Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

My private blowtorch clone
My private blowtorch clone
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th May 2020, 07:54 PM   #41
hesener is offline hesener  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Munich, Germany
My private blowtorch clone
Quote:
Originally Posted by DontHertzMe View Post
It's a great setup . I was just wondering what values you chose for the chokes and filters. Did you tune it to a specific frequency?
In fact I didnt, I used chokes I had for another project (a tube linestage, actually). Usually, I would calculate the input impedance (voltage / current at nominal operation) and use that impedance to calculate the filter so optimum damping without ringing could be achieved, but it doesn't hurt to make the caps a little larger, since this is not the output of a class-D amplifier. So, gut feeling it was , and it seems it worked.

Forgot to mention, of course when calculating a corner frequency has to be chosen , so that the damping at the "problem frequency" (usually the switching frequency of the DCDC converters) is high enough. There is a great book by Richard Ozenbaugh on EMI filter design that explains that procedure in detail.
__________________
Paradise documents are here: Link list

Last edited by hesener; 25th May 2020 at 07:55 PM. Reason: forgot something
  Reply With Quote
Old 25th May 2020, 08:09 PM   #42
BesPav is offline BesPav  Russian Federation
diyAudio Member
 
Join Date: May 2011
Location: Russia, Moscow
Quote:
Originally Posted by hesener View Post
Did you measure the harmonics of this stage, with real , not super-matched transistors?

No, just because distortion itself can't help to estimate amp's performance.

I suppose, that all we need - is overall amplifier stability, while sounding really depends of components of actual build.

While we are really can reach ~100 dB feedback depth through all audioband we will feel all the ugliness of our measurement setups.




Quote:
Originally Posted by hesener View Post
A very useful circuit indeed.
Also with independently biased LTPs could be designed something like this.
  Reply With Quote
Old 25th May 2020, 08:17 PM   #43
hesener is offline hesener  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Munich, Germany
My private blowtorch clone
I just wanted to check if the correction of mismatching that your circuit provides actually changes the distortion profile. I found that mismatch shows up as distortion, maybe 70dB down but still tells us something...

And of course you are right, distortion only is not enough, and with feedback a lot of issues can be covered (and some others brought forward).

I like that circuit, simple and elegant! do you control the corner frequency of the common mode control somehow? It seems it provides a lot of CM gain in the audio band
__________________
Paradise documents are here: Link list
  Reply With Quote
Old 25th May 2020, 08:31 PM   #44
BesPav is offline BesPav  Russian Federation
diyAudio Member
 
Join Date: May 2011
Location: Russia, Moscow
Quote:
Originally Posted by hesener View Post
I just wanted to check if the correction of mismatching that your circuit provides actually changes the distortion profile. I found that mismatch shows up as distortion, maybe 70dB down but still tells us something...
Bad case matching obviously results in 1ma for 10 ma devices. This could be mostly eliminated with slightly different source degenerating resistances.

Quote:
Originally Posted by hesener View Post
I like that circuit, simple and elegant! do you control the corner frequency of the common mode control somehow?
No, i haven't tuned that behaviour now, but there are nothing complicated.

Quote:
Originally Posted by hesener View Post
It seems it provides a lot of CM gain in the audio band
Yes, curent-mirror-loaded LTP could provide up to 60-70 dB gain, so, again yes, loop could be unstable without proper tuning.


Oh, yes, mirrored second stage have much more swing, check attached.
Attached Images
File Type: png JFET IPS with BJT current mirrors.PNG (30.0 KB, 95 views)
  Reply With Quote
Old 26th May 2020, 02:25 PM   #45
catd is online now catd  Europe
diyAudio Member
 
catd's Avatar
 
Join Date: Mar 2017
Location: Germany
Hi!



Quote:
Originally Posted by hesener View Post
... so I settled for aluminum-filled nylon....

That's interesting...
Is the material conductive? I'm looking for something non-conductive for the same purpose, but for transistors in metal case where the collector is connected to the case.

greetings
  Reply With Quote
Old 26th May 2020, 03:21 PM   #46
hesener is offline hesener  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Munich, Germany
My private blowtorch clone
Don't think so, but I haven't checked. I would have to re-open the case to do that, it may take some time, sorry.....
__________________
Paradise documents are here: Link list
  Reply With Quote

Reply


My private blowtorch cloneHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Private messages Bonsai Forum Problems 26 24th May 2020 02:19 PM
When a Luxman clone is not a clone carlmart Solid State 68 3rd January 2020 09:16 AM
Generic Asian Clone driver board RE and Clone jacampb2 Car Audio 26 3rd July 2018 08:01 PM
FS: Drivers for JBL 250Ti clone (LE14, 108H clone, 104H-2 GordonW Swap Meet 10 20th May 2014 08:19 PM
Question regarding ProAc 2.5 Clone and Tempo 2 Clone zoooh Multi-Way 5 11th March 2003 08:19 PM


New To Site? Need Help?

All times are GMT. The time now is 01:17 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki