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36 watts per channel, so 72 watts total (24 volts times 1.5 Amps bias = 36 Watts). Add a few watts for losses, the PSU is not 100% efficient. Say 85 watts.
So with 120 volt mains 0.7 Amps once switched on and running. Could be more at switch on depending on the power supply you use.
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Just did the Resistance troubleshooting measurements. Voltage measurements to come
Left
Q1 - S 0.1 - D 4.65k - G 0.6k
Q4 - D 0.5k
R10 - G 333.7k
R9 - S .5k
R15 - B 5.36k - E 4.67k
R5 - C 10.36k
Q2 - G 10.46k - D 0.51k - S 4.7k
Right
Q1 - S 0.2 - D 4.53k - G 0.6k
Q4 - D 0.5k
R10 - G 331k
R9 - S 0.5k
R15 - B 5.22k - E 4.53k
R5 - C 10.45k
Q2 - G 10.56k - D 0.51k - S 4.6k
Left
Q1 - S 0.1 - D 4.65k - G 0.6k
Q4 - D 0.5k
R10 - G 333.7k
R9 - S .5k
R15 - B 5.36k - E 4.67k
R5 - C 10.36k
Q2 - G 10.46k - D 0.51k - S 4.7k
Right
Q1 - S 0.2 - D 4.53k - G 0.6k
Q4 - D 0.5k
R10 - G 331k
R9 - S 0.5k
R15 - B 5.22k - E 4.53k
R5 - C 10.45k
Q2 - G 10.56k - D 0.51k - S 4.6k
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That did it. Replacing the LSJ from diyaudiostore with the LSK variant fixed the issue. All voltages check out. Retested the Original JFETS, both DOA. Thanks for the help!
pleased to hear you have it working now.
Hi Lemonss,
I hope you do not mind me saying, but it might help others, that the LSJ74 is not a variant of the LSK170. They are not interchangeable.
The LSK170 is a N channel device (the gate arrow head points to the source and drain).
The LSJ74 is a P channel device (the gate arrow points away from the source and drain).
You have to use the N channel device in the ACA.
Well done fixing it by the way. Alan
That is very helpful and likely will be to others. I completely misread the datasheet for the LSJ74. Remeasured and they are perfectly fine, so looks like ill just have to put them to use in another amp build in the future
Turns out the whole issue was user error. Thanks for the help everyone. Here is a finished pic with zebra wood faces and silver power switches and a pass DIY B1 also in Zebrawood.
Lemonss, a beautiful, and I'm sure pleasant sounding setup.That is very helpful and likely will be to others. I completely misread the datasheet for the LSJ74. Remeasured and they are perfectly fine, so looks like ill just have to put them to use in another amp build in the future
Turns out the whole issue was user error. Thanks for the help everyone. Here is a finished pic with zebra wood faces and silver power switches and a pass DIY B1 also in Zebrawood.
Perhaps you could answer a question that I have not had satisfactorily answered in plain English to me despite the wealth of knowledge on this forum:
I see you have two ACA's. I presume that you are not listening in mono, therefore my assumption is that you have a "double mono" setup, that is to say that one RCA goes into each amp, and one speaker comes out of each amp?
I have asked before how to double up the power of the ACA's on this forum, and have had replies in the vein of: bridged mono, XLR etc but not had what is your setup explained, unless it's gone over my head....
TIA
16 ohm speakers
I have zu soul superflys, which are 16 ohm and 100db+ sensitivity. I noticed that the aca 1.6 into 16 ohm speakers in stereo only provides 4 watts (based on a chart I found in the forum). I believe that will be fine, but I was wondering if anyone has experience with this speaker-type and the aca? If so, any thoughts? My decision is whether to go stereo, or mono blocks, considering its 2x the cost... Thanks!
I have zu soul superflys, which are 16 ohm and 100db+ sensitivity. I noticed that the aca 1.6 into 16 ohm speakers in stereo only provides 4 watts (based on a chart I found in the forum). I believe that will be fine, but I was wondering if anyone has experience with this speaker-type and the aca? If so, any thoughts? My decision is whether to go stereo, or mono blocks, considering its 2x the cost... Thanks!
Semmyroundel Have you not had the pleasure of seeing 6L6 beautifully illustrated and detailed worded illustrated guide on the amp camp amp 1.6
With very clear and illustrated photographs and explanation it shows exactly how the way your wording at the use of two separate individual mono Blocked ACA with one single input two only one RCA on one block with only one speaker output coming out of only one block repeated for left mono Block and right channel mono Block.
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So after it warms up 10-20 minutes it sounds perfect and no problems with the poke test or voltage readings. So i did my poke test cold when the left channel sounds bad. I found C3 on the left channel affected the sound when poked so that has fixed it temporarily.
I will add some solder to C3 and the top of the boards. I will also make efforts to keep it cooler while running and hope the gremlins don't return...
Here are my resistance readings from a couple days ago:
Left
Q1 - S 0.1 - D 4.65k - G 0.6k
Q4 - D 0.5k
R10 - G 333.7k
R9 - S .5k
R15 - B 5.36k - E 4.67k
R5 - C 10.36k
Q2 - G 10.46k - D 0.51k - S 4.7k
Right
Q1 - S 0.2 - D 4.53k - G 0.6k
Q4 - D 0.5k
R10 - G 331k
R9 - S 0.5k
R15 - B 5.22k - E 4.53k
R5 - C 10.45k
Q2 - G 10.56k - D 0.51k - S 4.6k
Here are my voltage readings:
Left
Q1 - S 0 - D 11.99 - G 4.67
Q4 - D 23.99
R10 - G 3.94
R9 - S 4.66
R15 - B 12.35-12.7 - E 11.95
R5 - C 17.35
Q2 - G 17.34 - D 23.98 - S 12.74
Right
Q1 - S 0.024 - D 12.06 - G 4.6
Q4 - D 23.96
R10 - G 3.83
R9 - S 4.6
R15 - B 11.9-12.73 - E 12.05
R5 - C 17.43
Q2 - G 17.43 - D 23.98 - S 12.81
I will add some solder to C3 and the top of the boards. I will also make efforts to keep it cooler while running and hope the gremlins don't return...
Here are my resistance readings from a couple days ago:
Left
Q1 - S 0.1 - D 4.65k - G 0.6k
Q4 - D 0.5k
R10 - G 333.7k
R9 - S .5k
R15 - B 5.36k - E 4.67k
R5 - C 10.36k
Q2 - G 10.46k - D 0.51k - S 4.7k
Right
Q1 - S 0.2 - D 4.53k - G 0.6k
Q4 - D 0.5k
R10 - G 331k
R9 - S 0.5k
R15 - B 5.22k - E 4.53k
R5 - C 10.45k
Q2 - G 10.56k - D 0.51k - S 4.6k
Here are my voltage readings:
Left
Q1 - S 0 - D 11.99 - G 4.67
Q4 - D 23.99
R10 - G 3.94
R9 - S 4.66
R15 - B 12.35-12.7 - E 11.95
R5 - C 17.35
Q2 - G 17.34 - D 23.98 - S 12.74
Right
Q1 - S 0.024 - D 12.06 - G 4.6
Q4 - D 23.96
R10 - G 3.83
R9 - S 4.6
R15 - B 11.9-12.73 - E 12.05
R5 - C 17.43
Q2 - G 17.43 - D 23.98 - S 12.81
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Glad the 'poke' test worked for you. C3 is the input capacitor so will affect the sound! I would still recommend re-flowing all the joints though, cold or dry solder joints never get better only worse, especially with the thermal cycle they go through in the ACA.
Thanks for the feedback, and those readings are all spot on by the way. Alan
I re-flowed both boards and it works on cold boot. Thank you so much for walking me through this and for checking my work. I am so relieved it is sounding like itself again because i love the sound so much. With the B1 now, it is dead silent even with efficient speakers.
(coffee table is a subwoofer)
Very simplistically there are four options for the ACA.
First is the standard build, a stereo amplifier with left and right channels in one box. It puts out about 8 Watts per side into 8 ohm speakers. Less into 4 or 16 ohm speakers.
Second is 'Bridged Mono - balanced'. You Have to Have a pre amp or source that has a balanced output to use this mode. (That uses the XLR connector.) The effect is to basically 'bridge' the two channels together so it can have one side handle the positive half of the signal and the other the negative half. This way for the same supply voltage you get twice the available voltage 'swing'.
So for speakers that need more voltage to drive them (8 to 16 ohms) you get nearly twice the power 14 or 15 Watts.
Third is 'Bridged Mono - unbalanced'. This does not need the balanced input as it takes the output of one channel and feeds it to the input of the other channel via a resistor. You get the same doubling of power as the second option (15 Watts into 8 - 16 ohms), but can use a standard pre-amp.
Fourth is 'Parallel Mono'. This has both channels working together with both inputs connected together and both outputs connected together. As both halves are amplifying the same signal there is no voltage benefit, but you effectively double the output current. This is very useful if you have low impedance speakers of 4 ohms that are current and not voltage hungry. Again 14 or 15 Watts.
So there isn't a single simple answer... it depends on your source, RCA unbalanced or XLR balanced and the impedance of your speakers and how much power you want / need in order to make a choice.
As ThermalA says the build guide pretty well covers it, the table is enclosed.
Hope it helps a bit more than confuses, Alan
Attachments
Thanks 6L6, when I built my ACA, THAT photo hadn't been uploaded yet, and it was promised to be, which I see it has.
What's in a word?
That is double mono in anyone's book! Or at least using two separate amps to create two separate inputs to two separate speakers is a form of unbalanced stereo.
This is what I've been asking all long. I kept checking to see if those photos had been uploaded and they hadn't, of course as soon as I stopped looking because I had finished the amp, they were posted.
Alan4411: there are three options that you mention apart from the basic stereo build:
Second is 'Bridged Mono - balanced'. You Have to Have a pre amp or source that has a balanced output to use this mode. (That uses the XLR connector.) The effect is to basically 'bridge' the two channels together so it can have one side handle the positive half of the signal and the other the negative half. This way for the same supply voltage you get twice the available voltage 'swing'.
So for speakers that need more voltage to drive them (8 to 16 ohms) you get nearly twice the power 14 or 15 Watts.
Third is 'Bridged Mono - unbalanced'. This does not need the balanced input as it takes the output of one channel and feeds it to the input of the other channel via a resistor. You get the same doubling of power as the second option (15 Watts into 8 - 16 ohms), but can use a standard pre-amp.
Fourth is 'Parallel Mono'. This has both channels working together with both inputs connected together and both outputs connected together. As both halves are amplifying the same signal there is no voltage benefit, but you effectively double the output current. This is very useful if you have low impedance speakers of 4 ohms that are current and not voltage hungry. Again 14 or 15 Watts.
They are all mono, so the question is: can a stereo sound be heard from any of these?
ThermalAlchemy: I believe that the photos explain what words have failed to do.
I thank everyone for trying to help with the explanation, just one last question, because the wording has left me puzzled, and still hasn't made it any clearer, what of those three "mono" versions are in shown in step 54? Single ended?
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Perhaps what is missing in your puzzle is knowing that, other than for option 1, you need TWO amps! Identically wired, one receives the left channel, the other the right and with that you get stereo. You have one speaker connected to one amp, the other to the second one. So you have two mono blocks. None of the configurations 2 through 4 can be run in stereo with a single amp.
Maybe that helps clarify thins?
Maybe that helps clarify thins?