Borbely Audio

[biovizier]

Anyone tried their kit? Specifically the phono or buffer units?

[Leolabs]

I havent try any of them ,but the schematics are great.Should be sound very nice.

[fab]

I only tried the All Fet Power Amp output Statge board EB-1199/114 with components and everything was perfect (all closely matched transistors, which is the main reason I bought the kit).

I would expect the same quality of kits for buffer units but I have not tried.

You can find a lower price Borbely kit from http://www.welbornelabs.com/classa.htm
but I could not get the schematics from Melbourne. It is not a buffer but a line amp (which could probably be set with low gain). I have not ried it either because I need the schematics first.

By the way Erno Borbely is the designer of the old Hafler DH-200/220 amps.

Good luck

[john-china]

why does the Amp which borbely designed have high open loop gain , and low open loop bandwidth that is only 2 khz?

it conflicts with theory of prof. leach about low tim


i am confused about that .

[amplifierguru]

Hi John-china,

TIM is a misnomer for Slewing Induced Distortion (SID). Robert Cordell debunked this in "Another View of TIM" Audio Feb1980.

Any amplifier that has enough slewing rate to produce a 10KHz full output sinewave will not suffer from SID (or TIM) on music.

Open loop bandwidth has nothing to do with it or integrated op-amps with 10HZ open loop BW and 120 dB gain would suffer from it. But they don't because the signal handling in the individual stages is enough to ensure they do not overload.

In a power amplifier of output 50V, the slewing rate need only be 3V/us to be free of this type of distortion. Designers usually ensure is is 3 to 10 times this so THD is low at HF. Emitter degeneration of input stages and higher currents in successive stages are the usual methods.

Hope that helps,

Cheers,
Greg

[AndrewT]

Hi JohnC,
I have read both Leach and Borbely although not directly compared them.
Are you sure they conflict with each other?
Refer me to an example so that I can read again.

[john-china]

Originally posted by AndrewT
Hi JohnC,
I have read both Leach and Borbely although not directly compared them.
Are you sure they conflict with each other?
Refer me to an example so that I can read again.

almost in Amp designed by borbely audio , open loop gain is above 85db, open loop frequence is only 2.2khz -3db ,

so i think conflict with prof. Leach

[Upupa Epops]

Be sure, that EB knows, what he doing....

[Sigurd Ruschkow]

I have many of Borbely's kits. The SB1 is an exceptionally good buffer. As is the SB2.
They both deserve the best PS one can get, and the 254 is such a PS.

If you search this forum, you can find threads on both the SB1 and the 254 by me.

The phono amp I am planning to buy from B. is his new one called /420 (an improved 419).


Sigurd

Originally posted by biovizier
Anyone tried their kit? Specifically the phono or buffer units?

[biovizier]

I am planning to use these items with an S&B stepup. With this I would use either the jfet phono or possible the S&B RIAA unit with 2 superbuffers. Which do you think would work best?