I switch the amp on using regular white eight socket with a red glowing switch that I plug the laptop bricks to. I am sure you own one in your house. Try that instead of placing a switch between the PSU and the amp. I hear nothing with my two laptop bricks.
Will try that. Maybe my laptop bricks are faulty, or not properly designed?
Added 10000uf capacitor between the switch & ACA. Haven't tried yet.
I also had the turn-off thump, on my sensitive Fostex my heart skipped a beat 😀
I simply added a DPST switch between the amp outputs and the spkrs posts. Just remember the following :
When powering the amp : Turn-on that new switch once the amps starts to get warm.
When powering down the amp : Turn-off that new switch BEFORE you close the amp.
BR,
Eric
I've got the Fostex drivers (Hornshoppe Horns) but just a slight clunk and not a thump. My bricks are plugged into a strip.
You can just connect two GR grade parts in parallel if Idss is too low and P1 cannot be adjusted to the proper idle voltage.
Most of the power supply bricks I've seen have a universal 100-250VAC input. They may act differently when used at 240V than they do at 120V. This might explain why some builders experience a turn off thump.
If the power supply won't start with a big capacitive load, connect a 10W resistor of perhaps 3 to 5 Ohms in series with the cap. That will allow the power supply to start. If there is still big thump, connect a 3 Amp diode across the resistor, cathode (banded end) towards the amp and power supply end of the resistor.
With GR grades mounted I can adjust P1 to 10V. Added 10000uf capacitor between power switch and ACA. It seems its almost prevent power off thump. Now there is a faint noise, its hardly audible.
I also have finnished the first ACA Version with Notebooks 19V,3,2A PSU.
The Supplies running a bit hot, so i add a little Aluplate to absorb the Heat.
No Problems with set up and running. Switch on- no noise, Switch off a bit "zzzrrrttzzz"- from decharching Cap.
I mean other DIYA Member wrote- not dramatically for Speakers.
I was searching a Little Amp to drive my Fostex FE126E Hybrid Horns(with CR-correction)- like Fostex Planes. They working very well together, bit more air(glossy) in the Highs, then withother Amps itested out.
I've ordered 4 Bords for next 2Pairs, now in modified Version- i'll taste it out.
Next Step i've to arranged a nice Enclousure.
Happy Building to All.
Regards.
The Supplies running a bit hot, so i add a little Aluplate to absorb the Heat.
No Problems with set up and running. Switch on- no noise, Switch off a bit "zzzrrrttzzz"- from decharching Cap.
I mean other DIYA Member wrote- not dramatically for Speakers.
I was searching a Little Amp to drive my Fostex FE126E Hybrid Horns(with CR-correction)- like Fostex Planes. They working very well together, bit more air(glossy) in the Highs, then withother Amps itested out.
I've ordered 4 Bords for next 2Pairs, now in modified Version- i'll taste it out.
Next Step i've to arranged a nice Enclousure.
Happy Building to All.
Regards.
Yeah, my impression too. I also have the 70's space movie sound when I turn it off. 🙂
Next up is F4 and F5. I will probably end up using an F5 for the 15" driver in a midbass horn, as it seems to be the more pure sounding amp, from what i have read, and tubes for higher frequencies. Unless the F4 + a tube preamp integrates better with the tube amp above.
Next up is F4 and F5. I will probably end up using an F5 for the 15" driver in a midbass horn, as it seems to be the more pure sounding amp, from what i have read, and tubes for higher frequencies. Unless the F4 + a tube preamp integrates better with the tube amp above.
I plan on building the ACA as monoblocks after I'm done with my son's F5 (backwards order for a newbie, I know). Call me a fool but I'm gonna try wiring point-to-point on perf board. Other than check and double-check against the schematic, are there any pointers for P2P layout and soldering I should know? Which critical connections to keep short?
I know I have asked this before but I am going to try once more before starting my own thread.
I have my two ACAs built up and they are being fed by a JFET based phono preamp which has ~40dB of gain and the ACA shoud have ~14dB.
What would be a good way to implement a volume control here? Perhaps a buffer->dual ganged pot->buffer placed in between the preamp and power amp? I'm new to this so any advice appreciated.
I have my two ACAs built up and they are being fed by a JFET based phono preamp which has ~40dB of gain and the ACA shoud have ~14dB.
What would be a good way to implement a volume control here? Perhaps a buffer->dual ganged pot->buffer placed in between the preamp and power amp? I'm new to this so any advice appreciated.
RIAA then buff in front of vol
ACA is having high enough input impedance , so use - say- 10K vol and enjoy
ACA is having high enough input impedance , so use - say- 10K vol and enjoy
Wanted to share my experience with this amp. I'm feeding ACA's directly from squeezebox touch, hi-res flac files. I'm building B1 in the meantime.
ACA's driving full range philips drivers, alnico version AD4000M's in a sealed 140 liter cabinet. This drivers are spec'ced to max 10W. More or less 3W from ACA is more than enough for this old full rangers. Insane amount of detail, deep bass and crystal highs! Tried few old restored amps with 4000M's, ACA's are perfect match so far.
So, thanks Mr.Pass for this eye-opening experience..
ACA's driving full range philips drivers, alnico version AD4000M's in a sealed 140 liter cabinet. This drivers are spec'ced to max 10W. More or less 3W from ACA is more than enough for this old full rangers. Insane amount of detail, deep bass and crystal highs! Tried few old restored amps with 4000M's, ACA's are perfect match so far.
So, thanks Mr.Pass for this eye-opening experience..
I'm attempting to build a dual mono ACA (two supplies, one chassis) and will be mounting one ACA PCB to each heatsink of the same chassis.
I was looking closely at the ACA PCB noticed that the layout has plated through hole mounting holes and those are connected with a trace that runs around the board to provide ground to various components. Because the mounting holes are conductive and the ACA kit (presumably) uses metallic standoffs (as will I), they appear to connect what I would normally consider signal ground to chassis ground at the heatsink.
I thought it was generally accepted that signal grounds should normally come back to a star ground (which then connects to the power supply ground) to avoid noise. If that's the case, why are the through holes plated and effectively connected to chassis ground? Is this simply a compromise for simplicity of installation for the intended audience?
I was looking closely at the ACA PCB noticed that the layout has plated through hole mounting holes and those are connected with a trace that runs around the board to provide ground to various components. Because the mounting holes are conductive and the ACA kit (presumably) uses metallic standoffs (as will I), they appear to connect what I would normally consider signal ground to chassis ground at the heatsink.
I thought it was generally accepted that signal grounds should normally come back to a star ground (which then connects to the power supply ground) to avoid noise. If that's the case, why are the through holes plated and effectively connected to chassis ground? Is this simply a compromise for simplicity of installation for the intended audience?
Question about ACA output device placement.
I'm in the design/gathering materials stage of an ACA build (mono blocks). The heat sink for each block will be approx. 4" x 7", vertically oriented (fins vertical also), but tilted back 45 deg. Using the attached layout grid, what do you think would be the best placement on the heat sink for the two output devices?
Thanks...
I'm in the design/gathering materials stage of an ACA build (mono blocks). The heat sink for each block will be approx. 4" x 7", vertically oriented (fins vertical also), but tilted back 45 deg. Using the attached layout grid, what do you think would be the best placement on the heat sink for the two output devices?
Thanks...
Attachments
One more question 😉
Last night I noticed something. When turning on ACA, there is a faint sweep tone sound for few seconds. After 5-10 seconds that noise gone. However when I put my ear close to speaker I can hear constant noise after that. Constantly switching between low & high noise, some kind of waveform.. It's very faint. But it's there.
What can cause this?
Last night I noticed something. When turning on ACA, there is a faint sweep tone sound for few seconds. After 5-10 seconds that noise gone. However when I put my ear close to speaker I can hear constant noise after that. Constantly switching between low & high noise, some kind of waveform.. It's very faint. But it's there.
What can cause this?