#1
So, I just had the sweet privilege of hearing and amp that noone has ever heard before.

I've built probably about 8-10 amps now...all but 2 were other designs (mostly from AX84.com), just finished up the third of my own design. The overall design has a few tricks and cool things that haven't really been put in an amp...should have a wicked blues and rock tone and be able to get to metal pretty well. If ppl want a more extended technical description of what it does, let me know and I'll be glad to post...going to bed in a few min here, so I'm not going to take the time now.

Because I'm broke, I built the thing into a cake pan ($2.99 vs $50 for a proper chassis), currently sitting on top of a plywood cab a friend and I built. The tubes on it, left to right, are a 6SJ7 (out of production pentode), 12AX7, 6SL7 (in production dual triode), and 6V6. It's a 5 watt amp, still too loud for my apartment.

How does it sound? Right now, like sh!t. There's a bad cap in it somewhere that's totally screwing things up...works for 5 seconds, sounds like it's dying, works for 3 seconds, dies, etc...need to replace a part or two and then things should get better. In the few seconds where I can get it working, sounds pretty cool...too much bass, so that the distortion is kindof blat-y, but that's easily remedied with a new cap or two of differing values. Coolest part: you can turn everything up to "10", no hiss, no squeal, no hum, nothing. Goes to show what amps COULD be if amp manufacturers were willing to spend $2/amp on good quality shielded wire.

I attached two pics here, 1 exterior and 1 gut shot. Hope you enjoy.
Attachments:
P1120149.JPG
P1130150.JPG
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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#2
That interests me about the shield wire. Can you do this to production amps as a mod?
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#4
Quote by dcdossett65
That interests me about the shield wire. Can you do this to production amps as a mod?


some have it already, some don't, some implement it well, some don't.

Another thing that prolly helps is that I ran heater wiring in really tight twists, instead of on the PCB where it's radiating all sort of EMI crap for tube grids to pick up.

And I used the "headphone trick", only using my oscilloscope, to place the transformers so there's as little coupled hum as possible.

Lots of stuff... *Shrugs* an amp is a whole package...if you screw up one thing, it's gonna suck (or be less good).
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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#6
Quote by guitarcam123
looks good


Thanks! sorry the pictures blow. Will get some bigger ones up on photobucket when I get a chance...want to get things sorted first, then I have a ton of tweaking to do before it'll be recordable.
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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#7
seems like a cool build! I like the cake tin idea, I've never thought of those as an enclosure for larger projects. And that's is REALLY interesting that it's noiselsss..
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#9
Quote by james4
looks pretty sweet

which ax84 projects have you built before?



Thanks!

I built the P1, P1-ex, the Clean and Lead I preamps into a 20 watt SE amp, and was one of the original developers of the Lead II (I didn't build one of the original 3, I worked w/ the ppl building them). I built John Hynes Lead II into a 50 watt version, currently rebuilding that one. And I helped a bit on the Talon development, even if it isn't an official AX84 amp.

My favorite? Lead II. Next favorite? P1. Yeah...the little 5 watt jobby. sweetness.
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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#10
Just checked voltages, I do indeed have a leaky capacitor (and it's the one I thought it was...makes me feel good being right for once). Replacing it tomorrow along w/ some other voltage adjustments, should be better then. then the tweaking can begin.

Better pics to follow. Anyone interested in a schematic? I could draw one up...
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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#11
Hey, it's the guy who posts in my build's build.

That's really cool. I like the cake pan idea.
Once I have a better overall understanding of everything that is going on in the amp, I plan on designing my own, instead of tweaking older designs. Hopefully next semester will help out. I'm an EE major at Arkansas, but as a Freshman, I only have core classes.

I look forward to hearing soundclips.
#12
Quote by end_citizen
Hey, it's the guy who posts in my build's build.

That's really cool. I like the cake pan idea.
Once I have a better overall understanding of everything that is going on in the amp, I plan on designing my own, instead of tweaking older designs. Hopefully next semester will help out. I'm an EE major at Arkansas, but as a Freshman, I only have core classes.

I look forward to hearing soundclips.


Sweetness! I graduated from UW Madison last Dec in engineering. trust me on this, don't blow off classes for guitar stuff like I did. NOT GOOD.

The best thing you can do for learning how to design stuff is to build something simple-ish, and then buy all sorts of caps and resistors and start tweaking, see what happens. good stuff.
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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Kit Amp Building Tutorial
#13
Quote by DLrocket89
Sweetness! I graduated from UW Madison last Dec in engineering. trust me on this, don't blow off classes for guitar stuff like I did. NOT GOOD.

The best thing you can do for learning how to design stuff is to build something simple-ish, and then buy all sorts of caps and resistors and start tweaking, see what happens. good stuff.

You graduated from UW Madison?! My cousin graduated from there like 2 years ago... I think from engineering as well...

But sorry to hijack the thread... Cool amp though...
#14
I did indeed.

More Pictures:

Front: http://i201.photobucket.com/albums/aa17/DLrocket89/Cake/Front.jpg
Left: http://i201.photobucket.com/albums/aa17/DLrocket89/Cake/Left.jpg
Right: http://i201.photobucket.com/albums/aa17/DLrocket89/Cake/Mojo1.jpg
Bottom: http://i201.photobucket.com/albums/aa17/DLrocket89/Cake/Bottom.jpg
Mojo: http://i201.photobucket.com/albums/aa17/DLrocket89/Cake/Mojo2.jpg

Bonus point to whoever figures out what "Mojo" does.

Figured out what was wrong...turns out it wasn't a bad cap, it was a "lack of cap". Most tone stacks are such that it has enough capacitors to block DC...well, this was my first go around with a James tone stack (a passive version of a Baxandall tone stack). Turns out the James doesn't block DC, so you need another cap in front of the tone stack. Damn. Added one, things were better. I had put one wire in a wrong place too, effectively bypassing the tone stack. Fixed that too. I'm not liking the tone stack really...not enough adjustment, just doesn't make enough change to be worthwhile.

Impressions of the amp so far are mixed...there is waaay too much bass up front (a consequence of the LEDs that you see on the board, when biasing tubes they allow a bunch of bass through). So much bass that it sounds like the amp is taking a giant crap if you palm mute with everything cranked. That's a (relatively) easy fix...gonna get to that tomorrow hopefully. It's going through a 12" Weber Blue Dog, which isn't the best thing for low end clarity, maybe that's it...

The top end distortion sound is dang near "perfect" for what I like though...good stuff...bright, cutting, but not *icepick in the ears*. so...score one there. Should get better w/ less bass too. Hopefully.

Quote by kcdakrt
DLrocket89 makes my ug experience better!


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