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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Salas DCG3 preamp (line & headphone)
Salas DCG3 preamp (line & headphone)
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Old 25th February 2018, 12:42 PM   #2661
beardman is offline beardman  Denmark
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Hi Salas
no need for more top..the opa2134 is just fine..

i will just try many small things to se what happening...just fun

i have no problem to play without the serve opamp..but i will not do that for long...again just fun to try
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Old 25th February 2018, 12:52 PM   #2662
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
Alright then
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Old 25th February 2018, 03:47 PM   #2663
nashbap is offline nashbap  United States
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Salas, I'd like to understand how Beardman says that the OPA 2134 makes the top end more clear. It would seem to me that any opamp used in the servo section would only be a negative the aim being to get as small a negative as possible.

nash
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Old 25th February 2018, 03:59 PM   #2664
nashbap is offline nashbap  United States
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Quote:
Originally Posted by Salas View Post
@ Beardman

If you need more top attack in your system try with a 10k log volume potentiometer.
Salas, does this come at the expense of losing some mid and lower or does it just highlight the top end more? Or does it make the entire presentation seem clearer? Love to try it out but thought I ask first.
Thanks, nash
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Old 25th February 2018, 04:19 PM   #2665
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
Quote:
Originally Posted by nashbap View Post
Salas, I'd like to understand how Beardman says that the OPA 2134 makes the top end more clear. It would seem to me that any opamp used in the servo section would only be a negative the aim being to get as small a negative as possible.

nash
Several operational amp chips in the servo position can possibly leave a detectable trace of their "DNA" behind. Bit of their THD, IMD, load damping, and self noise as integrators in other words. Beardman prefers a chip residual with little more sense of sparkle in his full system but he also recognized that the BOM's AD823 does not alter the raw preamp's tone when he compared it VS empty socket. So he is not without a compass, he is just salting his food to his own taste. Maybe marrying better with his TKD pot. Some other members reported hearing nothing when changing proper offset resulting op-amps types there in the past though.
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Old 25th February 2018, 04:28 PM   #2666
Salas is offline Salas  Greece
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Quote:
Originally Posted by nashbap View Post
Salas, does this come at the expense of losing some mid and lower or does it just highlight the top end more? Or does it make the entire presentation seem clearer? Love to try it out but thought I ask first.
Thanks, nash
Makes the whole presentation tilt to leaner and faster. Can feel cleaner if the total audio system's in room sound is rather heavy but can feel anxious if the in room sound is rather dry.
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Old 25th February 2018, 04:33 PM   #2667
nashbap is offline nashbap  United States
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Thank you.

Just the explanation I needed.
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Old 25th February 2018, 04:45 PM   #2668
nashbap is offline nashbap  United States
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Originally Posted by manniraj View Post
@Salas, that means that as we discussed earlier in the thread for my build I will be reusing the Salas BiB PSU boards (+/-IRF) with a 23-0-23v 1A (dual secondaries) RCORE transformer. So I got a 150R 5W load resistor for the BiB psu boards to set the voltage to +/-17V DC for the DCG3. Am I correct in assuming that the DC output voltage for DCG3 should be fixed at +/-17V?

Thanks
manniraj, where did you get the R core from?

Thanks, nash
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Old 25th February 2018, 05:03 PM   #2669
manniraj is offline manniraj  India
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Quote:
Originally Posted by Salas View Post
No matter DCSTB or BiB or other PSU its output has to be set at +/- 17V as noted in the DCG3 schematic.
Thanks Salas, but using a 0-23V*2 1A RCORE with BiB @ +/-17V DC output may be over rated! Do you think regulators on the BiB board have to drop the voltage to 17v and hence more heat dissipation?
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Old 25th February 2018, 05:19 PM   #2670
Salas is offline Salas  Greece
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If you can manage for large heat sinking on the BiB's CCS MOSFET it will like the large voltage drop to sounding bit cleaner. But its mainly a waste of energy and torturing that MOSFET. Drop voltage on a power resistor by using external rectification and external first reservoir making CRC to the BiB's reservoir skipping its own diodes or use a lower output transformer.
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