Well dropping out of regulation wouldn't be any fun, thanks for pointing that out.
Thinking about this, I'm moving this over to the power supply forum.
Listening with the ACA makes great fun! Thank you Nelson Pass and all for their contributions.
Sometime ago I've bought from a DIYer, who wanted to go the Hiraga-way, assembled ACA boards with premium parts, ready for 24V-supply. After some experience with heatsinks I've bought a minidissipante 3U to fit in at the end 4 boards for a 4ch-amp (bi-amping). The listening with my Goodmans Triaxiom 212C (listening position 1 foot behind sweet spot, or elsewhere in the room) is very exciting and it was easy for me to let my 6B4G triode PP amps go. At high level peaks in the mid and high frequencies often it had been to aggressive for me, probably because of audible distortions?
I checked out different input caps and power supplies. At the moment I'm very comfortable with an old 3x1mF Fribourg canister, an old Siemens 0.082mF and a Duelund JDM 0.011mF. The goal is, beside to substitute the probably PCB containing canister to simplify my temporary input capacitor setup. The supplies I've in use are an old linear Studer-Revox PSU for their mixing desk and a newer one with electronics from Taiwan. With the newer PSU there are better and more details. I like the old linear PSU better for more soul in the music (musicality) and being less distracted from the different recording qualities.
Eric
Sometime ago I've bought from a DIYer, who wanted to go the Hiraga-way, assembled ACA boards with premium parts, ready for 24V-supply. After some experience with heatsinks I've bought a minidissipante 3U to fit in at the end 4 boards for a 4ch-amp (bi-amping). The listening with my Goodmans Triaxiom 212C (listening position 1 foot behind sweet spot, or elsewhere in the room) is very exciting and it was easy for me to let my 6B4G triode PP amps go. At high level peaks in the mid and high frequencies often it had been to aggressive for me, probably because of audible distortions?
I checked out different input caps and power supplies. At the moment I'm very comfortable with an old 3x1mF Fribourg canister, an old Siemens 0.082mF and a Duelund JDM 0.011mF. The goal is, beside to substitute the probably PCB containing canister to simplify my temporary input capacitor setup. The supplies I've in use are an old linear Studer-Revox PSU for their mixing desk and a newer one with electronics from Taiwan. With the newer PSU there are better and more details. I like the old linear PSU better for more soul in the music (musicality) and being less distracted from the different recording qualities.
Eric
I built my first ACA in early 2021.
Now I've just finished my second (late 2022).
When I was finishing up, I noticed that capacitor C2 was different between them. It's longer in the newer kit. Both sound great in stereo. I'm tempted to say the new one sounds a touch better to my ears.
When wired up as monoblocks (rca) though, they sound a little imbalanced. The first ACA is a bit louder than the second.
Is it possible that what I'm hearing is the difference between these two capacitors (C2)?
If so, I suppose I'll want to figure out what they are and match them.
Thanks for listening.
Now I've just finished my second (late 2022).
When I was finishing up, I noticed that capacitor C2 was different between them. It's longer in the newer kit. Both sound great in stereo. I'm tempted to say the new one sounds a touch better to my ears.
When wired up as monoblocks (rca) though, they sound a little imbalanced. The first ACA is a bit louder than the second.
Is it possible that what I'm hearing is the difference between these two capacitors (C2)?
If so, I suppose I'll want to figure out what they are and match them.
Thanks for listening.
I am building the Aleph J an would like to know how to modify it for a balanced input. Is there any schematic or simple explanation? I have a balanced DAC source.Fully balanced? Of that list, none, though the BA-3 can be made fully balanced, but I would get at least one amp built and under your belt before taking on a BA-3b. (And the Burning Amp series are, in my opinion, still the coolest amps Papa has given the community...)
The Aleph J has a differential front-end and it can be driven from a balanced source natively. It's also one of the most beautiful sounding amplifiers available, anywhere.
An F5, or Aleph J, F4, F6, M2x, and the like (as these are all built around the same basic template of PSU requirements and rejected heat, output power, etc...) Can be built for around $600-700. And significantly less than that if you have the ability and equipment to make your own chassis. (Which, let's face it, most people don't...)
thank you
I don’t know what you would consider cheap. I ran mine with a bottlehead moreplay. I’ve since swapped out the ACA for an aleph j.
Some of you guys may remember I built a pair of Amp Camp amps back in 2020 while I was recovering from a total hip replacement. You can see my build thread in the ACA amp with Premium parts thread from that time-frame.
Here's just a piccie of the interior as a refresher.
Anyhoo, when I connected up my main system (First Sound preamp and C-J LP70S stereo tube amp), and powered up the LP70S amp the other night, I noticed a "buzz/hum" in the right channel, which, after literally disconnecting literally everything in the system save for just the CJ amp connected to speakers, I simply could not eliminate. My guess is a tube in the LP70S has gone bad, which seems to be more frequent with tubes these days.
Have to now troubleshoot that...urg.
Anyhoo, given that, the night before last I set up my little ACAs, and connected them to my First Sound dual-mono preamp. These amps have always quite impressive-sounding, especially so when run as bridged mono-blocks.
They sounded as good as I remembered on their own, but quite frankly, I was blown away when I connected the ACAs to my new Shunyata Research ground-plane noise reduction hub system, named ALTAIRA (after Prof. Morbius' daughter in Forbidden Planet). Specifically, a Signal Ground (aka SG) hub specificially for the "digital stack" (Holo May KTE DAC and UpTone EtherREGEN Ethernet switch), and a separate Signal Ground hub segment for the analog amplification components, my dual-mono First Sound Presence Deluxe preamp (with dual-mono external power supplies with ~300,000 µF of capacitance) and the dual-mono configured bridged ACAs.
Here's a pic of the ACAs and the Altaira(s). The SG Altaira on top of the ACAs is resting on two HRS Nimbus Spacers and Couplers and is the "analog amplification segment", and is connected using Shunyata Alpha chassis ground cables to the chassis ground terminals of the First Sound preamp's main control unit (MCU) and it's external dual mono power supplies (for a total of 3 ground connections). The Amp Camp amps are also connected to this "analog amplification" Altaira using Venom RCA chassis ground cables ("CGC"s) connected to unused RCA inputs on each each ACA monoblock. The SG Altaira at the back of the photo is dedicated solely to the digital stack, and is connected with a Venom CGC to the Holo May KTE DAC's unused S/PDIF input and an Alpha CGC to EtherREGEN's ground terminal. Each Altaira is connected at it's 7th terminal using Omega CGCs to separate ground terminals to a Shunyata Everest power distributor.
Using this this system with the ALTAIRA system stripped out so much noise, hash, grunge, and grain from the presentation that it completely transformed the quality and performance of the system powered by these wonderful little amps for pretty much every "audio attribute" you can think of. The Altaira system also improved the clarity, imaging, added more body to voice and instruments, more air to the presentation, and the dynamics and "slam" really improved. The "hall" ambience is much more fleshed-out and present, and "vapor trail", that decay you can hear trailing off into the performance space, is notably more "tangible." Most importantly, the system sounds much more natural, "organic", and most-importantly, musically-involving.
It's always interesting that one often don't realize how much noise is really in a system until it's been removed. And once you hear the system with all that noise, hash, and grunge removed, you can't "go back." It literally does not sound like the same system...at all.
I know we love our ACAs, and we have Papa to thank for these incredible amplifer designs, but, Man! 🤯 You've not truly heard how brilliant this design is until you've heard them connected to this ALTAIRA system.
Just remarkable.
Here's just a piccie of the interior as a refresher.
Anyhoo, when I connected up my main system (First Sound preamp and C-J LP70S stereo tube amp), and powered up the LP70S amp the other night, I noticed a "buzz/hum" in the right channel, which, after literally disconnecting literally everything in the system save for just the CJ amp connected to speakers, I simply could not eliminate. My guess is a tube in the LP70S has gone bad, which seems to be more frequent with tubes these days.
Have to now troubleshoot that...urg.Anyhoo, given that, the night before last I set up my little ACAs, and connected them to my First Sound dual-mono preamp. These amps have always quite impressive-sounding, especially so when run as bridged mono-blocks.
They sounded as good as I remembered on their own, but quite frankly, I was blown away when I connected the ACAs to my new Shunyata Research ground-plane noise reduction hub system, named ALTAIRA (after Prof. Morbius' daughter in Forbidden Planet). Specifically, a Signal Ground (aka SG) hub specificially for the "digital stack" (Holo May KTE DAC and UpTone EtherREGEN Ethernet switch), and a separate Signal Ground hub segment for the analog amplification components, my dual-mono First Sound Presence Deluxe preamp (with dual-mono external power supplies with ~300,000 µF of capacitance) and the dual-mono configured bridged ACAs.
Here's a pic of the ACAs and the Altaira(s). The SG Altaira on top of the ACAs is resting on two HRS Nimbus Spacers and Couplers and is the "analog amplification segment", and is connected using Shunyata Alpha chassis ground cables to the chassis ground terminals of the First Sound preamp's main control unit (MCU) and it's external dual mono power supplies (for a total of 3 ground connections). The Amp Camp amps are also connected to this "analog amplification" Altaira using Venom RCA chassis ground cables ("CGC"s) connected to unused RCA inputs on each each ACA monoblock. The SG Altaira at the back of the photo is dedicated solely to the digital stack, and is connected with a Venom CGC to the Holo May KTE DAC's unused S/PDIF input and an Alpha CGC to EtherREGEN's ground terminal. Each Altaira is connected at it's 7th terminal using Omega CGCs to separate ground terminals to a Shunyata Everest power distributor.
Using this this system with the ALTAIRA system stripped out so much noise, hash, grunge, and grain from the presentation that it completely transformed the quality and performance of the system powered by these wonderful little amps for pretty much every "audio attribute" you can think of. The Altaira system also improved the clarity, imaging, added more body to voice and instruments, more air to the presentation, and the dynamics and "slam" really improved. The "hall" ambience is much more fleshed-out and present, and "vapor trail", that decay you can hear trailing off into the performance space, is notably more "tangible." Most importantly, the system sounds much more natural, "organic", and most-importantly, musically-involving.
It's always interesting that one often don't realize how much noise is really in a system until it's been removed. And once you hear the system with all that noise, hash, and grunge removed, you can't "go back." It literally does not sound like the same system...at all.
I know we love our ACAs, and we have Papa to thank for these incredible amplifer designs, but, Man! 🤯 You've not truly heard how brilliant this design is until you've heard them connected to this ALTAIRA system.
Just remarkable.
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Have you considered using just an H2 and a pot? Cheap and could work well. Has 14 dB gain. But THD is highish but could be euphonic. Also inverts phase so swap the speaker cables. https://diyaudiostore.com/collections/misc-pcbs/products/h2-harmonic-generator
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One of my (two) ACA v1.8 amps has recently started to intermittently cycle on and off while in use. This happens occasionally in stereo mode, but regularly in Parallel Mono mode (using RCA inputs). The symptoms are loss of output, both front panel LEDs go out, and the LED on the power brick goes out. The power loss lasts for approximately one second. I tried another Meanwell power brick (which works fine with my other ACA amp), and the problem follows the amp, not the power supply. This happens across different speakers (e.g., Klipsch Chorus, Paradigm Titan). Any help is appreciated.
Check the voltage across the 0.47 and 0.68 ohms. Look at the circuit diagram and check the correct part values are fitted.
Your fault sounds like one (or both) ACA's are drawing more current than the PSU can deliver. There should be around 0.38 volts across the 0.47 ohm and 0.55 volts across the 0.68 ohm.
Your fault sounds like one (or both) ACA's are drawing more current than the PSU can deliver. There should be around 0.38 volts across the 0.47 ohm and 0.55 volts across the 0.68 ohm.
You say you swapped power supplies. Did that include the power cord? I'm stuck on the power brick LED extinguishing. So you might try (if the swap did not include it) changing the power cord itself with the supply you are swapping. I fixed broadcast gear for many moons and occasionally they fail.
Thank you for your responses! These were helpful in (hopefully) resolving my problem. First, checking the voltages across R1 - R4, as suggested by Mooly, was informative. I found the voltages were not stable. Zen Mod's question regarding the relationship of volume level and the drop out behavior was also helpful; there did not seem to be a relationship. Based on these pieces of information I guessed it was a bad solder joint, or intermittent short to ground. I pulled both circuit boards, re-soldered all solder joints and clipped the end off a wire that extended significantly below the bottom of the board and may have been intermittently shorting to the chassis.
The voltage readings are now stable, although a bit lower than suggested by Mooly. But I think this is normal as I get the same readings on my other ACA amp which works properly. So far I have played the amp for several hours without any problems. Fingers crossed this has solved the problem.
tjw59 thanks for your suggestion on the power cord. I swapped both the power supply and the power cord - it made no difference. I also thought that the led going out on the power brick was an odd symptom. But, at least in this case, it appears the amp was causing the erratic behavior of the power supply.
The voltage readings are now stable, although a bit lower than suggested by Mooly. But I think this is normal as I get the same readings on my other ACA amp which works properly. So far I have played the amp for several hours without any problems. Fingers crossed this has solved the problem.
tjw59 thanks for your suggestion on the power cord. I swapped both the power supply and the power cord - it made no difference. I also thought that the led going out on the power brick was an odd symptom. But, at least in this case, it appears the amp was causing the erratic behavior of the power supply.
Thanks for the update pleased to hear you have hopefully sorted it.
I think the 'wire' the most likely cause. Only an intermittent problem around Q3 and R8 and R15 can really cause intermittent excess current flow. I can't just think of anything else 'dry joint' related that would cause excess current.
pleased to hear you have hopefully sorted it.I think the 'wire' the most likely cause. Only an intermittent problem around Q3 and R8 and R15 can really cause intermittent excess current flow. I can't just think of anything else 'dry joint' related that would cause excess current.
Hey guys,
I recently built and configured my ACA in monoblock configuration.
For some reason my left ACA is playing noticeably lower. I tested this by swapping back and fourth. The other side is much louder. I’m not sure what’s the culprit. Any ideas?
I recently built and configured my ACA in monoblock configuration.
For some reason my left ACA is playing noticeably lower. I tested this by swapping back and fourth. The other side is much louder. I’m not sure what’s the culprit. Any ideas?
