simple hi-fi phono amp

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dcribbs1412
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simple hi-fi phono amp

Post by dcribbs1412 »

My oldest...25 is into classic vinyl albums.
I'd like to build him a simple stereo tube amp for a turntable.
Any suggestions are greatly appreciated

D
John_P_WI
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Re: simple hi-fi phono amp

Post by John_P_WI »

May I suggest that you send Gingertube (Ian) a pm? Quite the knowledgeable guy.
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Cantplay
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Re: simple hi-fi phono amp

Post by Cantplay »

You want a phono pre, or pre and amp?

MM or MC input?

John
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Stevem
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Re: simple hi-fi phono amp

Post by Stevem »

For the preamp look up a schematic for a Dynaco PAS 2, easy build and since it will only be used with a turntable you can leave off the selector switch.
Note that you can still get transformers for these !
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rp
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Re: simple hi-fi phono amp

Post by rp »

there's always this classic.

http://www.amazon.com/Mullard-Tube-Circ ... 1882580036

Mine's in storage so I can't check the phono pre's if they are for modern MM carts or the older Crystal or Ceramics which had very high output. If your kid is using an MC you might be better off checking ebay for clone boards of modern 'classic' amps like Conrad Johnson PV2, PV5 - tons of stuff like that out there. I'm not sure if this includes a phone stage, or can say anything about the seller:

http://www.ebay.com/itm/PV5-12AX7-12AT7 ... 3379e054cc

If you copy a vintage pre from the Mullard book or a Dynaco totally dump the tone circuit, all of it, T, B, Loudness, Filters - you can really hear the negative impact on the sound even when set flat, and use very good film pots for the Volume and Balance - at least an Alps Blue Velvet. You'll need to keep the phono circuit far from the power supply, the reason that in Hifi amp and pre are often in separate boxes.

One big tip from experience, these old circuits were tested and voiced with the resistor and cap technology of the 50s and 60s, like vintage guitar amps shotgunning them with metal films and fancy caps will likely give you a strident amp, at first you'll go wow at the resolution but then pretty quick the nasty tone will start to grate. Build it with fair quality caps and resistors first then upgrade judiciously here and there.

BTW IIRC Triode offers dynaco kit copies, w/ chrome chassis and all that. and this http://www.dynakitparts.com/index.php?route=common/home

one more thought, as it's it's stereo and it's two of everything, if money matters, then your problem is the preamp w/ phono part, cheap answer is to build a simple tube amp with a passive volume pot (a good one again) and then buy something like this:

http://www.crutchfield.com/S-OYSpAjV3DG ... -PEQ3.html
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rp
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Re: simple hi-fi phono amp

Post by rp »

found this to doing a quick search, can't recommend on sonics or the seller but just pointing out options for you. Phono stage stuff is supposedly very tricky so this kind of stuff seems to me like a good option to a scratch build.

Worry is that more complicated modern tube hifi circuits are made to compete w/ solid state so it can have cold hard sterile sound from things like added regulation and revealing parts, to get a good sound necessitates experience. The old Mullard and Dynaco stuff are soft warm big sounding and forgiving for basic DIY, not very revealing but nice and enveloping - ie tubey.

edit: forgot link:

http://www.ebay.com/itm/12AX7-ECC83-MM- ... 338b820ae0
Last edited by rp on Mon Sep 08, 2014 8:16 pm, edited 1 time in total.
dcribbs1412
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Re: simple hi-fi phono amp

Post by dcribbs1412 »

Thanks guys
pm'ed Gingertube

Looking at a AT LP-60 turntable, so MM input ?
trying to keep cost down...

rp
thanks for all the info
I like the idea of "cheap answer is to build a simple tube amp with a passive volume pot (a good one again) and then buy something like this"
gonna see what I can find as far as simple tube amp

D
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rp
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Re: simple hi-fi phono amp

Post by rp »

You are all set to go with that TT, it has a built in phono stage :D

Any hifi tube amp circuit of your choice with a passive pot and you are off to the races. Balance pot is kind of essential IMO w/ TT but if kid is not critical listener, ie strapped into an Eames chair placed in the sweet spot w/ speaker height and placement tweaked after 3 day's laborious trial and error, you can do w/o.

A-T is a venerable audio company that kept a commitment to analog TT technology, they make very fine carts, their forte was consistency. Can't say much about this all in one TT given the cost constraints and the fact that it's likely all from China now but A-T was known for giving it their best shot.

Don't know how flush you are but in hi-fi land it's source first, biggest money should go into source -> pre -> amp -> speakers, and it's true, if it ain't there at the beginning the best amp and speakers in the world won't reproduce it. If the vinyl becomes an addiction this is the cheapest quality entry point, but you'll also need a phono pre:

http://www.needledoctor.com/Rega-RP1-Tu ... tegory=353
tele_player
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Re: simple hi-fi phono amp

Post by tele_player »

The LP60 has a built-in phono preamp, so it can go into the line input on any hi fi preamp.

That preamp is switchable, in case you have an amp with a MM input.

Edit: rp posted this info while I was writing.
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randalp3000
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Re: simple hi-fi phono amp

Post by randalp3000 »

great thread, I'm looking to build a tube phono pre with RIAA tone circuit. Been looking at the one in the RCA tube manual but I'll check out some of these others.

thanks
rp
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martin manning
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Re: simple hi-fi phono amp

Post by martin manning »

A number of phono pre kits are available too.
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rp
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Re: simple hi-fi phono amp

Post by rp »

This appears to be the Mullard book in full :!:

http://basaudio.net/blog/wp-content/upl ... ifiers.pdf

I've always wanted to build a 5-10 or 5-20 straight up un-modded 1950s style with all 1W ABs, Vitamin Qs, and Oil Filter Caps. Most likely I'd get the audio equivalent of a feather bed and a bowl of treacle but so what. Maybe you can do it and let me know.
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rp
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Re: simple hi-fi phono amp

Post by rp »

and for budget hifi I would'nt think twice and use Edcor, check this out:

http://tubelab.com/articles/component-t ... nsformers/

about half way down.
dcribbs1412
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Re: simple hi-fi phono amp

Post by dcribbs1412 »

like to use some 6v6's and 12au7's I have on hand
no experience with Edcor, but I hear only good things
some examples of simple amps I found.

big thanks to rp for the mullard manual download 8)


D
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Last edited by dcribbs1412 on Mon Sep 08, 2014 10:26 pm, edited 1 time in total.
matt h
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Re: simple hi-fi phono amp

Post by matt h »

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Last edited by matt h on Fri Mar 27, 2015 4:43 am, edited 1 time in total.
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