I just bought a couple of mono Rawson Aleph 5 clones on Audiogon. They just got shipped ground.. very well packed, boxes looked fine.
One of the amps sounds great, the other one does not warm up. I can hear some sound but it never really gets going. The LED comes on and I hear some sound through but the amp does not warm up. I looked inside and I can't see anything burnt, the amp looks very well made, it has the Nelson Pass boards.
The circuits look simple enough, but all I got is a voltmeter. is there someplace I could take a simple voltage measurement?
Before I send them back to the seller (heavy) I wonder if anyone knows where in Southern California I could get a technician to take a look at it.
Thanks
One of the amps sounds great, the other one does not warm up. I can hear some sound but it never really gets going. The LED comes on and I hear some sound through but the amp does not warm up. I looked inside and I can't see anything burnt, the amp looks very well made, it has the Nelson Pass boards.
The circuits look simple enough, but all I got is a voltmeter. is there someplace I could take a simple voltage measurement?
Before I send them back to the seller (heavy) I wonder if anyone knows where in Southern California I could get a technician to take a look at it.
Thanks
So much for this forum being half useful.
I asked a real question and you just give me useless value judgements of absolutely NO value.
BTW, not only do this amps have Nelson's boards but so does my own First Watt B1 buffer. So please keep your value judgements away.
Do you know someone in SoCal that can repair them or not. If you do, then kindly let me know, if not please keep your opinions to yourselves.
BTW, if you have any idea where I can measure the circuit I would appreciate it. I suspect that the bias is not correct.
And the build quality and the parts look pretty good. I am a physicist by training but do EE and CS for a living.
Jeez... I did not expect the Spanish Inquisition.
I asked a real question and you just give me useless value judgements of absolutely NO value.
BTW, not only do this amps have Nelson's boards but so does my own First Watt B1 buffer. So please keep your value judgements away.
Do you know someone in SoCal that can repair them or not. If you do, then kindly let me know, if not please keep your opinions to yourselves.
BTW, if you have any idea where I can measure the circuit I would appreciate it. I suspect that the bias is not correct.
And the build quality and the parts look pretty good. I am a physicist by training but do EE and CS for a living.
Jeez... I did not expect the Spanish Inquisition.
BTW, I have noticed that the blue LED in the front panel is not fully turning off. It's still on very dimly but obvious in a dark room.
It's as if the power supply is not fully discharging the capacitors. If this is a power supply problem, I suppose I ought to be able to use my voltmeter to measure the rails.
Any ideas what to look for?
Oh... how should I discharge the caps without causing trouble? Last time I built a power supply I did not put in a switch... I know what I'm doing, I am a professional Well, to be short. I put the caps backwards....
It's as if the power supply is not fully discharging the capacitors. If this is a power supply problem, I suppose I ought to be able to use my voltmeter to measure the rails.
Any ideas what to look for?
Oh... how should I discharge the caps without causing trouble? Last time I built a power supply I did not put in a switch... I know what I'm doing, I am a professional Well, to be short. I put the caps backwards....
nice opinion/advice is welcome , but when someone say that his amp are fire in the house - that's not welcomed advice , and when someone say that he's crook constantly producing and selling someone else's IP , that's also not welcomed opinion
consider this one as mild , torturing you softly
Monty Python - Spanish Inquisition Torture Scene - YouTube
however - posting question without proper info (set of nice and clear pictures) is counter-productive
give a call to Mr. Rawson - he certainly knows what can be with his amps , without using crystal ball
You make 1 post, wait a few hrs, get a few bad replies? (facts Not Value Judgments) And we are not 1/2 useful? Value Judgments?
Are you making an implied Value Judgment?
Sorry, my opinion is, you won't get very far with that attitude. What you've already said will alienate you from many even giving you an answer
100's of people here do. Read my last comment
But, you asked for it! This is the best audio forum on the web. Maybe you call that a value judgment but, we would have told you before you bought them Not To! Face it, you've made more mistakes than buying those amps. You need to loose that insulting attitude.
OK, You put your self in trouble, and i can tell you what, i am BANNED for life on Audiokarma for telling people to avoid buying similar amp in forum classifieds ...
I even point on photo what all was wrong in this "BUILD" but mod and then admin told me i don't have right to post negative comment about items for sale! Well - there goes my big mouth and - there come customer like YOU ....
You can post positive [to bust sale] but don't even think about posting negative comment ...
Now, did you contact person who sell you particular AMP on the first place ?
Then contact the builder - cuz no one on this forum knows what he did wrong in your particular amps ...
And post the photos of amps interior and PCBs ...
Dont get frustrated with comments here, cuz is your fault - do some research before you do something like that ...
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I strongly doubt it, as you ask questions about the most basic stuff imaginable:
Have you ever heard of resistors?
I am not a troll...
That my friend was a joke.... that's why I only have a meter! And its a Radio Shack analog meter from the early 80s.
As "in proffessional driver in a closed road"
Or as in Hunter Thompson.
I am not a troll, I really exist and I really have those amps in the living room now.
BTW, ever since the beginning of my career, I've had outstanding metrology at work... Do you perhaps remember the HP 1980 scope?
Of course, nowadays it's all digital and done with JTAG analyzer and stuff like emulators.
No, I am not a troll
Yeh! Very professional.
Come on………..this has to be a troll.
That my friend was a joke.... that's why I only have a meter! And its a Radio Shack analog meter from the early 80s.
As "in proffessional driver in a closed road"
Or as in Hunter Thompson.
I am not a troll, I really exist and I really have those amps in the living room now.
BTW, ever since the beginning of my career, I've had outstanding metrology at work... Do you perhaps remember the HP 1980 scope?
Of course, nowadays it's all digital and done with JTAG analyzer and stuff like emulators.
No, I am not a troll
No, I'm not a troll. At work I have lots of metrology stuff, I just don't bring it home.
And if you read the context of my being a "professional" you'd understand that it's a joke.... ever read Hunter S. Thompson?
Anyhow, since seems all you guys want to do is ridicule me (and I've been reading these forums for a very long time) I guess I might as well just go find a local tech. The seller has offered to have it fixed and the circuits look simple. The boards look fine so it might be a voltage regulator,
Oh, I thought Rawson had retired. I don't suppose you might now hot to get a hold of him?
And if you read the context of my being a "professional" you'd understand that it's a joke.... ever read Hunter S. Thompson?
Anyhow, since seems all you guys want to do is ridicule me (and I've been reading these forums for a very long time) I guess I might as well just go find a local tech. The seller has offered to have it fixed and the circuits look simple. The boards look fine so it might be a voltage regulator,
Oh, I thought Rawson had retired. I don't suppose you might now hot to get a hold of him?
Ok, all value judgements aside. Nothing in the amp looks mechanically broken, the LED turns on but takes a long time to discharge. The amp does not get warm but I do get some sound out of it.
So, what part of the amp/circuit would be most likely the one to have failed? I assume that the power supply might be the most likely to fail mechanically as the seller maintains it was working before he shipped them.
So, I would suppose the FETs are not being biased at the right level, likely just at a very low level so they put out a few tenths of a watt or so, enough for me to hear a signal on the speaker (Maggies).
I'm just trying to discern where in the circuit I ought to look first and perhaps I might see mechanical damage and I could take some voltage measurements.
I suppose I could take a picture of the interior.
So, what part of the amp/circuit would be most likely the one to have failed? I assume that the power supply might be the most likely to fail mechanically as the seller maintains it was working before he shipped them.
So, I would suppose the FETs are not being biased at the right level, likely just at a very low level so they put out a few tenths of a watt or so, enough for me to hear a signal on the speaker (Maggies).
I'm just trying to discern where in the circuit I ought to look first and perhaps I might see mechanical damage and I could take some voltage measurements.
I suppose I could take a picture of the interior.
TonyEE -
Please excuse the knee-jerk reaction that the name "Rawson" evokes on this forum. The guy made amps for the purposes of selling, something that is specifically prohibited by Pass, and also not very Kosher... But does mean that he outright stole from Pass. Needless to say, he's a bit of a Pariah 'round these parts.
The second problem is that generally the amps tend to disregard safe wiring practices. Not always, but unfortunately in most examples you can see (plainly, from photographs) that it's an electrical accident ready to happen.
If you take them to a tech, please don't be surprised if he will refuse to work on them or will only work on them if he puts a number of things straight, obviously at an additional cost. If he says something like that, understand it's because he has your safety in mind.
Now I see that there are a few ways to progress from your point of view, whichever is best is up to you -
1) Return them as non-operational and be done with it.
2) Attempt to have them fixed, which may be opening a huge can of worms.
3) Use the chassis and transformers and build something yourself. This is a DIY forum, after all...
My vote is for #3, personally.
I bet, however, that you will choose #1
Please excuse the knee-jerk reaction that the name "Rawson" evokes on this forum. The guy made amps for the purposes of selling, something that is specifically prohibited by Pass, and also not very Kosher... But does mean that he outright stole from Pass. Needless to say, he's a bit of a Pariah 'round these parts.
The second problem is that generally the amps tend to disregard safe wiring practices. Not always, but unfortunately in most examples you can see (plainly, from photographs) that it's an electrical accident ready to happen.
If you take them to a tech, please don't be surprised if he will refuse to work on them or will only work on them if he puts a number of things straight, obviously at an additional cost. If he says something like that, understand it's because he has your safety in mind.
Now I see that there are a few ways to progress from your point of view, whichever is best is up to you -
1) Return them as non-operational and be done with it.
2) Attempt to have them fixed, which may be opening a huge can of worms.
3) Use the chassis and transformers and build something yourself. This is a DIY forum, after all...
My vote is for #3, personally.
I bet, however, that you will choose #1
the PSU may or may not be ok. that the LED don't go of tells me that there is no bleeder resistors in the PSU. and the amp do not turn on. the reason can be that only the pluss rail has conection to the amp. the LED is conected from + rail to GND. if the negativ rail don't have conection, the amp will not turn on. a week sound may be heard anyway. this is acctualy the innput signal going to the speaker.
I think I'll try #2. I'll fiind a tech and show him the amp. If he feels it's safe enough to work I'll ask for a number.
The seller has agreed to pay for the repair. If the repair is too high then I will return the amps.
The sad thing is that the one that works sounds VERY GOOD. I mean, it sounds much better than my Audio Research D70 MkII amp.
I suppose I could compare both amps and see what the resistance is from the LED to the GND. Also look at the resistance from the negative rail to ground. The schematic shows a thermistor.to ground,
Also, the LED seems to be between +34V to the neutral...
The seller has agreed to pay for the repair. If the repair is too high then I will return the amps.
The sad thing is that the one that works sounds VERY GOOD. I mean, it sounds much better than my Audio Research D70 MkII amp.
I suppose I could compare both amps and see what the resistance is from the LED to the GND. Also look at the resistance from the negative rail to ground. The schematic shows a thermistor.to ground,
Also, the LED seems to be between +34V to the neutral...
OK, the circuit board is 327791. I just checked out the rail voltage on both amps. +/- 34 VDC. Compared it to both the chassis ground and the (-) output.
Interestingly, when I turn off the power, the rails in the good amp drop very quickly.. draining through the caps? In the bad amp, they decay very slowly.
These amps are monoblocks so they have six FETs and six PS caps.
Interestingly, when I turn off the power, the rails in the good amp drop very quickly.. draining through the caps? In the bad amp, they decay very slowly.
These amps are monoblocks so they have six FETs and six PS caps.