Pavel Dudek's (Upupa Epops) amplifiers

Status
Not open for further replies.
Jump to Latest
#121
Upupa Epops said:
Answer to questions : Antisaturation diode is in this case BAV 21. Bias current is 250 mA.
In all my amps I'm using antisaturation circuit at VAS. This really simply connection ( only two diodes in each polarity ) create switch amplification of VAS to low gain when output voltage is near limitacion. If this stage have low gain, junctions aren't saturated and amps have much more better behaviour in clipping ( much shorter recovery time ).
Personally I highly recomment to use this circuit to Krell's and Leach's builders - pics tell more...
At pic is switch to lower gain ( by 1 kHz )...
Click to expand...
Hi Upupa,
could you talk me through what the diodes are doing as clipping is approached and past?
Could I set this up in a sym to see what is happening? How?

I see a LED for D15 & D16, is volts drop here not critical?
 
#122
At cathode of D3 is constant voltage, while at anode is voltage swing. When voltage at anode rise to higher value than at cathode, D3 switch and cause 100 % voltage feedback to input of VAS. D15 shift DC condition at cathode of D3 for better behaviour of this circuit. The same is in oposite polarity.
 
#123
Hi, Pavel,

Thanks for the info 😀
Usually the anti clipping cct is placed :
- 2 diodes parrarel with opposite directions at collectors of differential pair
- 2 diodes from VAS, one is sensing the rail voltage (so the VAS collector cannot be higher than the rail).

Yours is different, not these 2. What is the merit using this kind of anti-clipping?
 
#125
You don't mix two things - what you describe, is voltage limiter, not antisaturation circuit ( as I understant correctly ). True antisatutation circuit change " near rail level " amplification in all feedback loop, insofar that can't saturated all junctions ( mainly in VAS ), which bring much more overall stability at this " critical moment ".
 
#129
You are right in your own accent because your design is intended for audiophiles. Meanwhile I desgin for pro-world therefore my approach is reliability oriented.....😀

Even if the amp is loaded with anti saturation circuit
The diodes still protect the amp from heavy clipping overdrive in case of high frequency signals with open load as well as reactive loads
 
#130
Indeed interesting for some relic audio.
 

Attachments

  • justagigolo2.jpg
    justagigolo2.jpg
    53.5 KB · Views: 1,296
#133
Dear Pavel,

I have found both schematics and a parts list for DPA386se, but am unable to find a PCB layout. Was it not available though Amaterske Radio?

I have already built Pavel Macura's PM-AB1, but need something more powerfull for bass reproduction.

Yet another Pavel.
 
Status
Not open for further replies.
Top Bottom