I think I found the issue.
I have replaced R12 with 90.9 ohm instead of 90.9 k ohm.
There were no soldering issues with the board components joints, as they were working properly before I exchanged them.
I picked up a couple ACA kits and waiting on the chassis'. I've been through this thread and was looking for opinion. I'm a complete rookie. Wondering if its worth sourcing and building with the premium parts (surprisingly inexpensive) given that I have no experience in these things. I am counting on the step by step instructions provided to get them built. Thoughts?
This design is very consistent in sound with regards to parts, good parts from any first-tier supplier (Mouser, DigiKey, etc...) and it will work and sound great. 
Which is to say, the parts in the kit are perfect. Changing things when you have no idea what they do is essentially an exercise in spending money that’s not needed nor will make a difference.
Which is to say, the parts in the kit are perfect. Changing things when you have no idea what they do is essentially an exercise in spending money that’s not needed nor will make a difference.
This design is very consistent in sound with regards to parts, good parts from any first-tier supplier (Mouser, DigiKey, etc...) and it will work and sound great.
Which is to say, the parts in the kit are perfect. Changing things when you have no idea what they do is essentially an exercise in spending money that’s not needed nor will make a difference.
Great advice and really where I was leaning. Those rabbit holes are hard to avoid in this hobby.
A lack of knowledge question to be asked.
Did not feel this question was appropriate for the regular normal Amp Camp Amp threads. Since this appears to be the hot rod version of the ACA
Is it possible to use this MOSFET (IXFK120N20P or IXFK140N20P in a simple circuit as the ACA ?.
I just seen Steve Guttenburg‘s review of the Gato AMP 150 amplifier in seeing this MOSFET and ACA was the first thing that popped in my mind .
I see here in DYIaudio we have a thread called ( 50 W single Ended BAF2015 Schade enabled ) that uses these MOSFETs.
Would it be possible in such a low component count simple circuit as the ACA to implement this of course at much higher voltage us. Even swing this babies voltage at 60 V in each direction . Of course disregarding all safety ?
Been watching this thread since the beginning just not dabbled in it myself.
But I see some of the most inquisitive minds who like to dabble in different are on this thread
Did not feel this question was appropriate for the regular normal Amp Camp Amp threads. Since this appears to be the hot rod version of the ACA
Is it possible to use this MOSFET (IXFK120N20P or IXFK140N20P in a simple circuit as the ACA ?.
I just seen Steve Guttenburg‘s review of the Gato AMP 150 amplifier in seeing this MOSFET and ACA was the first thing that popped in my mind .
I see here in DYIaudio we have a thread called ( 50 W single Ended BAF2015 Schade enabled ) that uses these MOSFETs.
Would it be possible in such a low component count simple circuit as the ACA to implement this of course at much higher voltage us. Even swing this babies voltage at 60 V in each direction . Of course disregarding all safety ?
Been watching this thread since the beginning just not dabbled in it myself.
But I see some of the most inquisitive minds who like to dabble in different are on this thread
"Is XYZ possible" means, to me anyway, "Could 200 NASA scientists possibly achieve XYZ, in less than 10 years, spending less than 500 million dollars per year?"
And here I think the answer is yes. I think "it is possible" to use the IXFK140N20P in a simple circuit similar the ACA. I even think it is possible to do so in a low component count (if you only count electronic components), simple circuit.
And here I think the answer is yes. I think "it is possible" to use the IXFK140N20P in a simple circuit similar the ACA. I even think it is possible to do so in a low component count (if you only count electronic components), simple circuit.
one of Singing Bush iterations ( look for thread of same name) is exactly that - realization of Papa's recipe from one of BAF lectures
in fact, that's just one of realizations
you can take it as further step in ACA style amp - lower mosfet being fooled to act and think as Triode
The basic ACA circuit topology has shown itself to be quite versatile to careful modification. Even a simple substitution of IRFP140 for the IRFP240 can lead to a worthwhile improvement, especially when using higher power supply voltage (say 28V to 30V). Going beyond that, a few forum members have reported positive experiences using devices such as the FQH44N10 or even the Semisouth SJEP120R100 in the Q1 position, combined with a more common IRFP044 in the Q2 position. These tend to use even higher supply voltages. Have a look at the discussions in this thread around posts in the early #300s.
I think it is certainly possible to use the IXFK parts mentioned, as long as some careful work is done to find suitable operating conditions for those parts. I would expect higher bias currents and larger heatsinks to be necessary..
I think it is certainly possible to use the IXFK parts mentioned, as long as some careful work is done to find suitable operating conditions for those parts. I would expect higher bias currents and larger heatsinks to be necessary..
Thank you for all the input and information.
The ACA is an excellent beginning learning tool to experiment with. Low component count equals low cost unless you get exotic with your parts. I don’t mind learning with a little smoke, sparks, and fire arc flash without it life would be boring.
Sense cheap Chinese resistors bought by the thousands are less than 0.004 cents each (eBay China) and for bread boarding instead of using expensive three dollar a piece Vishay resistors.
I was just wondering if anybody within this thread on this form has personal experience with this MOSFET. Figured somebody would buy a set and run with it to see how it works.
Looks like I got some homework to do. And guaranteed smoke
The ACA is an excellent beginning learning tool to experiment with. Low component count equals low cost unless you get exotic with your parts. I don’t mind learning with a little smoke, sparks, and fire arc flash without it life would be boring.
Sense cheap Chinese resistors bought by the thousands are less than 0.004 cents each (eBay China) and for bread boarding instead of using expensive three dollar a piece Vishay resistors.
I was just wondering if anybody within this thread on this form has personal experience with this MOSFET. Figured somebody would buy a set and run with it to see how it works.
Looks like I got some homework to do. And guaranteed smoke
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Exactly what I was thinking first time I saw that trafo. Maybe a dual 160VA and top mounted?
They're not ACAs, but these two builds with external donuts were inspiring. Over or under, both stunning.
https://www.diyaudio.com/forums/pass-labs/166784-pictures-diy-pass-amplifier-545.html#post6464429
https://www.diyaudio.com/forums/pas...niversary-sony-vfet-clone-18.html#post6556190
https://www.diyaudio.com/forums/pass-labs/166784-pictures-diy-pass-amplifier-545.html#post6464429
https://www.diyaudio.com/forums/pas...niversary-sony-vfet-clone-18.html#post6556190
Premium or Exotic parts only
While I was wiring my ACA v1.8 I got the the SCCB by late Allen Wright and I could not continue wiring with the new found knowledge on interconnects. I also wanted to see what people have done to improve on the ACA amp, which is why I'm here. TungstenAudio has provided a list of upgrades including changing Q1, Q2, changing the amount of feedback and increased bias to 1.6A. PS. Thank you
Text based table of TungstenAudio for those of us on mobile where Zip files and Excel is not a real option:
While I was wiring my ACA v1.8 I got the the SCCB by late Allen Wright and I could not continue wiring with the new found knowledge on interconnects. I also wanted to see what people have done to improve on the ACA amp, which is why I'm here. TungstenAudio has provided a list of upgrades including changing Q1, Q2, changing the amount of feedback and increased bias to 1.6A. PS. Thank you
Text based table of TungstenAudio for those of us on mobile where Zip files and Excel is not a real option:
Code:
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| | | ACA v1.6 | | TungstenAudio | | Brand | Material | Mouser P/N | Comments |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R1 | | 0,47 | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R2 | | 0,47 | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R3 | | 0,68 | | 0,68 + 2 | | Panasonic | Metal Film Resistors, 3W, 5% | 667-ERX-3SJ2R0V | Parrallel with R3 and R4 or 0.51Ω |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R4 | | 0,68 | | 0,68 + 2 | | Panasonic | Metal Film Resistors, 3W, 5% | 667-ERX-3SJ2R0V | Parrallel with R3 and R4 or 0.51Ω |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R5 | | 100 | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R6 | | 100 | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R7 | | 10k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R8 | | 1k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R9 | | 1k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R10 | | 332k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R11 | | 10k | | 20k | | Vishay | Metal Film Resistors, 1/4W, 1% | 71-RN65C-F-20K | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R12 | | 39,2k | | 90,9k | | Vishay | Metal Film Resistors, 1/8W, 1% | 71-RN60C90R9F | Feedback resistor. Parrallel with C5 10pF |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R13 | | 10k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R14 | | 1k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R15 | | 2,21k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| R16 | | - | | 68,1k | | | Metal Film Resistors, 1/4W, 1% | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| | | | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| C1 | | 3300uF | | 4700uF | | Nichicon | Electrolytic - 25V, 20% | 647-LKG1V472MESBBK | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| C2 | | 1000uF | | 1000 uF | | Nichicon | Electrolytic - 16V, 20% | 647-RNL1C102MDS1KX | Nichicon RNL series |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| C3 | | 10uF | | 10uF | | Elna | Electrolytic Silmic II - 35V, 20% | 555-RFS35V100ME3#5 | Input cap |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| C4 | | 10uF | | 100uF | | Nichicon | Polymer Capacitors - 35V, 20% | 647-RL81V101MDN1 | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| C5 | | - | | 10 pF | | Cornell Dubilier | Mica Capacitors - 300V, 5% | 598-CD5CC100JO3F | Parrallel with R12 |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| | | | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| P1 | | 5k | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| | | | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| Q1 | | IRFP240 | | IRFP140 | | Infineon | | 942-IRFP140NPBF | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| Q2 | | IRFP240 | | IRFP140 | | Infineon | | 942-IRFP140NPBF | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| Q3 | | ZTX450 | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+
| Q4 | | LSK170 | | | | | | | |
+-----+--+----------+--+---------------+--+------------------+-----------------------------------+--------------------+-------------------------------------------+I'm here because I want mainly to upgrade to premium or Exotic parts, without changing their values or anything else about the circuit - which means resistors and capacitors in the signal path. After reading "Resistor non-linearity.." by Simon Ed I have come to the conclusion to use Vishay/Dale RN65E resistors and the 3rd harmonic being -35dB lower then Panasonic metal film resistors. See the attachment for RN65E distortion
After reading some 500 pages of articles on capacitor distortion and sound I'm actually more confused now than before:
and "Capacitor sound" by late Cyril Bateman. First of all the choice depends on DC bias and AC signal amplitude as well as the capacitance needed.
Batemans articles cover a range up to 100uF but not bigger. For C3 I would use two 22uF 63V bi-polar (Nitai or Black Gate if I can find some) or a single 10uF metallised PET (Evox Rifa). But metallised PET have to be measured for distortion for every single caps, since that varies a lot - basically you need to hand pick them.
I will try Wima MKS2 but there was nothing in the article suggesting MKS2 being the bese choise. Elna Silmic I (one) was not impressive in Batemans articles and I guess Silmic II (two) isn't that much "silkier".
Another route is to go specifically for 2nd harmonics distortion and go for 10uF (Elna Silmic II or YXF) with a 1uF film capacitor shunt (Vishay / Roederstein MKP) or metallised PPS. The shunt seems to increase 2nd harmonics. ACA is not going to win measurement awards - so why not go crazy
The output cap is problematic at 3300 to 4700 uF - there is no real guidance in Batemans articles. Maybe use two or four bi-polars in series to lower the distortion? Is there a way of getting rid of C1 ??
I'm going to use the ACA as monoblocks with balanced XLR's if that info helps?
I should also be able to get rid of the switch and the XLR connector and just wire everything straight to the board using thin silver single strand as interconnects and use XLR just in one end connecting to the pre-amp.
After reading some 500 pages of articles on capacitor distortion and sound I'm actually more confused now than before:
and "Capacitor sound" by late Cyril Bateman. First of all the choice depends on DC bias and AC signal amplitude as well as the capacitance needed.
Batemans articles cover a range up to 100uF but not bigger. For C3 I would use two 22uF 63V bi-polar (Nitai or Black Gate if I can find some) or a single 10uF metallised PET (Evox Rifa). But metallised PET have to be measured for distortion for every single caps, since that varies a lot - basically you need to hand pick them.
I will try Wima MKS2 but there was nothing in the article suggesting MKS2 being the bese choise. Elna Silmic I (one) was not impressive in Batemans articles and I guess Silmic II (two) isn't that much "silkier".
Another route is to go specifically for 2nd harmonics distortion and go for 10uF (Elna Silmic II or YXF) with a 1uF film capacitor shunt (Vishay / Roederstein MKP) or metallised PPS. The shunt seems to increase 2nd harmonics. ACA is not going to win measurement awards - so why not go crazy
The output cap is problematic at 3300 to 4700 uF - there is no real guidance in Batemans articles. Maybe use two or four bi-polars in series to lower the distortion? Is there a way of getting rid of C1 ??
I'm going to use the ACA as monoblocks with balanced XLR's if that info helps? I should also be able to get rid of the switch and the XLR connector and just wire everything straight to the board using thin silver single strand as interconnects and use XLR just in one end connecting to the pre-amp.
Attachments
What is in the signal path?
And "I need your help" and that is to mainly identify which components are in the signal path. I have marked my attempt with green color for what I think is the signal path and attached an image.
At first the -OUT and +OUT was confusing, but the design is inverting so by switching the the polarity you get a non-inverting amp.
If my assumptions are close enough then R1-R6, R8, R10, R11 and C1 and C3 as mentioned before as well as P1. C2 and C5 (TungstenAudio mod) are feedback caps cancels out - correct?
R7, R9, R12, R13 and R14 have no impact on the audio signal - right?
This is my first DIY amp and that's why I went with a kit. I appreciate the help I can get.
And "I need your help" and that is to mainly identify which components are in the signal path. I have marked my attempt with green color for what I think is the signal path and attached an image.
At first the -OUT and +OUT was confusing, but the design is inverting so by switching the the polarity you get a non-inverting amp.
If my assumptions are close enough then R1-R6, R8, R10, R11 and C1 and C3 as mentioned before as well as P1. C2 and C5 (TungstenAudio mod) are feedback caps cancels out - correct?
R7, R9, R12, R13 and R14 have no impact on the audio signal - right?
This is my first DIY amp and that's why I went with a kit. I appreciate the help I can get.
