone is great and resale value stable. Obviously there are unknowns to any old amp bought sight unseen, but you could end up with a great little amp. Here's one I found on the Bay for example... http://www.ebay.com/itm/VINTAGE-1970s-FENDER-PRINCETON-GUITAR-AMPLIFIER-/110917848969?pt=LH_DefaultDomain_0&hash=item19d3380f89
barrymclark Posted July 19, 2012 Author Posted July 19, 2012 Wouldn't it be easier and possibly cheaper to look for an 80's Rivera-era Champ II or Silverface Princeton? SF Princetons (sans reverb) can still be good deals if you look hard enough. And the tone is great and resale value stable. Obviously there are unknowns to any old amp bought sight unseen, but you could end up with a great little amp. Here's one I found on the Bay for example... http://www.ebay.com/...=item19d3380f89 Too many knobs. Just want the one knob. And too little power and too many tubes. haha. It would be easier... but it would be the wrong amp.
kbp810 Posted July 20, 2012 Posted July 20, 2012 Well, let's start with transformers... Heyboer does make a champ PT that is rated for 3A heater current (which will accommodate a KT88) and still drops into the standard Champ Chassis (I'm sure others do as well, that's just the one I know of right off hand); but you'll likely want to seek out a bigger SE OT that you'll likely need to add a couple holes into the chassis to mount. You'll also want to beef up the filter caps as well. Solid state rectifier is easy, just a pair of diodes; or you could wire the rectifier socket for a tube, and then just use a plug in SS rectifier (which is just a couple of diodes in a plug that fits into the socket) - that gives you the option to experiement with a rectifier tube if so desired. You may also need to adjust the cathode resistor value for the KT88 as well, or add adjustable bias - Area 51 (thanks to Mavguy for that tip!) sells a really nice and easy to add fixed bias kit for the champ. Lastly, I'd also recommend adding a screen and grid resistor to the KT88, they'll help the tube live a longer life. I'm sure you're aware, but EF86's are wired differently from 12AX7's, and they are not interchangable; sounds like a neat idea though - I would recommend seeking one out that has been tested for noise and microphonics, they can be finicky tubes.
barrymclark Posted July 20, 2012 Author Posted July 20, 2012 Well' date=' let\'s start with transformers... Heyboer does make a champ PT that is rated for 3A heater current (which will accommodate a KT88) and still drops into the standard Champ Chassis (I\'m sure others do as well, that\'s just the one I know of right off hand); but you\'ll likely want to seek out a bigger SE OT that you\'ll likely need to add a couple holes into the chassis to mount. You\'ll also want to beef up the filter caps as well. Solid state rectifier is easy, just a pair of diodes; or you could wire the rectifier socket for a tube, and then just use a plug in SS rectifier (which is just a couple of diodes in a plug that fits into the socket) - that gives you the option to experiement with a rectifier tube if so desired. You may also need to adjust the cathode resistor value for the KT88 as well, or add adjustable bias - Area 51 (thanks to Mavguy for that tip!) sells a really nice and easy to add fixed bias kit for the champ. Lastly, I\'d also recommend adding a screen and grid resistor to the KT88, they\'ll help the tube live a longer life. I\'m sure you\'re aware, but EF86\'s are wired differently from 12AX7\'s, and they are not interchangable; sounds like a neat idea though - I would recommend seeking one out that has been tested for noise and microphonics, they can be finicky tubes.[/quote'] Hey Brian! Thanks for the info! I wish I understood half of it... but it gives me things to look up! The idea with the EF86 was that it might give me more clean headroom. Thing with tube amps is they have a sweet spot and I am trying to get that sweet spot up to the volume of competing with a rock drummer. I want it on the edge of breaking up right at those levels. Also wanting ridiculous touch sensitivity like the Roland JC. Any change in dynamics is a punch in the ear so you better mean it. No room for slop. It is correct in saying that since there is no attenuation on the preamp tube in the Champ then it is running full tilt? Sent from my iPad using Forum Runner
barrymclark Posted July 20, 2012 Author Posted July 20, 2012 Well, let's start with transformers... Heyboer does make a champ PT that is rated for 3A heater current (which will accommodate a KT88) and still drops into the standard Champ Chassis (I'm sure others do as well, that's just the one I know of right off hand); but you'll likely want to seek out a bigger SE OT that you'll likely need to add a couple holes into the chassis to mount. You'll also want to beef up the filter caps as well. Solid state rectifier is easy, just a pair of diodes; or you could wire the rectifier socket for a tube, and then just use a plug in SS rectifier (which is just a couple of diodes in a plug that fits into the socket) - that gives you the option to experiement with a rectifier tube if so desired. You may also need to adjust the cathode resistor value for the KT88 as well, or add adjustable bias - Area 51 (thanks to Mavguy for that tip!) sells a really nice and easy to add fixed bias kit for the champ. Lastly, I'd also recommend adding a screen and grid resistor to the KT88, they'll help the tube live a longer life. I'm sure you're aware, but EF86's are wired differently from 12AX7's, and they are not interchangable; sounds like a neat idea though - I would recommend seeking one out that has been tested for noise and microphonics, they can be finicky tubes. Wanting a buttery, velvety clean. Almost like there is a touch of reverb present that is just enough to affect the tone but not enough to actually make someone think there is a reverb present.
big bob Posted July 21, 2012 Posted July 21, 2012 Berry, build the amp for the build, not for a specific tone.. You will be much happier.
212Mavguy Posted July 21, 2012 Posted July 21, 2012 if you want to use an ef86 it's best to have that tube socket set up for a moderate gain, and have that socket follow 12ax7, 12at7 or 12au7, because ef86's are prone to being microphonic, and you don';t want a microphonic tube in V1, even if other amp builders have done it, doesn't mean that it is a sound practice. So that means an extra socket in that chassis, no big deal. have those two tubes and sockets wired for lower gain each and it might sound much better than a single tube and socket with the gain cranked up. I have an old amp that uses an ef86 in v1, but the gain factor is low.
barrymclark Posted July 21, 2012 Author Posted July 21, 2012 Berry' date=' build the amp for the build, not for a specific tone.. You will be much happier.[/quote'] Well, this is primarily for fun. In the end, I want every amp to sound like Ch2 on my JC120 with the tone knobs all at noon, distortion and reverb at 9 o\'clock and the FX circuit on but all controls minimized where the tone is impacted but there isn\'t a vibrato noticable. haha. Why can\'t they build amps that sound like that? Oh wait.. Sent from my iPad using Forum Runner
barrymclark Posted July 21, 2012 Author Posted July 21, 2012 Ok, I was really making this more difficult than need be. I am taking Brians subtly given advice and advice and not going EF86. Just no flexibility. 5f1 circuit in a Champ chassis. It will be 5751/SS Rectifier/KT88. Roughly 25w output. 12\" Eminence Red Coat Red Fang ceramic 50w. 103db @ 1m. Combo config. This is just a labor of love and nothing else. I may opt for unnecessarily premium components just because. Haha. Or not. We will see. I guess I\'ll order the chassis first. Saw one for $34.
212Mavguy Posted July 21, 2012 Posted July 21, 2012 The most important unnecessarily premium component(s) you will purchase is a massive output transformer, Barry. If you really want to walk your talk, you need very, very big iron for that. Am speaking from the experience of having gone down that road you are now on for quite some time, and having built, tweaked several times, and currently playing through almost exactly what you are trying to do, even to the point of sourcing premium parts from Hong Kong and Taiwan besides all over the US. I have that massive output transformer in my Champ build, bigger than the power tranny, it weighs 5-7 pounds and has to be mounted in the bottom of the cab. You can get one like it Made by Hammond or Heyboer, mine is Heyboer, 5000 ohm primary, 30w rated, 4/8/16 secondary. Besides being a great open mic secret weapon guitar amp, that amp is comfy with a Baritone or bass played through it, I upped the values in the filter section of the power supply by 50%, another good thing to do for a jazz Champ. Drives a 2/15 just fine, and it has all the kind of capabilities you speak of. It is insanelyly loud with a lot of punch running a 5ar4 and GE 6550a.. Just don;t expect a quiet noise floor with a single ended amp, it will be noisy with that '88 played loud no matter what you do. nature of the circuit. And that transformer is the secret of the jaw drop factor of that amp, it has it in spades.
barrymclark Posted July 21, 2012 Author Posted July 21, 2012 I hear ya! Hey, that kind of anchor oughta keep her from tipping. Hiss I don\'t mind. I play a JC120 after all. I will keep the PT in mind. I am looking at a few manufacturers of trannies at the moment. Pretty much brands i am familiar with. Thinking of going fixed bias.
big bob Posted July 21, 2012 Posted July 21, 2012 I hear ya! Hey, that kind of anchor oughta keep her from tipping. Hiss I don\'t mind. I play a JC120 after all. I will keep the PT in mind. I am looking at a few manufacturers of trannies at the moment. Pretty much brands i am familiar with. Thinking of going fixed bias. I used classic tone transformers and they work great. Plus they are made in Chicago just down the street from where I lived for 10 years.
barrymclark Posted July 21, 2012 Author Posted July 21, 2012 I used classic tone transformers and they work great. Plus they are made in Chicago just down the street from where I lived for 10 years. Yep. That is one of them. Heyboer and Edcor are the other two. Oh, and Mercury Magnetics. Gotta wonder though if there is really any difference for the money. Those can be almost three times the cost. Sent from my iPad using Forum Runner
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