For the 590:
Nominal Impedance 6 ohms
Crossover Frequencies 1.5kHz
Sensitivity (2.83V@1m) 92dB
Frequency Response 35Hz-40kHz
Now wondering how the ACA will do with Wharfedale Linton's.
Sourcing out-of-stock ACA components
I was all set to order an ACA kit, but the DIYAudioStore is now sold out until the fall
. (Why do they have such a long restocking cycle?)
What is the collective wisdom here about instead buying the chassis, power supply and PCB board and trying to source the remaining parts myself? Would you discourage someone new to kit building audio gear like myself from attempting it?
Many thanks in advance.
-Steve
I was all set to order an ACA kit, but the DIYAudioStore is now sold out until the fall
. (Why do they have such a long restocking cycle?)What is the collective wisdom here about instead buying the chassis, power supply and PCB board and trying to source the remaining parts myself? Would you discourage someone new to kit building audio gear like myself from attempting it?
Many thanks in advance.
-Steve
the ACA amp are capacitor coupled to the speakers so there in no danger of speaker burnouts....a shorted speaker will just maintain a class A status of the amp and will not be burned out because of that....
there are other ss amps without active SOA protection that gets burned out when speakers are shorted, even with fuses....not the ACA...
there are other ss amps without active SOA protection that gets burned out when speakers are shorted, even with fuses....not the ACA...
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Because no one wants to be blamed if they don't show up! But we should have some more kits in about a month! Big Difference!
I was all set to order an ACA kit, but the DIYAudioStore is now sold out until the fall
What is the collective wisdom here about instead buying the chassis, power supply and PCB board and trying to source the remaining parts myself? Would you discourage someone new to kit building audio gear like myself from attempting it?
Many thanks in advance.
-Steve
It Lives! Fitted the correct value R12's this morning and both amps are now working!
Thanks to all especially Alan who guided me through my mistake. Spent the afternoon listening to a single stereo amp with Alpair 10.3's - absolutely fantastic sounding, just what I was expecting. The Alpairs had never been quite right for me but with the ACA its a great combination and more than plenty loud enough.
Will fit second amp with RCA - single ended, expecting great things.
Anyone reading this and thinking about this amp, go for it!!
So today I spent a few hours trying to locate a fault in one of my ACAs. I have been running these in bridged mono for a few month until recently I noticed that the RH channel was dropping out. If I placed my ear close to the speaker I could hear a faint, distorted output. If I turned the Amps of for a few seconds, it would come back, but then start to drop out again. I then wired in parallel mono and this worked ok for a few hrs until the same thing stated to happen.
I started the diagnosis by hooking up the faulty amp in Stereo mode an by doing so noted that the Left Hand channel was not working. Knowing this allowed me to focus on the faulty board. I next hooked up a transistor tester to check each transistor, all seemed ok. Using a scope I hooked up chA to the rca input and using chub started to probe from output to input. There was absolutely no signal on R2, nor R5. I worked back to R11 and noted some really strange behaviour. ChA scope now on output I probe Chablis on input terminal and both sides on R11. I could see chA scope trace showing the amp out working for a short while, then dropping to zero. Finally I used a non conductive probe ( bic biro) and gently pushing on R11 would bring the signal back. Hooray - 1 dry solder joint!
I loosened off the board and reflowed the joint and all working fine. The dry joint was failing as the amp heated up.
If you have an intermittent channel, moe than likely a dry joint!
I started the diagnosis by hooking up the faulty amp in Stereo mode an by doing so noted that the Left Hand channel was not working. Knowing this allowed me to focus on the faulty board. I next hooked up a transistor tester to check each transistor, all seemed ok. Using a scope I hooked up chA to the rca input and using chub started to probe from output to input. There was absolutely no signal on R2, nor R5. I worked back to R11 and noted some really strange behaviour. ChA scope now on output I probe Chablis on input terminal and both sides on R11. I could see chA scope trace showing the amp out working for a short while, then dropping to zero. Finally I used a non conductive probe ( bic biro) and gently pushing on R11 would bring the signal back. Hooray - 1 dry solder joint!
I loosened off the board and reflowed the joint and all working fine. The dry joint was failing as the amp heated up.
If you have an intermittent channel, moe than likely a dry joint!
I way under guesstimated the size of the heat sink I used for my ACA. Instead of the using the heat sink I originally planned on using, I opted for a lighter (easier to work) heat sink that I salvaged out of a long dead, circa late 90's JVC receiver that I purchased as a teenager.
After powering up the amp, after about 10 minutes, the heat sink was getting uncomfortable to touch. I had a temp sensor that was reading about 45C on the heat sink. The sensor didn't have very good contact, so I suspect the temp was a bit higher, and I just shut it down before anything was damaged.
I assume this new heat sink will be more than substantial. I have a student version of Autodesk Inventor, so I modeled the profile, and after I trim it down to 8.5"x4.5" to fit the case, it will be around 1.22pounds, and have 435 square inches of surface area. Rather than make another assumption, how would I go about calculating the heat dissipation of the new heat sink.
After powering up the amp, after about 10 minutes, the heat sink was getting uncomfortable to touch. I had a temp sensor that was reading about 45C on the heat sink. The sensor didn't have very good contact, so I suspect the temp was a bit higher, and I just shut it down before anything was damaged.
I assume this new heat sink will be more than substantial. I have a student version of Autodesk Inventor, so I modeled the profile, and after I trim it down to 8.5"x4.5" to fit the case, it will be around 1.22pounds, and have 435 square inches of surface area. Rather than make another assumption, how would I go about calculating the heat dissipation of the new heat sink.
Attachments
It's more a question of how confident do you feel?
The parts for the board are very easy to source as there is a bill of materials for the latest ACA board v1.8 if you search the forum.
The JFets and Mosfets are in the store.
If you check the build guide all the back panel sockets are easy to copy and source (Speaker sockets with solder tags will make life easier).
All cable is a mix of 16 or 18 guage, again easy to source.
The stand offs and allen bolts to mount the mosfets and board to the heatsink are all 3mm, again check the build guide and copy what's on there including the washers.
Keroferm pads are tricky to source in small quantities but good old cpu paste and mica pads will do fine instead, plenty of these on ebay.
I think that's it.
If you want to make your own chassis (lots of work) I can recommend building around these heat sinks.
1pcs Aluminum Heatsink Heat Sink Thermal Pad Transfer Blades Silver 200x90x30mm | eBay
1pcs Aluminum Heatsink Heat Sink Thermal Pad Transfer Blades Silver 200x90x30mm | eBay
What Mark said
I go very conservative on estimated restocking dates these days. It's not worth the drama when things go wrong and we cannot meet people's expectations. Sign up for notifications when the parts kit comes back in stock and you'll get an email as soon as they are back in stock.The design comes from this thread "Mark Audio Alpair 10.3/A10p MLTL". Been using them with various chip amps but the one fault was occasional brightness with some recordings, this is not the case with the ACA.
My pair of ACAs are on the 2 outer shelves, a big part of the appeal for me was the small case to fit the amps on the shelves. I went for the deeper version of the case to compensate for the lack of airflow and all seems fine temperature wise.
My favourite speakers are however the TABAQ with P830987, I have these in another room with an F5. Worth checking out the long running TABAQ thread if you are unfamiliar, they must be the best, simplest and cheapest diy build ever!!
