A little more twisted than usual.... - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 8th October 2006, 12:51 AM   #11
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Quote:
Originally posted by BillH
Russ, count me in.

Do the twisted amps handle low impedance loads? I'd like to build an pair of amps of 60 to 100 watts each to drive ESLs. Will the amp's protection circuit handle an overcurrent condition well?

Thanks to you and Brian for your work so far.
Your welcome. Its a lot of fun for me too.

If you run the TXO with 2 output (TPM-LM3886) PCBs in parallel per side (4 total TPMs) then you could easily drive just about any load. And would be able to do 200+ watts.

As for overcurrent protection there is nothing I have designed explicitly for that on the PCBs, as that would limit the design somewhat, but the LM3886 itself does afford some degree of protection.

BTW, PCBs have been ordered... we will keep you all posted.

Cheers!
Russ
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 14th October 2006, 05:54 PM   #12
juma is offline juma  Germany
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Berlin
Hi Russ,
I thought that your SuSy schematic with OPA549 (http://www.diyaudio.com/forums/attac...amp=1156203340) would be nice for a 100W/8 Ohm amp my friend wanted me to help him with so I prototyped it quickly today ("fly by wire" - not even a decent p2p). I only changed it so that OPA549 works as an inverting amp and I used OPA1632 (according to datasheet it has a bit more voltage swing than THS4131).
The result was so good that I thought I have to report it back. It was a quick, couple of hours listening and comparing with two designs based on LM3886 (one single chip NI, the other bridged with OPA1632) and I'm almost sure that this one even surpasses them. The OPA549 amp was powered by regulated (LT1083) +-26 V supply. The next step is to build it properly (my friend insists on PCB although I'm a p2p believer).

Thanks for your inspiring effort.

Here is the schematic I used:
Attached Images
File Type: gif sysy-inv-opa549.gif (26.7 KB, 3972 views)
  Reply With Quote
Old 14th October 2006, 06:05 PM   #13
diyAudio Member
 
BrianDonegan's Avatar
 
Join Date: Dec 2004
Location: TPA HQ (The Basement)
The OPA is nice, but lacks internal common mode offset control, which is why we are using the THS version.
__________________
Twisted Pear Audio
  Reply With Quote
Old 14th October 2006, 07:48 PM   #14
juma is offline juma  Germany
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Berlin
Yes Brian, you are right. I didn't give it much thought, because in this circuit DC offset on speakers (and to ground) is less than 5 mV.
Anyway, there are situations where this property of THS4131 is important.
  Reply With Quote
Old 14th October 2006, 10:03 PM   #15
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Quote:
Originally posted by juma
Hi Russ,

Thanks for your inspiring effort.

Here is the schematic I used:

Great job Juma!!


Yes the OPA549 at low gain is a great power stage for the Twisted Driver.

We are actually going to produce PCBs for OPA549 as well as the LM3886.

Inverting the OPA549 is not a bad idea at all.

Cheers!
Russ
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 14th October 2006, 10:22 PM   #16
juma is offline juma  Germany
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Berlin
Quote:
Originally posted by Russ White

I would run it at even lower gain then you are. You are not really even coming close to pushing the driver.
Hi Russ,
I was thinking like this:
Typical source output = 2V RMS = 2.82 V peak
OPA1632 amplifies it 4.4 times = 12.4 V peak (realistic voltage swing with a bit of a headroom)
OPA549's gain = 3.03 (bandwith cca. 300 KHz)
So, gain per side of bridge = 4.4 x 3.03 = 13,33 V/V (10K / 750 R)
Total gain = 26,66 V/V - pretty much standard value for this power but can be even lower, as you said.
Inverted configuration is reported to have less distortion and sounds better, and I can only agree.
  Reply With Quote
Old 14th October 2006, 10:45 PM   #17
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Quote:
Originally posted by juma


Hi Russ,
I was thinking like this:
Typical source output = 2V RMS = 2.82 V peak
OPA1632 amplifies it 4.4 times = 12.4 V peak (realistic voltage swing with a bit of a headroom)
OPA549's gain = 3.03 (bandwith cca. 300 KHz)
So, gain per side of bridge = 4.4 x 3.03 = 13,33 V/V (10K / 750 R)
Total gain = 26,66 V/V - pretty much standard value for this power but can be even lower, as you said.
Inverted configuration is reported to have less distortion and sounds better, and I can only agree.

Yes I actually thought better of my remark and edited it. I think your gain is fine.

Good work!
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 15th October 2006, 11:02 AM   #18
diyAudio Member
 
Join Date: Jul 2001
Location: The Netherlands
How did you manage to make those beautiful 3D images?
  Reply With Quote
Old 16th October 2006, 06:40 AM   #19
diyAudio Member
 
Greg Erskine's Avatar
 
Join Date: Jan 2002
Location: Sydney/Australia
Looks like Eagle and Eagle 3D to me.
__________________
Greg Erskine
  Reply With Quote
Old 16th October 2006, 10:33 AM   #20
diyAudio Member
 
Join Date: Mar 2002
Location: Krakow, Poland
Default TXS parallel

Russ,
You told about paralleling OPA 549, did you mean method from TI Application Note or paralleling two moduls for example TXS ?
__________________
peter
  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
need an opinion..... as is usual Madmike2 Multi-Way 12 17th March 2008 01:15 PM
Not your usual hum problem. Please help. madisonears Chip Amps 10 28th February 2008 12:44 AM
A Dummy Load different from the usual fotios Solid State 5 1st March 2007 09:38 AM
Not the usual box..... (PIC) MCH Multi-Way 9 11th February 2006 12:13 AM


New To Site? Need Help?

All times are GMT. The time now is 11:33 AM.


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