Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dscottguitars on October 22, 2013, 09:46:01 pm
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Here is the finished product and hopefully soon to be more:
~50W 6L6 Push Pull
High/Low Power Switch- from 460v to 320v on the plates
Switchable Rectifier- solid state or tube (source)
Switchable Bias- fixed or cathode (response)
Adjustable Negative Feedback- from clean to mean touch sensitive feedback
4 or 8 ohms
Line out for recording or PA
Two channels- each with gain, bass, treble and volume controls
3 Button Footswitch:
-channel
-gain boost (switches in preamp tube stage)
-mid boost
Voltage ports for plate voltage, and cathodes to adjust bias without opening the amp
This amp sounds awesome! From very clean on channel 1 to squeaking distortion on channel 2 with gain boost. The tone stack is the James (Bandaxall) tone circuit I got from the Duncan tone calculator and has excellent response. Much more than the Fender circuit I've used in the past. Now it's time to get some of my guitar playing friends to try it out for me-I'm not a seasoned electric player-just wannabe...
The only change I plan on making is a larger chassis. This one is 14x8, the next one will be 16x9, as it's a bit too tight inside.
Thanks to this forum and everyone that has helped me along the way.
Daniel Scott
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More pics and schematic...
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awww hell no dude,don't change a thing.that is awesome.great work.how about some sound samples?you don't expect us to take your word for it do ya?
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I don't have a way to record it yet. I tried with my nice camera but all I get is distortion- not from the amp. Here is a pic of the guts and as you can see, it needs a bigger chassis. It's quiet and all, but I'd feel more comfortable with space...
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I dig the wood--walnut? Nice work. I know how much blood, sweat and tears goes into these builds--especially with all of the tone accoutrements. I would say that based on the gut shot, it might be tough to try to reverse engineer. :icon_biggrin: The James/Bandaxall is a nice change from the routine FVM stack. Enjoy! Regards
dennis
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I love it when a plan comes together, nice work
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Great work on the amp and cabinets. Did you make the cool guitar as well? That's an eye catcher for sure.
Robert
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Very nice dscott!!! I noticed the NFB is 142:1 :icon_biggrin:
I like the chello-guitar too. That's like a Swiss army knife including kitchen sink ;) Glad I won't ever have to work on it, lol. That's about as tight as Queen Latifah jumpsuit!
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Thanks for the great comments all,
Yes, I made the guitar. And, it is a bitch to work on/modify. I used mini switches for the high/low power and rectifier and thick cloth wire-big mistake that I won't make again. I found regular size switches for the next one and plan on using teflon coated wiring.
Jojokeo: Somehow the pot value didn't show, it's 10K which puts that ratio to 172:1 down to 4.55:1; aka clean to mean!
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Okay so all ya gotta do is fire up the iPhone, computer, or something so we can all close our eyes and hear the kitty purr, meow, and roar like a lion.
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Very nice. What iron did you use?
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Iron?? Transformers?? If that's what you mean I used Weber. http://taweber.powweb.com/store/magnetic.htm (http://taweber.powweb.com/store/magnetic.htm) They seem fine, although an acquaintance of mine thought they were inferior. They aren't expensive, but I'm not sure if I could tell any difference unless I had two 'exact' amps to compare them to an expensive brand.
Jojo, I tried a recording with my computer and it sounds like shit. I can't get a true reproduction. I need to get a good recorder of some kind.
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Jojo, I tried a recording with my computer and it sounds like shit. I can't get a true reproduction. I need to get a good recorder of some kind.
you can get pretty good 'bare bones' results w/ a fairly inexpensive digital interface to plug into before the computer such as PreSonus or many others, a Shure or Sennheiser microphone, & use a free recording software program like Audacity. But a simple video from your phone or digital camera at least gives okay results too. It doesn't have to be perfect and sometimes better if it isn't. Don't worry or feel compelled like you have to. It's only us that like to see how things turn out is all. It's like showing your school project to your family.
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Here are some youtube clips:
They actually sound much better once uploaded to youtube than directly on my computer. I had the input volume quite low on the built in mic.
Please don't critique my electric guitar skills as they are not that good.
The settings are: high power, SS rectifier, fixed bias, NFB at 170:1 ratio, bass and treble about 2/3 up,
Channel 1: gain at half, volume all the way up
Channel 2: gain all the way up, volume at half
Channel 1: clean adds gain and mid boost
Channel 1 clean (http://www.youtube.com/watch?v=J9l1hscmkUU#)
Channel 2: adds gain boost and then mid boost
Distortion Channel (http://www.youtube.com/watch?v=xibkB3T4uDg#)
Channel 2: intro to Electric Funeral by Black Sabbath gain boost on
Distortion Channel Black Sabbath (http://www.youtube.com/watch?v=FXBUKPZEv7E#)
Here is my acoustic guitar plugged in:
Settings: NFB about 16:1 ratio, bass at 8, treble at 9, gain at 6, volume at 10, gain boost on.
Note: there is NO preamp in this guitar, just a straight pickup-Schatten glued under the bridge plate, and plugged directly into the amp...
Clean Channel Acoustic Guitar (http://www.youtube.com/watch?v=_RuKZT_2-7Y#)
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:bravo1: