Pa is often referring to resistor as "Current Source" ....... so why not
though, I'm not really sure which schm you're thinking of, regarding R4 nomenclature ...... there are few of them floating around
though, I'm not really sure which schm you're thinking of, regarding R4 nomenclature ...... there are few of them floating around
All of these values are within the tolerances of a 5% resistor, meaning that every resistor value listed could be more off from its value, than the one you picked as a replacement. 😛
It is great to see this thread come alive again, I like Craigl59 am using the full upgrades with the rthatcher power filter, it sounds really open on top with that filter. I am thinking of trying the 36v PSU on my other ACA. I have to add that resistor on the jfet first so that is my next mission. I was also thinking of trying Audio Note Kasei or Mundorf AG 4700uf at C1 and seeing what that sounds like in comparison to the "Fine tune" Nichicon.
I would also say that I think changing the transistors to the FHQ44n10's was huge and I liked them so much better than the 140's or 240's.
I would also say that I think changing the transistors to the FHQ44n10's was huge and I liked them so much better than the 140's or 240's.
So, planning to give the 36v Meanwell a try and will add a 1k resistor to the D of Q4.
Tungsten: Can I just add that resistor to the leg of the d on Q4 (trim the leg etc) Or is it better to cut the trace?
Rthatcher: Do you think you filter can handle 36V, what if I changed the 1000uf cap to a 50v?
Has anyone tried the 36v Meanwell?
I'm running the FQH44N10 and I hear they like to run with more voltage.
Tungsten: Can I just add that resistor to the leg of the d on Q4 (trim the leg etc) Or is it better to cut the trace?
Rthatcher: Do you think you filter can handle 36V, what if I changed the 1000uf cap to a 50v?
Has anyone tried the 36v Meanwell?
I'm running the FQH44N10 and I hear they like to run with more voltage.
I would probably cut the trace rather than trying to lift one leg of Q4, but it’s your call.
Note that the 36V Meanwell uses a different connector than the 24V one. You can either install the larger receptacle into your chassis, or convert the 36V cable to a barrel plug. Again, your call.
Note that the 36V Meanwell uses a different connector than the 24V one. You can either install the larger receptacle into your chassis, or convert the 36V cable to a barrel plug. Again, your call.
Zamjazz27 writes:
"Hw did the M2X turn out????!?!?"
Have both M2xs working splendidly, and the problem was mine -- had the wrong resistor value as noted above. Feel very dumb but this problem was generated by the SQL query at Mouser that shows 221k resistors in the same result listing output as 221 ones. My multimeter did not show the "K" value as large as necessary and now am very careful with resistors.
Have finished 3 daughterboards for these M2xs -- MoutainView, Tucson, and Austin. Austin appears to be a tight board for soldering UNTIL you build the WB2018 Linestage. Then it seems spacious.
Paul in WA provided the help I needed for the power supply parts and I can't thank him enough times. Have now ordered a set of PSU circuit boards from Gareth in the UK and they are held up by the British post. Am finding that I like the Tucson board with the Burson OpAmp best and this was, also, recommended by Paul. Have developed a system for switching to any of the 4 amps I currently run and am going to produce a thread showing the process soon.
Have a second DC generator coming tomorrow that will be used to test the Austin board with the +/- 24vdc. Want to do this as recommended above out of the box so that any burning will be limited. Am trying to find now where to connect the +/- DC to the daughterboard. Any help here would be appreciated.
Here is a photo of the M2x. Having the PSU as a separate box makes all the difference for noise. If I put the two boxes right next to each other, there is some bleed through. So, instead put the PSU on a different level and this makes for a totally dead quiet amp. You also have to zero out the DC offset, of course, and this requires the trimpot and resistor changes detailed above.
Again need to thank all of the fine people who got me to a state where I could build this amp. Am now building variants of the B1 Korg Preamp and getting ready to fire up the WB2018 Linestage. Am waiting on boxes from Italy and transformers from China -- always seems to be the case.
The B1 preamps are marvelous-sounding but are, of course, marred by the microphonics of the NuTube.
"Hw did the M2X turn out????!?!?"
Have both M2xs working splendidly, and the problem was mine -- had the wrong resistor value as noted above. Feel very dumb but this problem was generated by the SQL query at Mouser that shows 221k resistors in the same result listing output as 221 ones. My multimeter did not show the "K" value as large as necessary and now am very careful with resistors.
Have finished 3 daughterboards for these M2xs -- MoutainView, Tucson, and Austin. Austin appears to be a tight board for soldering UNTIL you build the WB2018 Linestage. Then it seems spacious.
Paul in WA provided the help I needed for the power supply parts and I can't thank him enough times. Have now ordered a set of PSU circuit boards from Gareth in the UK and they are held up by the British post. Am finding that I like the Tucson board with the Burson OpAmp best and this was, also, recommended by Paul. Have developed a system for switching to any of the 4 amps I currently run and am going to produce a thread showing the process soon.
Have a second DC generator coming tomorrow that will be used to test the Austin board with the +/- 24vdc. Want to do this as recommended above out of the box so that any burning will be limited. Am trying to find now where to connect the +/- DC to the daughterboard. Any help here would be appreciated.
Here is a photo of the M2x. Having the PSU as a separate box makes all the difference for noise. If I put the two boxes right next to each other, there is some bleed through. So, instead put the PSU on a different level and this makes for a totally dead quiet amp. You also have to zero out the DC offset, of course, and this requires the trimpot and resistor changes detailed above.
Again need to thank all of the fine people who got me to a state where I could build this amp. Am now building variants of the B1 Korg Preamp and getting ready to fire up the WB2018 Linestage. Am waiting on boxes from Italy and transformers from China -- always seems to be the case.
The B1 preamps are marvelous-sounding but are, of course, marred by the microphonics of the NuTube.
Attachments
TungstenAudio and Zammjazz27:
Wanted to add that I have added RkThatcher's CLC filter to my ACAs and this makes a tremendous difference. Am now going to use one of Gareth's transformer PSUs that produces 24vdc and see how the ACAs sound with this PSU board -- it will just barely fit into the case. Am finding that the PSU makes a tremendous difference on sound quality and want to hear how good the ACA boards can become with the premium upgrades we have all adopted.
And every time I work on the ACAs, I thank TungstenAudio for his substantial help and for suggesting that my dual-smps idea might work. Those who embrace the advantages of "give it a try" are the best.
Wanted to add that I have added RkThatcher's CLC filter to my ACAs and this makes a tremendous difference. Am now going to use one of Gareth's transformer PSUs that produces 24vdc and see how the ACAs sound with this PSU board -- it will just barely fit into the case. Am finding that the PSU makes a tremendous difference on sound quality and want to hear how good the ACA boards can become with the premium upgrades we have all adopted.
And every time I work on the ACAs, I thank TungstenAudio for his substantial help and for suggesting that my dual-smps idea might work. Those who embrace the advantages of "give it a try" are the best.
Tungsten thanks for the quick reply, I think I am pretty comfortable cutting the trace. I found this meanwell at parts express and it uses the same barrel connector as the aca, what do you think?
https://www.parts-express.com/Mean-...pter-with-2.5-x-5.5mm-Center-Positive-129-225
Craigl59, wow that amp looks amazing, you are really inspiring me to build on of these 25w amps next summer! The rthatcher filter seems to really open up the top end and allow for much more clarity around spatial cues and details. I was shocked at the change, it is a little less warm sounding though. I may add my 1000uf cap back on the v+ input on the board and see how that works in tandem.
What is Gareth's transformer PSU?
I completely agree this thread has been so much fun to follow and "giving it a try" has been such a learning experience and the sound out of this amp is so good! Next might try a dual 36v smps ACA!
https://www.parts-express.com/Mean-...pter-with-2.5-x-5.5mm-Center-Positive-129-225
Craigl59, wow that amp looks amazing, you are really inspiring me to build on of these 25w amps next summer! The rthatcher filter seems to really open up the top end and allow for much more clarity around spatial cues and details. I was shocked at the change, it is a little less warm sounding though. I may add my 1000uf cap back on the v+ input on the board and see how that works in tandem.
What is Gareth's transformer PSU?
I completely agree this thread has been so much fun to follow and "giving it a try" has been such a learning experience and the sound out of this amp is so good! Next might try a dual 36v smps ACA!
ZamJazz27: Here you go:
https://www.audiosy.net/2021/03/17/first-look-artemis-single-rail-power-supply-rev-b/This is the 24 VDC supply suitable for the ACA (if it will fit -- won't know for sure until it arrives). The site also has a bi-polar version that will do the +/- 24vdc required for many of the other Pass builds. Found Gareth on this site and he is very good to talk with -- but the shipping from the UK is impossible. Packages sent to them languish for 2 or more weeks before they bother to send them out to the other country.
The more I build, the more I grow tired of 1) product unavailability and 2) shipping time and cost. The new reality is that you must order from all over the world and the chances of things going wrong are endless. OHHH for the old days when there were Radio Shacks and electronic stores in town with parts and used items aplenty.
https://www.audiosy.net/2021/03/17/first-look-artemis-single-rail-power-supply-rev-b/This is the 24 VDC supply suitable for the ACA (if it will fit -- won't know for sure until it arrives). The site also has a bi-polar version that will do the +/- 24vdc required for many of the other Pass builds. Found Gareth on this site and he is very good to talk with -- but the shipping from the UK is impossible. Packages sent to them languish for 2 or more weeks before they bother to send them out to the other country.
The more I build, the more I grow tired of 1) product unavailability and 2) shipping time and cost. The new reality is that you must order from all over the world and the chances of things going wrong are endless. OHHH for the old days when there were Radio Shacks and electronic stores in town with parts and used items aplenty.
oh cool!
Also this Meanwell 36v looks even better than the one I linked before: https://www.parts-express.com/36-VD...with-2.5-x-5.5mm-Center-Positive-Plug-120-063
Also this Meanwell 36v looks even better than the one I linked before: https://www.parts-express.com/36-VD...with-2.5-x-5.5mm-Center-Positive-Plug-120-063
The 160W (4.4A), 36V Meanwell PSU looks legitimate. Convenient barrel plug adapter.
That second one is not a Meanwell brand, it is only listed as a Parts Express brand. No specification on how it recovers from over current condition. No specification for ripple, or much of anything else. Looks dodgy.
That second one is not a Meanwell brand, it is only listed as a Parts Express brand. No specification on how it recovers from over current condition. No specification for ripple, or much of anything else. Looks dodgy.
Tungsten thanks!, I didn't catch that the second one was unbranded.
Also, I found this photo earlier in this thread from strongbow. Is this the correct placement of R16, I would think this would create a low pass filter with C4, would it be better to place R16 on the longer trace heading up to the jfet?
Also, I found this photo earlier in this thread from strongbow. Is this the correct placement of R16, I would think this would create a low pass filter with C4, would it be better to place R16 on the longer trace heading up to the jfet?
The photo shows the preferred location for R16. You want to create the low pass filter with C4.
I posted ACA Filter PCB gerbers on the GB thread. One post (#136) for the regular board, and a separate post (#137) for the dual SMPS version. Enjoy!
https://www.diyaudio.com/community/...supply-filter-kits.376245/page-7#post-6887742
https://www.diyaudio.com/community/...supply-filter-kits.376245/page-7#post-6887742
36v update! So I was able to get R16 in at 1K, first time cutting a trace and it all went well. I used the Meanwell linked above with the barrell connector from part express. I adjusted the bias up to 18.5 volts. I also replaced the caps in rhthatcher's board with 1000uf 50v Nichicon FW and I also have the same cap across the voltage input on each board. One interesting thin is that there is no sound at start-up, used to have that little squelch sound.
So how does it sound? Well, Tungsten, unsurprisingly was right again, the FQH44N10 does seem to like to run at a higher voltage. Trying to describe the sound without sounding over the top. The sound is so solid but also so liquid and effortless. It sounds fantastically balanced and every instrument seems to be more fleshed out. The real strength in this amp now is how it is able to make your speakers disappear, the low level details that create the space around the instruments are amazing, the long trailing decay of a cymbal or reverb is amazing. I felt like every aspect of my system had been upgraded significantly.
I'll be doing a little comparison with my other ACA which is dual 24v smps with the rhthatcher board today... but it isn't going to be close. I will be pulling this amp apart again and making it a dual 36v smps (although I don't know if that will really make an improvement?)
The amp does run hot, really hot, I'm not sure if running it off 36v makes it run hotter, but I am going to keep an eye on it
So how does it sound? Well, Tungsten, unsurprisingly was right again, the FQH44N10 does seem to like to run at a higher voltage. Trying to describe the sound without sounding over the top. The sound is so solid but also so liquid and effortless. It sounds fantastically balanced and every instrument seems to be more fleshed out. The real strength in this amp now is how it is able to make your speakers disappear, the low level details that create the space around the instruments are amazing, the long trailing decay of a cymbal or reverb is amazing. I felt like every aspect of my system had been upgraded significantly.
I'll be doing a little comparison with my other ACA which is dual 24v smps with the rhthatcher board today... but it isn't going to be close. I will be pulling this amp apart again and making it a dual 36v smps (although I don't know if that will really make an improvement?)
The amp does run hot, really hot, I'm not sure if running it off 36v makes it run hotter, but I am going to keep an eye on it
Glad you like the way they sound. 
The higher supply voltage will certainly lead to more power and hotter heatsinks. As long as they don't burn your fingers, or any nearby dog noses, the higher temperature is Ok. There are ways of improving the thermal dissipation that may be worth trying. Or simply transplant the amps into the Mini Dissipante 3U, 250mm deep chassis.
The higher supply voltage will certainly lead to more power and hotter heatsinks. As long as they don't burn your fingers, or any nearby dog noses, the higher temperature is Ok. There are ways of improving the thermal dissipation that may be worth trying. Or simply transplant the amps into the Mini Dissipante 3U, 250mm deep chassis.
And while you're at it, buy a Dodge Hemi to flesh out the hot rod scenario (LOL).
Am starting on a two-transformer build of the ACA and wondering if it would also benefit from 36vdc. Is that board still available that already has the trace-cut adjustment made? Have prepared a BoM of all the parts with TungstenAudio's original improvements and can make that available if anyone is interested.
Congrats, Zamjazz27!
Am starting on a two-transformer build of the ACA and wondering if it would also benefit from 36vdc. Is that board still available that already has the trace-cut adjustment made? Have prepared a BoM of all the parts with TungstenAudio's original improvements and can make that available if anyone is interested.
Congrats, Zamjazz27!