Balance no reading
Hi,
Just got done my two amps and went to adjust balance. No problem with the second amp I built but first amp would not register. I checked all wiring connections to the boards and they look ok. I checked voltage at the switch and got 24 V. Then I took off a rail on each board and checked that nothing was touching that should not and everything looked ok. Any ideas. Pics included.
Thanks,
J
Hi,
Just got done my two amps and went to adjust balance. No problem with the second amp I built but first amp would not register. I checked all wiring connections to the boards and they look ok. I checked voltage at the switch and got 24 V. Then I took off a rail on each board and checked that nothing was touching that should not and everything looked ok. Any ideas. Pics included.
Thanks,
J
Attachments
First thing to check is your wiring...
On the image attached the black wire is going to the V+ connection. I cannot follow the whole run, but suspect that black is the -ve lead?
Next is some of the soldering on the back panel is very shallow in places, might not be the problem now, but will let you down in the future.
Alan
On the image attached the black wire is going to the V+ connection. I cannot follow the whole run, but suspect that black is the -ve lead?
Next is some of the soldering on the back panel is very shallow in places, might not be the problem now, but will let you down in the future.
Alan
Attachments
Hi, I like to share my ACA build for headphone: using IRF830. (This FET needs higher gate stopper)
I have it running for now at 330 mA, case stays cool.
I have a NVVV power supply, RC per channel of 0,25 ohm/3.300uF.
Works like a charm. I have 0.47 uF input and I have 470 uF output, all to reduce the turn-on thump.
I have speaker output too so I can use it for bi-amping if needed; then the ACA can be revved up a bit to say 500 - 600 mA and deliver 2 watts in 8 ohm.
bandwidth @ 50 ohm (my Fostex RP phone) is < 7 Hz - 270 KHz.
I have the 2k2 attenuation of the bias. So it gives lower output impedance. test: Moving from 51 ohm to 7 ohm (parallel the 8 /51 ohm) gives a drop of less than 1 dB. [It is a great amp for sensitive fullrangers]
I have it running for now at 330 mA, case stays cool.
I have a NVVV power supply, RC per channel of 0,25 ohm/3.300uF.
Works like a charm. I have 0.47 uF input and I have 470 uF output, all to reduce the turn-on thump.
I have speaker output too so I can use it for bi-amping if needed; then the ACA can be revved up a bit to say 500 - 600 mA and deliver 2 watts in 8 ohm.
bandwidth @ 50 ohm (my Fostex RP phone) is < 7 Hz - 270 KHz.
I have the 2k2 attenuation of the bias. So it gives lower output impedance. test: Moving from 51 ohm to 7 ohm (parallel the 8 /51 ohm) gives a drop of less than 1 dB. [It is a great amp for sensitive fullrangers]
Anybody measured distortion spectra of the ACA? Archimago did in MEASUREMENTS: Pass Amp Camp Amp (ACA) 1.1. The crossroads between objectivism and subjectivism, and reconsidering von Recklinghausen.. One of the magic to note is that the ACA has composition of H2/H3 > 20dB for output power up to ~3W, very close to top quality SE DHT amplifier, exceptional design rarely found on solid state amplifier at any price. Thank you Papa Pass. 
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I have been out of the loop for a while (busy elsewhere):
I am still planning on doing an amp with a transformer. For my multi amped setups small power amp like ACA is a Papagod given gift.
About 3 years back Papa said he already had a working prototype of an M2-like ACA; he called it initially an ACA.2 but then said that the diyaudio (store) management decided it should be a separate line amp called something else. Has he released that design yet? Did I miss it?
> If not then @Papa: care to comment about the timing? Thx.
it was mentioned in this and another thread (cannot remember where):
https://www.diyaudio.com/forums/pass-labs/310169-m2-story.html#post5136220
I am still planning on doing an amp with a transformer. For my multi amped setups small power amp like ACA is a Papagod given gift
.About 3 years back Papa said he already had a working prototype of an M2-like ACA; he called it initially an ACA.2 but then said that the diyaudio (store) management decided it should be a separate line amp called something else. Has he released that design yet? Did I miss it?
> If not then @Papa: care to comment about the timing? Thx.
it was mentioned in this and another thread (cannot remember where):
https://www.diyaudio.com/forums/pass-labs/310169-m2-story.html#post5136220
Anybody measured distortion spectra of the ACA? Archimago did in MEASUREMENTS: Pass Amp Camp Amp (ACA) 1.1. The crossroads between objectivism and subjectivism, and reconsidering von Recklinghausen.. One of the magic to note is that the ACA has composition of H2/H3 > 20dB for output power up to ~3W, very close to top quality SE DHT amplifier, exceptional design rarely found on solid state amplifier at any price. Thank you Papa Pass.
single ended single stage amplification, even tubes will have a hard time replicating this feat...
ACA2 with a transformer?
https://www.diyaudio.com/forums/pass-labs/310169-m2-story-3.html#post5155039
https://www.diyaudio.com/forums/pass-labs/310169-m2-story-3.html#post5155783
https://www.diyaudio.com/forums/pass-labs/310169-m2-story-3.html#post5155039
https://www.diyaudio.com/forums/pass-labs/310169-m2-story-3.html#post5155783
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I just completed 2 ACAs last weekend and hooked it up to my source and speakers. I understand the benefits of monoblocking both channels. But can someone explain to me the expected sound differences between the three options this amp gives me . . i.e. balanced mono, parallel mono and bridged mono, I'm a bit new to this game.
Bridged and balanced are broadly the same. The 1st a trick to be able to get away with a pre without balanced out. They have 2x the Rout which pushes that important factor from middling damping to much less so the impedance of your loudspeaker becomes nore important.
Bridged and balanced turn the single ended ACA into essentially a PP amp with a quite different distortion profile.
Paralleled is still SE and will sound like a stereo ACA with more power, it also has half the Rout so moves into the class of amplifiers that care little about speaker impedance. Fortunatley we are seeing more & more speakers happy with highish Rout, i am eager for a friend to try balanced ACA on his FHXL with Alpair 10PeN.
Both parallel & bridged/balanced output twice the nomial power. But given that a single channel of ACA is happiest with a nominal 8 load, bridged /balanced is going to move that to 16Ω (each channel sees 8Ω) and parallel happiest with 4Ω (each channel sees 8Ω).
So power wize, bridged/balanced for higher impedance speakers with flattish impedance curves (or those that rwally want to see a high Rout amp (ie Fostex FExx6), parallel for lower impedance load with wilder impedance curves.
What is your application?
dave
Hi Dave:
Thank you the explanation. I am driving some GR-Research speakers that I built from a kit (X-Statik Kit) with an external 3 way cross-over with the Sonic Cap and Mills resistor upgrades that he Danny recommends. The speakers are a hybrid open-baffle design presenting an 8 ohm load with 91 dB sensitivity.
rolf
Thank you the explanation. I am driving some GR-Research speakers that I built from a kit (X-Statik Kit) with an external 3 way cross-over with the Sonic Cap and Mills resistor upgrades that he Danny recommends. The speakers are a hybrid open-baffle design presenting an 8 ohm load with 91 dB sensitivity.
rolf
Looking for some help. Built my amp camp with premium parts with an external power supply.
Two torroidal transformers that are 22V 200VA so I see 28V rails with CapMX power supplies. Everything tested fine on the work bench with DBT but after trying to hook it all up today I’m blowing fuses.
I have a 3A slow blow on the back and one slo blow 2.5A on each transformer. The only inrush limit I have is a thermistor across each power button.
Do I need more inrush limiters or am I using too small of fuses?
Two torroidal transformers that are 22V 200VA so I see 28V rails with CapMX power supplies. Everything tested fine on the work bench with DBT but after trying to hook it all up today I’m blowing fuses.
I have a 3A slow blow on the back and one slo blow 2.5A on each transformer. The only inrush limit I have is a thermistor across each power button.
Do I need more inrush limiters or am I using too small of fuses?
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