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 14th April 2006, 11:18 PM   #1
psyche is offline psyche  Greece
diyAudio Member
 
Join Date: Jun 2005
Location: Athens
Default Amplifier upgrading!!!!!!!!!

Hi there,

My name name is Padelis and I am from Greece.I electronics here in Greece and I decided to build and amplifier for my home project studio.I bought a kit from a company here in Greece which is an 2x60watt amp.On the schematic the output transistors are bdw83 and the provided transistors are 2sd817(upgrade???).So what i want to ask you is what to do in order to make this amp better.I would like less distortion, more watts and be a little faster.I know that if i want to change the output transistors i will have to change the drivers too.So here i am to the more experts diyers asking for help and opinions!!!!

Thanx in advance
Padelis.
Attached Images
File Type: jpg picture00251.jpg (94.9 KB, 769 views)
  Reply With Quote
Old 14th April 2006, 11:35 PM   #2
quasi is offline quasi  Australia
diyAudio Member
 
quasi's Avatar
 
Join Date: Sep 2004
Location: Adelaide, Australia
Default Kalimera Padeli, ti kanis;

Can you please attach a schematic. It will be easier for people to offer advice.

Cheers
  Reply With Quote
Old 15th April 2006, 12:26 AM   #3
CBS240 is offline CBS240  United States
diyAudio Member
 
CBS240's Avatar
 
Join Date: Aug 2005
Location: K-town
Maybe you could use a complementary design instead of quasi. Not that quasi is bad, it's just that there exists in these modern times some pretty good complementary output transistors.(no offense quasi ) You may not have to change the drivers, just use them in emitter follower darlington arrangment. Also wouldn't hurt to add small base resistors to those outputs. In doing this, you may also want to include a Vbe multiplier for bias and thermal stability instead of diodes as class AB emitter followers can be sensitive to temp. and bias changes. Loading the VAS with a current source might work also, however there are designs that don't use a CCS.
__________________
All the trouble I've ever been in started out as fun......
  Reply With Quote
Old 15th April 2006, 01:21 AM   #4
quasi is offline quasi  Australia
diyAudio Member
 
quasi's Avatar
 
Join Date: Sep 2004
Location: Adelaide, Australia
It seems as though you have already bought the amp kit.

The BDW83 is specified as a darlington and I cannot find information about the 2SD817. A more modern transistor would be a TIP142.

The number of changes required would not work well with the existing kit PCB so I would build as is and see what you think.

Use any upgrade money you have to build an excellent power supply using a 500va transformer with a seperate bridge and capacitor bank for each amp module. Use at least 10,000uf per rail (20,000uf total) per amp module.

Cheers
  Reply With Quote
Old 15th April 2006, 01:24 AM   #5
quasi is offline quasi  Australia
diyAudio Member
 
quasi's Avatar
 
Join Date: Sep 2004
Location: Adelaide, Australia
Offence? me?

None taken CBS240. I actually like complimentary transistor output stages. For high power I prefer quasi-comp because watt per buck it's hard to beat.

Cheers
  Reply With Quote
Old 15th April 2006, 01:27 AM   #6
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
Looks like from early seventies. Not a nice idea to build an amplifier like this. Try something else, more worth bothering.
regards
Adam
  Reply With Quote
Old 15th April 2006, 08:04 AM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
persist with the kit and get it working. I do not recommend spending extra money modifying this rudimentary quasi design.

As Quasi said build a good supply and case and allow for a new amplifier PCB to be substituted later.
__________________
regards Andrew T.
  Reply With Quote
Old 15th April 2006, 08:39 AM   #8
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
psyche:

That circuit is really terrible (not due to the quasi output stage but due to the lousy rest) and probably from early seventies as it has ben already pointed out. Also, ECA book tells that 2SD817 is a Toshiba 1500V 1.5A TV horizontal deflection transistor, thus not suitable at all for an audio amplifier. Furthermore, Toshiba electronic components website does not contain any reference to that device (meaning that it was discontinued a long ago) and I couldn't find any other alternative manufacturer in google, so what you have are FAKE transistors, forgeries (very common in Southern European countries).

In my opinion you have been scamed, so it would be a good idea to return everything to the supplier and ask for your money back.

Also, remember that this forum is full of great projects to build, you just have to be patient and search. You should also search for threads on fake components and read them because I feel that local stores on your country are flooded of fake transistors and ICs (as it happens in Spain and Italy).
  Reply With Quote
Old 15th April 2006, 09:59 AM   #9
diyAudio Member
 
bogdan_borko's Avatar
 
Join Date: Nov 2005
Location: serbia, zajecar
Oh man, who sold you that kit in 2006. ???
  Reply With Quote
Old 18th June 2006, 02:52 PM   #10
psyche is offline psyche  Greece
diyAudio Member
 
Join Date: Jun 2005
Location: Athens
Hi there,

soryy for been away for soooooooooo long but i had completely forgot that thread.a few corrections:
the output transistors are 2sd718

I have built this amp a few months ago and it sounds simply good.I was just wondering if i could improve its performance, thats all! Now i am ready to build a new amp from the schematics that are posted here in the forum but i can't decide which one to build.These are all great.BTW what would you recommend me to build?Have in mind that i will use it in my studio.

Thank you guys you are great

Padelis
  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
Upgrading an op amp in mic pre?? synap2012 Chip Amps 3 7th May 2008 02:26 PM
Upgrading DM2 beamnet Multi-Way 2 7th December 2007 03:00 PM
Upgrading parts in an integrated amplifier imperfectcircle Solid State 9 15th February 2007 10:44 PM
Upgrading R50 KEF TL essence Multi-Way 26 29th January 2007 09:15 PM


New To Site? Need Help?

All times are GMT. The time now is 12:26 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