It’s interesting you say what you did about speaker cables Extreme_Boky... originally the ACA’s swapped location with my M2... getting short RCA cables (low capacitance cables)... BUT the speaker cables were long (but not crazy). Now they have very short speaker cables and long-ish RCA cables.... and they’re super quiet now... and sound even better than before the change. Go easy, I only know enough to be dangerous🙂
I do not have any issues. I use ACA's in a mono-block config. My speaker coupling cap is 10,000uF. Everything else is as per original schematics. Funny thing is that I did notice the turn-on "fuuuuzzzzzzz" sound when I tried ACA as a stereo amp... there was also just a slight "thump" when turning it off. But this disappeared when I started using them as monoblocks. When used as a monoblock, the ground is not closing the big capacitor discharge path (via a speaker) - back to a positive binding post. I also think that changing the capacitance of the CCS 1,000uF cap would change the start-up "fuuuuzzzzzzz" sound duration, so it becomes more like "fuuzz", "uuzzzz" or even "zzzz"😀... but this requires time and measurements for stability. is it worth pursuing this? Don't know, some DIY-ers may find it interesting/challenging.
I guess you include capacitive type loads in that then? I know it’s out if it’s depth but I’ve been tempted to try the little ACA with my ERaudio electrostatic mini panels 🙂 The panels are currently being run with a DIY F5 which is quite happy with them, but I’m aware that the F5 is likely to be much happier into demanding loads than the ACA.
505 Mini Panels
Cheers,
Matt.
Ouch. My speakers are 86dB efficient. What I described as a turn-off thump (when I used ACA as a stereo amp), your speakers may experience in an entirely different way "baanggg" or "kabummm" or (pls insert your interpretation on a dotted line "..........") or even kappputt.
Seriously now, I'd be very careful indeed with the cones so free to move in/out...
Sorry, I apologize. I didn't mean to **** you off. This has been discussed many times on here and even after my first response to you, several posts were made saying the same thing that I stated.
Mine happens in both channels as I assume does everyone else that has the stock stereo units?
ACA is very happy with my 86dB / 4-ohm flat-ish impedance speakers. It drives them with great authority and to very respectable levels.
What it is (the ACA) not happy with, is the speakers' cables capacitance. It is also not impressed by interconnects capacitance - but I use unshielded-everything anyway... of a very low capacitance and inductance.
If you want to try your sensitive/expensive speakers, but are afraid they will get damaged, use a 4ohm resistor in parallel to a connected speaker, then turn the amp ON, remove the resistor... listen... listen some more, and then, just before you turn the ACA OFF, unplug everything from the speaker binding posts. But I know what is going to happen... you will like the little fella so much that you will immediately forget about everything else... !!
Just feed it a nice signal of low output impedance, use unshielded interconnects, and pay attention to speaker cables (just use a solid core copper wire🙂)
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For whatever it’s worth, anomaly or not, if I power on the ACA’s first, and give them a moment, but less than a minute, the power ON sound is very discrete, specially if the last item powered on is the pre-amp. During play, pause, or off they are quiet.
Thanks for the info. So the amps can be switched back and forth for single ended stereo or single ended bridged mono. And the amps are always balanced mono, assuming you connect with XLR’s. Just curious if the switch needs to be switched to mono for the balanced mono when connecting with XLR’s?
Also, is the intent for getting the “no front power switch cutout” option anything but cosmetic? How are the amps supposed to be powered on and off without the front power switch (outside of finding another place to mount it)? Thanks again for the input.
Does it have a formula to calculate the output power of an ACA amp.?
For example: Supply voltage ? Constant Current? Load impedance?
Then the output Watt would be ?????
For example: Supply voltage ? Constant Current? Load impedance?
Then the output Watt would be ?????
The rear switch is ONLY for the RCA input. It has no bearing on the XLR input.
On the V1.5 version of the ACA, the rear switch was used for power. On the V1.6 version it became the stereo/mono switch. Can anyone who has the NON front power switch comment on how you turn the unit on? That's a good question. Is there a rear hole for the new power switch or do you use the existing rear switch for power and not for stereo/mono or for both?
Here's the impedance plot of the little electrostats, which bears an unfortunate resemblance to that of the Quad '57. XO is via simple capacitor plus MiniDSP at around 250Hz. Mr Pass mentioned in an earlier post that the ACA will definitely not be happy with the '57. I am curious to try my electrostats out on the ACA but don't want to damage the amp. If the sound is no good, then I'll simply change back to the F5. However, if either the ACA or the electrostatic panels are likely to get damaged, I just won't hook them up together...
Note that the Y axis starts at -2 ohms, so minimum impedance is actually around 2 ohms @ 20kHz.
Cheers,
Matt
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For Balanced XLR you want the switch in the 'stereo'position, to avoid feeding the right channel with the output of the left one.
But, if you don't have the front switch, what makes more sense to me is to use the back switch as on/off switch and use the 'jumper cable' solution for mono RCA,just as the 1.5 instructions.
Make much more sense to me that way.
Best regards,
Rafa.
But, if you don't have the front switch, what makes more sense to me is to use the back switch as on/off switch and use the 'jumper cable' solution for mono RCA,just as the 1.5 instructions.
Make much more sense to me that way.
Best regards,
Rafa.
Update.
With many thanks to Jason and the Guys in Italy, I received my chassis today.
And also a big thank you too Nelson and all those involved in bringing this design into kit format.
I Power on my system with dedicated line from my main house Power circuit panel dedicated circuit breaker through dedicated wall switch to a dedicated power wall outlet for stereo system only. This powers up my DYIaudio universal power supply in a separate case. That powers ACA.
You could use a remote power strip with a switch or a power line conditioner that has a remote turn on with either a 12 V activated circuit or 110 / 220 or line switch remotely. There is also remote Bluetooth or Wi-Fi controlled wall switches that you can turn on and off with your cell phone.
Here's the impedance plot of the little electrostats, which bears an unfortunate resemblance to that of the Quad '57. XO is via simple capacitor plus MiniDSP at around 250Hz. Mr Pass mentioned in an earlier post that the ACA will definitely not be happy with the '57. I am curious to try my electrostats out on the ACA but don't want to damage the amp. If the sound is no good, then I'll simply change back to the F5. However, if either the ACA or the electrostatic panels are likely to get damaged, I just won't hook them up together...
Note that the Y axis starts at -2 ohms, so minimum impedance is actually around 2 ohms @ 20kHz.
Cheers,
Matt
Hi Sub Sonic,
What speakers are you using with the ACA?
Matching Idss LSK170 or 2SK170 in ACA necessary?
Hi all, I just received the ACA 1.6 kits for a dual mono build. So I received 4 LSK170-C jFets and I measured the Idss of them:
Jfet 1: 12.12 mA
Jfet 2: 14.52 mA
Jfet 3: 15.45 mA
Jfet 4: 16.54 mA
As the classification is C, this means the jFet are within the band of 10-20mA. However, they differ significantly. Is it necessary to match the LSK170 jFets in the two channels of a stereo ACA build, or can I just adjust the bias in each channel with any Idss and put them in bridged mode afterwards?
I still have a number of Toshiba 2SK170-BLs with matched Idss to 9mA, so I could use those instead if necessary.
Cheers,
Walter
Hi all, I just received the ACA 1.6 kits for a dual mono build. So I received 4 LSK170-C jFets and I measured the Idss of them:
Jfet 1: 12.12 mA
Jfet 2: 14.52 mA
Jfet 3: 15.45 mA
Jfet 4: 16.54 mA
As the classification is C, this means the jFet are within the band of 10-20mA. However, they differ significantly. Is it necessary to match the LSK170 jFets in the two channels of a stereo ACA build, or can I just adjust the bias in each channel with any Idss and put them in bridged mode afterwards?
I still have a number of Toshiba 2SK170-BLs with matched Idss to 9mA, so I could use those instead if necessary.
Cheers,
Walter
Hi elb,
I’m currently using Nola Brio clones with the ACA, the setup is on the work desk and sounding very nice with the transmission line sub beneath 🙂. At home I have a DIY F5 driving ERaudio electrostatic panels, which is what the impedance plot above is for. MiniDSP and a capacitor perform a high pass at around 250 Hz.
Cheers,
Matt.
I’m currently using Nola Brio clones with the ACA, the setup is on the work desk and sounding very nice with the transmission line sub beneath 🙂. At home I have a DIY F5 driving ERaudio electrostatic panels, which is what the impedance plot above is for. MiniDSP and a capacitor perform a high pass at around 250 Hz.
Cheers,
Matt.
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