DIY Audio Projects Forum

Hi from south Alabama, USA
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Author:  AttilaTheHun [ 19 Apr 2013, 17:23 ]
Post subject:  Hi from south Alabama, USA

My name is Bruce Raymond. I know enough about electronics to be dangerous :-)

I'm a guitar player and decided that it would be fun to build a guitar preamp. I'm curious as to what I can design and build. For better (or worse) the fun part is always the designing and then building something to see how close my design comes to reality. As long as I learn something in the process I'm happy.

I'm about half way through Merlin Blencowe's book "Designing Valve Preamps for Guitar and Bass", which I find extremely well written. He's got good physical explanations of what's going on. The book is light on theory, but that leaves space for other explanations. Reading the book with it's classical design approach makes me wonder about simulation (LTSpice). How good are spice simulations of valve/tube circuits? I suppose that's a loaded question. What's the definition of good? And how do you account for things like saturation in transformers?

I'm planning on experimenting with pentodes (picked up a bunch of 6AG5's and 6AU6's). One idea I am fascinated with is controlling the screen voltage to implement a compression scheme. Basically, rectify and low-pass filter the signal and use the result to control the screen grid voltage. I haven't seen any writeups on that, but it's so obvious that I'm sure somebody else has already played with it. I'd love to know how those experiments turned out ("A Tube Compressor for the Common Man" appears to be a different concept).

I also picked up four non-working AudioSource Amp5.3 monoblocks ($10/ea - the power transformer has to be worth more than that). I'm looking around for a schematic. I've written to AudioSource to try to buy one. I'm waiting to see what the response is. Does anybody have any experience using an Amp5.3 as an instrument amplifier? Offhand, the heatsinking looks way too light, so that will probably have to be beefed up. I wonder about the rest of the power supply?

I'm pleased to be here. It's always nice to find people who are compelled to say "I wonder what would happen if I did ...".


Author:  Gio [ 20 Apr 2013, 08:28 ]
Post subject:  Re: Hi from south Alabama, USA

Hi Bruce. Welcome to the forum. Looks like you are well on your way. The Amp5.3 is fan cooled so the heatsinking is prob fine.
Please feel free to ask your questions in the forums.


Author:  Geek [ 20 Apr 2013, 17:48 ]
Post subject:  Re: Hi from south Alabama, USA

AttilaTheHun wrote:
My name is Bruce Raymond. I know enough about electronics to be dangerous :-)

.....and experienced enough to live to tell about it.

Welcome! :D

Author:  mwhouston [ 20 Apr 2013, 19:30 ]
Post subject:  Re: Hi from south Alabama, USA

I always get a great thrill out of listening to a new build for the first time. Most of the time they sound good. Audio DIY can be a great sport. I use the term "sport" losely here.

Keep us informed of any projects and progress through them. It's fun to see projects unfold.

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