The MPSA92/42 are listed as 625mW, 50 MHz devices. Will they OK for the predriver stages?
Simulator only shows .2 watts at the pre-driver , .32 W ...even with loading.
Drivers are 1W at rest , 10W with a 2R output loading.
92/42's should be good , as the pre-drivers are affected minimally as loading
increases.
My OPS .... I have never detected any heat at all at the 1381/3505's . The
Harmon-Kardon 680/990 both use small footprint <1W devices , as well.
You should be fine , watch those pinouts.
OS
Drivers are 1W at rest , 10W with a 2R output loading.
92/42's should be good , as the pre-drivers are affected minimally as loading
increases.
My OPS .... I have never detected any heat at all at the 1381/3505's . The
Harmon-Kardon 680/990 both use small footprint <1W devices , as well.
You should be fine , watch those pinouts.
OS
Thanks OS, the MPSA92/42 are more easily available here. So I'll go with the MJE340/350 for Q101, Q102, Q103 and Q104 on the OPS and the MPSA for Q105 and Q106 and Q15 and Q16 on the Vindicator V(fa). Of course I'll have to redo the board designs.
Hari
Hari
(below) Slew OPS will easily handle a 3.2ma Vindicator VAS I.
Either use 330R for R48 , or adjust R49 to about 150R (the trimmer).
As you see , I just raised R26/R27 to 220R.
Like all the other slewmaster IPS's (with zeners) , R15/16 need to be adjusted
to the rails AND be a higher wattage.
With these values , and less than 60V rails .... I think even to-92's will
have enough derating .
OS
Either use 330R for R48 , or adjust R49 to about 150R (the trimmer).
As you see , I just raised R26/R27 to 220R.
Like all the other slewmaster IPS's (with zeners) , R15/16 need to be adjusted
to the rails AND be a higher wattage.
With these values , and less than 60V rails .... I think even to-92's will
have enough derating .
OS
Attachments
OS, thanks, I'll update the schematic with the revised values. My final target for the 3-P OPS is 65V rails.
Hari
Hari
Even at 65V rails , I think the 92/42's will work fine. As long as
the VAS is <4ma.
Worst case , you could change the ratio on the two cap multiplier
resistors for <60V IPS rails.
OS
what about the clip indicator can we use this with kypton V? or CFA?
https://www.youtube.com/watch?v=L9sVY_wdDKw
https://www.youtube.com/watch?v=L9sVY_wdDKw
What do you think it would do to change the behavior of the circuit in a big way? I think you may be jumping to conclusions. Try simulating it. It will probably work well in some circuits but not others. I think there are a lot of worse ways to mess up an amp.
I will , but not any worse than what anti-parallel diodes would do across the
LTP collectors.
(below) T13 or 14 saturate , forward bias T25 .... causing T26 to conduct turning
the LED on.
Short of clipping , the reverse leakage of t25 might affect the LTP.
I've noticed on lower Z circuits like this or the Kypton V .... no issue.
On a higher Z current mirrored input section , reverse leakage is a
bigger issue (like a "blameless").
Here is better one - Clip Indicator (LED) for any power amp
Runs right off the output (real low Z).
Another - Project 146
Clipping Indicator For Audio Amplifiers Circuit Diagram
These all assume you KNOW at what point your amp clips and references
the actual output waveform to a rail. At least this does not require input
stage "meddling". 😀
OS
Attachments
Is the value of CXa/CXb on the Vindicator V(fa) critical? I'm not able to source film caps of 39pF. Only 33pF/47pF available. 39pF is however available on ceramic/ceramic MLCC types.
Thanks
Hari
Thanks
Hari
Actually, try the Groner TIS without them initially.
It was mentioned that this TIS has peaking >7mhz. I did not see this
in any simulation including using a tian to probe the TIS independently.
I decided to at least include Cxa/Cxb as an option because this "peaking"
was mentioned by both Groner and Kleinschmidt.
The main 68-82pf local compensation (C11) might be enough (according to
both the bode of the TIS and global simulations).
This is a new design - bear with me ... 😀
OS
OS, we'll more than just bear with you 😀 You have been a veritable gold mine for us diyers 😎 I'll leave them out initially and see how it sounds, then I'll take a call.
Thanks
Hari
I'm planning to finish two slewmaster monoblocks for subwoofer use. I have two working spooky ips and the ops just need drivers and output trannies before it's ready.
Each slewmaster will have a 2x55V 800va transformer, so it should give 78-80v rails.
I want to use these subwoofers Dayton Audio UM15-22 15" Ultimax DVC Subwoofer 2 ohms Per Coil
Will 5p 0302 and 0281 be up for the task, or would you use MT200 devices for this project?
Each slewmaster will have a 2x55V 800va transformer, so it should give 78-80v rails.
I want to use these subwoofers Dayton Audio UM15-22 15" Ultimax DVC Subwoofer 2 ohms Per Coil
Will 5p 0302 and 0281 be up for the task, or would you use MT200 devices for this project?
