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

Solid State Talk all about solid state amplification.

One of the Top Solid-State CFA amp design
One of the Top Solid-State CFA amp design
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 2nd January 2018, 08:48 PM   #211
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by AndriyOL View Post
Thanks for your contribution, but it's too complicated for me.
But the schematic you showed is equally complicated, and here you can see the missing buffer at the cold input (-).
  Reply With Quote
Old 2nd January 2018, 09:28 PM   #212
AndriyOL is offline AndriyOL  Ukraine
diyAudio Member
 
Join Date: Jul 2008
Location: Lviv
Do you mean LF411 opamp? Could you please show how it can be implemented in the schematic I used?
__________________
If for pristine and pure adoration - it's diyAudio dedication!

Last edited by AndriyOL; 2nd January 2018 at 09:36 PM.
  Reply With Quote
Old 3rd January 2018, 02:01 AM   #213
mjona is offline mjona  New Zealand
diyAudio Member
 
Join Date: Jul 2007
Location: Upper Hutt
He means the 4 transistor arrangement of Q31,Q32,Q35, and Q36.

I have simulated the amplifier with a balanced signal input. Used that way it has very low distortion as can be seen from the attached FFT.

If your DAC lacks a volume control and or balanced inputs you will have to decide what approach you want to take. For instance do you want the benefits of balanced line feeds between your DAC and the amplifier or is it OK to house both the inverting circuit and buffer on new boards inside the main amplifier case.
Attached Images
File Type: png Balanced.PNG (119.1 KB, 229 views)
  Reply With Quote
Old 3rd January 2018, 07:11 AM   #214
AndriyOL is offline AndriyOL  Ukraine
diyAudio Member
 
Join Date: Jul 2008
Location: Lviv
Thanks Mjona. It looks very promising.
How to convert this in THD+N in %? Perhaps we might need models from actual devices used to calculate the noise?
I still didn't have the dac, just plan to buy it sometime. It should have the volume control and for sure differential outputs.
Where to house inverting circuit with buffer depends on functionality and free space on the amp board. I have a limited space on heatsink. If to integrate it to the amp board it cannot be disabled if used SE input only. When I tried to ground negative input it increased a bias current of negative input transistor pair and disbalance the DC offset, don't know how will it behave with buffer.
__________________
If for pristine and pure adoration - it's diyAudio dedication!
  Reply With Quote
Old 3rd January 2018, 06:49 PM   #215
mjona is offline mjona  New Zealand
diyAudio Member
 
Join Date: Jul 2007
Location: Upper Hutt
On paper the first three places after the decimal point are zero. I am not touting here - I use simulations with a certain amount of trust to see if a design is workable or not.

If space is a problem you might think in terms of an IC based buffer on a board with adhesive plastic mounts on a vertical surface near the input terminals.

If the purchase of a DAC is not an immediate proposition then you could include the inverter on the same board as the buffer.

In that case consider making the inverter IC, socketed so it can be removed, and, providing header pin/shorting links to allow a re-route option for the ground and buffer connections for external balanced signal inputs.

Any buffer IC will need to have sufficient current to drive the low impedance of the inverting input to the power amp.

OPA551 can run off +/- 30 volts and is unity gain stable. You should be able to drop a little voltage from the lower rails in your power output stage with some series diodes and a pair of decoupling capacitors.

Otherwise you could make some +/- 15 volt rails and use pairs of LF411's if the ones used for the buffer is used in conjunction with pairs of low power transistors.

Some headphone amplifiers use the last approach so you could investigate these one and convert a choice to unity gain. Some of these projects have tidy and compact layouts - project boards for IC use are common enough to find.

Having accomplished what you have done already, you can do all of this.
  Reply With Quote
Old 3rd January 2018, 11:08 PM   #216
AndriyOL is offline AndriyOL  Ukraine
diyAudio Member
 
Join Date: Jul 2008
Location: Lviv
Frankly speaking I don't like the ICs, I would prefer full descrete approach.
To make this schematic working will I need only buffer on negative input transistor pair? Clould you show the file you simulated? I think it could be made as add on module if space won't allow.
__________________
If for pristine and pure adoration - it's diyAudio dedication!
  Reply With Quote
Old 4th January 2018, 02:21 AM   #217
mchambin is offline mchambin  France
diyAudio Member
 
Join Date: Mar 2011
Why do you dislike op amps and prefer discrete ?
Why re invent perfectly well designed and easy to use components ?
__________________
Transistor junction temperature is not transistor case temperature.
  Reply With Quote
Old 4th January 2018, 03:14 AM   #218
mjona is offline mjona  New Zealand
diyAudio Member
 
Join Date: Jul 2007
Location: Upper Hutt
Quote:
Originally Posted by AndriyOL View Post
Frankly speaking I don't like the ICs, I would prefer full descrete approach.
To make this schematic working will I need only buffer on negative input transistor pair? Clould you show the file you simulated? I think it could be made as add on module if space won't allow.
If you don't like ICs then you would have to dislike the entire recording process and any DAC processor.

I became involved here because keantoken provided a simulation to work with with.

I have suggested that you learn to use SPICE so you can do your own simulations and made my position of being involved here being due to keantoken having simulated your power amplifier.

I stopped using discrete components in pre-amplifier stages about 20 years ago and have not made any study of examples on this site - of which there must be a large range from which to make a selection.

Finding a circuit which can match an IC in performance in those circumstances is going to require a survey and multiple simulations which will be no small commitment of the time of others if there are any takers.

Hopefully there will be someone viewing who knows of a discrete circuit you can use and one with a SPICE simulation to back it up.

If you find such an example I will be happy to look at it.
  Reply With Quote
Old 4th January 2018, 08:36 AM   #219
AndriyOL is offline AndriyOL  Ukraine
diyAudio Member
 
Join Date: Jul 2008
Location: Lviv
Quote:
Originally Posted by mchambin View Post
Why do you dislike op amps and prefer discrete ?
Why re invent perfectly well designed and easy to use components ?
Descrete circuit sounds more natural than IC.
__________________
If for pristine and pure adoration - it's diyAudio dedication!
  Reply With Quote
Old 4th January 2018, 08:51 AM   #220
AndriyOL is offline AndriyOL  Ukraine
diyAudio Member
 
Join Date: Jul 2008
Location: Lviv
Quote:
Originally Posted by mjona View Post
If you don't like ICs then you would have to dislike the entire recording process and any DAC processor.

I became involved here because keantoken provided a simulation to work with with.

I have suggested that you learn to use SPICE so you can do your own simulations and made my position of being involved here being due to keantoken having simulated your power amplifier.

I stopped using discrete components in pre-amplifier stages about 20 years ago and have not made any study of examples on this site - of which there must be a large range from which to make a selection.

Finding a circuit which can match an IC in performance in those circumstances is going to require a survey and multiple simulations which will be no small commitment of the time of others if there are any takers.

Hopefully there will be someone viewing who knows of a discrete circuit you can use and one with a SPICE simulation to back it up.

If you find such an example I will be happy to look at it.
I'm not happy with digital recordings, but why make things even worse?
If I'm going to use differential signal from the dac than I don't need inverting IC, only buffer on the cold input?
Your last simulation was with buffer addition? Is it too good to post it here?)
__________________
If for pristine and pure adoration - it's diyAudio dedication!

Last edited by AndriyOL; 4th January 2018 at 09:00 AM.
  Reply With Quote

Reply


One of the Top Solid-State CFA amp designHide 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
Tubelab Solid State OPT design hellokitty123 Tubelab 3 30th December 2017 12:35 PM
How to design solid state amplifiers. rutager Chip Amps 10 19th January 2017 12:41 PM
Best books for solid state design? Bitrex Solid State 26 8th March 2015 11:13 AM
25 WPC stereo amp design, help? (Solid state) cmjohnson Solid State 21 17th April 2011 10:25 PM
Started to design solid state amp + calculations Bensen Solid State 11 22nd May 2005 03:55 AM


New To Site? Need Help?

All times are GMT. The time now is 08:14 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki