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-   -   Need a good phono stage design.. (http://www.diyaudio.com/forums/tubes-valves/156564-need-good-phono-stage-design.html)

ncdrawl 11th December 2009 12:28 AM

Need a good phono stage design..
 
I enjoy the EAR products, but they are a bit too spendy for me..

MC and MM preferred, need PCB Schematics, etc.


tube of course..

Eli Duttman 11th December 2009 01:57 AM

If you want to deal with LOMC carts., either step transformers or Allen Wright's hybrid cascode will be necessary. Even the quietest, high gm, triodes lack an adequate noise factor for μV. level signal work.

ncdrawl 11th December 2009 02:14 AM

ok, scratch the MC requirement. I prefer MM anyway, for a number of reasons.

What out there is good, not too difficult?

Original Burnedfingers 10th January 2010 07:14 PM

ncdrawl

check out Hagerman Technology LLC: Cornet2 Vacuum Tube Moving Magnet Phonostage DIY Kit

or http://glass-ware.stores.yahoo.net/aiphprkit.html

just several phono preamps available out there

Miles Prower 10th January 2010 08:35 PM

Quote:

Originally Posted by ncdrawl (Post 2042468)
I just wish that someone would answer the goddamn question.

Simmer down there, sport.

Quote:

but I posted a very simple question.
No you didn't. Asking for a good phono stage design is opening up a very big can of worms. There are just ESSSSSSSSSS-LOADS of phono designs out there: hollow state, solid state, and hybrids. You have designs which use NFB and designs that don't. Designs that vary from extremely simple to the elaborate. And you will find those who will swear that their favorite is "the best", and they can give you plenty of reasons as to why they think so. Others will naturally disagree.

How does anyone really know?

You might want to give This design a look-see.

barretter 10th January 2010 08:47 PM

What you want to do is one of the trickier things in valve/tube electronics. It took me several years to achieve a decent result, but you have a head start as you can buy Morgan Jones's book "Valve amplifiers" which has several designs and will be very helpful.
If you don't want to go down that route, you can find unstuffed pcbs from Hong Kong at reasonable prices which claim to be versions of famous commercial preamps. For instance, for $20-30 you can buy a "T Audio Phono Amplifier" which says it is based on the Matisse preamp. It only uses 2 valves/tubes (a 12AX7 and a 12AT7) but you will also have to source all the other components and build a separate 300V HT + heater voltage power supply. The circuit diagram/schematic also has to be downloaded so I should make sure about that before parting with any money.

ThorstenL 11th January 2010 01:40 AM

Hi,

Quote:

Originally Posted by ncdrawl (Post 2009292)
I enjoy the EAR products, but they are a bit too spendy for me..

Then why not build a copy of the EAR 834P?

I covered the design and some minor mods a few years ago at the Audio Asylum and following that a number of people also build their own.

EAR 834P Copy Phono Preamplifier

The text is in german, but the schematics are there.

Of course, the same person also build one of my designs and actually liked that even better than the EAR copy:

Simple Phono Preamp build #1

Simple Phono Preamp build #1

(Second link has a very nice buildup of this and links to threads here where the design originated)

On the other hand Roman "Romy The Cat" Bessnov prefers the EAR 834P realised with Air or Vacuum capacitors for the equalisation.

Quote:

Originally Posted by ncdrawl (Post 2009292)
MC and MM preferred, need PCB Schematics, etc.

I would suggest not use a PCB, hard wired really does sound better.

There are several Threads on building "my" Phono Stage design, including a wooly mammoth sized one about building and debugging the design by "Kofi Annan", worth seeking out. My posts are notable under the nom du guerre "Kuei Yang Wang".

I also have a thread with a simple J-Fet Mc Pre-Pre. This comes highly recommended on bang4bucks and with the easily available 2SK389/LSK389 you can save yourself the hassle of selecting the Fet's for channel Matching

Ciao T

sled108 11th January 2010 02:43 PM

1 Attachment(s)
A Simple Question deserves a Simple Answer....

Pano 11th January 2010 03:20 PM

Thanks Sled!
I built a similar preamp about 25 years ago and was very pleased with it.
It needed a rumble filter, but otherwise I could not have been happier.

This should be a nice project for anyone.

planet10 12th January 2010 03:56 PM

1 Attachment(s)
Quote:

Originally Posted by Eli Duttman (Post 2009350)
Allen Wright's hybrid cascode

Attachment from (and more examples there):

Schematics

needs a really good power supply.

dave


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