Hello,
I have also found that the amp sounds “nicer” with the 1uF cap across the resistor between the driver emitters.
The green cap is the one I used, after trying the amp both with and without it.
\Jens
I have also found that the amp sounds “nicer” with the 1uF cap across the resistor between the driver emitters.
The green cap is the one I used, after trying the amp both with and without it.
\Jens
An externally hosted image should be here but it was not working when we last tested it.
Hello djk,
Thanks for the responce,
I am new to the forum , to be frank I am not an engineer, I am just a DIY guy,
I wanted a high power amp at a budjet price, the devices used in the circuit were
not avilible , hence I made do with what was avilible , I used 2N3773/MJ4502 in
the output,in the protection I only reduced the emitter resistors of the output
transistors to 0.25 ohms, I wanted to use 0.2 ohms but they were not avilible, I
think I should have altered the base resistors of Q10 & Q11, I hope you could help
here.
I made the leach amp version 4.5 one year ago,over the years I have made many
poweramps from projects in magazines and company application information
notes , but I like this the best , there may be better but I am happy here, I am very
impressed with the text Mr Leach wrote in detail for every stage, I read the text
several times before attempting to make the power amp. I used 8+8 transistors in
the output mounted on large heatsinks with cooling fans , rest is the original
design , yes I used all equvalant devices and some resistances of nearest values
due to non availibty as 330ohms instead of 300ohms,& 33ohms instead of
30ohms. R1 22k,R2 1k8,R17&18 12k,R19 1k2, I made the transformer 40v-0-40v
20 amp myself , powersupply filters 6x10000mfd ,30000mfd each side.I use the
Amp in bridge mode and it works fine even at 2ohms load .The Amp has been
working very well since I made it until recently, I had a couple of problems this
month, one side started giving hum,on checkup I found that there was an ofset
voltage of 0.33v in the output, it took me two days of my free time to find the fault
which was failure of Q8, the emitter base had shorted internally , but as there is a
33ohm resistor across the emitter & base it was difficult to detect the problem, the
second time two powersupply filter caps actually bursted.I have replaced the faulty
caps and the Amp is fine again.
cheers
Thanks for the responce,
I am new to the forum , to be frank I am not an engineer, I am just a DIY guy,
I wanted a high power amp at a budjet price, the devices used in the circuit were
not avilible , hence I made do with what was avilible , I used 2N3773/MJ4502 in
the output,in the protection I only reduced the emitter resistors of the output
transistors to 0.25 ohms, I wanted to use 0.2 ohms but they were not avilible, I
think I should have altered the base resistors of Q10 & Q11, I hope you could help
here.
I made the leach amp version 4.5 one year ago,over the years I have made many
poweramps from projects in magazines and company application information
notes , but I like this the best , there may be better but I am happy here, I am very
impressed with the text Mr Leach wrote in detail for every stage, I read the text
several times before attempting to make the power amp. I used 8+8 transistors in
the output mounted on large heatsinks with cooling fans , rest is the original
design , yes I used all equvalant devices and some resistances of nearest values
due to non availibty as 330ohms instead of 300ohms,& 33ohms instead of
30ohms. R1 22k,R2 1k8,R17&18 12k,R19 1k2, I made the transformer 40v-0-40v
20 amp myself , powersupply filters 6x10000mfd ,30000mfd each side.I use the
Amp in bridge mode and it works fine even at 2ohms load .The Amp has been
working very well since I made it until recently, I had a couple of problems this
month, one side started giving hum,on checkup I found that there was an ofset
voltage of 0.33v in the output, it took me two days of my free time to find the fault
which was failure of Q8, the emitter base had shorted internally , but as there is a
33ohm resistor across the emitter & base it was difficult to detect the problem, the
second time two powersupply filter caps actually bursted.I have replaced the faulty
caps and the Amp is fine again.
cheers
What thing make "low tim" in low tim amplifier?
http://users.ece.gatech.edu/~mleach/lowtim/instage.html
with the value of R7 and R10 are 300, my orcad says that the circuit oscillate
Is there a zero tim amp?
http://users.ece.gatech.edu/~mleach/lowtim/instage.html
with the value of R7 and R10 are 300, my orcad says that the circuit oscillate
Is there a zero tim amp?
thanh said:What thing make "low tim" in low tim amplifier?
http://users.ece.gatech.edu/~mleach/lowtim/instage.html
with the value of R7 and R10 are 300, my orcad says that the circuit oscillate
Is there a zero tim amp?
The amplifier is fast enough that no normal audio signal
will drive it into slew rate limiting. That is, the maxium rise
time of the circuit will be faster than any input signal.
In theory, if the amplifier cannot be overdriven, then it has no such distortion. There is some argument as to whether transient intermodulation distortion is 'real'; in practice just about any modern amplifier that is properly designed will not exhibit tim.
"with the value of degeneration resistors is 470 and gain is 33 ,BW is 3Mhz
with the value of degeneration resistors is 12 anf gain is 33, BW is 26Mhz"
Either your sim doesn't work or you have something wrong.
R11 and R12 split the signal with R7 and R9, the gain has to go down when you increase R7 and R9.
with the value of degeneration resistors is 12 anf gain is 33, BW is 26Mhz"
Either your sim doesn't work or you have something wrong.
R11 and R12 split the signal with R7 and R9, the gain has to go down when you increase R7 and R9.
Dear rajeev luthra,
It's fine to hear that the Leachamp is doing well its job. I think it's a fine construction better than a lot of amps available on the market for money.
You bridge two amps. Is the bridge stable and which "preamp" you use for inverting the input signal going to the second of the two bridge amps.
Wopo
It's fine to hear that the Leachamp is doing well its job. I think it's a fine construction better than a lot of amps available on the market for money.
You bridge two amps. Is the bridge stable and which "preamp" you use for inverting the input signal going to the second of the two bridge amps.
Wopo
Hello djk,
Yes the complementry of Mj4502 is Mj802 but I had no choice as Mj802 was not
avilible when I made the Amp . Mj 4502 was avilible as it is used in powersupply
in some colour Tv sets ( all the transistors I used in the leach amp were avilible as
Tv spare parts ) , the Vceo of Mj 4502 is 90v and the Dc voltage is 55v max 60v
each side in my amp on no load with a 40v-o- 40v transformer, however as I said
the amp has been working fine since one year , am I fortunate ? I was wondering if
Mj4502 could work up to 75vdc. We use the amp at max power in bridge mode
and there has been no failure in the output devices, it is very stable .
Now a dealer has promised to arrange Mj15024/Mj15025 I plan to make another
two poweramps similar to my eirlear one but I intend to use transformers of
50v-o-50v & 65v-o-65v with change in components to work at these voltages. I
hope I will not have any problems , and if I do I will contact you for help, I hope you
will obliege. I have already started working on the 2nd amp.
I want know a little more on how to fine tune the protection circuit as per desired
requirements, I do manage somehow using thumbs rule and common sence .
Yes the complementry of Mj4502 is Mj802 but I had no choice as Mj802 was not
avilible when I made the Amp . Mj 4502 was avilible as it is used in powersupply
in some colour Tv sets ( all the transistors I used in the leach amp were avilible as
Tv spare parts ) , the Vceo of Mj 4502 is 90v and the Dc voltage is 55v max 60v
each side in my amp on no load with a 40v-o- 40v transformer, however as I said
the amp has been working fine since one year , am I fortunate ? I was wondering if
Mj4502 could work up to 75vdc. We use the amp at max power in bridge mode
and there has been no failure in the output devices, it is very stable .
Now a dealer has promised to arrange Mj15024/Mj15025 I plan to make another
two poweramps similar to my eirlear one but I intend to use transformers of
50v-o-50v & 65v-o-65v with change in components to work at these voltages. I
hope I will not have any problems , and if I do I will contact you for help, I hope you
will obliege. I have already started working on the 2nd amp.
I want know a little more on how to fine tune the protection circuit as per desired
requirements, I do manage somehow using thumbs rule and common sence .
Leach SuperAmp
I am a beginner in DIY audio. I built a Ver 4.5 Leach Amp few years ago, and I find it sound very good even though I used budget priced components.
Last year, I built a pair of 250W monoblocks based on the Leach SuperAmp design. With previous experience, I have achieved even better result with these Amps. Back then, I was using these Amp with a pair of highly tweaked Acoustic Energy AE308. Recently, I have changed my loudspeakers to Mark Levinson Red Rose series, Rosebud Two. These are much lower sensitivity design than the AE308, and I find my Leach SuperAmp bass output become weak because of that.
Is there anyone out there could advise me on making any modification to the circuit so that I can get more bass output out of the Amps?
I am a beginner in DIY audio. I built a Ver 4.5 Leach Amp few years ago, and I find it sound very good even though I used budget priced components.
Last year, I built a pair of 250W monoblocks based on the Leach SuperAmp design. With previous experience, I have achieved even better result with these Amps. Back then, I was using these Amp with a pair of highly tweaked Acoustic Energy AE308. Recently, I have changed my loudspeakers to Mark Levinson Red Rose series, Rosebud Two. These are much lower sensitivity design than the AE308, and I find my Leach SuperAmp bass output become weak because of that.
Is there anyone out there could advise me on making any modification to the circuit so that I can get more bass output out of the Amps?
"Is there anyone out there could advise me on making any modification to the circuit so that I can get more bass output out of the Amps?"
A few questions.
What is the rated impedance of the speakers, and what does the DC resistance measure?
How many dB/2.83V/1M are they?
What is the ±V of your Leach SuperAmp ?
How many VA is the transformer rated?
Size of the main filter caps?
A few questions.
What is the rated impedance of the speakers, and what does the DC resistance measure?
How many dB/2.83V/1M are they?
What is the ±V of your Leach SuperAmp ?
How many VA is the transformer rated?
Size of the main filter caps?
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