audio-talk

the gain isnt too much of a problem as ive got some 10:1 sowter stepups, 12:1 cheapies and i saw a set of 15:1s on fleapay too, Using them 12B-wotsits it might be a problem of too much!! Unlikely to need step-ups then btw i wish i could do the math mike! figures arent my strong point (except the fe...

Andrew wrote:Agreed, but the 6072A is a very nice valve <snip> provided you don't get a noisy one, is as good as NOS Amperex.

I'm not arguing with you, but cressy says he'd rather not use ECC83's. Nuffink to do wi' me guv!

No alright put it another way, 1k load will be nearly 6dB down. X3.2.
= about 16H.

Say 30H will get you 5k @ 25 Hz.

gm = 6.3mA/V, Ri = 1030

Gain is not huge is it, I'm getting just under X6 if 10k anode load, 6.42 even if 100k.

So for 6k minimum @ 10 Hz say, looks like 100H. Gets X5.54

75H would be about 5k @ 10 Hz. Or is that not what you wanted to know?

pre65 wrote:see this

http://www.audio-talk.co.uk/phpBB2/viewtopic.php?t=1210

Oh I see, well if it's a commercial recording then it looks very lop-sided. Like it's starting to overload somewhere

Back to ECC83's again.. For some reason can't view that pic full size.. No could be cressy's idea has something going for it ~ as above kind of thing but with 7F8W's Two valves per envelope, 300V supply, 22k anode resistors, a staggering 4.5mA/V gm, giving a V gain of X99 (apparently). Ia 6mA, grid ...

....a mate encoded my rips to MP3 or summat and used a program called Adobe Audition to do it. .... now then, the signal wasn't sitting on the 0V line... one side was amplified more than the other I'm sure. Could that be as a result of the incorrect biasing? Is this you playing your bass through yo...

Oh my word, never seen that in my cool edit pro

Alright well theoretically, 7F8W might have a gain of X100 with a 22k anode resistor.

BTW the RCA one uses 7025, = 12AX7A, = ECC83

Trouble is if you don't want to use ECC83 etc. what are you going to do for gain? Cartridge output is going to be something like 5 microvolts at 20 Hz. Could be a cascode stage I suppose

Dave the bass wrote:Ahem... £48 P+P!

Buyer beware

Coming from Hong Kong ennit? Hmm, 90 quid nearly for a box

Sounds like a plan

Yes just say what the problem is and how to proceed

I'd be interested in seeing a list tho

pre65 wrote:I looked to see if Mike did these transformers,but his are a different size (and price).

'My ones' are what Maplin used to stock. The maker (Danbury) used to make most of their TX's actually, before they dumped him

We believe the stock is now Chinese in origin

Be interested to know what you reckon they sound like.

You've started something now! For what it's worth I'm using a slightly tweaked variation of Bob Danielak's vacuum tube phono pre-amp. http://www.geocities.com/bobdanielak/phono.html 1st stage is paralleled 6SL7, remainder 6SN7's. Gain's not a lot TBH but the best one I've had so far. Basic layout ve...