I have mis-read this one earlier... To clarify:
I would like to place the ACP+ PCB inside the standard ACA case (with custom front panel for the volume knob and headphone jack).
Is there enough space inside the ACA case?
I cannot tell what are the dimensions of the space inside the ACA case, nor the ACP+ PCB dimensions.
Continuing ACA trouble
Hi Alan and Thomas. Thanks for sticking with me on my issues!
-Meter definitely reads .997 ohms both b4 and after removing Out+ and Out - at the board.
-No connection between black wire/terminal and chassis.
-No soldered wires are touching chassis.
-Mode selector switch is in down position (stereo).
If above all negative, Thomas states short is perhaps in the board. Where do I start for checking this?
I've attached better pics now the boards are mostly detached.
Thank you again for your knowledge and guidance.
Craig
Hi Alan and Thomas. Thanks for sticking with me on my issues!
-Meter definitely reads .997 ohms both b4 and after removing Out+ and Out - at the board.
-No connection between black wire/terminal and chassis.
-No soldered wires are touching chassis.
-Mode selector switch is in down position (stereo).
If above all negative, Thomas states short is perhaps in the board. Where do I start for checking this?
I've attached better pics now the boards are mostly detached.
Thank you again for your knowledge and guidance.
Craig
Attachments
Craig,
Nothing obviously wrong from your pictures. Caps and transistors all in the correct place and the right way round. As far as I can tell (colours are hard to decide on the pictures) the resistors are in the proper places. The resistance and voltage reading in post #9107 are all near enough. So something odd going on.
Let's recap your problem. Please explain the 'sounds bad' a bit more. What is your source / input to the ACA? What sort of volume do you get? Dose the distortion start at 1/4 volume, 1/2 volume, etc.? How efficient are your speakers etc.?
Next what sort of meter are you using to do the resistance measurements, auto ranging or one where you select the range? Can you take a resistance measurement with your meter probes shorted together - let us know the result - a picture would help?
I'm still not comfortable with the 0.997 reading - and no point pulling anything else apart if we are not on the right track...
Alan
Nothing obviously wrong from your pictures. Caps and transistors all in the correct place and the right way round. As far as I can tell (colours are hard to decide on the pictures) the resistors are in the proper places. The resistance and voltage reading in post #9107 are all near enough. So something odd going on.
Let's recap your problem. Please explain the 'sounds bad' a bit more. What is your source / input to the ACA? What sort of volume do you get? Dose the distortion start at 1/4 volume, 1/2 volume, etc.? How efficient are your speakers etc.?
Next what sort of meter are you using to do the resistance measurements, auto ranging or one where you select the range? Can you take a resistance measurement with your meter probes shorted together - let us know the result - a picture would help?
I'm still not comfortable with the 0.997 reading - and no point pulling anything else apart if we are not on the right track...
Alan
ACA Troubles
Hi Alan:
Auto ranging meter. Probes touching displays variable Ohms between .1 to .4.
Current system: Imac with Audirvana via ethernet > Allo US Bridge Signature>Schiit Bifrost2 dac>Eastern Electric Minimax Tube integrated>Hornshoppe Horns (modified 2 way system using ESS Heil AMT tweeter for top end: all as designed by the man who builds the speakers).
This system sounds great, with no obvious issues/distortion etc. I purchased the ACA to replace tubes in my system, but was waiting for the Korg B1 preamp to arrive, which I'm working on right now.
I purchased a very inexpensive preamp to use with the ACA to compare with the Korg B1. Not sure what adjectives are most apt, but in comparison to my existing tube setup, the sound seems gravely and somewhat distorted, at all volume levels, and at higher volume levels I get an occasional bad sounding twang from the AMT tweeter. Unlistenable.
I never considered whether the cheap preamp is the culprit, but assumed my build quality was bad when troubleshooting showed Q1 voltage to be way off.
Advice, suggestions...
Thank you for all of your help thus far.
Craig
Hi Alan:
Auto ranging meter. Probes touching displays variable Ohms between .1 to .4.
Current system: Imac with Audirvana via ethernet > Allo US Bridge Signature>Schiit Bifrost2 dac>Eastern Electric Minimax Tube integrated>Hornshoppe Horns (modified 2 way system using ESS Heil AMT tweeter for top end: all as designed by the man who builds the speakers).
This system sounds great, with no obvious issues/distortion etc. I purchased the ACA to replace tubes in my system, but was waiting for the Korg B1 preamp to arrive, which I'm working on right now.
I purchased a very inexpensive preamp to use with the ACA to compare with the Korg B1. Not sure what adjectives are most apt, but in comparison to my existing tube setup, the sound seems gravely and somewhat distorted, at all volume levels, and at higher volume levels I get an occasional bad sounding twang from the AMT tweeter. Unlistenable.
I never considered whether the cheap preamp is the culprit, but assumed my build quality was bad when troubleshooting showed Q1 voltage to be way off.
Advice, suggestions...
Thank you for all of your help thus far.
Craig
Attachments
Just reading along and wondered how this was going...
Could the impedance of the speaker system be just to low for the ACA. Against that though would be the efficiency of the speaker.
Maybe try on some other speakers if you can.
Generally if the DC conditions of the ACA are correct (mid rail bias point OK and current draw correct) then its going to work normally.
If you suspect the preamp then try feeding the ACA direct with just a passive volume control at the input.
Good luck
It will be tomorrow before I look in again.
Could the impedance of the speaker system be just to low for the ACA. Against that though would be the efficiency of the speaker.
Maybe try on some other speakers if you can.
Generally if the DC conditions of the ACA are correct (mid rail bias point OK and current draw correct) then its going to work normally.
If you suspect the preamp then try feeding the ACA direct with just a passive volume control at the input.
Good luck
It will be tomorrow before I look in again.
Craig hi,
Thanks for the recap. I believe now the way you describe the volume levels available that the ACA is working. (That and the resistance and voltage figures you reported.)
Now I think the 0.997 ohm reading is actually 0.997K ohms or 997 ohms which would be correct. The picture you posted of a 'short circuit' has the decimal point one place to the left, not 3.
Not familiar with any of the equipment you listed but I see the valve amp has 8 watts push pull output.
Valve amps normally sound smooth right into 'clipping' (being pushed into their output limit.) and can sound more powerful than their power rating.
The ACA is not so benign, it starts to clip very sharply past a certain point, enough to give any tweeter a good twang! It should though sound smooth and not distorted right up to that point.
Best suggestion is to re-build it, taking care with the Keratherm washers etc.
Then try different speakers and pre-amp as Mooly suggests. I googled the horns and they are 8 ohms, but those tweeters are 4 ohms impedance so who knows what their combined impedance is through the range?
So many variables ehy?
Happy to help (and sometimes hinder...) let us know your developments,
Alan
Thanks for the recap. I believe now the way you describe the volume levels available that the ACA is working. (That and the resistance and voltage figures you reported.)
Now I think the 0.997 ohm reading is actually 0.997K ohms or 997 ohms which would be correct. The picture you posted of a 'short circuit' has the decimal point one place to the left, not 3.
Not familiar with any of the equipment you listed but I see the valve amp has 8 watts push pull output.
Valve amps normally sound smooth right into 'clipping' (being pushed into their output limit.) and can sound more powerful than their power rating.
The ACA is not so benign, it starts to clip very sharply past a certain point, enough to give any tweeter a good twang! It should though sound smooth and not distorted right up to that point.
Best suggestion is to re-build it, taking care with the Keratherm washers etc.
Then try different speakers and pre-amp as Mooly suggests. I googled the horns and they are 8 ohms, but those tweeters are 4 ohms impedance so who knows what their combined impedance is through the range?
So many variables ehy?
Happy to help (and sometimes hinder...) let us know your developments,
Alan
Hi Craig -
Your meter is reading 0R2. You can confirm your readings and your display by manually setting the range on your meter using the button on your DMM. Mine will clearly show a k or M even when in auto-ranging mode. Grab a few resistors of known value and test them if you're unsure.
Either way, if your DMM is showing more than about 1 ohm with just the probes touching, your meter is broken, your probes are "bad", or something else would be amiss. It is not "correct" to have a high resistance with just the test leads.
Alan, if I am incorrect, my apologies to both you and Craig. However, your statement that shorting the probes and the reading being nearly 1000 ohms "...would be correct" does not make sense to me.
Best,
Patrick
Edited for horrible early morning grammar.
Your meter is reading 0R2. You can confirm your readings and your display by manually setting the range on your meter using the button on your DMM. Mine will clearly show a k or M even when in auto-ranging mode. Grab a few resistors of known value and test them if you're unsure.
Either way, if your DMM is showing more than about 1 ohm with just the probes touching, your meter is broken, your probes are "bad", or something else would be amiss. It is not "correct" to have a high resistance with just the test leads.
Alan, if I am incorrect, my apologies to both you and Craig. However, your statement that shorting the probes and the reading being nearly 1000 ohms "...would be correct" does not make sense to me.
Best,
Patrick
Edited for horrible early morning grammar.
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Thanks Patrick,
Craig's meter is just fine. It reads 0.2 ohms (0R2) with the leads shorted - so just contact and wire resistance.
The ''nearly 1000 ohms ...would be correct" is reference to the Red to Black speaker terminal or OUT+ /- test I asked for.
I know you are under pressure over there, more coffee required! ;-)
Alan
Craig's meter is just fine. It reads 0.2 ohms (0R2) with the leads shorted - so just contact and wire resistance.
The ''nearly 1000 ohms ...would be correct" is reference to the Red to Black speaker terminal or OUT+ /- test I asked for.
I know you are under pressure over there, more coffee required! ;-)
Alan
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Craig,
As Alan mentioned a few pages back, your bad Q1 voltage at the source doesn't make sense since it is directly connected to ground so it's more likely to be a measurement issue.
Have you tried using the preamp with your integrated and see if you hear a similar distortion? You can start with the preamp at a volume control level similar to what you were using when testing the ACA, and the volume control of the tube integrated all the way down, and then gradually raise the integrated's volume control and see what happens.
As Alan mentioned a few pages back, your bad Q1 voltage at the source doesn't make sense since it is directly connected to ground so it's more likely to be a measurement issue.
Have you tried using the preamp with your integrated and see if you hear a similar distortion? You can start with the preamp at a volume control level similar to what you were using when testing the ACA, and the volume control of the tube integrated all the way down, and then gradually raise the integrated's volume control and see what happens.
BIG thanks to all of you chiming in. It was because of the helpfulness of this form that I decided to try building some kits. Perhaps my ACA build is a metaphor of current events in the USA; seems to be screwed up at the moment, but give it some measured time and hopefully all will be well...
-I'll put back together the ACA, and remeasure per 6L6 troubleshooting info.
-Give me a couple more days and I'll complete the Korg B1 so i have a better preamp to try.
-I'll follow up with all of you with my discoveries, and try to answer your helpful questions/suggestions.
My small music room is now being shared with my working from home wife, so evenings are my primary work/listen time. I'll be back in touch soon.
Cheers
Craig in Seattle
-I'll put back together the ACA, and remeasure per 6L6 troubleshooting info.
-Give me a couple more days and I'll complete the Korg B1 so i have a better preamp to try.
-I'll follow up with all of you with my discoveries, and try to answer your helpful questions/suggestions.
My small music room is now being shared with my working from home wife, so evenings are my primary work/listen time. I'll be back in touch soon.
Cheers
Craig in Seattle
Also besides the speakers, have you tried different inputs? You can quickly try something simple like an iPod/iPhone with 1/4 jack output and see if you have the same output. I have an old gen 1 iPad I use for testing of projects like this that I keep around, as well as an old pair of fairly efficient bookshelf speakers that I won't mind if they get fried for initial testing.
Considering ACA Mono for JBL M2
Hello everyone,
First post here so please tolerate my silly questions.
I own a pair of JBL M2s in my 2 channel, dedicated room and believe they are 92dB efficient. I typically never listen above 90 but sometimes hit 95 according to my trusty SPL meter. I currently have Purifi (400W) modules on each the horn and woofer (no internal xover, thus they are biamped for those that aren’t familiar with the M2).
This looks like a fun project! I’d like to get some help with the ordering process for the complete MONO kit. I’m thinking of building 4 mono amps. What should I be ordering or thinking about here????
Thanks
Paul
Hello everyone,
First post here so please tolerate my silly questions.
I own a pair of JBL M2s in my 2 channel, dedicated room and believe they are 92dB efficient. I typically never listen above 90 but sometimes hit 95 according to my trusty SPL meter. I currently have Purifi (400W) modules on each the horn and woofer (no internal xover, thus they are biamped for those that aren’t familiar with the M2).
This looks like a fun project! I’d like to get some help with the ordering process for the complete MONO kit. I’m thinking of building 4 mono amps. What should I be ordering or thinking about here????
Thanks
Paul
