To my ears , both Aleph J and F5 sound terrific owing to a superb design by the Master and have their unique signatures. If at all, my preference would tilt slightly towards F5 purely due to it's simpler design and easier build than AJ.
About rail fuses...
Should i add fuses to the rails? And if so should i add to both rails or just one of them? If only one rail should have a fuse, which one?
I read somewhere here that some of the pass amps were designed for fuse only on the negative rail... so it seems safest to ask =)
Addition: Does the same apply to the f5 also?
Should i add fuses to the rails? And if so should i add to both rails or just one of them? If only one rail should have a fuse, which one?
I read somewhere here that some of the pass amps were designed for fuse only on the negative rail... so it seems safest to ask =)
Addition: Does the same apply to the f5 also?
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Hello,
I hope this not against forum rules. Could someone please send me the Aleph J service manual via PM? I understand these are hard to obtain due to IP abuses, but I am a DIY hobbyist with no commercial intentions whatsoever. I do have the Aleph 3 PDF from way back when and the Aleph J schematic, but would love to have the complete document to print.
I have just purchased a CNC router and want to make the 'J' my first project with it. I plan (or hope) to CNC my own PCBs and chassis. My goal is to produce a scaled down vertical amplifier that resembles a smaller Levinson 33H.
I hope this not against forum rules. Could someone please send me the Aleph J service manual via PM? I understand these are hard to obtain due to IP abuses, but I am a DIY hobbyist with no commercial intentions whatsoever. I do have the Aleph 3 PDF from way back when and the Aleph J schematic, but would love to have the complete document to print.
I have just purchased a CNC router and want to make the 'J' my first project with it. I plan (or hope) to CNC my own PCBs and chassis. My goal is to produce a scaled down vertical amplifier that resembles a smaller Levinson 33H.
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If I'm not mistaken this is the manual here: FIRST WATT PRODUCTS
Or direct link: http://www.firstwatt.com/pdf/prod_aj_man.pdf
Or direct link: http://www.firstwatt.com/pdf/prod_aj_man.pdf
Thanks. That is the product owner's manual sans schematics. I assume Nelson published a service manual in the interim? Of course I could deduce everything needed from this thread. I just like being able to print and read the service manuals.
You was right, R7 was not properly installed. But now my dc offset is about 58 mv. I will try to adjust the dc offset with a trim pot at R8.
Thanks a lot!
Are 30v dc rails ok?
I am putting together a PS using my surplus transformers. They measure 22-0-22v on secondary. With full wave bridge and caps, I am going to get around 30vdc on each rail.
My question is: should I change anything on Aleph j circuit to take this higher supply voltage. Reduce bias current? What impact.
Thanks.
I am putting together a PS using my surplus transformers. They measure 22-0-22v on secondary. With full wave bridge and caps, I am going to get around 30vdc on each rail.
My question is: should I change anything on Aleph j circuit to take this higher supply voltage. Reduce bias current? What impact.
Thanks.
It's alive and it siiiiiings! 
But only one channel at the moment... but second transformer should arrive not too far into the future...
I did both an F5 and an Aleph J, then A/B compared before deciding I liked the AJ more.
The AJ was just sound... lovely sound... I think I understand what people mean when they say it sounds sweet and light on the ears.
The F5 by contrast was sharp, mostly not really noticeable but was very noticeable on one track i listened to which was heavy on trumpets. It sounded very sharp and as if the trumpets was played inside a tin can, not pleasant at all : /
Thanks nelson for all these schematics so we can test which we enjoy best!
Now the question is just if I dare to mod it and remove one mosfet pair and trim the bias to make it a 15W amp instead...
// Olle
But only one channel at the moment... but second transformer should arrive not too far into the future...
I did both an F5 and an Aleph J, then A/B compared before deciding I liked the AJ more.
The AJ was just sound... lovely sound... I think I understand what people mean when they say it sounds sweet and light on the ears.
The F5 by contrast was sharp, mostly not really noticeable but was very noticeable on one track i listened to which was heavy on trumpets. It sounded very sharp and as if the trumpets was played inside a tin can, not pleasant at all : /
Thanks nelson for all these schematics so we can test which we enjoy best!
Now the question is just if I dare to mod it and remove one mosfet pair and trim the bias to make it a 15W amp instead...
// Olle
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The F5 was never really built into the box, I still have it on a temporary heat sink but probably won't use it, will soon slaughter it an build my second Aleph J channel 
Gain in my case isn't really a problem since my DAC outputs 5V RMS, and if that isn't enough I can forward to my preamp for as far as i know up to 20V RMS, way too much for this but it's a headphone amp / preamp combo =)
About biamping, is it really that great even for mid/tweet crossover? I can understand that it's a given when crossing woofer or sub since the filter components would be monstrous but how about a small first-order speaker crossover at ~ 4000 - 5000 hz? Would biamping still be an advantage or is it an improvement below threshold of hearing?
And more about amping since we are already discussing, if I've understood correct Class A is supreme unnecessary overkill for a subwoofer amp. I have plans for a cute 430 litres subwoofer crossed at ~ 40 hz planned but haven't decided on amp. At the momvent I lean towards a Class D amp but since the driver of it has maximum of 45W RMS I don't really need much efficiency to drive it, hence my wonderings about optimal amp for it =)
// Olle
Gain in my case isn't really a problem since my DAC outputs 5V RMS, and if that isn't enough I can forward to my preamp for as far as i know up to 20V RMS, way too much for this but it's a headphone amp / preamp combo =)
About biamping, is it really that great even for mid/tweet crossover? I can understand that it's a given when crossing woofer or sub since the filter components would be monstrous but how about a small first-order speaker crossover at ~ 4000 - 5000 hz? Would biamping still be an advantage or is it an improvement below threshold of hearing?
And more about amping since we are already discussing, if I've understood correct Class A is supreme unnecessary overkill for a subwoofer amp. I have plans for a cute 430 litres subwoofer crossed at ~ 40 hz planned but haven't decided on amp. At the momvent I lean towards a Class D amp but since the driver of it has maximum of 45W RMS I don't really need much efficiency to drive it, hence my wonderings about optimal amp for it =)
// Olle