The Birth and Evolution of a Phono Stage.

[Mike]

Ok... This all started because I need a phono stage and I've been doing a bit of waffling about it recently received some suggestions, one of which I've taken as a bit of a challenge. So here goes....

The Plan:

To try and demonstrate that with a bit of basic knowledge and asking some questions it's possible to build a good quality phono stage for not a lot of money. In this case, no more than £200, hopefully considerably less.
Wherever possible everything will be sourced via t'internet or re-cycled from stuff that's lying around. All questions/answers will come via this forum to show the value of the on-line community.

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So, here we go. Feel free to ask questions, offer advice, pour scorn and mockery etc. over the next few weeks and we'll see what happens!


Cheers,
Mike.

P.S.There may not be much happening today as one of our cat's has died and we've just had to bury him, so I'm not really in the mood.

[WikiBoy]

P.S.There may not be much happening today as one of our cat's has died and we've just had to bury him, so I'm not really in the mood.

That is serious shit man you have my sympathy.

I lub my pooky (who dat!) and he is getting old. I have always had cats I hate it that they die. Dogs - huh! - horrible smelly things. Cats, so much internal energy and comunication. They are little people, you just need to learn the language.

[Mike Reed]

As the owner and worshipper of a stereo pair of monoblock cats (in black, of course) (monoblAck?), you have my sympathy. You don't say what the cause of death was, but if old age, consider the life you gave him (or her).

The father cat of mine loves to sit between the speakers for hours; you can see his ears twitching. He does prefer rock 'n roll to classical; the beatier the better.

His son has no interest in music at all. Kids nowadays......!

Never a dull moment with moggies; one of Nature's most successful species.

[Marco]

Agreed - and very well put, Richard. Sorry to hear about your cat, Mikey

We have three 'moggies' - two of them are 16 going on 17, and one is 11, so you have my sympathies.

Maybe your phono stage project will help take your mind off it?

Marco.

[anthonyTD]

Agreed - and very well put, Richard. Sorry to hear about your cat, Mikey

We have three 'moggies' - two of them are 16 going on 17, and one is 11, so you have my sympathies.

Maybe your phono stage project will help take your mind off it?

Marco.

hi mike,
my sympathy too mate, although it has been said that most who have commented have cats, or prefer cats, i remember my old colly cross dog, he was 17 when i had to eventually agree to let him go, broke my heart, even as i write this, it still hurts like hell...although their gone, you never forget them...
anthony

[Filterlab]

Sorry to hear about your cat mate, they're great characters - oh the stories I could tell you about Smudge (my cat from years back), full of mystery and snigger inducing moments, that's cats.

[Mike]

Thanks for the sympathies guys, Gibson (bless him) is now buried under the Acer tree at the bottom of the garden next to Mouli (she was my fave cat), but we still have some critters left, so life goes on...

Lister - Gibson's brother is still going strong at 17 years young.
Ginny - the staffy, big daft girly dog.
Milo - the Leopard Gecko.
Idris - the Bearded Dragon - jeez he can move fast!

And a pond full of various fishy folk, who are accompanied at the moment by monumental amounts of frog spawn and humping frogs!

More phono stuff tomorrow.

[Mike]

By shian7, shot with u30D,S410D,u410D at 2008-03-30


It all starts with this, an NVA phono board and regulator.

There are a few mysteries to solve here, for starters the phono board has bee supplied with a few components deliberately missing, all part of the challenge you see!
But first things first. Non of this will do anything without a power supply so that's the first place to start, we'll be needing a transformer or perhaps four, in fact! The phono board has four gain stages (two per channel) each of which is capable of being powered separately, so I have a few of choices:

1. One PSU feeding all for 'stages'.
2. One PSU with four individual regulated outputs.
2. Four separate PSU's.

At he moment I leaning toward option 2 as reasonable balance between cost and performance, but I'll have to do a bit of pricing up first. At the moment the only clue about this PSU design is from Richard suggesting a 18-0-18 (or upward) transformer, I'll have to have a look at this regulator board and try to work out what I/P voltage it needs (after rectification and smoothing) and what it's O/P is.

Hmmmm, decisions, desisions.........

Cost so far: £100 exactly. Gulp, thats half the budget gone already!

[Mike]

Ok, A quick peek at the pair of TO220 reg chips tell's me they're LM317 (+37V) and LM 337 (-37V), so the 18-0-18 tranny is making some sense now.

A very eye straining squint at the op-amps on the phono board (hopefully) tell's me they're OP37G jobs, which want a supply of 22V.

Time to find a tranny and do some fiddling!



P.S. in the interest of the 'finding everything on t'internet' promise, I looked it up on the RS website to make sure. I recognised the reg's but I'm clueless with op-amps!

[Mike]

By the way....... when I've finished poncing about with all this solid state stuff I'm still going to build a valve one.

So there!