need a good low parts phono tube preamp schematic....

[subliminalmsg]

Hi Ivey

I know this goes against what you said earlier about the 12AU7 being different but would your schematic work with the 12AX7's(I have lying around). Also i live in the Uk so i presume I just have to watch what Im doing with the transformer and the rest should be ok? Plus I a new to this so i don't know what the output stage for the 12AU7 stage will be and the 12AT7 stage also, could you tell me?

[bman22]

Hello all,

I recently came upon access to sever thousand like new tubes. I have a really nice Bang & Olufsen record player, and I would like to build a tube preamp for it. I have access to 12AX7's and AU's, as well as many many other tubes. Im just wondering what the best tube to use would be, and also, as I live in the US, I don't have 250v running through my walls, so, should I look for a transformer, or are there any schematics that use 120v? If you have any good schematics for a full out amplifier as well, I may be interested in that too.

[SY]

No matter where you live, you need a transformer. Running direct off mains is insanely dangerous.

Given the question, I would look toward a prepackaged kit. Avoid Chinese Ebay vendors.

[bman22]

I have neither the want or money to purchase a kit, as they are quite expensive (usually due to the inclusion of the tubes, which I already have), and also because i think building your own is much more fulfilling. I have been looking around for a suitable transformer, but have yet to come upon a great one. Anybody have a link or model number for a good transformer?

[aardvarkash10]

**** about face. The power transformer is the LAST thing you look for since it's specification is going to be determined by your circuit.

Many have built the Hagermann phono stages in there varoius forms - ss, octal and nine-pin.
SY (just above you) has an excellent phono design - His Masters Noise - see the link to the article on the homepage here.
There are plenty of others including Pete Millett's designs.
Many have geneological links back to the RCA RIAA design which is easily sourced on-line.

regardless of how you do it, to do it properly requires top quality parts. Kit or otherwise, its not a cheap or easy exercise since you are dealing with a very low signal level in a very noisy environment.

A kit at the very least gives you a higher level of outcome certainty.

[SY]

I should also point out that tubes might be $30-50 or so for any reasonable design. If that's choking you, LP is not your medium.

If you build it yourself from any design that requires you to figure out layout, grounding, and the like, your chances of success are close to zero. Phono stages are the trickiest bits to get right.

[bman22]

Well, in that case, could you suggest a preamp kit, preferably about as cheap as you can get. I know tubes are an expensive subject, but, with as many as I have access to, it seems just like a waste to NOT use them.

[aardvarkash10]

Glassware has two options, both currently showing out of stock!

Some swear by Broskie, some at him, but you can't deny the build quality - it will probably be worth the wait...

[ThorstenL]

Hi,

Originally Posted by bman22

I have neither the want or money to purchase a kit, as they are quite expensive (usually due to the inclusion of the tubes, which I already have), and also because i think building your own is much more fulfilling. I have been looking around for a suitable transformer, but have yet to come upon a great one. Anybody have a link or model number for a good transformer?

I would agree with others, worry about the transformer last.

I suggest that you read the original thread for my (KYW is my alter ego) simple Phono:

DC Phono Thread - includes the "Valve El Cheapo Design"

There is also "build" thread with many problems in the build being resolved which will help giving you a good idea of the issues implementing a Phonostage.

Kofi Annan in +B Plus

It is REALLY worthwhile taking the time to go through all of it.

Afterwards build whatever you like, my design, Tim De Paravicini's EAR834 (which is surprisingly good given what it is) or anything else taking your fancy.

Ciao T