Born Again Vinylista Phono Stage

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izzy wizzy
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#61 Re: Born Again Vinylista Phono Stage

Post by izzy wizzy »

mainscablesrus wrote:CBA with all that DIY shite, just buy one?

Instant sonic nirvana?

This DIY lark is all well and good but why spend decades fannying about with something that may sound crap when its done?

Just curious.
I wouldn't expect anything else from a vendor ;)

I started down this route by copying commercial stuff; good, highly rated commercial stuff.

And then my stuff became better.

And then some vendors asked me to make stuff for them but I couldn't be arsed and it wasn't going to pay better than the day job.

Some peeps have made my stuff and sold their commercial gear costing much much more.

There are, I bet, many here who have similar stories and we're here to pass on the odd tale or two so that others can build gear that is better than commercial stuff at many times the cost.

And on the way. it's a hell of a lot more fun than fronting up a lot of money only to find in a year, it's been superceded by the x.2 version.

Oh and BTW, I still have some commercial stuff but I know it's time is limited :bounce:

cheers,

Stephen
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#62 Re: Born Again Vinylista Phono Stage

Post by Cressy Snr »

Yikes! :shock:
Repeat after me.

“I will not be put off, I will not be put off. Not this time.”
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#63 Re: Born Again Vinylista Phono Stage

Post by Cressy Snr »

I have a few ideas and have decided to start simple. Some of you will be pleased to note that ECC83s will not feature, mainly because I don’t have any. On the other hand I have a boatload of E88CC and 6N23P, so I might as well have a look at trying to do something with them.

Meanwhile I’ve fitted a new EZ80 in the power supply of the Cole LCR stage and changed out the Russian Brimar ECC88s for some Teslas. This required the CCS on each valve to be readjusted to match up the currents front to back and side to side.Our Ant gave the Lenco a bit of a fettle this morning, and it all sounds perfectly fab.

It won’t when I’ve done my phono but it’ll be educational, and I have to start somewhere or I won’t start at all.
Last edited by Cressy Snr on Wed Aug 11, 2021 7:18 pm, edited 4 times in total.
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Nick
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#64 Re: Born Again Vinylista Phono Stage

Post by Nick »

Just to add to Dave's old post
This DIY lark is all well and good but why spend decades fannying about with something that may sound crap when its done?
Where do you think the ones you buy come from? Having seem inside a lot of expensive commercial phono stages, I have yet to see something that probably wasn’t first done and published as diy.
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#65 Re: Born Again Vinylista Phono Stage

Post by IslandPink »

I just had a quick trawl through EBay and found that
1. E280F's are now >£40 each so bang goes the idea they are a cheap sub for D3a
2. 6J52P's on the other hand are only £1 each !
What's the triode gain of a 6J52P, anybody ?
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#66 Re: Born Again Vinylista Phono Stage

Post by izzy wizzy »

Just a thought. As Steve is a MM user. Do some of the more mental pentodes as triodes have a lot of miller? Doesn't bother an MC with trafo (although I think it might for some but that's another story) but capacitive loading for an MM is something that MM users like to adjust.

Might that point to a cascode or pentode or low gm/high mu triode 1st stage? Cascode88 wouldn't be too problematic. Then 5687 or similar 2nd. Plenty of valve rolling choices too.
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#67 Re: Born Again Vinylista Phono Stage

Post by Cressy Snr »

Right!
I’ve drawn up 2 phono stages:
first one is an ECC88 version which is an example exercise from Morgan Jones book.
Second one is the WAD Phono II ECC83 version, but with an ECC82 cathode follower on the output rather than the ECC83 of the original.
I’ve found a few ECC83s hence the inclusion of the old WAD phono 2, with my mod of the output end.

MJ ECC88:
745A4A3F-D4C0-4111-BE59-67D3D8B0F27E.jpeg
745A4A3F-D4C0-4111-BE59-67D3D8B0F27E.jpeg (54.94 KiB) Viewed 2609 times
WAD ECC83:
0832E997-2187-455D-844E-B7B6466B4046.jpeg
0832E997-2187-455D-844E-B7B6466B4046.jpeg (58.27 KiB) Viewed 2609 times
These are the valves I have. I want something that gives decent sound and uses easily obtainable valves that are reasonably priced. Just need to work out the load resistor for the ECC82 output stage of the modded WAD Phono II.
Any reason why I can’t build either one of them?
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#68 Re: Born Again Vinylista Phono Stage

Post by Nick »

Only problem I can see with both of them is that you may have problems finding 1% RIAA caps that can take the B+ before the valves warm up.

As you have some depletion mosfets I would use those as the CF loads.
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#69 Re: Born Again Vinylista Phono Stage

Post by Cressy Snr »

OK,
Thanks Nick.
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#70 Re: Born Again Vinylista Phono Stage

Post by IslandPink »

Maybe you can find some of these in the UK.
https://www.datacsmv.com/index.php?main ... _id=196340
The 200pf is easier to get, plenty of those around.
I have used these for filters in the main amp, they are pretty good.

I had a check in my stash and the biggest I have in 250V is 3n3 , sorry.
Last edited by IslandPink on Thu Aug 12, 2021 11:08 pm, edited 1 time in total.
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#71 Re: Born Again Vinylista Phono Stage

Post by IslandPink »

ps. I'd prefer the first circuit since the ECC88 will make the first coupling cap sound more transparent... assuming it's running higher current than the ECC83.
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#72 Re: Born Again Vinylista Phono Stage

Post by izzy wizzy »

Silver micas come as 1% 500v and sound great IMHO
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#73 Re: Born Again Vinylista Phono Stage

Post by Cressy Snr »

Cheers Stephen. I'll look into getting some of those.
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#74 Re: Born Again Vinylista Phono Stage

Post by Cressy Snr »

OK, a question to the panel. Please forgive my ignorance of this stuff. I want to learn:
Below I've put two drawings of the ECC83 based phono.
Original
Screenshot 2021-08-13 at 13.21.28.png
Screenshot 2021-08-13 at 13.21.28.png (21.39 KiB) Viewed 2536 times
Modded by me (perhaps naively)
Screenshot 2021-08-13 at 13.20.59.png
Screenshot 2021-08-13 at 13.20.59.png (21.7 KiB) Viewed 2536 times
As can be seen I've swapped the position of the eq and the coupling cap/grid resistor. Jones argues that putting the coupling cap and grid resistor after the eq section, rather than before it, reduces interaction between them.
My question is that there is probably a 'you can't just' caveat to this. IOW, by reversing the positions of the two sections, is this messing up the first stage eq, and should well be therefore left alone?
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#75 Re: Born Again Vinylista Phono Stage

Post by IslandPink »

I prefer the second version because the 8n2 cap is biased up with more voltage. That's how I have the network in my phono, although in my case it's all in one RIAA. I don't think he difference between the two in terms of RIAA accuracy is very much, but to quantify it would really need me to check it on Spice.
I still don't like the idea of a 1ma valve, driving a cap through a 316k resistor, being able to preserve low signal levels, though. That's why I favoured the ECC88 circuit.
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