Lite Audio Phono Stage

[Dave the bass]

Originally Posted by James D

Grounded grid configuration gives you low input impedance and high output impedance and functions as a voltage amplifier only so voltage gain but no power or current gain. OK for an mc input but not real smart.. except its noise performance is a little better - not enough to be significant though...

James

Thanks James, so if I switch out the 1uF cap connected to the anode but leave the 47K resistor switched in I've effectivley bypassed that 1st stage of the ECC83? At the moment I've got only the 47K resistor switched in, sounds OK on our 'cruddy' Eagle Stereo SS amp at work, I've fed the o/p of the phono pre into the tuner i/p on the Eagle to test it yesterday.

DTB

[Global]

I'm posting from memory here and apologies if I'm misunderstanding you but AFAIK, the first gain stage is only used for MC cartridges and the input impedance for MM is fixed at 47K.

Mark

[James D]

DTB,

Yep that would work fine.

Once you have built the valve power amp and upgraded your speakers you will no doubt want to build a phone amp with passive eq. rather than active... you will be well out on the slippery slope by then

James

[Global]

Found it!

http://i36.photobucket.com/albums/e2...-37circuit.gif

Edit - I had intended to post the image rather than a link to it but no matter what I told Photobucket to do with its size it still took up too much space here!

Mark

[Clive]

I had the same re-size problem with photobucket on this forum the other day.

It may be some sort of caching problem. I found in the end when I manually refreshed the page I had the re-sized image. Strange, as it wasn't working this way previously.

Clive

[Global]

Quite right Clive but now I've made the original too D*** small!!!!!

Later!

Mark

[prince of darkness]

A link to a pdf of this circuit was posted earlier in the thread. I've copied it below for anyone who missed it.

http://www.tommytube.com/dunkin/LS37.pdf

[Global]

So not only is my image to small but it's already been posted.

Typical of the kind of day I'm having!



Mark

[Dave the bass]

Thanks everyone for all the advice, 'preciate it.

Originally Posted by James D

DTB,

Once you have built the valve power amp and upgraded your speakers you will no doubt want to build a phone amp with passive eq. rather than active... you will be well out on the slippery slope by then

James

Slippery slope eh. Open up the safety gate, I'm comming through!

Aslong as I get this project working nicely I WILL build an all-valve power amp, I'd like to feed my Technics CD player, JVC Tuner and Aiwa Cassette deck all directly into the power amp, no tone controls etc etc. Just volume (of course).

I've got a pair of Rogers Studio 1a's I bought back in 1990 that I'm very happy with so I doubt I'd change them. EVERTHING else yes!!!!

I like the DIY approach on this forum, I'd imagine I'm in the same position as a lot of folk here, don't have the budget for 'high end' stuff but that doesn't stop us going for high end sound via a spot of DIY. Are most of you chaps in Electronics or hobbyists? I'm an Electronics Technician for a Cancer Charity in London, very little audio work but lots of Incubators and fluid mixing/heating/cooling/ manipulation.

I'd like to be able to listen to few different designs before I commit any money really, I went to the Audiojumble last month in Tonbridge and it was really good to actually hear various equipments working. I noticed there are few kits at http://www.worldaudiodesign.com/ , I take it they have a lot to do with HiFi World magazine?

So many choices...low power 300B SE? PP EL34 type? Dunno, its all good innit

DTB

[prince of darkness]

Hi Dave,

With regard to World Audio Design, they were closely associated with Hi-Fi World (originally their kit subsiduary but subsequently sold). Unfortunately they are now out of business (the forum is still running, but it's anyones guess for how much longer). World Designs is now closely linked with the mag, but being a new company has yet to build up the sort of range WAD used to offer.