Greetings all,
I finally took the plunge and bought 4 Hashimito 20k:600Ω and 2 Sowter 1280 RIAA!! My searches around the web got me settled on this design (cf. attachement). I'd like to have your insight on 4 aspects (since I modified the original schematic)
--- Is the 600Ω attenuator in the right place? (before the line ouput trans)
--- Is the mono switch ok in this area?
--- the 600Ω resistor after the line input trans necessary?
--- And last, does a headphone output jack a good idea? Does this phono/preamp have enough gain/power? (ie 80Ω headphone)
Thank you so much for your consideration,
All the best,
Olivier
I finally took the plunge and bought 4 Hashimito 20k:600Ω and 2 Sowter 1280 RIAA!! My searches around the web got me settled on this design (cf. attachement). I'd like to have your insight on 4 aspects (since I modified the original schematic)
--- Is the 600Ω attenuator in the right place? (before the line ouput trans)
--- Is the mono switch ok in this area?
--- the 600Ω resistor after the line input trans necessary?
--- And last, does a headphone output jack a good idea? Does this phono/preamp have enough gain/power? (ie 80Ω headphone)
Thank you so much for your consideration,
All the best,
Olivier
The LCR should be terminated with single 600ohm load, and present to input as 600ohm so no need another 600 after the IT.
I would recommend to use best pentode circuit and IT for first stage (gain of 40+).
I would recommend to use best pentode circuit and IT for first stage (gain of 40+).
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Actually any pentode works, 6j49p-dru is bit low on gain just personal preference over e810f/d3a/6j51p etc.
You have 600ohm attenuator, I believe don't need extra 600ohm termination for the LCR.
Since you are making LCR yourself, I think also need to consider the DCR of the coils, there's a spreadsheet tool but I wasn't able to use it correctly.
For second stage IT output, a friend is using single 6am4+ll1692a with excellent result.
You have 600ohm attenuator, I believe don't need extra 600ohm termination for the LCR.
Since you are making LCR yourself, I think also need to consider the DCR of the coils, there's a spreadsheet tool but I wasn't able to use it correctly.
For second stage IT output, a friend is using single 6am4+ll1692a with excellent result.
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