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Old 2nd October 2010, 12:19 PM   #5061
leflu is offline leflu  Germany
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Join Date: Mar 2004
Location: Hoexter
Hello Everybody,
as you all must have read, im at the planing of this Pre.
Will use stereo Salas-Reg and EI-Core Transformator with
serial 18VAc to get 36VAc and then rectified to get 46VDc
before PSU-Regs. So there is some Voltage to drop down.
By the way, do you all have experiences with different
Diodes as rectifiers? Recommendations?
And then, CRC or CLC Who compared those and what about
Capacitance?

Greetings Ulf
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Old 2nd October 2010, 12:58 PM   #5062
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Quote:
Originally Posted by leflu View Post
Hello Everybody,
as you all must have read, im at the planing of this Pre.
Will use stereo Salas-Reg and EI-Core Transformator with
serial 18VAc to get 36VAc and then rectified to get 46VDc
before PSU-Regs. So there is some Voltage to drop down.
By the way, do you all have experiences with different
Diodes as rectifiers? Recommendations?
And then, CRC or CLC Who compared those and what about
Capacitance?

Greetings Ulf
Tx same box R-Core, the other kind of Tx better separate box.

About diodes Fairchild Stealth ISL9K8120P3_Q Fairchild Semiconductor Rectifiers
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Old 2nd October 2010, 02:35 PM   #5063
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Location: Southern Tier NY
Ulf,
I used a 2x18V xfmr. Had initially a torroid but then switched to R-core. As has been mentioned, the R core is smoother sounding. For diodes I used schotkey from the get go, For other builds I have used differing diodes, however, have come to prefer schotkey. MBR3100RLG's to be exact.

For the power supply I used a RCLC. The R being the voltage dropping resistor. The C1 is >10,000uF. L being .35H aircore and the C2 being 10,000 Low ESR caps. I even bypass C2 with a 1uFMKP and .047MKP. (Truthfully I can't hear a dif between bypassed or not but it is there anyways.) Ripple off of the PS is <<1mV measured. PSUDII calculates a similar result. The R was measured in-situ to obtain the correct voltage and for a given load will be a factor of the xfmr regulation. The L was an old speaker crossover inductor I had laying around. It is cheap and fits nicely between the caps. This configuration provides a LOW impedance source to the salas shunt reg.
Again I went the CLC route vs. CRC as my experience in the past has been the CLC has a faster and stronger presentation of transients and better detail. (That tends to be my pref in sound).

For my build, even though I went r-core, I am placing them in a seperate box. Primarily for aesthetics.

P.S. you probably will have more than 46V volts with the 2x 18V windings. I get close to 60V in no load and 54V under load of the RIAA. The picture of the r-core shown earlier looks exactly like mine.
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Last edited by SGregory; 2nd October 2010 at 02:37 PM.
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Old 2nd October 2010, 04:53 PM   #5064
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Quote:
Originally Posted by SGregory View Post
Ulf,
I used a 2x18V xfmr. Had initially a torroid but then switched to R-core. As has been mentioned, the R core is smoother sounding. For diodes I used schotkey from the get go, For other builds I have used differing diodes, however, have come to prefer schotkey. MBR3100RLG's to be exact.

For the power supply I used a RCLC. The R being the voltage dropping resistor. The C1 is >10,000uF. L being .35H aircore and the C2 being 10,000 Low ESR caps. I even bypass C2 with a 1uFMKP and .047MKP. (Truthfully I can't hear a dif between bypassed or not but it is there anyways.) Ripple off of the PS is <<1mV measured. PSUDII calculates a similar result. The R was measured in-situ to obtain the correct voltage and for a given load will be a factor of the xfmr regulation. The L was an old speaker crossover inductor I had laying around. It is cheap and fits nicely between the caps. This configuration provides a LOW impedance source to the salas shunt reg.
Again I went the CLC route vs. CRC as my experience in the past has been the CLC has a faster and stronger presentation of transients and better detail. (That tends to be my pref in sound).

For my build, even though I went r-core, I am placing them in a seperate box. Primarily for aesthetics.

P.S. you probably will have more than 46V volts with the 2x 18V windings. I get close to 60V in no load and 54V under load of the RIAA. The picture of the r-core shown earlier looks exactly like mine.
I will try your CLC configuration in my PSU.
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Old 2nd October 2010, 09:32 PM   #5065
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Default Russian Hardware

Quote:
Originally Posted by merlin el mago View Post
Hi Simon,

About intestage cap: no doubt russian FT3 0.1uF 600V +-5 tolerance are my 1st choice (are the 4 big space capsules), for RIAA best teflon film & foil or minimum silver mica, for output cap a very good combo with interstage russian teflons are Mundorf Paper In Oil Silver Gold Oil. The photo is showing russian teflons FT3 insterstage & Auricaps output.

Cheers, Felipe
Hi Everyone

Is everyone getting their Russian components from 'Siberian-Shop' ?
I just found them on the net yesterday.
They have several types of capacitor and lots of valves.
They also have some real cool filament number display tubes !
Used to have a 19" 4u 'Digital Measurements' DVM at work with filament number display, it was a monster, but VERY high voltage, and accurate.

Cheers Simon...
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Old 2nd October 2010, 09:39 PM   #5066
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Simon,
I used alexer1 on ebay. His store is SOVCOM. He had the FT-3 and polystyrenes I used.
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Old 2nd October 2010, 10:09 PM   #5067
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Default Thanks for the tip.

Quote:
Originally Posted by SGregory View Post
Simon,
I used alexer1 on ebay. His store is SOVCOM. He had the FT-3 and polystyrenes I used.
Hi SGregory
Are you Scott with the KT88's ?

Yes I was pleased to discover very hard to find R-Cores as would very much like to make my pre in 1x 19" 1u.
R-Cores down the left & amp to far right & screening in between as well.

I'm glad to hear you like your phono.
I think JFETS are the way to go for me also, I just like playing with valves, so was toying with the idea of a valve pre, as I am making a valve microphone and stereo mic preamp at the moment.

Maybe the Heathkit MA12 will keep me happy on that for a while, bit under powered ? I dunno, maybe.
Found loads of happy MA12 users on the net, but suprisingly can't find a schematic or constructors manual for it (there must have been thousands produced ?).

Thanks for the Sovcom tip, I have paper and notes EVERYWHERE at the moment, and have been on the net all the time since joining diyAudio (haven't picked up a soldering iron for weeks, Oh dear), getting there though.

Cheers Simon...
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Old 2nd October 2010, 10:36 PM   #5068
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Join Date: Apr 2003
Location: Southern Tier NY
I built this one with the help of everyone here on the forum: OPUS 5.0 A Modern Mullard.

Getting ready to tinker with it this winter.

I was like you with all of the papers but found over time the easiest way to control the paper is to put them in 3 ring binders. I keep one for each project and possible future project. I also keep a master notes log for ideas, xerox ideas, and measurements. Now my wife just coments on how many folders I have ;-).

If you have the same r-cores, don't trust the wiring to be correct per the tag. Measure it to make sure. Transformers are fine otherwise.
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Old 3rd October 2010, 09:20 AM   #5069
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Quote:
Originally Posted by merlin el mago View Post
Tx same box R-Core, the other kind of Tx better separate box.
@Merlin and all

I'd recommend to use a separate box for a phono stage anyway, better S/N ratio etc. Otherwise shield the power transformer with Mu-metal case inside the amplifier chassis.

@Ulf

LCRC is an option too.
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Old 3rd October 2010, 09:42 AM   #5070
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Quote:
Originally Posted by The Space Egg Corp View Post
Hi Everyone

Is everyone getting their Russian components from 'Siberian-Shop' ?
I just found them on the net yesterday.
They have several types of capacitor and lots of valves.
They also have some real cool filament number display tubes !
Used to have a 19" 4u 'Digital Measurements' DVM at work with filament number display, it was a monster, but VERY high voltage, and accurate.

Cheers Simon...
I bought kwtubes on ebay, serious full rated seller.
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