Looking for recommendation for Phono Stage

What people are working on at the moment
RhythMick
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#46 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

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...
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Nick
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#47 Re: Looking for recommendation for Phono Stage

Post by Nick »

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.
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RhythMick
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#48 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

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.
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izzy wizzy
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#49 Re: Looking for recommendation for Phono Stage

Post by izzy wizzy »

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
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#50 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

Today's location for audio circuit thinking...
1548191055022356.jpg
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IslandPink
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#51 Re: Looking for recommendation for Phono Stage

Post by IslandPink »

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 ?
"Once you find out ... the Circumstances ; then you can go out"
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pre65
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#52 Re: Looking for recommendation for Phono Stage

Post by pre65 »

Sitting on the toilet, working it out with a pencil ? :shock: :lol:
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RhythMick
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#53 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

pre65 wrote: Tue Jan 22, 2019 9:09 pm Sitting on the toilet, working it out with a pencil ? :shock: :lol:
Someone help that men tuck his stool in...
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Nick
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#54 Re: Looking for recommendation for Phono Stage

Post by Nick »

I thought Rudolf was back for a moment then.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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shane
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#55 Re: Looking for recommendation for Phono Stage

Post by shane »

Careful! Say his name three times and he’ll appear.
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#56 Re: Looking for recommendation for Phono Stage

Post by Lee S »

Strictly speaking Shane, the Duck-billed Platypus is not the only egg laying mammal in the world... there is another called an Echidna... :P :P :lol:
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shane
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#57 Re: Looking for recommendation for Phono Stage

Post by shane »

This is true, but whoever heard of an echidna that ate custard?
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pre65
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#58 Re: Looking for recommendation for Phono Stage

Post by pre65 »

shane wrote: Wed Jan 23, 2019 5:37 pm This is true, but whoever heard of an echidna that ate custard?
Eric does. :lol:
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Mike H
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#59 Re: Looking for recommendation for Phono Stage

Post by Mike H »

Image

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...
 
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#60 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

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."
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