"ST151" 100W amplifier

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
A

AndrewT

R.I.P.
Joined 2004
Re: Need details of st151(150 watts)

kibet85 said:
...i want to make st151 so that t can produce a power of around 150 watts on 4 ohms and it should be stable...i have a transformer of +\- 38 volts...
Click to expand...
my 35+35Vac transformer (supply rails +-50.5Vdc) can get 110W into 8r0 and 200W into 4r0.
If you set your target at 150W into 4r0 from a 38+38Vac transformer then you don't have a decent design.
 
K

kibet85

Member
Joined 2008
:D...hi andrew,thank you for the post..now,it seems u'v made it n it produces 200 watts..can u tel me tha components u used and advice me which pcb schematics i could use...tel me what modifications u did,n wat components i should use to get it to produce that amount of power...200 watts!
 
K

kibet85

Member
Joined 2008
Re: Re: Re: Need details of st151(150 watts)

AndrewT said:
I used a single pair quasi complementary 2n3773 to get that power.
If the st can only manage 150 from a higher voltage then, in my opinon, it's flawed.
Click to expand...


:( hi andrew,it seems ur not getting me...first have you built this thi7 amplifier,then how much power do u rate it to produce on 4ohms...lets start from there....
 
ostripper

ostripper

Member
Joined 2008
Nice sound amplifier design you have here. It is a classic topology
(called LIN)that has many flavors.
I noticed it is very close to the ampslab.com C200,many amps
on this forum use this circuit style (i.e amplifier under development,brother of quasi,etc).
Ampslab .com shows all the variants of this amp, different outputs,
quasi-complimentary(all NPN), adding current mirrors(brother of
quasi) and real fancy, current mirrors and cascode (C300 ampslab).

P.s. red LED much better current source than 2 diodes..:)
Also better drivers are MJE15030/31 to-220 8A,they will
drive ANY output section!
 
K

kibet85

Member
Joined 2008
Confirmation Needed...

Hi all,just finished soldering components on my home made pcb for the st151..now,the issues is,my transformer is rated +/- 38 ac...its about 4 amperes...was planning to use it on the st151.my capacitors are rated 4700 uf,100 volts....is that too much because i was told that like 53 volt rails...then,i have changed the following components...

bc547/bc557 to bc546/bc556...i have left the bd139/bd140 as stated...for the outputs,i want to use the tip35c/tip36c pair...is that okay coz the load intended is a 4 ohm pioneer 800 sub|(12 inch)...

for the schematics,i used the v1.7...is there anything i need to change as i saw something about the pot not being well placed and a caps placing...
 
K

kibet85

Member
Joined 2008
hi all,i have a problem with my st151..when i connect it to power,the 680 ohm resister is burning..m using the components that i said in my earlier post..for the outputs,i decieded to use mj15024 and mj15025 pair..when its smoking that resistor,i havent connected the output transistors...what could be the problem coz i have checked it for flaws and couldt find any!
 
F

fjr

Member
Joined 2009
Re: eventhough

sakis said:
this amplifier is arround for quite long now .... and the truth is that eventhough i ve seen it never built it or so ...

the question is if its possible to mod for 56+56 volt rails of course with biger transistors 2SA1302 3281 or 1943 5200

thanks
Click to expand...

http://st151.uw.hu/images.load.php?id=ACAF1081-D010-49F1-BF85-B3C65A7CEE9A
Picture of a +/-56V supplied ST151 amplifier.
I've found a thread too about it in a hungarian diyaudio page. Who built the +/-56V version writed the following:
Outputs: 2SA1943/2SC5200
Drivers: MJE340/350
VAS/VAS-CCS: MJE340/350
LTP/LTP-CCS: MPSA42
Everything was OK with it.

Files are here: http://sixtek.uw.hu/st151.htm

Sorry I can't help in translation. But the schema/PCB/etc.. seems "universal".

Good luck!
 
W

wahab

Member
Joined 2009
sakis said:
this amplifier is arround for quite long now .... and the truth is that eventhough i ve seen it never built it or so ...

the question is if its possible to mod for 56+56 volt rails of course with biger transistors 2SA1302 3281 or 1943 5200

thanks
Click to expand...

Yes, it is possible, but some components value should be
slightly modded as well...

BC547 should be replaced by 2sc2240.

Q3 and Q6 (BD139/140) must be replaced by 2SC3423/2SA1360
and Q7/Q8 by 2SC4793/2SA1837...

As mentionned in a previous post, C4 must be 4.7pF.
 
M

mosfets

Banned
Joined 2008
wahab said:
This amp look like a simplified ADCOM GFA555, using the same
catastrophic compensation scheme...
QUOTE]

I was actually thinking that too(Adcom) but not so much. Very good for me to study what the past(some present) masters were/are up to. NP has implemented way more tricks of the trade in the 555 than ever. Makes me want to look into the past at Thresold stuff and dig some more to compare/study.

BTW the Naim Nap250 runs very clean and lean. I think it could be made into a little fat Class A amp?
Click to expand...
 
W

wahab

Member
Joined 2009
mosfets said:
wahab said:
This amp look like a simplified ADCOM GFA555, using the same
catastrophic compensation scheme...
QUOTE]

I was actually thinking that too(Adcom) but not so much. Very good for me to study what the past(some present) masters were/are up to. NP has implemented way more tricks of the trade in the 555 than ever. Makes me want to look into the past at Thresold stuff and dig some more to compare/study.

BTW the Naim Nap250 runs very clean and lean. I think it could be made into a little fat Class A amp?
Click to expand...


The Naim seems a little better in comparison..
They increased the lag compensation to 39pF
and they added a 1.8k resistor in serial with the
lead compensation cap to limit its devastating effect
on stability..

Yes, it will surely make a good class A amp, but beware of the
increased thermal dissipation.

You ll have to upgrade the heatspreader and perhaps add
a second air of output devices, which is problematic, as it s
a quasi complementyary design.
Click to expand...
 
M

mosfets

Banned
Joined 2008
Yes, it will surely make a good class A amp, but beware of the
increased thermal dissipation.

You ll have to upgrade the heatspreader and perhaps add
a second air of output devices, which is problematic, as it s
a quasi complementyary design.
Click to expand...

Yes if you have the original chassis you are limited to Heat and limited with Class A. :eek:
What a great project if you had the enclosure from NAIM to make "your" own version. I want to find one now...and an ADCOM 555 chassis too ! :)

I LOVE blown up amplifiers:hug:
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom