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Good luck if you decide to do it - I'll be watching with interest
If I had the time and energy to build a guitar amp from scratch I would not go "store bought" and re-invent the wheel.
I would make something new based on the ideas and circuits of Merlin Blencowe, especially the vast tonal possibilities of the EF86!
I would also go for very low noise ,( something I am a bit anal about!) using either parallel triodes or a cascode front end.
Other amp techs might like to chip in? (tho' there would be no chips in the audio path!).
Dave.
http://i255.photobucket.com/albums/hh143/werdnayarg/DSC_0237.jpg
http://i255.photobucket.com/albums/hh143/werdnayarg/DSC_0734.jpg
[ECC83] -> [EF86] -> [MOSFET Follower] -> [Single Ended EL84] -> [10" Greenback]
+
[ECC83 Tremolo to EL84 grid]
My own design, incorporating Merlin's 'triode/pentode morph control', honed with many, many iterations.
Isn't the Z-Wreck a version of the Trainwreck Liverpool? (If so, the font of almost all knowledge is The Amp Garage - TAG [1] )
If I were to build an AC30, I think it should have the tremolo and vibrato circuits in, too.
[1] I may just have broken the first rule of TAG...
I can also recommend Steven Grosvenor's "service engineer's guide to the AC-30" if you want schematics and layouts.
http://www.thevoxac30guide.com
Easily worth twice the £10 he asks for it. And a nice bloke too
I tend to leave the morph control at the same setting (about 2/3rds of the way towards pentode), and have speculated about hard-wiring it and using the pot for a mid control instead. If I was building it again, I wouldn't bother with a front panel control.
IME, the EF86 sounds really bad if it is driven to cut-off (which is easy to do in the 2nd stage), and quite a bit of my tweaking was related to biasing it and the previous stage to stop this happening. It also sounds bad if the grid is driven positive, but thankfully one can get away with a huge grid stopper to tame this (no Miller effect).
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
The EF86 will not worsen noise if used as a later stage at a higher level and lower gain. It is a basic principle of all low noise design that noise is determined almost wholly by the front unless you make a complete pig's ear of subsequent stages!
Noise determined by RF stopper: Agreed, replace mostly by an inductor (a la Self) and, as said, an extra (to Miller) shunt capacitor. This would definitely be needed if a cascode were used.
Noise not a problem with AC30? Said I would not build an AC30! I did say I had a bit of thing about noise and I would love to find the time to experiment.
There are quieter guitars than Teles! In any case, guitars are not the only ways guitar amps are used. My interest is mostly in a recording, "studio" amplifier.
Dave.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
I don't doubt the cabinet and speakers were beyond saving, but really think twice before modifying an original 60s AC30 chassis with intact transformers, many people would pay a good amount just for that to rebuild another one.
Seriously, I love the AC30 sound, I love the Vib/Trem - which is very unique to the AC30, not at all the same as tremolo - actually reverb is easier to do externally these days - and really does come into its own when you jumper the channels, since you can blend in just a little and still get the great tone of the other channels. Jumpering is easy and if you use short right-angle cables you can leave them in place permanently, so I don't see it as a hassle. I rarely run an AC30 without it.
Lighter and more practical amps just don't sound the same, which is why you see so many AC30s on pro stages even today. The only reason I sold my last one was because a friend really wanted it - I could easily see myself buying another at some point. Truly one of the great amps.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein