Greg,
Thanks for your help! I'll see about removing those input caps from the pre.
I don't want to try to make these amps into something audiophyle, just get past the limits designed in due to their intended purpose. (As a rear channel amp hooked to cheap speakers, any signal below 50 Hz would be a waste.)
And I realize that knowing only a little is just enough to get into trouble! So I asked first.
Thanks, Jim
Thanks for your help! I'll see about removing those input caps from the pre.
I don't want to try to make these amps into something audiophyle, just get past the limits designed in due to their intended purpose. (As a rear channel amp hooked to cheap speakers, any signal below 50 Hz would be a waste.)
And I realize that knowing only a little is just enough to get into trouble! So I asked first.
Thanks, Jim
Just wanted to give a follow up for me using them as amps for bass shakers. One amp powering two 4ohm bass shackers will work if you keep the volume low enough, but then, you can hardly feel them. With the volume all the way up, the amp will turn on and off. Maybe I'll pull one of the amps out of the basement and use one amp per shaker.
I would be happy to see this unit schematic folks
Because the transistor type was used, by me, into the seventies... some Texas Instruments transistors alike those ones.... i would be happy to listen that sound once again.
Can you upload to me, of course if you have it dear friends.
panzertoo@yahoo.com
regards,
Carlos
Because the transistor type was used, by me, into the seventies... some Texas Instruments transistors alike those ones.... i would be happy to listen that sound once again.
Can you upload to me, of course if you have it dear friends.
panzertoo@yahoo.com
regards,
Carlos
output transistors
Hi,
As it shipped from the factory the output transistors are not really the limiting factor in the output power. The transformer is nicely sized for a 2x20w amp, at ~100va. The rail droops pretty quickly as it drives low impedance loads. Based on the quick measurements I performed the TIP parts are not really stressed beyond their capacity. The heatsink on the other hand is too small to allow continuous output into even 8 ohms...hence the shutdowns when both channels are run full power.
The transistors you mention are better from the perspective of quality, but aren't going to transform this little guy into a hulking brute. The MJL1302 and it's complement are probably better still, though much higher bandwidth, which could cause complications.
I still think these things are outstanding value for money, I bought a pair of the speakers too, $5 more gets the same amp, and a pair of 2 way speakers, that don't totally embarrass themselves.
If anyone wants the receiver boards, let me know, I have a set of 5 or 6 of them that I have no use for...never did find one of the transmitters...
HTH
Stuart
Hi,
As it shipped from the factory the output transistors are not really the limiting factor in the output power. The transformer is nicely sized for a 2x20w amp, at ~100va. The rail droops pretty quickly as it drives low impedance loads. Based on the quick measurements I performed the TIP parts are not really stressed beyond their capacity. The heatsink on the other hand is too small to allow continuous output into even 8 ohms...hence the shutdowns when both channels are run full power.
The transistors you mention are better from the perspective of quality, but aren't going to transform this little guy into a hulking brute. The MJL1302 and it's complement are probably better still, though much higher bandwidth, which could cause complications.
I still think these things are outstanding value for money, I bought a pair of the speakers too, $5 more gets the same amp, and a pair of 2 way speakers, that don't totally embarrass themselves.
If anyone wants the receiver boards, let me know, I have a set of 5 or 6 of them that I have no use for...never did find one of the transmitters...
HTH
Stuart
Referring to post #89.
I installed my first one into the shell of my old Yamaha M-45. . .
without the preamp the amplifier has about 15dB of gain. . .the
amp is between the original RC input on the M-45 followed by
the input trims. . .quiet. . .after rotating the transformer until the
hum went away. . .
My second amp just purchased about a month ago has a hum
after I bypassed the preamp board. . .might have to look into
old caps. . .something is leaking from the power supply into
the amp section. . .
I installed my first one into the shell of my old Yamaha M-45. . .
without the preamp the amplifier has about 15dB of gain. . .the
amp is between the original RC input on the M-45 followed by
the input trims. . .quiet. . .after rotating the transformer until the
hum went away. . .
My second amp just purchased about a month ago has a hum
after I bypassed the preamp board. . .might have to look into
old caps. . .something is leaking from the power supply into
the amp section. . .
Yet more questions...
I just bought one of these on eBay for use as an amplifier for my PC. Bypassing the internal pre-amp seems like a good idea, but I don't have an outboard pre-amp to use with it.
So...
1. How does the sound quality compare to a Gainclone? Would I be better off just putting a pair of LM3875s in the chassis?
2. Assuming I bypass the pre-amp, what should I use to replace it? An op-amp with a gain of 2.7 seems like it should work - will the +/- 15v power supply provide enough current for a decent one?
3. Are there any other easy-to-replace parts that will make a big difference in quality?
Thanks!
I just bought one of these on eBay for use as an amplifier for my PC. Bypassing the internal pre-amp seems like a good idea, but I don't have an outboard pre-amp to use with it.
So...
1. How does the sound quality compare to a Gainclone? Would I be better off just putting a pair of LM3875s in the chassis?
2. Assuming I bypass the pre-amp, what should I use to replace it? An op-amp with a gain of 2.7 seems like it should work - will the +/- 15v power supply provide enough current for a decent one?
3. Are there any other easy-to-replace parts that will make a big difference in quality?
Thanks!
There have been some posts about replacing
the opamps and running it with the existing
+/- 15 VDC supply and it required more current
the the supply could muster; but using just a
very simple preamp might be able to use the
exiting power supply. . .the original preamp was
a little noisy. . . the amp is decent without the
preamp . . .not better than a gainclone but it
is already built.
The makeup grain would be more like 10 dB to 12 dB
as I measured it after taking out the exiting preamp.
The amp has only about 15dB of gain without the
preamp.
This amp is not audiophile. . .this amp just works and
at a really cheap price. . .turn it on and forget about it.
Input caps. . .sure but they would cost more the amp.
Upgrade the output zobel. . .couldn't hurt.
Make sure to rotate the transformer to reduce hum. . .
especially if you keep the original preamp section. . .
Test those supply caps and bridge rectifier. . .one of my
amps has hum in the left channel. . .probably an old
supply cap. . .
the opamps and running it with the existing
+/- 15 VDC supply and it required more current
the the supply could muster; but using just a
very simple preamp might be able to use the
exiting power supply. . .the original preamp was
a little noisy. . . the amp is decent without the
preamp . . .not better than a gainclone but it
is already built.
The makeup grain would be more like 10 dB to 12 dB
as I measured it after taking out the exiting preamp.
The amp has only about 15dB of gain without the
preamp.
This amp is not audiophile. . .this amp just works and
at a really cheap price. . .turn it on and forget about it.
Input caps. . .sure but they would cost more the amp.
Upgrade the output zobel. . .couldn't hurt.
Make sure to rotate the transformer to reduce hum. . .
especially if you keep the original preamp section. . .
Test those supply caps and bridge rectifier. . .one of my
amps has hum in the left channel. . .probably an old
supply cap. . .
suggestions and ideas needed
Is it a good idea to use the transformer, chassis and parts for an Elliot Sound projects(amp or preamp) or others?
Amp power supply:
http://sound.westhost.com/project04.htm
amp(Gain Clone 3886):
http://sound.westhost.com/project115.htm
The Accurian transformer might not have high enough VA for a Gainclone?
Some preamp projects here and I am interested in building something with XLR out:
http://sound.westhost.com/projects-2.htm
Looks like +/-15v is needed. Can I get +/- 15v from the Accurian transformer?
Comments?
Is it a good idea to use the transformer, chassis and parts for an Elliot Sound projects(amp or preamp) or others?
Amp power supply:
http://sound.westhost.com/project04.htm
amp(Gain Clone 3886):
http://sound.westhost.com/project115.htm
The Accurian transformer might not have high enough VA for a Gainclone?
Some preamp projects here and I am interested in building something with XLR out:
http://sound.westhost.com/projects-2.htm
Looks like +/-15v is needed. Can I get +/- 15v from the Accurian transformer?
Comments?
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