thats not so strange. its the fets that drain the caps. as long they are not on in the defect amp, there is almost no draining of the caps.
I found the problem... one broken solder joint from the board to the FETs... I think its the zener diode to the input ( 4VDC). I just re soldered it ( truly wretched technique, I am RUSTY ).
Sort of figures, it was a mechanical problem after all.
I can't see any thermistors on these amps. Maybe it's time to think about brushing up on my soldering skills ( did get a new iron a month ago ) and modify these amps.
The guy who sold them to me said they'll do 120w into 4 ohms... what do you think? they have six FETs and six caps on the PS.
I will post pictures this weekend.
BTW- I am not a troll!!!!
Sort of figures, it was a mechanical problem after all.
I can't see any thermistors on these amps. Maybe it's time to think about brushing up on my soldering skills ( did get a new iron a month ago ) and modify these amps.
The guy who sold them to me said they'll do 120w into 4 ohms... what do you think? they have six FETs and six caps on the PS.
I will post pictures this weekend.
BTW- I am not a troll!!!!
OK, I fixed it a while back, I've been sitting listening to music. Told the family to turn down the TV and let Dad play his music.
They all loved it.
As it turnes out, there was indeed a mechanical failure: a wire carrying 9VDC from the PC board to the FETs had broken off. I resoldered it and now it works great.
I took pictures of the amps with my old camera which has lower resolution than my DSLR (great pictures, PITA to share). I'll post later.
They all loved it.
As it turnes out, there was indeed a mechanical failure: a wire carrying 9VDC from the PC board to the FETs had broken off. I resoldered it and now it works great.
I took pictures of the amps with my old camera which has lower resolution than my DSLR (great pictures, PITA to share). I'll post later.
I realize that the 4 FET circuit is rated at 60W to 8ohms and 90W to 4 ohms.
But these amps have six (vs four ) caps and six FETs... so the way I figure, there are two pairs of current sources instead of a single pair. So they might well be able to provide enough current to keep the voltage up into 4 ohms... hence the claim by the seller that they are rated at 120W into 4 ohms.
When I have time I will reopen them and see if I can reverse engineer what he did. For sure I need to add thermistors into it.
Another thing that bugged me is that he did not make them identical from a mechanical standpoint. The wire colors are not consistent and on one side he chose one FET to connect the wire while on the other amp he chose a different FET. I realize that it makes no difference sonically or electrically but I tend to be anal retentive about such things.
But these amps have six (vs four ) caps and six FETs... so the way I figure, there are two pairs of current sources instead of a single pair. So they might well be able to provide enough current to keep the voltage up into 4 ohms... hence the claim by the seller that they are rated at 120W into 4 ohms.
When I have time I will reopen them and see if I can reverse engineer what he did. For sure I need to add thermistors into it.
Another thing that bugged me is that he did not make them identical from a mechanical standpoint. The wire colors are not consistent and on one side he chose one FET to connect the wire while on the other amp he chose a different FET. I realize that it makes no difference sonically or electrically but I tend to be anal retentive about such things.
Last edited:
For the record, it does not have my boards, which have never been made
available in any form.
Then I'm confused. There is a board on this amp that has your name. The part number is 327791 and it says on it Thankyou nelson pass. Could this be a Frankenstein amp? You know? That's what they call Hondas that mix the block from one engine and the head from another.
There's another thread here that refers to that board:
http://www.diyaudio.com/forums/pass-labs/136330-aleph-clone-id.html
My son and I have been talking about making it to next years amp camp... maybe if I show up I'll call myself Joe or Fred?
BTW- thanks for responding. I've been following you and your stuff for eons. I just don't have the money to buy it, even used. Put two kids through college ( one still in there ). I did put together a B1 buffer, stashed it in a cigar humidor. Looks and sounds great. I was thinking of building a seven foot woofer tubular tower... but I think I'd paint it white.
There's another thread here that refers to that board:
http://www.diyaudio.com/forums/pass-labs/136330-aleph-clone-id.html
My son and I have been talking about making it to next years amp camp... maybe if I show up I'll call myself Joe or Fred?
BTW- thanks for responding. I've been following you and your stuff for eons. I just don't have the money to buy it, even used. Put two kids through college ( one still in there ). I did put together a B1 buffer, stashed it in a cigar humidor. Looks and sounds great. I was thinking of building a seven foot woofer tubular tower... but I think I'd paint it white.
Last edited:
Are those the abominations you bought?
Rawson Monoblock amplifiers 60 watts (Aleph 5 Clones) | Solid state | Saint Louis, Missouri 63112 | AudiogoN - The High-end Audio Community
Just what you'd expect from a "Rawson" build, it's about as bad as it gets. Does this thing even have a fused primary?
And the silkscreen writing just adds insult to injury. What a disgrace.
Rawson Monoblock amplifiers 60 watts (Aleph 5 Clones) | Solid state | Saint Louis, Missouri 63112 | AudiogoN - The High-end Audio Community
Just what you'd expect from a "Rawson" build, it's about as bad as it gets. Does this thing even have a fused primary?
And the silkscreen writing just adds insult to injury. What a disgrace.
What part of "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" didn't you get from earlier?
OK, I think the point is made, but nobody expects the OP to send the amps
back and so on.
My concern here is that, having seen these photos before, it looks like that the
Thermistor which may be the AC inrush current limiter has no insulation on its
long leads, and may be a hazard.
If it is not the inrush Thermistor, but the ground isolator, then it still looks to
be misplaced, as the chassis must be directly attached to AC Earth.
And did someone say that there is no fuse?
The only important thing here is to confirm that this build is not a shock or
fire hazard.
back and so on.
My concern here is that, having seen these photos before, it looks like that the
Thermistor which may be the AC inrush current limiter has no insulation on its
long leads, and may be a hazard.
If it is not the inrush Thermistor, but the ground isolator, then it still looks to
be misplaced, as the chassis must be directly attached to AC Earth.
And did someone say that there is no fuse?
The only important thing here is to confirm that this build is not a shock or
fire hazard.
Are these your amps?
Ok, let's look...
First, the inrush thermistor is not connected in a way that is immediately obvious from this photo, but what I can see doesn't look safe, as one end of it appears to be attached to the primary only by the thermistor lead. It kinds looks like the lead is wrapped around another primary wire on the IEC for a bit of support, which if so is a fire waiting to happen. I would like to see a better photo.
2nd, it's not immediately evident of the fuse is wired in the circuit.
3rd, and this a biggie, there is no 3rd-wire mains earth to chassis. Let me repeat that - chassis is not connected to AC safety earth. Correct that at once, right now, before you use the amps again. If there is a wiring fault live AC will be on the chassis. Which is even more scary as there doesn't appear to be a fuse.
- The transformer centertap is attached to chassis... but not AC safety earth... WTF??
- Woefully undersized filter resistors.
- Is there solder on the black wire attached to the bridge?
-Why, on God's green earth, is speaker black attached to ground through a 3ohm resistor?? Did he ground-lift the amp through the speaker terminal? if so, then it runs back to chassis at the screw where the orange and green attach, completely un-doing a PSU lift, and making some utterly uncomprehensible grounding scheme, all while the transformer is connected directly to the chassis, and AC earth is completely ignored.
If these are the amps you bought, please understand, this is dangerous. Genuinely, seriously, I'm not kidding, I'm not exaggerating, PLEASE DON"T PLUG THESE IN AGAIN until it's set right, Dangerous.
Ok, let's look...
First, the inrush thermistor is not connected in a way that is immediately obvious from this photo, but what I can see doesn't look safe, as one end of it appears to be attached to the primary only by the thermistor lead. It kinds looks like the lead is wrapped around another primary wire on the IEC for a bit of support, which if so is a fire waiting to happen. I would like to see a better photo.
2nd, it's not immediately evident of the fuse is wired in the circuit.
3rd, and this a biggie, there is no 3rd-wire mains earth to chassis. Let me repeat that - chassis is not connected to AC safety earth. Correct that at once, right now, before you use the amps again. If there is a wiring fault live AC will be on the chassis. Which is even more scary as there doesn't appear to be a fuse.
- The transformer centertap is attached to chassis... but not AC safety earth... WTF??
- Woefully undersized filter resistors.
- Is there solder on the black wire attached to the bridge?
-Why, on God's green earth, is speaker black attached to ground through a 3ohm resistor?? Did he ground-lift the amp through the speaker terminal? if so, then it runs back to chassis at the screw where the orange and green attach, completely un-doing a PSU lift, and making some utterly uncomprehensible grounding scheme, all while the transformer is connected directly to the chassis, and AC earth is completely ignored.
If these are the amps you bought, please understand, this is dangerous. Genuinely, seriously, I'm not kidding, I'm not exaggerating, PLEASE DON"T PLUG THESE IN AGAIN until it's set right, Dangerous.
Last edited:
