Do the outputs the same, just link the two Black posts together with suitable wire as in the pictures. Done.
For the inputs you have a choice,
1: buy an RCA 'Y' splitter or adaptor like this (example only) : https://www.amazon.co.uk/Female-Spl...t=&hvlocphy=9045390&hvtargid=pla-803463600413
2: wire both the centre pins of the RCA sockets together inside the ACA. Again you can use either input socket and or output pair. Alan
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Not sure if what I'm about to ask or comment on belongs here? But I'm building an ACA and am running into some VERY basic soldering questions—having a high technical aptitude, but never having done a project like this before. This may be me being overly detailed and therefore I am a bit in my own way—I want a successful build though! Here goes:
From the 1.6 build guide—it wasn't at all clear to me that I was supposed to solder the connections to the various "posts" that are on the backs of the XLR and RCA and Power ports. "Soldering" isn't expressly stated when making these connections—not that I found or read anyway. The pictures kinda seem to show solder joints with the wires stuffed into the female ends of those devices, but there's multiple connection styles in play. The video of the interior wiring also seems to show soldered connections, but as mentioned, it's not written anywhere and what would I know about some type of push fit connection? Haha. For instance, the connection from XLR terminal 1 to the ground bus. Clearly the wire to the bus is wrapped and soldered. The connection to the XLR though is a bit mysterious to a noob. Do I "lay" the wire into the U-shaped trough of the XLR connection and make sure I have a conical tip on my iron and get down in there to solder the joint? How long is the lead? I'm assuming yes, but later in the guide there's a warning about wiring the power switch that talks about not frying it with excessive heat—and there's a link to get a replacement! The XLR plastics don't seem much more robust to me and because I don't have experience I'm not sure how much heat will be needed or how delicate the XLR plastics are...My research and thus far limited experience has informed me that higher heat for shorter times seems to work well.
My Hakko is seriously nice—to me—and I have it at around 620F, which seems to work well using the Cardas solder from the links related to the the build info. I've watched all the videos. One thing that I think might make these connections more noob-proof is to pre-tin both the wire and the XLR terminals. Seems basic to me... but I'm throwing it out there to the DIY pros for feedback.
I'm sure this won't be the end of my questions. Ha!
From the 1.6 build guide—it wasn't at all clear to me that I was supposed to solder the connections to the various "posts" that are on the backs of the XLR and RCA and Power ports. "Soldering" isn't expressly stated when making these connections—not that I found or read anyway. The pictures kinda seem to show solder joints with the wires stuffed into the female ends of those devices, but there's multiple connection styles in play. The video of the interior wiring also seems to show soldered connections, but as mentioned, it's not written anywhere and what would I know about some type of push fit connection? Haha. For instance, the connection from XLR terminal 1 to the ground bus. Clearly the wire to the bus is wrapped and soldered. The connection to the XLR though is a bit mysterious to a noob. Do I "lay" the wire into the U-shaped trough of the XLR connection and make sure I have a conical tip on my iron and get down in there to solder the joint? How long is the lead? I'm assuming yes, but later in the guide there's a warning about wiring the power switch that talks about not frying it with excessive heat—and there's a link to get a replacement! The XLR plastics don't seem much more robust to me and because I don't have experience I'm not sure how much heat will be needed or how delicate the XLR plastics are...My research and thus far limited experience has informed me that higher heat for shorter times seems to work well.
My Hakko is seriously nice—to me—and I have it at around 620F, which seems to work well using the Cardas solder from the links related to the the build info. I've watched all the videos. One thing that I think might make these connections more noob-proof is to pre-tin both the wire and the XLR terminals. Seems basic to me... but I'm throwing it out there to the DIY pros for feedback.
I'm sure this won't be the end of my questions. Ha!
Yes, you solder all the connections.
For the XLR and RCA centre connections it will help if you 'tin' the wire ends first. Then you can load a little extra solder on the tip of the iron, hold the tinned wire in place (in the trough) and put the iron against the two parts, the solder on the iron will help transfer heat to the joint and also flow into it. Add a little more solder if it looks poor. All to do with experience and every one has a different technique too.
As for length, just strip the same length of insulation as the length of the 'trough' it will fit in.
Alan
For the XLR and RCA centre connections it will help if you 'tin' the wire ends first. Then you can load a little extra solder on the tip of the iron, hold the tinned wire in place (in the trough) and put the iron against the two parts, the solder on the iron will help transfer heat to the joint and also flow into it. Add a little more solder if it looks poor. All to do with experience and every one has a different technique too.
As for length, just strip the same length of insulation as the length of the 'trough' it will fit in.
Alan
So, this little amp is pretty incredible. I haven't plugged it into our main system yet with turntables etc, I'm waiting on the B1 buffer project so I have a couple of inputs and volume—and more build fun.... but it sounds incredible running out of a Mac into some older B&W CM1s in the office. I'll be building a second ACA for bridged mono (will taste test parallel mono too) in the main system. I'm comparing the ACA to a quite low-end but well respected NAD 326BEE. Is that class A/B? I can't find any info. The ACA has a clarity to it that's driving me nuts—in a good way. And very bassy, again in a good way. Could be my speaker placement too... under a desk. Can't wait to hear some vinyl!!!!! Keith Jarrett Köln concert? OMG.
My comments about the build—Loved being able to ask noob questions and have responses that treated me like a human. Thanks guys!
The LEDs were by far the hardest (slightly annoying?) part of the process. My kit was devoid of shrink tube... I have a lot though, and one layer allowed me to press-fit without bunching, but not tight enough to hold properly. I dabbed a bit of hot glue to secure it better—still not great—I think a small (small!) amount of a PVA or polyurethane glue would be better—will try on the next build.
Wiring and assembling the case was also dicey—requiring some finesse. I think next time I will secure the front panel before the back panel as the front panel screws are hard to reach once the back is on... and the LEDs are right in the way on the lower screws. (and spot fit the top and bottom panels for alignment.)
It gets pleasantly warm. Nothing crazy. Almost full out on the Mac volume with these speakers. 2 ACAs is definitely the way to go for the main system, I like to crank it in the country... On my way to the F5 or Aleph J!
Incredibly happy with this amp and it was super fun to build. Another one is on the way!
My comments about the build—Loved being able to ask noob questions and have responses that treated me like a human. Thanks guys!
The LEDs were by far the hardest (slightly annoying?) part of the process. My kit was devoid of shrink tube... I have a lot though, and one layer allowed me to press-fit without bunching, but not tight enough to hold properly. I dabbed a bit of hot glue to secure it better—still not great—I think a small (small!) amount of a PVA or polyurethane glue would be better—will try on the next build.
Wiring and assembling the case was also dicey—requiring some finesse. I think next time I will secure the front panel before the back panel as the front panel screws are hard to reach once the back is on... and the LEDs are right in the way on the lower screws. (and spot fit the top and bottom panels for alignment.)
It gets pleasantly warm. Nothing crazy. Almost full out on the Mac volume with these speakers. 2 ACAs is definitely the way to go for the main system, I like to crank it in the country... On my way to the F5 or Aleph J!
Incredibly happy with this amp and it was super fun to build. Another one is on the way!
Good Job! These really are pretty incredible sounding and buttloads of fun to build. Welcome to the club. Noob no more!
I'm currently running two ACA 1.6's in a bi-amped configuration with a pair of B&W CM5 S2's. I think it sounds much better than bridging mono. Just something else to try.
Enjoy!
Lots of people has used the ACA for this (including myself various times). I sat next to an 8 year old and coached him to build one (his soldering was impeccable ) We invited a 9 yr old to the Amp Camp and his dad (who was no pro) helped him build ACAs. Incidentally there were 2 women there who built amps, one a girlfriend, one a daughter.
There was even a Dad with a 4yr old girl, and we have a photo of her poking the big cap into the PCB!
There was even a Dad with a 4yr old girl, and we have a photo of her poking the big cap into the PCB!
The ACA doesn't really have a balanced mode. There are a couple different ways of bridging the two channels in a chassis. If you feed the ACA with a balanced signal, the two channels are simply running in a form of bridged mode.
The output capacitors are always necessary. Without them you will have excessive offset voltage, 10 or 12 Volts, at your speakers.
The output capacitors are always necessary. Without them you will have excessive offset voltage, 10 or 12 Volts, at your speakers.
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Because the feedback comes from the speaker side of the output cap, there is a good chance you will reverse bias the input cap depending on what is driving the ACA. If you can't live with the output caps, you'll need a different amp.
The ACA is powered by a single-rail PSU. Eliminating the output capacitors is not a feasible modification.
Enjoy the amp as designed (which is easy, fun, and wonderfully musical) and while listening to it, build another amp. (Aleph J, or if you have a preamp capable of very big output swings, F4)
And here's some great information about the subject of coupling caps (and why you shouldn't worry about them) -
SYclotron Audio | Why are people obsessed with coupling caps?
SYclotron Audio | Why are people obsessed with coupling caps? Part 2
SYclotron Audio | Capacitor Obsessions- The Zombie Awakes (edited to add data 2/21/18)
Enjoy the amp as designed (which is easy, fun, and wonderfully musical) and while listening to it, build another amp. (Aleph J, or if you have a preamp capable of very big output swings, F4)
And here's some great information about the subject of coupling caps (and why you shouldn't worry about them) -
SYclotron Audio | Why are people obsessed with coupling caps?
SYclotron Audio | Why are people obsessed with coupling caps? Part 2
SYclotron Audio | Capacitor Obsessions- The Zombie Awakes (edited to add data 2/21/18)
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I would remove C3 and set a capacitor in series with R12, in front of R14.
It should run.
Just try.-)
Do use ONE psu for all 4 amps!
The ACA is powered by a single-rail PSU. Eliminating the output capacitors is not a feasible modification.
Enjoy the amp as designed (which is easy, fun, and wonderfully musical) and while listening to it, build another amp. (Aleph J, or if you have a preamp capable of very big output swings, F4)
And here's some great information about the subject of coupling caps (and why you shouldn't worry about them) -
SYclotron Audio | Why are people obsessed with coupling caps?
SYclotron Audio | Why are people obsessed with coupling caps? Part 2
SYclotron Audio | Capacitor Obsessions- The Zombie Awakes (edited to add data 2/21/18)
Here to testify that the Aleph J is a great next step from the ACA.
Although I haven't built mine yet, it would seem that the M2x would be a good 2nd DIY amp candidate if the the input transistors for the Aleph J can't be found for reasonable cost.
Now that I've been convinced that dual mono PS is the way to go, I regret that I didn't go that way from the from the get-go.
I've built an ACA, and working on a second one—with my 9-yr-old daughter—likely after we run these a bit in parallel modes in our main system, one will end up in her room!....
I'm looking at the F5 for the next build. Any thoughts on that? Specific to noobiness... I'm still reading everything—totally not fully comprehending the PSU aspect of it, pretty confused really at the moment—I did buy a transformer though at the top of the recommended range... And will ask f5 specific questions in those respective threads... but since "next amp build" thoughts were flowing... anyone see a reason why I should build something else? (on the way to building them all!!!! haha)