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12ax7 tube preamplifier kit

mcgarick

mcgarick

Super Member
12ax7 or 12AU7 tube preamplifier kit

Hello
Anyone know of a good stater 12ax7 OR 12AU7 tube preamplifier kit?
I want something to build thats inexpensive and great sounding,easy-fun to build for a novice.
Thanks for any recommendations.
 
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I don't know of a kit. But you may be able to snag something like a tuner from eBay and then use the schematic from one of the major amplifier manufacturers like Scott, EICO, Sherwood or Fisher. It could be a fun project. The reason I mention a tuner is because it would possibly have a power transformer that would be just right for your project. You can get a chassis from several of the online electronics shops like AES, Radio Daze, and even DigiKey. Just a thought...
 
My Bottlehead Foreplay II uses 12AU7 tubes, I believe the current model does also. The original Foreplay kits were $99! The current one is substantially more expensive.
 
It says on the site that with some minor changes it can take 12ax7's

Tube socket holes are designed for octal sockets and will take special octal size four pin sockets as well as our Bottlehead hole shrinkers, which allow the installation of nine pin miniature sockets. The kit is supplied with two 12AU7s and a 0D3, but the combination of these new features opens the door to all sorts of interesting experimental circuits using nine pin miniature tubes like the 12AU7/T7/X7 family, 12BH7, 6DJ8/6922/7308 family, 6N1P, 5687/7119, octals like 6SN7, 6DN7, 6EM7, even antique four and five pin tubes like the O1A, 26, 27, 37, 56, 76 - the list is huge!
 
Is this a magnetic phono preamp? That needs LOTS of gain, and 12AX7 is a possible choice. Likewise, if you're building a preamp with tone controls, there will be a fair amount of loss and you'll need gain to make that up. If you just need a volume control and input selector, you don't WANT much gain, and 12AX7 has WAY too much. With some power amps, a "passive preamp" (volume control only) is enough.
 
As stated above, the bottlehead kit is excellent.

A really cheap alternative, would be the aric audio pre-amps. If you contacted him, he might send you the parts. I had him build me a pair of mono pre's a few years ago.

They sound good, but are finicky as hell. I still love them though. Over the years, they have outed several higher priced pre-amps.
 
Why dont you research a schematic, source some parts and build your own.
The RCA design looks very nice. With the added attraction, in that by, saving money on kit form. You can by better iron, caps,wire etc... Kit as a bundle are nice but there are sacrifices. someone else gain, pun intended.
I might add, I built a sourced Pas x, stock trx, and I chose to go with boards as I needed phono.
There are a lot of knowing and helpful people here. Go for it, this road has been gone down before.
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golana said:
The Chinese one on FleaBay, sounds good!
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I think I might buy one. How is the control over volume at low levels with that? I've found it's hard to find a pot that has precision at low listening levels. It's like the voulme is all or nothing. The pot I have now has an imbalance at really low levels, so I can't use my amp for light background music because it only plays the left channel and it drives me nuts.
 
hypertone said:
I think I might buy one. How is the control over volume at low levels with that? I've found it's hard to find a pot that has precision at low listening levels. It's like the voulme is all or nothing. The pot I have now has an imbalance at really low levels, so I can't use my amp for light background music because it only plays the left channel and it drives me nuts.
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My amp has gain control pots so, I haven't played around with that. I can say I like this one, well made and has given me no problems. It's 3-4 week wait to recieve 'em though at least mine was.
I saw cheap ones to assemble yourself, it'd be some soldering time. Then do your own gain curve. Calculator here http://homepages.tcp.co.uk/~nroberts/atten.html,
 
I sometimes forget things like my phone number also. I did exactly that last year If yoou'd like to know where, I'll pass it along. Very well made, They have no PCB's for them, I'll use a RS board w/wires and clips.
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