New transistor arrived yesterday and now the aleph is all up and running. Thanks team for the help and thanks 6l6 for the guide 😁 the amp sounds wonderful.
All I need now is a pre amp (thinking the ba3 front end)
Oh and a better shelf than this old desk
All I need now is a pre amp (thinking the ba3 front end)
Oh and a better shelf than this old desk
Attachments
If you want a manly chassis for this fine amp get on board
https://www.diyaudio.com/forums/pass-labs/360807-ultimate-4u-500mm-chassis-38.html#post6410433
https://www.diyaudio.com/forums/pass-labs/360807-ultimate-4u-500mm-chassis-38.html#post6410433
In a fault condition, the CL60 will get hot, it's possible a plastic one could melt
I can attest to that! In fact mine glowed like burning charcoal in the center and smoked like crazy.
Russellc
Don't get me wrong, I have 2 BA3 FE and love them, but also consider the Iron Pre once it hits the store. It is a fabulous match with my Aleph J.
Russellc
My in-laws are in town until 12/3, so my audio room is out of commission. But while they were gone a little bit ago, I put the shorting pins into my XLRs and switched cables to SE. In addition to the static in the right channel, I now have hum in both channels. There is zero hum with XLRs connected.
I have already replaced the damaged Q2 in the right channel, though it made zero difference, so perhaps the damage was superficial. In my quote above, see all my chassis photos.
In trying to embed/upload the video files of the hum and static, it won't accept .MOV, so here are the links:
AJ_hum_01 | Appeal to Emulsion | Flickr
aj_hum_02 | Appeal to Emulsion | Flickr
Any ideas or suggestions?
Well I've already bought the stuff to do the ba3 pre. But you've convinced me. I'll do both 😂
I explained the root cause couple of pages back...
The input stage on the AMP PCB needs to be relocated to be physically close to the RCA sockets at the back of the amp. Then, the hook-up wiring would be short... just look at Nelson's amps... he "terminates" his input loom as soon as it enters the AMP.
The input stage on the AMP PCB needs to be relocated to be physically close to the RCA sockets at the back of the amp. Then, the hook-up wiring would be short... just look at Nelson's amps... he "terminates" his input loom as soon as it enters the AMP.
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let's just brainstorm the topic of pre-amp here for a second.
Aleph J is a two-gain stage, single-ended pure class-A output amplifier. It simply can not get any better than this. In other words, the source signal will be amplified by the least possible number of transistor: one for voltage gain, one for current gain.
Placing any pre-amp (additional gain stages) and an extra pair of interconnects (AND RCA contacts!!) between the source and Aleph J, would be criminal... but I em Extreme in my approach.... to simplicity.
If you use a transformer for voltage gain you can reduce the transistor count even further. The First Watt M2 amplifier does exactly this.
Of course it opens up the possibility of a disagreement: which is sonically better, a transistor voltage amplifier or a transformer voltage amplifier ?
Of course it opens up the possibility of a disagreement: which is sonically better, a transistor voltage amplifier or a transformer voltage amplifier ?
I know how you feel. The BA3 is a great pre, and has some gain if you get into a situation where you need gain. You will love the FE.
Russellc
Well i actually have been using it without the using the pre amp in my old Yamaha amp and I do prefer it like that. But I would still like to try a couple preamps and see if i like the that way
I plan on building an F4 at some point in the coming months anyway so if i dont like the ba3/aleph combo I can always use it for that. Ill look into this iron pre too as I dont think I can go to wrong with having an extra preamp around as long as the funds allow it
If you did not already have the BA-3 FE, I would recommend the Pass DIY B1 with Korg Nutube preamp. It works very nicely with the Aleph J to produce a rich, natural sound. The gain is overkill for my man cave, but works very well in my living room that shares a larger, open floor plan with my dining area and kitchen. This little triode preamp gives my Audio Research LS7 tube line stage a good run for the money.
I understand that Wayne’s Burning Amp line stage is also an excellent preamplifier. Let’s face it, we’re a spoiled bunch with an almost infinite number of choices for the path to audio nirvana.
I understand that Wayne’s Burning Amp line stage is also an excellent preamplifier. Let’s face it, we’re a spoiled bunch with an almost infinite number of choices for the path to audio nirvana.
The korg nutube b1 was actually the one I originally wanted. But I missed the pre order. Though I'd still like to build it at some point, I'll probably wait till they're back in stock with the full kits.
All these choices and I know I'll likely end up doing most of them 😂 too hard to say no
All these choices and I know I'll likely end up doing most of them 😂 too hard to say no
offset and bias problems
I had the amp running for over 200 hours and decided to replace R7 and R27 with a fixed resistor. The offset and bias were rock solid. While I had the amp boards out, I wanted to take care of a few things on the power boards - like get them hardwired to the amps boards.
Heres what I did:
Power supply boards - from diyaudio
replace 3k bleeder resistor to 10K
replace 5K LED resistor to 10K
remove outbound snubber capacitor
remove outbound snubber resistor
remove euroblocks and hardwire connections
On the amp boards from diyaudio:
remove R8 and replace with 1K ohm resistor
remove R7 and replaced with appropriate resistor
remove R27 and replaced with appropriate resistor
replace LED resistors with 10K resistor
After getting everything buttoned up I had some issues. The fixed resistors didn't give the results I was hoping for - offset and bias were off. Things were so far off, Q5 and Q7 smoked a bit on one amp and turned the 0.47 resistor, on the other channel, brown that it was so hot. I replaced the pots, but no good.
Once the pots were back in and powered it back up, the offset was 5V at minimum and bias was high at partial. I powered up using a variac and could only get to 40% before offset went to 15 and bias tried to run over 1V. I shut everything down.
I tested power supply voltage before connecting to the amp board, 25.3 for both + and -. The - side ran anywhere from 1 to 7 lower that the + once connected back to amp boards. The negative side also takes about 10 minutes to drain caps, the + about 30 seconds.
Maybe I've been looking at this too long and have overlooked da simple mistake. TIA for any insight into the problem.
I had the amp running for over 200 hours and decided to replace R7 and R27 with a fixed resistor. The offset and bias were rock solid. While I had the amp boards out, I wanted to take care of a few things on the power boards - like get them hardwired to the amps boards.
Heres what I did:
Power supply boards - from diyaudio
replace 3k bleeder resistor to 10K
replace 5K LED resistor to 10K
remove outbound snubber capacitor
remove outbound snubber resistor
remove euroblocks and hardwire connections
On the amp boards from diyaudio:
remove R8 and replace with 1K ohm resistor
remove R7 and replaced with appropriate resistor
remove R27 and replaced with appropriate resistor
replace LED resistors with 10K resistor
After getting everything buttoned up I had some issues. The fixed resistors didn't give the results I was hoping for - offset and bias were off. Things were so far off, Q5 and Q7 smoked a bit on one amp and turned the 0.47 resistor, on the other channel, brown that it was so hot. I replaced the pots, but no good.
Once the pots were back in and powered it back up, the offset was 5V at minimum and bias was high at partial. I powered up using a variac and could only get to 40% before offset went to 15 and bias tried to run over 1V. I shut everything down.
I tested power supply voltage before connecting to the amp board, 25.3 for both + and -. The - side ran anywhere from 1 to 7 lower that the + once connected back to amp boards. The negative side also takes about 10 minutes to drain caps, the + about 30 seconds.
Maybe I've been looking at this too long and have overlooked da simple mistake. TIA for any insight into the problem.
Make sure that the resistors you inserted, instead of the trim-pots, are correctly soldered to their correct eyelets - it can get confusing a bit (trim-pots with their three pins; two of which are shorted via PCB traces)
Double-check the wiring. Also, make sure the wires are not protruding the AMP PCB's too much; otherwise, they'll be touching the ground.
You had to remove the AMP PCB's - make sure that there are no shorts on any MOSFET's, to ground.
Double-check the wiring. Also, make sure the wires are not protruding the AMP PCB's too much; otherwise, they'll be touching the ground.
You had to remove the AMP PCB's - make sure that there are no shorts on any MOSFET's, to ground.
What would cause Q5 and Q7 to pull enough amps to cause the loading resistors to smoke?
I pulled all the MOSFETs last night and found 4 of them that were bad. I could only check using the diode check on my multimeter. Placing negative test probe on the drain and positive on the source, I got a reading of .532, reversing the test leads and there isn't any reading. This is from a new MOSFET. My burnt ones allow current to flow in either direction testing drain and source and I get readings from gate to sink, and gate to source.
Will using the diode test like this tell me if if the MOSFET bad?