I hope that IS the problem. Since the LED is on it's own circuit, it seemed logical that it was a power issue.
I made an opposite mistake on mine. I drilled out the DC jack hole to use a better jack, then proceeded to run the NEGATIVE wire thru the switch. Since the outside of the jack (negative) was always touching bare case metal, the amp would always be on. Unfortunately, I thought I had a bad switch, and spent days on a simple problem.
Live and learn.
Mike
Let's hope its the PSU jack, that's easy to fix!
It is pretty funny, there have been very few problems getting the amps to work, but most of them have to do with the power jack! One problem I think is that people measure which tabs are functional without the PSU plug inserted, not thinking that inserting the plug changes things. Those PSU plugs (pretty much all PSU plugs) have a built in switch so when used with a battery powered device, inserting the PSU plug disconnects the batteries.
It is pretty funny, there have been very few problems getting the amps to work, but most of them have to do with the power jack! One problem I think is that people measure which tabs are functional without the PSU plug inserted, not thinking that inserting the plug changes things. Those PSU plugs (pretty much all PSU plugs) have a built in switch so when used with a battery powered device, inserting the PSU plug disconnects the batteries.
The two problems that I faced was the PSU jack whose two tabs I soldered were the wrong two of three tabs....after resoldering different tabs it worked great.
The other problem I had on the second monoblock was that the RCA input was shorting due to melted insulation....once I fixed that everything was fine...hope this helps a bit.
The other problem I had on the second monoblock was that the RCA input was shorting due to melted insulation....once I fixed that everything was fine...hope this helps a bit.
When I first built the ACA the PSU socket was the bit that caused me the most stress. The original build thread picture wasn't great and wiring the different legs was a matter of educated guess work. The picture is better now.
Even after that 6L6 and I exchanged about 13 emails and several pictures of my ACA trying to figure out why it kept blowing my PSUs.
It turned out that one of the legs on the PSU socket was loose and would rotate round when the case was knocked. The supply would short and bam. I went through 3 PSUs before we sorted it.
Even after that 6L6 and I exchanged about 13 emails and several pictures of my ACA trying to figure out why it kept blowing my PSUs.
It turned out that one of the legs on the PSU socket was loose and would rotate round when the case was knocked. The supply would short and bam. I went through 3 PSUs before we sorted it.
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Sorry if this has been asked before but I searched and could not find my answer. I just purchased the PCBs since the kit is sold out and before I place my digikey order for parts I'd like to source the 2SK170. Which grade (gain??) should I be looking for? And do I need a matched pair? Or is that just for push/pull or other applications with multiple 2sk170s per channel.
Here is what Papa Pass told me a while ago:
By the usual standards the D version would be the most desirable, and probably would command a premium. The B through D and most of the A would not be a problem for the ACA, and a slight adjustment would allow down to the 2.5 mA figure without problems.
Most of my projects would want a B or C grade as most desirable, but it’s not a big deal.
By the usual standards the D version would be the most desirable, and probably would command a premium. The B through D and most of the A would not be a problem for the ACA, and a slight adjustment would allow down to the 2.5 mA figure without problems.
Most of my projects would want a B or C grade as most desirable, but it’s not a big deal.
309 or 310
sort proper source resistor to have no more than 10mA though Jfet and proper biasing of output mos
edit - it seems proper starting value for J310's Rs is in range of 680R
start biasing with bias pot's wiper cranked to zero
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I am pairing my ACA with the phono preamp from boozehound, both designs have set amounts of gain. What do you think would be best way to add in a volume control ?. The preamp has ~40dB of gain and from what I remember the ACA has about 14dB of voltage gain built in. Would a simple voltage divider between pre and power amp work? Could I implement a dual gang pot into the aca?
Thanks so much! That was it. Listening to them right now.
And thanks for the new build guide -- that would have answered several questions that I was puzzling over from the original build guide. Proves you have never have too many pictures!
I think I'll enjoy them before I start to think about that extra resister fix...
Fred
Tiny stereo amp build:
Until about a year ago, I used an Altec Lansing setup on my PC. The sound isn't great, and especially so once the subwoofer died. Since then, I've been struggling along with just two of the little, tinny-sounding plastic things on my desk.
Time to upgrade. Bought a Zhaolu D3 DAC off the forum, and picked up a pair of JBL Control One monitors from the dealer. As I listen in the near field (about 1 meter between my ears and each speaker cabinet) amp power is not a concern. Lacking an amplifier, and not wanting something the size of a VCR on my desk, I decided to build a tiny low watt amp from a kit, and fabrication, heat sinks, power supply, enclosure, connectors etc.
So here goes! I was looking for a pretty easy desktop amp to build, a pure Single Ended class A design because it has the more desirable even order harmonics......and has no cross-over distortion. My vote..... would be for a Nelson Pass design. NP designs are solidly engineered and they usually sound fantastic with many different rigs. If the ultimate goal is musicality, the NP designs are well proven and there is a wealth of information and variation out there for you to try. I'm focusing mostly on Nelson Pass' published plans because they're simple and therefore somewhat easier to build. Design elegance also tends to lead to better sound, since there are fewer elements corrupting the signal.
All in all it’s a fun project. The simple chassis built around the heat sinks. It is about construction techniques, to take an existing PCB-based component and put it in a box. Overall, the look is pleasing and hopefully somewhat different enough to be interesting.
Will post the listening impressions after completing the build.
Thanks for reading
Until about a year ago, I used an Altec Lansing setup on my PC. The sound isn't great, and especially so once the subwoofer died. Since then, I've been struggling along with just two of the little, tinny-sounding plastic things on my desk.
Time to upgrade. Bought a Zhaolu D3 DAC off the forum, and picked up a pair of JBL Control One monitors from the dealer. As I listen in the near field (about 1 meter between my ears and each speaker cabinet) amp power is not a concern. Lacking an amplifier, and not wanting something the size of a VCR on my desk, I decided to build a tiny low watt amp from a kit, and fabrication, heat sinks, power supply, enclosure, connectors etc.
So here goes! I was looking for a pretty easy desktop amp to build, a pure Single Ended class A design because it has the more desirable even order harmonics......and has no cross-over distortion. My vote..... would be for a Nelson Pass design. NP designs are solidly engineered and they usually sound fantastic with many different rigs. If the ultimate goal is musicality, the NP designs are well proven and there is a wealth of information and variation out there for you to try. I'm focusing mostly on Nelson Pass' published plans because they're simple and therefore somewhat easier to build. Design elegance also tends to lead to better sound, since there are fewer elements corrupting the signal.
All in all it’s a fun project. The simple chassis built around the heat sinks. It is about construction techniques, to take an existing PCB-based component and put it in a box. Overall, the look is pleasing and hopefully somewhat different enough to be interesting.
Will post the listening impressions after completing the build.
Thanks for reading
Attachments
I love using copper on a chassis when you can find it. It's a great size overall and looks like it will conduct the heat away well. I've just bought the ACA boards and will start the project soon. In the meantime, I'm trying to find some heat sinks I can build around. Bigger is better as I'm likely to keep the amp on quite a bit. If anyone has any ideas on where to buy them since the store is out of the complete kit, it would be most appreciated.
Vinnie
Vinnie
I should note I will be using a newer Audio Technica turntable into the phono preamp kit into the ACAs into some vintage "acoustic" bookshelfs. My assumption is that between the preamp and ACAs I could get away with a buffer with attenuation pot somewhere down the line, no need for an active gain stage with volume pot.