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Old 14th March 2012, 08:12 PM   #7391
Salas is online now Salas  Greece
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I have received today one nice aluminum box for my RIAA preamp. How to proceed with grounding the case ? My pcb's (preamp, shunt) and RCA connectors will be isolated from the case but i think will be good to have the case connected to ground. Also where to connect the ground wire that comes from TT ?
I usually reference the chassis with a single wire from the VinGND point at Riaa board. After that, any grounding post non insulated to chassis can ground the TT. Without a referenced chassis hum goes up, so its not an option, its a must. Did you find out what went wrong last time and your phono became silent by the way?
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Old 14th March 2012, 09:40 PM   #7392
atupi is offline atupi  Romania
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Oh, that situation shame on me, it was a human error. On the dau before a changed several interconnects and i was trying to use the wrong end of an interconect
That's way i had all voltages correct
Also i received some Mundorf Mcap 0.1uf/630v for interstage connection.
I'm so nervous to see the case populated with pcb's.
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Old 14th March 2012, 10:10 PM   #7393
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Which model? The simple supreme?
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Old 14th March 2012, 11:55 PM   #7394
Djinn is offline Djinn  Norway
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100n will be enough for bypass.
I do have 0.1 uF FT-3, but I was hoping to get a use for the 0.22uF 200V FT-3 that I have and these were cheaper to. Regarding mixing resistor and caps I just ordered Shinkoh, Z-foil, and 1M AMRG in matched pairs. I also have some PRP and Takman in cabon and metal film so getting it togheter with the "correct" mix is the next stage. The Salas BIB 1.2 shunts worked just perfect. What resistors did you use in the 1M riaa?
PS! the riaa is primaraly intended for a sme III with a shure V15III.
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Old 15th March 2012, 12:14 AM   #7395
Salas is online now Salas  Greece
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*BIB are 1.1
Many different 1M in many builds. Shinkoh, Takman REY, DALE, KIWAME, plain Jane.
SMEIII & V15 Type III & IV go hand in glove. Try listen to some high MC at a point also, this pre does well with them too.
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Old 15th March 2012, 10:53 AM   #7396
atupi is offline atupi  Romania
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Originally Posted by Salas View Post
Which model? The simple supreme?
Yes, simply supreme because my audio chain is not so high end and think i cannot hear so subtle differences. I ordered also some Vishay 1837 15nf and 0,1uf.
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Old 15th March 2012, 11:16 AM   #7397
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Very good sensible parts choices. Why you would need 0.1uF 1837 when you got the Supreme, and not 0.047uF 1837 to complement the 0.015uF 1837 in the Riaa filter? They are 1% saving you from buying many and sorting out.
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Old 15th March 2012, 11:25 AM   #7398
atupi is offline atupi  Romania
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Sorry i ordered 1837 0.015 and Mkp1845 47nF 0.047uf 250v .
Also i have a scope from a colleague. What measurements to do as i have it?
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Old 15th March 2012, 11:37 AM   #7399
Salas is online now Salas  Greece
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1845 are 5% at their best tolerance J variance. You would need an LCR to check them out. 1837 would be care free.
You can check that the regulator is trouble free by using the oscilloscope on AC input and 5mV/div, 10uS. Looking for a clean straight line on the screen with probe between B+ and GND. No small frequency riding, no noise hash. If you make an inverse-riaa input filter to very tight tolerance spec and you got a function generator you may check 1kHz square waves are good also. That will prove good Riaa shape. Our phono uses Lipshitz Riaa classic, no extra supersonic pole. Just for fun testing, not really to worry about when with tight Riaa caps and resistors in the phono, has been tested before it gives compliant Riaa if made well.
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Old 16th March 2012, 12:56 AM   #7400
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Salas could you please have a quick look at the k170 I found. Do they look legit? I got them for something like 20c a piece. I have no 9v supply right now to measure their Idss, but the vendor said they were matched to 8-10mA

Click the image to open in full size.

Thanks a lot for your time
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