Hi brinker, I was just looking at your photo in post #377. They do "just" fit:
RJM Audio Emerald Phono Stage Help Desk - Page 38 - diyAudio
I know very little about the various brands of audio caps, except that some cost more than my entire project did. I spent the last year building vacuum tube guitar amps where it's the speakers, and to some extent the tubes, that have the biggest effect on tone.
Thanks Richard, I actually considered these smaller 100V caps:
Jantzen Alumen, Z-Cap 2.20µF 100VDC
But, they are over 2 1/2 times as expensive at $50 each. I can always upgrade caps down the road.
I'm shopping for a new cartridge, and I'd rather put more money into that at this point. I can either buy a new stylus for my Goldring 1042 at $300, or go in a completely different direction like the MC Denon 301 MKII at around $400. Then there's the Hana EL at $475. You see my point, cartridges are marketed to keep getting you to spend an extra $100 more...
RJM Audio Emerald Phono Stage Help Desk - Page 38 - diyAudio
I know very little about the various brands of audio caps, except that some cost more than my entire project did. I spent the last year building vacuum tube guitar amps where it's the speakers, and to some extent the tubes, that have the biggest effect on tone.
Thanks Richard, I actually considered these smaller 100V caps:
Jantzen Alumen, Z-Cap 2.20µF 100VDC
But, they are over 2 1/2 times as expensive at $50 each. I can always upgrade caps down the road.
I'm shopping for a new cartridge, and I'd rather put more money into that at this point. I can either buy a new stylus for my Goldring 1042 at $300, or go in a completely different direction like the MC Denon 301 MKII at around $400. Then there's the Hana EL at $475. You see my point, cartridges are marketed to keep getting you to spend an extra $100 more...
The caps arrived today, so I wired up the preamp boards. Unfortunately, I don't have time to power it up and take measurements now. It will have to wait until tomorrow. I assume it's a good idea to use my dim-bulb tester for the first power up, yes? And, of course, I still need to install the op amps and the jumpers.
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I think a simple smoke test is ok. With the op amps off connect the power supply then plug in the power supply. If nothing goes "bang" then you move in with the voltmeter to check that pin 4 and 7 of the op amps sockets is at the right voltage, trim with the trim pot, power off, add the op amps, power up again, wait 10-15 minutes, readjust the trim pot, and you should be good to go.
Thanks Richard. I'm not totally clear on how and where I'll be taking voltage measurements.
Do I measure from socket pin 4 to ground and then pin 7 to ground, or between 4 and 7? What voltage should I see?
Then, am I right that I measure between V+ and Ref and V- and Ref and use the trim pot to balance those reading?
Any other readings I should take?
Thanks in advance!
Do I measure from socket pin 4 to ground and then pin 7 to ground, or between 4 and 7? What voltage should I see?
Then, am I right that I measure between V+ and Ref and V- and Ref and use the trim pot to balance those reading?
Any other readings I should take?
Thanks in advance!
OK... I balanced the voltages with the trim pots and here's what I got.
Right Channel:
IC1 pin 4: 12.97VDC
IC1 pin 7: 12.99VDC
IC2 pin 4: 12.97VDC
IC2 pin 7: 12.99VDC
Left Channel:
IC1 pin 4: 11.95VDC
IC1 pin 7: 11.95VDC
IC2 pin 4: 11.95VDC
IC2 pin 7: 11.95VDC
Is the right channel a bit too high?
Right Channel:
IC1 pin 4: 12.97VDC
IC1 pin 7: 12.99VDC
IC2 pin 4: 12.97VDC
IC2 pin 7: 12.99VDC
Left Channel:
IC1 pin 4: 11.95VDC
IC1 pin 7: 11.95VDC
IC2 pin 4: 11.95VDC
IC2 pin 7: 11.95VDC
Is the right channel a bit too high?
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No, your in-/outputs are wrong.
In+/- from one board goes to one white RCA, and Out+/- on the same board goes to the other white RCA. Obviously the other board then utilise the red RCA pair.
It's fairly obvious on RJMs build photo RJM Audio - The Emerald Phono Stage
The 2nd COM slots, is if you don't join the COM line early from the bridge, and take them separately to each board - which I have done (currently don't have a photo of it).
In+/- from one board goes to one white RCA, and Out+/- on the same board goes to the other white RCA. Obviously the other board then utilise the red RCA pair.
It's fairly obvious on RJMs build photo RJM Audio - The Emerald Phono Stage
The 2nd COM slots, is if you don't join the COM line early from the bridge, and take them separately to each board - which I have done (currently don't have a photo of it).
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indeed, if I have the XLR on the opposite side, I will put the ground between the RCA. I'd like to keep the faceplate clean, but I understand it's less practical. Now, should I expect interferences? I have made a few amplifiers like that, and I never had any problem as long as the power cables are neatly routed along the chassis. I don't know with this preamp.