Amp Camp Amp - ACA

Hi all, Question about the Switch on the back and the XLR connector. From the pictures posted for the 1.6 build that the XLR connector is installed along with the unbalanced input RCA inputs. Is the Switch on the back used to switch between using the Amp as a mono block or Stereo? I'm confused to this addition from the 1.5 version.

Yes I'm a novice building, and please excuse me if this has been covered elsewhere :).

Good luck on all your builds.

Mark
 
Mpitogo, that is one nice setup! :) I especially like the McIntosh and the Denon TT. Is it a direct drive? I ask because I was able to score a nice DP-1250 a few months back and found it to be phenomenal (not quite SP-10 material, but good enough for me at least).

Motospark, the short answer is 'yes'. But I'll let those more experienced than myself chime in with more details as I haven't yet tried mine in bridged mode.
 
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motospark -

The switch is not necessarily used to make it a monoblock, if you use the XLR, it's going to be bridged automatically. It is, however, used to make it bridged mono from the RCA inputs.

Stereo single ended, use RCA connectors on both RCA jacks and attach L and R speaker to the respective speaker posts.

Monoblock XLR, use the XLR jack and take speaker output from the two black posts.

Monoblock RCA, use the Left RCA for input, leave the right empty, flip the switch up, and take speaker output from the two black posts.
 
Hello,

Just finished building an amp camp amp. Very nice sounding, plenty loud with my 4PI speakers. Surprising how much bass they drive the 15" driver with.
Great kit. Thanks to all who worked so hard to produce them.

Greg


I own those exact speakers and was looking forward to how they sounded with the ACA's!


Are you using one or did you build mono blocks?
 
...Whenever I run into these mishaps, especially with SMD components, I use Chip Quik...
I'll keep my fingers crossed for you...
Best,
Anand.

Thanks a lot! Yeah, that sounds like an amazing thing! I'll be sure to have it for any future builds.

Hi Rafa,
Most likely it will be fine.
If you have a multimeter with a 'Diode' test on the ohms range you can check it out...

Alan
Thanks! I'll do that test tomorrow before doing the cable work inside the chassis.

I hope all is good, thanks for all the good wishes. Best regards,
Rafa.
 
In regarding to the cabling inside the case, I had an electronics question: why are we combining the chassis earth or ground to the negative of the power supply?

Is this a requirement? Is it easier? Would there be any benefits / Problems if one were to separate the chassis with the negative voltage?

As always, just trying to understand the process behind what we do. Thanks in advance,
Rafa.
 
ACA power supply is located remotely, so I suppose just an AC path between PCB ground and chassis should suffice. The point that should be AC coupled to chassis could be the RCA socket shield (negative, return) ingress point, the capacitor should be ceramic or silvered mica (capacitor legs should be as short as possible), value? Depends what frequency range you are trying to protect the ACA from. Paralleling few ceramics (0.01uF, 0.1uF) should work just fine and will give you a "broad-spectrum protection".

Things get a whole lotta different the moment you place the mains voltages (110/230V AC) inside the ACA... this is when the solid connection is required between IEC mains connector ground pin, chassis, and the PCB ground. In case of catastrophic failure of a transformer, the AC currents have to get to the mains supply ground somehow, via a path that provides minimal resistance (that minimal resistance must not be you if God forbid you touch the chassis: hand, body, legs, shoes, floor)

For DC supply voltages that are above let's say 40 or 50 V (required to power the amplifier electronics), the failure of a component that shorts such DC supply to ground, could also give a small shock, if you touch the chassis; hence the PCB ground has to be connected to chassis (and to mains ground) as well.

ACA is an output amplifier with a gain of 10dB only and a 24V DC external power supply - no need to worry about anything. What the assembly guide photos show, is perfect.
 
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:up: Excellent! The fact they've aged so well (mine is ~35-40 years old) is a testament to their build quality. The 1250 I picked up came equipped with a Grace 707 and DL 103. I'd always wondered what all the fuss was surrounding DD turntables and MC cartridges. Now I know.

And just to keep things on topic, that will be the next source I test on the ACA...

Nice, clean build on your monoblocks, btw. Yours was among those I used as a guide for dressing the interior wires.
 
Recommended speakers?

Hello,

I am building the mono kit from DIY Audio. This is my first entry into low power amps. I don't own, nor know anything about, high efficiency speakers. I've built plenty pairs of speakers before (other peoples designs), but they invariably were 7 to 8 ohm two way monitors of about 86dB efficiency.

Can anyone recommend some speakers that mate well with the ACA amp? I can build the design if it is not too complex, and don't mind buying something commercial if it is a sensibly priced.

I'm sorry if this has already been discussed in this thread. My eyes boggled when I saw it is over 500 pages long.

Thanks!
 
Amost done :) Switch ?

motospark -

The switch is not necessarily used to make it a monoblock, if you use the XLR, it's going to be bridged automatically. It is, however, used to make it bridged mono from the RCA inputs.

Stereo single ended, use RCA connectors on both RCA jacks and attach L and R speaker to the respective speaker posts.

Monoblock XLR, use the XLR jack and take speaker output from the two black posts.

Monoblock RCA, use the Left RCA for input, leave the right empty, flip the switch up, and take speaker output from the two black posts.

Ok then I don't need to use the switch at all then if I'm doing Stereo on a single unit? Or should I say Omit the switch and run the wires directly from each board to the RCA Inputs? I'm actually up to the wiring stage, I have test fitted the enclosure and made adjustments, just need to wire it up. Oh and I am using the front panel power switch.



Mark
 
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aljordan: Scan your local Craigslist ads for some of the makes mraudioguru listed. Chances are you'll find something sooner or later. For instance, a quick search of my area turned up gobs of Klipsch stuff at decent prices (to say it's ubiquitous is an understatement). I'd stay away from a lot of the home theater sets though, unless they come as a set with a good main pair. Just do your homework, get the best you can afford, and you'll be rockin' the house before you know it.

motospark: That's correct. The parts for switched bridging are there (at least if you ordered a kit with a front switch), but you don't have to use them if you don't want.
 
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Ok then I don't need to use the switch at all then if I'm doing Stereo on a single unit?

Or should I say Omit the switch and run the wires directly from each board to the RCA Inputs?

Mark

The switch is only in the circuit if you use it. The wires already run from the board to the RCA jacks, (if wired correctly). You can leave the switch out, but again, it really isn't in the path unless you flip it up.
 
Ok then if

The switch is only in the circuit if you use it. The wires already run from the board to the RCA jacks, (if wired correctly). You can leave the switch out, but again, it really isn't in the path unless you flip it up.

Ok so if I wire the amp the way I see it in the pics from this link as long as I don't flip the switch it runs as a Stereo amp? By the way thanks for your help.

aca16


Oh! Duh, I'll just omit the back switch and the XLR completely.
 
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