Apologies if this has been asked before. I can't seem to access any other posts.
I'm confident I can build the ACA, but don't want to spend the money on something that may last me a year before upgrading.
The aleph j (or possibly an f5) is really what I want long term, but it does me no good if I can't build it properly.
And another factor - cost. The ACA kit is a few hundred. I'm guessing an aleph j would approach a thousand. Stop me if I'm wrong.
Thanks
I'm confident I can build the ACA, but don't want to spend the money on something that may last me a year before upgrading.
The aleph j (or possibly an f5) is really what I want long term, but it does me no good if I can't build it properly.
And another factor - cost. The ACA kit is a few hundred. I'm guessing an aleph j would approach a thousand. Stop me if I'm wrong.
Thanks
I'm in the same boat. Thought hard about the ACA, but what I really want is an F5 and I don't have the money for both. Problem is I am not confidant in my skills/abilities to complete the task. When reading the build threads, there are so many options and variables discussed that it leaves me confused. I really need a f5 kit like the ACA or someone locally to help me come up with the parts and help me with the build.
The answer somewhat depends on your electronics knowledge and ability with a soldering iron. As a novice you can learn an awful lot reading the Zen articles and everything else on www.passdiy.com. 
(Papa Pass trademarks)
There are or likely soon will be build guides so you can follow pretty much step by step. Member 6L6 has been kind enough to do this for several amps. As an aside, my first DIY amp used a pair of 6L6GCs that I biased heavily enough that the plates glowed cherry red.
IF everything goes well, you can just stuff the boards, attach to the heat sinks and wire up the PSU connections and enjoy great sound. With meticulous attention to detail, soldering skill you CAN make this happen. Triple check the part value and orientation before placing it on the board. Not all parts are directional, but semicondcutors and electrolytic caps are. Electros are funny. the part marks the negative lead and the board usually marks the positive side. You'll get the hang of it. Small diodes have a stripe that you match to the silk screen on the board. Larger diodes and transistors AKA FETs AKA Mosfets have a package shape that identifies orientation and guides you to the proper lead. Start by soldering in the low lying parts 4-5 at a time - resistors and small diodes. Then small cap(acitor)s, then transistors and tall caps.
I know the options can be confusing. The good thing about building a proven design like either of these is you can pick one of the suggested options and get good results. Different options change the flavor slightly, like adding a bit of cayenne or salt, but won't make the amp fail.
If you don't have a Variac or other autotransformer to bring the voltage up slowly when you are testing, make a light bulb tester. It's simply a light bulb in series with a power outlet so that if there is something major wrong with your amp the bulb will limit the current. A search of the forums will turn up a number of threads showing how to build one if you need help.
Unlike some AB amplifiers, you cannot test either the A-J or F5 without mounting them on heatsinks.
If you have a problem, there are plenty of helpers on this site. There are any number of namby pamby pantywaists around the forum who will suggest a chip amp kit for a first build. No disrespect intended, all in good fun, but you can do better. Chip amps are not terribly expensive and hard to mess up, but IMHO the main difference from an F5 is more parts.
The Aleph J requires matching Jfets, about the only part that requires any special skill. Matching requires a voltmeter and a power supply. Or you could buy matched pairs from forum member Spencer at Store | FET Audio About the only source of real 2SJ74s anymore. There is some rumbling that we may soon be able to get good jfets from the forum store soon.
Take my suggestion to GO FOR IT (and all other advice) with a grain of salt and temper it with your knowledge of your own abilities. Basic electronic theory came pretty easily to me. My second scratch built amp was a pair of A75s that I modified to run on much higher rails. They are still running 12 years later, although I missed uprating a couple of resistors which have scorched the boards and burned off their outer coating.
You're not having fun or learning as much if you aren't letting the magic smoke out of your parts.
(Papa Pass trademarks)There are or likely soon will be build guides so you can follow pretty much step by step. Member 6L6 has been kind enough to do this for several amps. As an aside, my first DIY amp used a pair of 6L6GCs that I biased heavily enough that the plates glowed cherry red.
IF everything goes well, you can just stuff the boards, attach to the heat sinks and wire up the PSU connections and enjoy great sound. With meticulous attention to detail, soldering skill you CAN make this happen. Triple check the part value and orientation before placing it on the board. Not all parts are directional, but semicondcutors and electrolytic caps are. Electros are funny. the part marks the negative lead and the board usually marks the positive side. You'll get the hang of it. Small diodes have a stripe that you match to the silk screen on the board. Larger diodes and transistors AKA FETs AKA Mosfets have a package shape that identifies orientation and guides you to the proper lead. Start by soldering in the low lying parts 4-5 at a time - resistors and small diodes. Then small cap(acitor)s, then transistors and tall caps.
I know the options can be confusing. The good thing about building a proven design like either of these is you can pick one of the suggested options and get good results. Different options change the flavor slightly, like adding a bit of cayenne or salt, but won't make the amp fail.
So go for it, malibujeff.DIYAudio Store said:
If you don't have a Variac or other autotransformer to bring the voltage up slowly when you are testing, make a light bulb tester. It's simply a light bulb in series with a power outlet so that if there is something major wrong with your amp the bulb will limit the current. A search of the forums will turn up a number of threads showing how to build one if you need help.
Unlike some AB amplifiers, you cannot test either the A-J or F5 without mounting them on heatsinks.
If you have a problem, there are plenty of helpers on this site. There are any number of namby pamby pantywaists around the forum who will suggest a chip amp kit for a first build. No disrespect intended, all in good fun, but you can do better. Chip amps are not terribly expensive and hard to mess up, but IMHO the main difference from an F5 is more parts.
The Aleph J requires matching Jfets, about the only part that requires any special skill. Matching requires a voltmeter and a power supply. Or you could buy matched pairs from forum member Spencer at Store | FET Audio About the only source of real 2SJ74s anymore. There is some rumbling that we may soon be able to get good jfets from the forum store soon.
Take my suggestion to GO FOR IT (and all other advice) with a grain of salt and temper it with your knowledge of your own abilities. Basic electronic theory came pretty easily to me. My second scratch built amp was a pair of A75s that I modified to run on much higher rails. They are still running 12 years later, although I missed uprating a couple of resistors which have scorched the boards and burned off their outer coating.
You're not having fun or learning as much if you aren't letting the magic smoke out of your parts.
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Thank you for the details response!
I've built a few kits, ptp and PCB, so I'll consider my soldering skills at least adequate. Have also read all Pass have published. I can read and understand a schematic.
In order to take the plunge I guess I'd need someone to offer matched parts, which seems likely. And a build guide to show how to best route wires, voltage test points, where to use quality caps, etc.
I'm hoping this will be my fall/winter priest.
I've built a few kits, ptp and PCB, so I'll consider my soldering skills at least adequate. Have also read all Pass have published. I can read and understand a schematic.
In order to take the plunge I guess I'd need someone to offer matched parts, which seems likely. And a build guide to show how to best route wires, voltage test points, where to use quality caps, etc.
I'm hoping this will be my fall/winter priest.
Go for it, and enjoy the project. You can get matched parts now - the link to Spencer's shop above.
Twist the power leads together a few times per inch (depending on the thickness used) and rout them near the case. Twist your signal leads too. Look for examples in completed work that do not look like a maze of wires.
For the Aleph J, there are really four test points. The three voltages listed on the schematic http://www.diyaudio.com/forums/pass-labs/224881-aleph-j-universal-mounting-spec-2.html#post3272332 and the output offset. The schematic voltages are reference voltages - as long as you are close you're fine, that means the amp is working. Then adjust R8 to minimize offset. Tweak half of the offset away, put the lid on the amp and wait at least half an hour before you check the offset again. It's a slightly more complex circuit than the ACA, but it will likely work right out of the box. If you run into trouble, there's help here.
Don't over think it. The expensive parts are the enclosure, heat sinks and power supply. Just watch cap polarity on the PSU. You aren't likely to blow anything on the amp but if you do, the parts aren't much.
Depending on your case, this could easily be a weekend project once all parts are in house. You can spend the rest of the Fall listening and enjoying your labor.
Twist the power leads together a few times per inch (depending on the thickness used) and rout them near the case. Twist your signal leads too. Look for examples in completed work that do not look like a maze of wires.
For the Aleph J, there are really four test points. The three voltages listed on the schematic http://www.diyaudio.com/forums/pass-labs/224881-aleph-j-universal-mounting-spec-2.html#post3272332 and the output offset. The schematic voltages are reference voltages - as long as you are close you're fine, that means the amp is working. Then adjust R8 to minimize offset. Tweak half of the offset away, put the lid on the amp and wait at least half an hour before you check the offset again. It's a slightly more complex circuit than the ACA, but it will likely work right out of the box. If you run into trouble, there's help here.
Don't over think it. The expensive parts are the enclosure, heat sinks and power supply. Just watch cap polarity on the PSU. You aren't likely to blow anything on the amp but if you do, the parts aren't much.
Depending on your case, this could easily be a weekend project once all parts are in house. You can spend the rest of the Fall listening and enjoying your labor.
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Go for it. Get a Jack of all Chassis, build a nice PSU, choose an amp circuit and have at it!
There will be an Aleph guide soon. (Soon meaning 'before Burning Amp', hopefully sooner. The transistors are easily available, members spencer has the jfets, buzzforb the mosfets, and the BJT are generic. Or you can buy a complete set from h_a . The rest of the parts are easily available from Mouser, Digi-Key, etc...
But the most important thing is to ask a question any time you get stuck or confused. The only stupid questions are the ones not asked. Ask in the thread, you will get an answer quickly. PM me if you like. This is a small community, and we are all happy to help.
Also - buy a good voltmeter. And a good soldering iron. Good tools last forever. Bad ones break, don't work, and will get replaced by the ones you should have built in the first place anyway...
There will be an Aleph guide soon. (Soon meaning 'before Burning Amp', hopefully sooner. The transistors are easily available, members spencer has the jfets, buzzforb the mosfets, and the BJT are generic. Or you can buy a complete set from h_a . The rest of the parts are easily available from Mouser, Digi-Key, etc...
But the most important thing is to ask a question any time you get stuck or confused. The only stupid questions are the ones not asked. Ask in the thread, you will get an answer quickly. PM me if you like. This is a small community, and we are all happy to help.
Also - buy a good voltmeter. And a good soldering iron. Good tools last forever. Bad ones break, don't work, and will get replaced by the ones you should have built in the first place anyway...
Just in case you don't appreciate the UMS and the DIY Audio store cases, just imagine building an amp with 12 pairs of MOSFETS and having to drill and tap each transistor and board mounting hole.
As many taps as I broke, that was the single most time consuming part of the build. On my last hole of 6 and crack. Lay it out again, drill and try again. This time I made it 4 holes. After a while I got the hang of it and could tell that I needed to back the tap out and clean my tap. Still not foolproof, but I'm better.
The cases I bought were group buy cases. Not ugly, but nowhere near as good looking as Jack of all Chassis. With Jack and one of the boards designed to the UMS, all you need to do is insert the screws and tighten them down.
As many taps as I broke, that was the single most time consuming part of the build. On my last hole of 6 and crack. Lay it out again, drill and try again. This time I made it 4 holes. After a while I got the hang of it and could tell that I needed to back the tap out and clean my tap. Still not foolproof, but I'm better.
The cases I bought were group buy cases. Not ugly, but nowhere near as good looking as Jack of all Chassis. With Jack and one of the boards designed to the UMS, all you need to do is insert the screws and tighten them down.
It looks like the info under the Store's Aleph J page has been updated to include lots of links for me to read, thank you to whoever is in charge of the store!
Thank you for the generous offer re asking questions. I'll definitely have a few. I couldn't agree more about tools - I recently invested in a used Fluke 8060 and bought a Hakko 939 solder station back when they were still made. And i have plenty of magnifiers, tweezers, etc.
I have used digikey and mouser before, but they can be intimidating. Example: if I want to buy a 1K ohm 1/4 W resistor, I have no doubt that the search would turn up dozens if not hundreds of choices.
And a huge thanks for any guide you can put together.
I had planned on cannibalizing a BK ST202 amp I have for it's chassis and buying appropriate heatsinks. Its a 4U rackmount. I'll look into the Store's offerings. Maybe I can do a hybrid of parts and save some $ and avoid tapping holes somehow.
Thank you for the generous offer re asking questions. I'll definitely have a few. I couldn't agree more about tools - I recently invested in a used Fluke 8060 and bought a Hakko 939 solder station back when they were still made. And i have plenty of magnifiers, tweezers, etc.
I have used digikey and mouser before, but they can be intimidating. Example: if I want to buy a 1K ohm 1/4 W resistor, I have no doubt that the search would turn up dozens if not hundreds of choices.
And a huge thanks for any guide you can put together.
I had planned on cannibalizing a BK ST202 amp I have for it's chassis and buying appropriate heatsinks. Its a 4U rackmount. I'll look into the Store's offerings. Maybe I can do a hybrid of parts and save some $ and avoid tapping holes somehow.
Lol... That was me.
(I'm not in charge of the store, but I do a bit of maintenance on some pages...)Yes, I completely agree about mouser being intimidating, and resistors are amongst the worst. That's what the offer is there for - to get you started in the big parts order.
I like the idea of salvaging the chassis. Can you give a rough measurement of the heatsinks? Alephs run hot.
Tapping is easy. Use oil. Any oil. and as soon as it gets even slightly binding, back out and clean the tap.
tap, tap, tap...
I have a question about heat sinks and tapping...
Is there any problem in the long term with making all the tapped holes "through holes"? Blind holes (ones that do not penetrate through the entire heat sink) have been my nemesis for years having assisted me in supporting my local hardware store's "tap room".
I have a question about heat sinks and tapping...
Is there any problem in the long term with making all the tapped holes "through holes"? Blind holes (ones that do not penetrate through the entire heat sink) have been my nemesis for years having assisted me in supporting my local hardware store's "tap room".
No problem at all. In fact, making a blind hole with a hand tap, at the (small) depth we need, would be very difficult, due to the conical tip shape of the tap itself.
Where do you think you need the most help? Building it? Initial power-up and adjustment? Figuring out what parts to buy?
The other question is do you have the tools for the job? You must have a good soldering iron, and one good DMM. (...and 2 more cheap ones, if you are buiding a F5, but that's easy.)
I understand. There are a lot of ways you could do it... But the other way of looking at it is that many of the small details are not critical, and can be done with whatever bits and pieces comes your way.
I bet that you can find someone to help locally. Ask in the F5 thread.
As for parts, I also think someone made a Mouser shopping cart for the F5 not that long ago, but again, there are people who are willing to help.
Get a store pre-drilled chassis. That's the single hardest part for most DIYers. The chassis is fantastic. The PSU is next, wait for the new store PSU PCB, and
get a good transformer. Buy the amp PCB of choice and contact member ' h_a ' for a transistor kit, he's the only guy who sells kits with all the transistors in one go.
Put all the parts together and you have an amp!
I'll add that you don't need to sweat the passive parts choice. (resistors and capacitors) One of the beauties of Pass amps is that they sing beautifully without needing special parts. Just buy parts that fit the footprint and meet the parameters specified.
A $0.10 resistor is fine. General purpose electrolytic capacitors are fine. IIRC, Pass uses Elna Silmics, so if available for the values you want it may be worth it. Where film caps are specified, anything that fits the footprint works. Chances are the footprint will allow polypropylene, so use those where possible. That's my concession to audiophile parts.
In the PSU, look for words in the spec sheet like high ripple current and low ESR. Particular numbers aren't all that important since you're overbuilding the supply by commercial standards anyway.
Once you get your amp up and running you can mess with "audiophile quality" parts if you really think they are necessary. With standard parts your amp will be head and shoulders (and navel, too) above a standard AV receiver, I doubt you'll be willing to take it out of your system long enough to mess with it.
A $0.10 resistor is fine. General purpose electrolytic capacitors are fine. IIRC, Pass uses Elna Silmics, so if available for the values you want it may be worth it. Where film caps are specified, anything that fits the footprint works. Chances are the footprint will allow polypropylene, so use those where possible. That's my concession to audiophile parts.
In the PSU, look for words in the spec sheet like high ripple current and low ESR. Particular numbers aren't all that important since you're overbuilding the supply by commercial standards anyway.
Once you get your amp up and running you can mess with "audiophile quality" parts if you really think they are necessary. With standard parts your amp will be head and shoulders (and navel, too) above a standard AV receiver, I doubt you'll be willing to take it out of your system long enough to mess with it.
I'm attaching 2 pix, one of the outside, one inside (we all like looking at equipment, right?).
The chassis is approx 16" wide, 13" deep, and 5.5" tall. The faceplate is 19" long.
I have no doubt that the existing heatsinks are inadequate (and in the wrong location) -- they're 4.75" x 4" x 2.25" (fin height).
It's got some huge caps inside - 4.5" high x 3"diam. 15,000uF 75VDC, 95VDC surge. But... they are probably 20 years old.
My plan is to use the chassis: remove existing heatsinks, buy ones the run the length on the sides, and cut some holes in the existing side walls to allow mounting parts to the heatsink.
Attachments
Yes, you will have to get some heatsinks the length of your chassis.
(Actually, you will probably have to get a pair per side, as it's much easier to find extrusions 6.5" wide than 13" wide.)
Make sure your heatsinks have fins that will be vertical. If they go the wrong way you will get it too hot. Salvage the posts, switch, lamp, jacks, etc... That stuff is expensive to replace.
Take a penny covered in a layer of paper towel dipped in acetone to rub off the silkscreen on your faceplate.
(Actually, you will probably have to get a pair per side, as it's much easier to find extrusions 6.5" wide than 13" wide.)
Make sure your heatsinks have fins that will be vertical. If they go the wrong way you will get it too hot. Salvage the posts, switch, lamp, jacks, etc... That stuff is expensive to replace.
Take a penny covered in a layer of paper towel dipped in acetone to rub off the silkscreen on your faceplate.
Since rif asked in the OP about cost: assuming if one wanted to do "everything new and high quality" by sourcing the pcb, chassis, and back panel parts from diyAudio along with a transistor kit from h_a and digi-key sourced passives, the F5 comes in at $735 and the Aleph J at $800 in parts cost. This method is the closest to having a complete kit ready where all the builder has to do is stuff boards, solder wires, and turn screws.
making it easy
Wow, that's pretty cool! About a quarter of the cost of new and easy enough to accomplish only thanks to Papa and diyAudio and 6L6 and didiet78 and several others on this thread:
http://www.diyaudio.com/forums/pass-labs/224881-aleph-j-universal-mounting-spec-3.html
All should be acknowledged for their giving
I'd like to spend a bit of that figure on the transistor kit from h_a but I don't know how to go about doing that. It does not seem to be done through the diy store... Please assist?
Again, big thanks to all those who give of themselves to we who are just starting out; we'd never even "get off the line" without the help of the broad shouldered crowd. You inspire! You rock!
Wow, that's pretty cool! About a quarter of the cost of new and easy enough to accomplish only thanks to Papa and diyAudio and 6L6 and didiet78 and several others on this thread:
http://www.diyaudio.com/forums/pass-labs/224881-aleph-j-universal-mounting-spec-3.html
All should be acknowledged for their giving
I'd like to spend a bit of that figure on the transistor kit from h_a but I don't know how to go about doing that. It does not seem to be done through the diy store... Please assist?
Again, big thanks to all those who give of themselves to we who are just starting out; we'd never even "get off the line" without the help of the broad shouldered crowd. You inspire! You rock!
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