My Borbely All-Fet Preamp with Subbu DAC

[merlin el mago]

If I remember well Les Bordelon was an autorized dealer of Erno Borbely.

 

[kannan_s]

Les Bordelon now sells his own designs, inspired by Borbely I think, and this probably eliminates the problem of sourcing legacy Toshiba devices.

do you have any link to find out his offerings?

 

[janegood]

do you have any link to find out his offerings?

info@LBAudioSystems.com
Les Bordelon [lbordelon@roadrunner.com]

 

[janegood]

info@LBAudioSystems.com
Les Bordelon [lbordelon@roadrunner.com]

LBAudio Systems - Home

 

[janegood]

If I remember well Les Bordelon was an autorized dealer of Erno Borbely.

Correct

 

[janegood]

Remote volume control for "Borbely/Bordelon" preamp

Anyone with experience of the Crystal CS3310 and the TI PGA 2310, using the IRVC chip from TaunTek Home Page ?

 

[ticknpop]

Actually all of Les’s products use the same Toshibas ( or substitutes if he has to, but not as good as the preffered Toshibas).

 

[phase]

Nice project you have, those Borbely parts were a great find, I’ll bet it sounds good.
I am gathering the components for a similar build that will use an SD memory card reader to a dac, then a version of a JC2 line driver.

 

[merlin el mago]

SB it seems a shame to AC couple the Borbely preamp through an electrolytic cap. The Borbely system I run is totally DC coupled all fet/jfet from dac or phono input to power amp output. The power amp uses Borbely’s dc protect / mute delay board for DC protection - the protection board design is in the Borbely DC 102 article. If you want to protect the preamp output from DC output and avoid any capacitor coupling you can use the DC 102 protect board and make it more sensitive by adjusting the reference voltage setting resistors to maybe 10 to 50mv. It also gives you a mute delay for turn on.

Don’t increase the value of any of the power suppy Electrolytic capacitors on the DC 102 DC protect board like any diyaudio guy would normally do. The cap values are delibereratly small so it turns off (mutes) right away when the preamp is turned off or the AC power fails. The input to the protect board can be a 10uf /63 volt polyester instead of the back to back 22uf/40 volt electrolytics.

Updates to the preamp design are to use OPA 140 or AD 4625 op amps for the servo. They have 1/5 or less than the noise of the AD 820. Replace the 33K2 current source resistor for the VAS cascode with a E102 jfet current source diode. Replace the VAS cascode’s LM385 voltage references with 2 series connected green LEDs ( not blue ones like Erno first used, they are too noisey).

AD 4625 op amps exist?

 

[ticknpop]

The ADA 4522 is a better chip to use for servos.

 

[merlin el mago]

Thank you.

 

[ticknpop]

Actually its 3 green leds in series for the VAS cascode LM336-5.0 replacement