The MONGREL (supersym II) - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 1st July 2010, 06:16 AM   #1
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Default The MONGREL (supersym II)

Ahhh - At it again , to refine what I know already works. The original supersym(s) are now a year old , they have not gone to the fiery pit ... they even are very pleasing to listen to .

I just had to try for more stability , lower THD and the "MONGREL" is what I came up with. It is STILL the same core circuit-a single ended LPT with the Otala/Hitachi VAS but with a few improvements.

1. - 2 current sources and a cascode on the differential - much better linearity and PSRR in the "front end" , also.. ABSOLUTE signal symmetry at the input pair.

2. - lower differential current,slightly higher VAS current - better for running standard type 2 or 3 EF's with difficult loads and better linearity .

3. - Standard double EF but with type 3 current sources - carrier "suckout" ,less Xover distortion.

4. - better Vbe (complimentary)


Picture 1 is the circuit.

Picture 2 is the BEST FFT I have ever produced from a class B. The distortion is damn low , too. (pix 3)

On this set of simulations , I nearly was able to go to sub 10pF for Cdom and the simulation did not "choke". Soon I will tweak the open loop gain and global compensation but I suspect it is already close by the impressive stability I have already observed.
It seems Mr. Carlos (DX) saw the first one (supersym) , because now his amps are "locked and loaded" full of CCS's , this is how you really use them .... each of the 4 (CCS's) has a very valuable electrical as well as a noticeable sonic improvement. We don't waste valuable part around here !!

OS

Any comments or suggestions would be highly appreciated.
Attached Images
File Type: gif mongrel.gif (94.0 KB, 10445 views)
File Type: gif FFT 2_3 power.gif (21.4 KB, 9330 views)
File Type: gif full power thd.gif (12.0 KB, 8428 views)

Last edited by ostripper; 1st July 2010 at 06:23 AM.
  Reply With Quote
Old 1st July 2010, 07:38 AM   #2
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
TOO MUCH OLG ... arggg.

see plot below... I guess I will be busy.
OS
Attached Images
File Type: gif OLG.gif (17.3 KB, 8185 views)
  Reply With Quote
Old 1st July 2010, 07:45 AM   #3
Nrik is offline Nrik  Denmark
diyAudio Member
 
Join Date: Feb 2005
Location: Copenhagen
Ostripper: eventhough you still want to fiddle with the OLG and feedback, then the project is still very impressive.
I hope many people will buildt it just like Symasym.
One question: What are the ethomylogical content of the names of your amps? How did you come up with these names "Symasym", "Mongrel" ?
They sound very cool and unique.
__________________
STOP - Hammertime!
  Reply With Quote
Old 1st July 2010, 08:13 AM   #4
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Good circuit, Pete.

Dominant pole around 1500Hz, HF pole around 5MHz? Man, that's fast!

Do you feel the EFII with CCS is better sounding and lower distortion?

Shows very high OLG despite loading down the VAS with 110K, too.

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 1st July 2010, 06:07 PM   #5
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Thank you , Hugh.

I did place the DC feedback components on the wrong side of the main feedback resistor. This is corrected in (attachment 1) . This brought max OLG to 65db and unity to a respectable 1.2mhz (attachment 2)... This amp would make a VERY good high output video amplifier. I am happy. I suspect even with the changes 80v/uS slew would be a walk in the park for this circuit.

Quote:
Do you feel the EFII with CCS is better sounding and lower distortion?
It is better sounding as well as more stable. The CCS's lower the high order harmonics of the Xover distortion by 6-10DB ! As a added bonus the OPS is more stable. This amp can almost work without Cdom .. WOW at 12pf it breaks out at 1.2mhz (unity gain point ?-attachment 3) and will run happy at 22p. Even while oscillating , it still stays electrically stable (it still amplifies) , this is unlike all my other simulations.

(Attachment 4-5) is the best symmetry I have seen from a single ended input stage.

Quote:
By Nrik -One question: What are the ethomylogical content of the names of your amps? How did you come up with these names "Symasym", "Mongrel" ?
The symasym was mike brittner's creation , I upped the power and used newer parts to make the "supersym" . The "MONGREL" is ... part symasym ,part doug self type 3 OPS , inproved pioneer input stage (CCS's , not a stupid resistor), and economical output devices... A REAL MUTT.

So the "boys" can play I have attached "mongrel.ZIP" , LT simulation. Unzip "mongrel.asc" and "mongrel.txt" into same folder or desktop. NO models to hunt down , all you need is in the text. The simulation reads from the text.
OS
Attached Images
File Type: gif correct_schema.gif (62.5 KB, 8091 views)
File Type: gif correct_OLG.gif (36.6 KB, 2079 views)
File Type: gif osc_7pf.gif (27.4 KB, 1019 views)
File Type: gif inputperfect.gif (36.9 KB, 1002 views)
File Type: gif vas_OPS.gif (36.8 KB, 779 views)
Attached Files
File Type: zip mongrel.zip (6.7 KB, 465 views)
  Reply With Quote
Old 1st July 2010, 07:16 PM   #6
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Square wave was good , except a tad bit of overshoot. (attachment 1) 50v/us at 47pF is acceptable. At 22pF I had 87V/uS ... but too much overshoot.

This is worthy of a few pieces of FR-4 (I'm gonna build it. )
Attached Images
File Type: gif SWmongrel.gif (11.1 KB, 1089 views)
  Reply With Quote
Old 1st July 2010, 07:55 PM   #7
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
This looks promising as a high power version of Symasym, which is a great sounding amplifier (I'm using 2 stereo ones!)

I look forward to seeing a PCB and mabye European equivalent parts. Will this amplifier be compatible with Symasym in terms of phase response, to be used in a bi/tri amplified active setup with the original?
  Reply With Quote
Old 2nd July 2010, 03:43 AM   #8
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
Quote:
I look forward to seeing a PCB and mabye European equivalent parts.
I already have most of this amp and some of the improvements up and running. (attachment 1) I added the current sources with 1 trimmer each to adjust the standing current between 25-60ma. at 40+ma this amp sounds nearly identical to the 200 watt class A $7000 genesis amp which I a/b 'ed it to.

phase wise this amp is nearly identical to the original "symasym" the cascode has 0 effect on phase and the CCS's at the OPS have no effect either.

As far as parts...
Input - ksa992/ksc1845 or 2n5551/5401 or any Vceo 160-< / Hfe 60 - 200

Vas - mje340/350 mediocre - 2sa1381 / 2sc3503 superior (video amp - Hfe 100 +)

drivers - mje15033/32 or 2sa1837 / 2sc4793

Any outputs MJ or MJW or NJW (on semi) Hfe 25 - 50 (250v+ Vceo)

PS voltage +-55 to +- 85VDC . on shutdown amp below still works down to +- 10v !! No turn on "thump" as well.

In both the real amp and the sim I have used all these with only minor adjustments. Very wide parts margin for this circuit.
OS
Attached Images
File Type: jpg supersym.jpg (181.9 KB, 2393 views)
  Reply With Quote
Old 4th July 2010, 12:29 AM   #9
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
I got it . No cutoff like the krill or super class A. A Little positive feedback into my type 3 CCS's and good to go.. !

Look at the plots (1,2) . One issue , at high power , OPS become more typical Class B. At 10-20w neither output cuts off and the FFT shows .0008 or less and almost no 3rd or 5th harmonic.

Circuit is the last attachment.
OS
Attached Images
File Type: gif nocutoffoverview.gif (23.9 KB, 1995 views)
File Type: gif nocutoff.gif (12.4 KB, 518 views)
File Type: gif mongrelnocutoff.gif (105.8 KB, 1535 views)
  Reply With Quote
Old 4th July 2010, 01:45 AM   #10
diyAudio Member
 
ostripper's Avatar
 
Join Date: May 2008
Location: Albany , NY (smallbany)
I did a .step command with input as the variable and this shows that it is normal for the type 3 to "resist" cutoff. Hence the low distortion components. I only augmented this effect with a little positive feedback.

This is shown in attachment 1 at various output levels.

OS
Attached Images
File Type: gif steppedfft.gif (26.9 KB, 1523 views)
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Symasym - the next generation (supersym) ostripper Solid State 261 26th July 2014 08:48 PM
Supersym patent Rescue Toaster Pass Labs 6 22nd January 2008 09:49 PM


New To Site? Need Help?

All times are GMT. The time now is 02:34 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2