After a couple of hours with the weller and a few more with the AVO changed the stage 2 valves from ecc81's to ecc82's. The stage does still clip the AD stage occasionally in loud passages ( when SUT) fitted. Whether of not the reduction in output impedance from changing the valve is benifical is not that apparent. Stage seemed quite enough without the SUT, i added the 10db of gain digitally in the DSP. So maybe with Marks word of warning about SUT's this is the way to go. Still need to add the cartridge matching resistors.
One thing i noted was when the filiment heater comes on the ecc82's glow quite brightly initially. - I throught this triolgy of valves (81 82 & 83) had the same heater requirements? As i only had a matched pair of Mullard mustards to hand - abit worring. Maybe i need to get a "stunt" pair of JJ's to play with until i am happy.
On the output impedance issue, maybe changing the valve to something with a little more gain, but lower output resistance if i am to go sans SUT. Ideas on a valve which would meet the requirements, ideally wanting a 300v ish supply. The ecc88 looks hopeful to my untrained eye?
BTW - on phono stages - one of the best i have heard was a Neumann studio mic amp - feeding a AD convertor with the RIAA being implimented via FIR straight into I2S ( The mic amp and AD convertor cost more than my car through)
Modify SRPP Phono Stage
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Paul Barker
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#17
Standard Mullard bright glow at start up.
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IslandPink
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#18
Valves like D3a , E810F and E280F run as triodes are very useful in this application . I'd prefer those to ECC88 myself, they all have 50 to 77 mu , so very helpful . My own phono, still going from 2005 in one form or another, uses D3a/RIAA/D3a . If you can run the D3a at 15ma+ then it'll be around 2k Zout or less . D3a's are getting expensive , so maybe have a look at E280F or E810F .vinylnvalves wrote: On the output impedance issue, maybe changing the valve to something with a little more gain, but lower output resistance if i am to go sans SUT. Ideas on a valve which would meet the requirements, ideally wanting a 300v ish supply. The ecc88 looks hopeful to my untrained eye?
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