Optimizing TDA7294 Output - Page 50 - 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 21st June 2013, 05:47 AM   #491
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Earlier I made an error when I said there was no need to remove the board from the Jim's Audio single layer TDA7294 kit. Indeed that was an error. The power, layout, of that particularly annoying board is quite bad sounding and I have not been able to remove the coloration. Well, not all of it. The best I could do with that board is reduce its contributions. But, that particular board does still manage to sing along with the music a little bit, and not correctly. The TDA7294 should not sound like that. Thus, I recommend to remove the board.

So, Bob, how do you feel about a point-to-point adventure?
Its either that or get the Parallel TDA7293 boards, which have only one coloration (easily fixed), at small signal, the routing of the nfb-shunt resistor, and that takes only about 2 minutes to fix, by sticking that ~730R resistor (or my resistor plus variable gain trimmer assembly) near the edge of the board, direct route from pin2 to the nfb-shunt cap. I like that one much better since the power layout doesn't make distortion. That is so much easier.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.

Last edited by danielwritesbac; 21st June 2013 at 05:52 AM.
  Reply With Quote
Old 25th June 2013, 01:55 PM   #492
diyAudio Member
 
Join Date: Jan 2011
it's been a month ,i put side by side tda7294 and lm3876, surprisingly they are almost the same sound.
  Reply With Quote
Old 26th June 2013, 09:17 PM   #493
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally Posted by simply14prem View Post
it's been a month ,i put side by side tda7294 and lm3876, surprisingly they are almost the same sound.
That probably means they're working right. Amplifiers in general, are definitely supposed to be fairly similar. We hope that any differences are both minor and favorable.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 11th July 2013, 04:31 PM   #494
Just DIY!
diyAudio Member
 
pinnocchio's Avatar
 
Join Date: Sep 2010
Location: Montreal
Any of you tried this excellent board?

TDA7293 X 4 BTL 350W Amplifer PCB Ultra Reliable | eBay

Click the image to open in full size.

Sounds really good. It is a parallel and bridged config. The sound will be influenced by the Opamp used but I use the OPA1612 (bipolar input) or OPA1642 (JFet input) which sound amazingly good!

You can also get rid of the opamp and use it as a stereo amp

I've built several of those and they're really good.

Ciao!
Do
__________________
PREAMPs : AMB α10 + JC-80 clone | Balanced DCB1 | LDR3x | AMPs: AMB β24 | Aleph 5 | FirstOne | ML-2 | TSSA | Telos 390 Clone | My_Ref FE
DACs : TPA Buffalo II + OPC's NTD1 I/V | TPA OPUS + IVY III | Moon 380D DSD Speakers : Jim Holtz Statements | Astasia SD | Tubasson Mark 2
  Reply With Quote
Old 11th July 2013, 05:26 PM   #495
redjr is offline redjr  United States
diyAudio Member
 
Join Date: May 2011
Location: Danbury, CT
Quote:
Originally Posted by pinnocchio View Post
Any of you tried this excellent board?

TDA7293 X 4 BTL 350W Amplifer PCB Ultra Reliable | eBay

Click the image to open in full size.

Sounds really good. It is a parallel and bridged config. The sound will be influenced by the Opamp used but I use the OPA1612 (bipolar input) or OPA1642 (JFet input) which sound amazingly good!

You can also get rid of the opamp and use it as a stereo amp

I've built several of those and they're really good.

Ciao!
Do
Gee thanks pinnocchio for pointing out to all of us another 7293 design! I'm up to my ears in 7293 variations and haven't had the time to start some of them, much less complete them. Too many projects.

I do recognize the branding of yuanjing though. I think he's got some other product designs out there too. Glad to hear this one is performing well for you. Unfortunately, my projects are on hold until I get moved to CT.

Thanks for sharing,
Rick

Edit: BTW, did you bought the full kit, or just the PCBs and supplied your own components? Did you do any parts swapping?
Edit 2: The eBay prices of these assembled amps seems to vary anywhere from $24USD to $42USD. That's a pretty wide swing, but shipping balances some of it out. I wonder which ones are more clones/fake than the others!
__________________
redjr

Last edited by redjr; 11th July 2013 at 05:49 PM.
  Reply With Quote
Old 11th July 2013, 06:36 PM   #496
Just DIY!
diyAudio Member
 
pinnocchio's Avatar
 
Join Date: Sep 2010
Location: Montreal
Quote:
Originally Posted by redjr View Post
Gee thanks pinnocchio for pointing out to all of us another 7293 design! I'm up to my ears in 7293 variations and haven't had the time to start some of them, much less complete them. Too many projects.

I do recognize the branding of yuanjing though. I think he's got some other product designs out there too. Glad to hear this one is performing well for you. Unfortunately, my projects are on hold until I get moved to CT.

Thanks for sharing,
Rick

Edit: BTW, did you bought the full kit, or just the PCBs and supplied your own components? Did you do any parts swapping?
Edit 2: The eBay prices of these assembled amps seems to vary anywhere from $24USD to $42USD. That's a pretty wide swing, but shipping balances some of it out. I wonder which ones are more clones/fake than the others!
I actually bought both the PCB versions and the fully assembled modules all from Jims Audio. Unfortunately he does not have any left PCB of the stuffed version and his were close to 70$ each 2-3 years ago and sounded really good and I'm sure were genuine components. On the assembled ones the only thing I swapped was the Opamp since the NE5532 does not do it for me... I would not buy this assembled amp from another reseller at 24$-42$... Those are most probably fakes or cheap/fake components.

The PCB board I stuffed myself using high quality components sounded a little bit better but Jims assembled boards had some pretty good components on it already except resistors and some of the film caps.

Ciao!
Do
__________________
PREAMPs : AMB α10 + JC-80 clone | Balanced DCB1 | LDR3x | AMPs: AMB β24 | Aleph 5 | FirstOne | ML-2 | TSSA | Telos 390 Clone | My_Ref FE
DACs : TPA Buffalo II + OPC's NTD1 I/V | TPA OPUS + IVY III | Moon 380D DSD Speakers : Jim Holtz Statements | Astasia SD | Tubasson Mark 2
  Reply With Quote
Old 11th July 2013, 07:08 PM   #497
redjr is offline redjr  United States
diyAudio Member
 
Join Date: May 2011
Location: Danbury, CT
Quote:
Originally Posted by pinnocchio View Post
I actually bought both the PCB versions and the fully assembled modules all from Jims Audio. Unfortunately he does not have any left PCB of the stuffed version and his were close to 70$ each 2-3 years ago and sounded really good and I'm sure were genuine components. On the assembled ones the only thing I swapped was the Opamp since the NE5532 does not do it for me... I would not buy this assembled amp from another reseller at 24$-42$... Those are most probably fakes or cheap/fake components.

The PCB board I stuffed myself using high quality components sounded a little bit better but Jims assembled boards had some pretty good components on it already except resistors and some of the film caps.

Ciao!
Do
Hey, that's good to know info. I do have a China vendor that I've purchased from before, and generally find most of his assembled modules fairly good. His board is assembled and looks like it has genuine parts - but one never knows. The PCB is identical with the ground plane and all. His price is at the higher end at $42USD.

The board doesn't look like it contains any exotic parts and fairly easy to source most stuff. I wonder about the 7293 chip itself though. Are those all fakes and clones now too? Are some better than others? At least Jim's Audio has the bare PCBs available. Maybe I'll go that root for this build should I decide to do it. Thanks again. Rick
__________________
redjr
  Reply With Quote
Old 12th July 2013, 06:15 AM   #498
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Default Dual mono TDA7293 parallel kit

See the modern, modular style paralleling without the ballast resistors?
Click the image to open in full size.
Favorite new style design: 2pack TDA7293 Parallel 170W Mono Amplifier Board Kits 29 | eBay
With the two pack of compact dual-layer boards in the link (ebay# 190862927141), it is possible to do higher quality builds like a pair of monoblocs, or dual-mono or virtual dual-mono with regs or virtual dual-mono with diodes.
And, when upgraded to fine tuned values, it can do very low heat output and good system symmetry.

Possible gain settings: 38x when using the on-chip vas.
Or here's a different idea: Unity gain in the case of setting both chips to slave mode, which disables the voltage amp, turns the board into a "latfet output pack" and can be used for a tube hybrid.

P.S.
What I haven't seen yet is a small signal op-amp added to do error correction mode feedback like this: THD & Loop Gain Enhancer Has anyone tried this with a chip amp? For example, with my ordinary schematic, the gain ends up at 38X. However, if we added the error correction/enhancer scheme that would turn the gain down for errors but not for music. Fascinating?
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 12th July 2013, 01:15 PM   #499
Lo_Tse is offline Lo_Tse  Canada
diyAudio Member
 
Join Date: Dec 2006
Quote:
Originally Posted by danielwritesbac View Post
See the modern, modular style paralleling without the ballast resistors?
Click the image to open in full size.
Favorite new style design: 2pack TDA7293 Parallel 170W Mono Amplifier Board Kits 29 | eBay
With the two pack of compact dual-layer boards in the link (ebay# 190862927141), it is possible to do higher quality builds like a pair of monoblocs, or dual-mono or virtual dual-mono with regs or virtual dual-mono with diodes.
And, when upgraded to fine tuned values, it can do very low heat output and good system symmetry.

Possible gain settings: 38x when using the on-chip vas.
Or here's a different idea: Unity gain in the case of setting both chips to slave mode, which disables the voltage amp, turns the board into a "latfet output pack" and can be used for a tube hybrid.

P.S.
What I haven't seen yet is a small signal op-amp added to do error correction mode feedback like this: THD & Loop Gain Enhancer Has anyone tried this with a chip amp? For example, with my ordinary schematic, the gain ends up at 38X. However, if we added the error correction/enhancer scheme that would turn the gain down for errors but not for music. Fascinating?


Hi, Daniel,

Have you tried out the corresponding 3-chips version by the same designer sold by the same EBay store? Thanks!

Regards,
  Reply With Quote
Old 14th July 2013, 04:08 AM   #500
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally Posted by Lo_Tse View Post
Hi, Daniel, Have you tried out the corresponding 3-chips version by the same designer sold by the same EBay store? Thanks!
Regards,
No, I didn't need it yet. Looks fine though.
Either of those parallel boards could use this schematic, except that the 3-chip model would have a 100uF bootstrap cap.

My 70's receiver-amp refit project has a custom fit center tap transformer, previously powering 55 watts per channel with frail discrete amp, now powering 90 watts per channel with the durable 2-chip TDA7293 parallel boards. Due to the transformer amperage capacity, I didn't need the 3-chip boards at this time. And, now I find out that the smaller 2-chip parallel units easily exceed the capacity of my speakers.

P.S. I bought a box of TDA7293 chips to play with for parallel amp point to point projects, so it is unlikely that I'll need boards for some time. More powerful speakers probably comes first.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.

Last edited by danielwritesbac; 14th July 2013 at 04:12 AM.
  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
OPtimizing the VBE MUltiplier fglabach Solid State 45 17th September 2014 08:22 PM
Optimizing active crossover atledreier Multi-Way 27 19th August 2011 03:53 PM
optimizing the VBE multiplier hienrich Solid State 80 29th November 2010 11:25 PM
Interesting linestage optimizing ideas PixelPlay Tubes / Valves 5 23rd June 2008 11:18 PM
optimizing for efficiency Dwiel Solid State 13 10th May 2005 10:31 PM


New To Site? Need Help?

All times are GMT. The time now is 02:14 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