How many pairs? - 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 19th June 2006, 08:23 PM   #1
kasiss is offline kasiss  Latvia
diyAudio Member
 
kasiss's Avatar
 
Join Date: May 2003
Location: LV
Question How many pairs?

I'm building an amp with 4 pairs of transistors (2sc5200, 2sa1943)
I'm litle confused wit SOA of them

What power supply voltage cold they handle for 8ohm and voltage for 2ohm load? (at max output power)

I red, that forfor that number of devices on load it is ~ +/- 55V (Is it true?)

pls help ....
  Reply With Quote
Old 19th June 2006, 09:08 PM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
just ran some numbers on 4pair 1943 @Tc=40degC

they can run to 185W into 4ohms at a phase angle of 60degrees. and be on the DC SOAR limit.

They can also push about 285W into 2 ohm at the same 60degree phase angle but this time they exceed the DC SOAR and are half way towards the 100mS limit.

A good indication of their suitability is what they can achieve into half load impedance. Into 1ohm 450W at 45degree phase angle but this time two thirds towards the 100mS SOAR limit.

the 2ohm and 1ohms loads were @+-43Vrails the 4ohm was +-45Vrails.

With +-55Vrails 145W 8ohms just outside the DC SOAR,
270W 4ohms well outside the 100mS SOAR.
470W 2ohm 22degree phase @DC and 40degree phase @ 100mS.

I usually design for DC SOAR with VI limiting, but other say I am too pessimistic and recommend 100mS.
You choose how reliable you need it to be.

BTW. into low loads and driven hard, big sinks will struggle to keep the Tc at or below 40DegC.
__________________
regards Andrew T.
  Reply With Quote
Old 20th June 2006, 04:33 PM   #3
diyAudio Member
 
Join Date: Jun 2005
Location: aa
Quote:
Originally posted by AndrewT

With +-55Vrails 145W 8ohms just outside the DC SOAR,
270W 4ohms well outside the 100mS SOAR.

Pls tel me how can i see or calculate it?

is the +-55Vrails 145W 8ohms for 4 pairs?

If i wold like to feed it with +/-60V ? What "safe power" i cold get?
  Reply With Quote
Old 20th June 2006, 05:04 PM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
Quote:
numbers on 4pair 1943 @Tc=40degC
this says so.
__________________
regards Andrew T.
  Reply With Quote
Old 22nd June 2006, 01:23 PM   #5
csl113 is offline csl113  Romania
diyAudio Member
 
Join Date: Nov 2004
Location: in the home
i think that the suply voltage should vary with the topology...

i mean that you can't put 4 pairs at the same voltage if one is in class A, one in class AB, B and H , there is a different voltage for each...

for exemple i wanted to see how high could i run a amp that had only one pair of 2sc5200/2sa1943.....at +/- 60V at a 8 ohm speaker load i couldn't blow it, but at +/- 68V it finaly distorid itself...

amp's with 4 pairs i run them at +/- 80V, and they run smoothly with 4 ohm loads ,and +/- 90V max in 8 ohm

a amp that had 3 pairs at +/- 80V runs 8-10h/day at near maximum for more then 10 years in a club and it never faild so far... (inside a 8 ohm subwoofer)

p.s. none of the above amp's had any VI limiters, only termic protection
  Reply With Quote
Old 22nd June 2006, 02:38 PM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
Quote:
amp's with 4 pairs i run them at +/- 80V, and they run smoothly with 4 ohm loads ,and +/- 90V max in 8 ohm
I told you that others say I am pessimistic.
__________________
regards Andrew T.
  Reply With Quote
Old 22nd June 2006, 02:51 PM   #7
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally posted by csl113
i think that the suply voltage should vary with the topology...
Yeah, opinions may vary.

Here's a picture of one with 6 Sanken output devices, the 150 watt versions, 2SA1215/2SC2921.
This one is 50 watts class A and 200 watts/8 Ohms in class AB.
You can imagine the size of the powersupply yourself. SK56 heatsinks(300mm long), 0.36 C/W. These blocks do not require a suitcase of spare fuses.
Attached Images
File Type: jpg active1top.jpg (53.1 KB, 165 views)
__________________
The buck stops Here
  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
wanted 2 pairs of b&w 150/14 dazfj Swap Meet 0 22nd January 2009 04:42 PM
FS: 4 Hi-Vi B3S drivers (2 pairs) type Swap Meet 1 7th March 2007 05:55 PM
two pairs or jordans for me and my dad? uzziah Full Range 14 9th November 2006 03:31 AM
FS: 3 pairs Used Heatsinks Gmorris Swap Meet 4 29th June 2005 04:18 PM
2 sub pairs in series...4+8 ChesterFuzzin' Subwoofers 7 17th August 2004 08:35 PM


New To Site? Need Help?

All times are GMT. The time now is 02:27 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