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Old 8th July 2011, 08:52 AM   #51
damohpi is offline damohpi  Australia
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while I agree with the post just above, IIRC the RIAA, coupling, etc. capacitors Allen used in the RTP-3D and SVP-2 were Kemet SMC series (PPS SMD)
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Old 9th July 2011, 12:56 AM   #52
cjcc67 is offline cjcc67  Australia
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Originally Posted by damohpi View Post
while I agree with the post just above, IIRC the RIAA, coupling, etc. capacitors Allen used in the RTP-3D and SVP-2 were Kemet SMC series (PPS SMD)
Interesting they're SMD.
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Old 18th July 2011, 06:21 AM   #53
cjcc67 is offline cjcc67  Australia
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Just thinking about the Power supply for the CC and voltage refs. Is there any point using chokes in addition to the ss regulators?
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Old 4th September 2011, 11:04 AM   #54
cjcc67 is offline cjcc67  Australia
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Currently working on building the RTP3
Vacuum State - High End Hifi Equipment

I have this cct to use as the ccs. I just want to check before I proceed that I connect the -25V to the supply (obviuos) and the 0v connection to 'point c' indicated on the schemtic between the two emmiter resitors of the MAT02?
I have a LOMC so won't be using them but am considering using a 4PDTswitch allowing the 332 ohm to be selected for mm.

2nd question is are two 0,47UF caps in parallel close enough in value to the 1.0 uf caps?
Rhanks for your help
Craig
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Old 4th September 2011, 11:16 AM   #55
cjcc67 is offline cjcc67  Australia
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I have matched 2sk369 for sale. PM me if you want some
Thanks i'll need a pair a bit later.
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Old 4th September 2011, 01:24 PM   #56
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Quote:
Originally Posted by cjcc67 View Post
Currently working on building the RTP3
Vacuum State - High End Hifi Equipment

I have this cct to use as the ccs. I just want to check before I proceed that I connect the -25V to the supply (obviuos) and the 0v connection to 'point c' indicated on the schemtic between the two emmiter resitors of the MAT02?
I have a LOMC so won't be using them but am considering using a 4PDTswitch allowing the 332 ohm to be selected for mm.

2nd question is are two 0,47UF caps in parallel close enough in value to the 1.0 uf caps?
Rhanks for your help
Craig
Hi Craig,

Looks like the "old" RTP3c schematic you linked to only were prepared for a single CCS and not a dual CCS as you plan to use.

The two CCS should not be connected to the zero point. Instead they should be connected to the respective emitters of the MAT02. Between the emitters you have one resistor to set the gain.

The second question. Which 1.0uF cap? The one connected to LM329? It's not critical but why not use a single 1.0uF?

The two 1.0uF coupling caps are critical and should be matched (as every other component in the RIAA correction circuit.)

I recommend to order the instruction CD from vacuumstate.com, the money spend will insure that one get the RTP3 build as intended. Second, use what Allen recommended of components and substitute later. Have fun!
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Old 4th September 2011, 01:39 PM   #57
cjcc67 is offline cjcc67  Australia
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Thanks Kim.
The gain for MC if i understand correctly is 0R therefore no resistors. This dual ccs is to have half the current 9.5 mA flowing in each side.
The coupling caps. I was thinking of using some russian teflon caps.
I agree about the cd. Unfortunately it is no longer for sale from vacuumstate. perhaps someone has one they are willing to sell?
Craig

Last edited by cjcc67; 4th September 2011 at 01:41 PM.
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Old 4th September 2011, 04:08 PM   #58
Alex M is offline Alex M  United Kingdom
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Originally Posted by Kim Bay Smidt View Post
The two 1.0uF coupling caps are critical and should be matched (as every other component in the RIAA correction circuit.)
I agree that the components in the shunt part of the correction circuit (between the anodes of the valves) should be chosen to at least 1% and matched between channels to within better than this, but in my opinion the coupling caps after the phone stage (which, incidentally, in the version I used are 0.47 uF) are less critical: with my values the LF corner frequency is around 7 Hz, and 5% deviations for this are unlikely to be audible

Alex
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Old 5th September 2011, 10:10 AM   #59
cjcc67 is offline cjcc67  Australia
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Alex,
Can you please confirm the connection methodology for the ccs and which loops you are measuring the 9.5 mA.
Cheers
Craig

Last edited by cjcc67; 5th September 2011 at 10:15 AM.
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Old 5th September 2011, 10:36 AM   #60
Alex M is offline Alex M  United Kingdom
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Originally Posted by cjcc67 View Post
Alex,
Can you please confirm the connection methodology for the ccs and which loops you are measuring the 9.5 mA.
Cheers
Craig
Hi Craig,

The circuit I sent you should be inserted between the -25V unregulated supply and the emitter resistors of the input stage (which are absent for the standard LOMC configuration, in which case the CCS is connected directly to the emitters).

You measure the voltage across each of the fixed 1K0 resistors in the CCS in turn and adjust the pots in series with these: when the voltage is 9.5 V across both of the resistors, the current through each should be 9.5 mA and the total through the tail of the input stage 19 mA.

Alex
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