Looking for recommendation for Phono Stage

RhythMick · Unread post by **RhythMick** » Mon Jan 21, 2019 6:09 pm

Thanks. So obviously looking for the squareness of the wave, but even that is a very visual judgement.

Totally agree ears are the final arbiter but if I'm going to try half a dozen options it will get quite difficult to compare I reckon. Still, if that's the best way I'm good. Perhaps 2 breadboards, winner stays on, keep trying to improve...

Unread post by **Nick** » Mon Jan 21, 2019 6:13 pm

Well, other than ears, the best way is you spend £15k-£20k on up to date audio analyser from AP, R&S or Keysight. You will be surprised how good a first step a square wave is though.

RhythMick · Unread post by **RhythMick** » Mon Jan 21, 2019 6:19 pm

Nick wrote: Mon Jan 21, 2019 6:13 pm Well, other than ears, the best way is you spend £15k-£20k on up to date audio analyser from AP, R&S or Keysight. You will be surprised how good a first step a square wave is though.

Fair point, thanks.

izzy wizzy · Unread post by **izzy wizzy** » Tue Jan 22, 2019 12:20 pm

RhythMick wrote: Mon Jan 21, 2019 6:09 pm Perhaps 2 breadboards, winner stays on, keep trying to improve...

I do something similar on the one I use. Mono the input and output with a combining connector and then modify one channel - swap back and forth.

Cheers,
Stephen

RhythMick · Unread post by **RhythMick** » Tue Jan 22, 2019 9:06 pm

Today's location for audio circuit thinking...

IslandPink · Unread post by **IslandPink** » Tue Jan 22, 2019 9:08 pm

That's all very well, but have you got a toilet where you can sit with a pad of paper, a pencil and a calculator ?

pre65 · Unread post by **pre65** » Tue Jan 22, 2019 9:09 pm

Sitting on the toilet, working it out with a pencil ?

RhythMick · Unread post by **RhythMick** » Tue Jan 22, 2019 9:12 pm

pre65 wrote: Tue Jan 22, 2019 9:09 pm Sitting on the toilet, working it out with a pencil ?

Someone help that men tuck his stool in...

Unread post by **Nick** » Tue Jan 22, 2019 11:59 pm

I thought Rudolf was back for a moment then.

shane · Unread post by **shane** » Wed Jan 23, 2019 11:02 am

Careful! Say his name three times and he’ll appear.

Lee S · Unread post by **Lee S** » Wed Jan 23, 2019 5:04 pm

Strictly speaking Shane, the Duck-billed Platypus is not the only egg laying mammal in the world... there is another called an Echidna...

shane · Unread post by **shane** » Wed Jan 23, 2019 5:37 pm

This is true, but whoever heard of an echidna that ate custard?

pre65 · Unread post by **pre65** » Wed Jan 23, 2019 6:15 pm

shane wrote: Wed Jan 23, 2019 5:37 pm This is true, but whoever heard of an echidna that ate custard?

Eric does.

Mike H · Unread post by **Mike H** » Wed Jan 23, 2019 6:58 pm

IslandPink wrote: Tue Jan 22, 2019 9:08 pm That's all very well, but have you got a toilet where you can sit with a pad of paper, a pencil and a calculator ?

Or even, just the toilet...

RhythMick · Unread post by **RhythMick** » Mon Jan 28, 2019 12:17 pm

Ooh that was a good week skiing. No snow since Dec 22 - pistes in remarkably good nick considering.

Now back to the important stuff. No not work, the next amp design.

Thomas Mayer also likes the D3A - http://vinylsavor.blogspot.com/2012/12/ ... h-d3a.html

"The low plate resistance makes this tube very suitable for transformer coupling. With a step down transformer, for example Lundahl LL1692A in 3.5:1 configuration or LL1660 in 4.5:1 the tube is perfect to drive a 600 Ohm LCR RIAA network. In such a configuration there would even be some gain left after the EQ network. With a step up transformer after the RIAA, for example Lundahl LL7903 in 1:4 confguration this could be boosted up for further amplification in a second D3a stage using another step down transformer for low output impedance. With a Lundahl LL2745 wired 2.8:1 at the output such a 2 stage phono preamplifier would have a MM gain of about 46 dB with an output impedance of less than 300 Ohms. This gain can be brought up to suitable levels for moving coil cartridges with a MC step up transformer."

audio-talk

Looking for recommendation for Phono Stage

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