I am almost done with a dual 36v smps version!
If anyone follows suit with making a 36v version please be aware that it runs hot!
Considering a bigger chassis and a dual mono 36v LPS down the road! but I think the next project for me is an open baffle experiment with Lii F15 drivers!
If anyone follows suit with making a 36v version please be aware that it runs hot!
Considering a bigger chassis and a dual mono 36v LPS down the road! but I think the next project for me is an open baffle experiment with Lii F15 drivers!
I am very new to the whole electronics-business, and chose to build "premium parts" version of the aca amp as one of my first soldering projects. After plugging it in, it unsurprisingly didn't work. One channel is getting hot, the other stays cold, neither is producing any audible output. I have started measuring resistances and voltages according to the troubleshooting diagrams in the build manual, but I am unsure whether the values also apply for this version. One thing I did noticed and found weird is that the voltage going into R10 is much higher than the voltage coming out. The input value obviously depends on P1, but the output is somewhere in the 200-500 mV, in any case way lower than the expected voltage at the gate of Q1.
Any help is greatly appreciated! I checked most of the connections and could find a cold solder. I have no real idea what to check next, and unfortunately I have only access to two multimeters without diode testing. Testing the mosfets is therefore possible, i guess, but I hope there are things I could check before getting into that. I have attached pictures of my mediocre soldering job, if this should be of any help.
Any help is greatly appreciated! I checked most of the connections and could find a cold solder. I have no real idea what to check next, and unfortunately I have only access to two multimeters without diode testing. Testing the mosfets is therefore possible, i guess, but I hope there are things I could check before getting into that. I have attached pictures of my mediocre soldering job, if this should be of any help.
Attachments
This is a difficult case where I have to say I don‘t know where to start. The construction itself is problematic, with obvious cold solder joints and inconsistencies between the two boards. There is also an excess of flux left on the boards, which prevents easy inspection.
First remove the extra 2.2 Ohm power resistors that were installed on top of whatever was below. Then clean off the excess flux using Isopropyl alcohol, take new pictures and try asking for help in the Amp Camp Amp sticky thread. There are more eyes on that thread that can help out.
First remove the extra 2.2 Ohm power resistors that were installed on top of whatever was below. Then clean off the excess flux using Isopropyl alcohol, take new pictures and try asking for help in the Amp Camp Amp sticky thread. There are more eyes on that thread that can help out.
The 36v dual smps version is up and running! The only other change I made this time is also trying Mundorf AG 4700uf 40v caps at C1.
I am immediately blown away by the transparency with this latest upgrade. There is an almost electrostatic sounding transparency in the midrange with a total lack of congestion. Every instrument and voice has its own space. The bass is deep and extended but without the trace of bloat that had been apparent before. The biggest improvement is how the speakers disappear, using the relatively affordable and efficient Klipsch RP600m speakers and the excellent Adcom GFP 750 preamp (also a Class A Mosfet Nelson Pass design)
The cumulative upgrades are:
Full Tungsten upgrades (Q1 and Q2 are FQH44N10's, R16 is 1k, C1 is upgraded to Mundorf AG 4700uf 40v, and R13 is 15k to dim LED on 36v supply)
rhthatcher power filter dual smps version (cap upgraded to Nichicon FW 1000uf 50v)
Nichicon FW 1000uf 50v on the voltage input of each board
2 Meanwell 36v smps power supplies
Caution: this version runs hot, and I may end up moving to a larger chassis with larger heatsinks.
I think this is pretty much the endgame for an smps powered ACA, it is so much better than the stock version or either monoblock configuration.
I am immediately blown away by the transparency with this latest upgrade. There is an almost electrostatic sounding transparency in the midrange with a total lack of congestion. Every instrument and voice has its own space. The bass is deep and extended but without the trace of bloat that had been apparent before. The biggest improvement is how the speakers disappear, using the relatively affordable and efficient Klipsch RP600m speakers and the excellent Adcom GFP 750 preamp (also a Class A Mosfet Nelson Pass design)
The cumulative upgrades are:
Full Tungsten upgrades (Q1 and Q2 are FQH44N10's, R16 is 1k, C1 is upgraded to Mundorf AG 4700uf 40v, and R13 is 15k to dim LED on 36v supply)
rhthatcher power filter dual smps version (cap upgraded to Nichicon FW 1000uf 50v)
Nichicon FW 1000uf 50v on the voltage input of each board
2 Meanwell 36v smps power supplies
Caution: this version runs hot, and I may end up moving to a larger chassis with larger heatsinks.
I think this is pretty much the endgame for an smps powered ACA, it is so much better than the stock version or either monoblock configuration.
Mundorf AG ? I have the rubycon on vfet kit2 as C1output ,
what you use before ? tnx
I was using the stock cap and then switched to a 4700uf Nichicon KG, I was hoping to find an Audio Note Kasei (based on the old black gate) to try as I'd used smaller Black Gates as output coupling caps in CD players years ago and loved the results. The Mundorf was another higher end cap with great specs that I though was worthy of trying out with an eye towards improving transparency and really opening up the ACA in terms of extension and low level detail as I think that output coupling cap can be pretty critical to the sound, which is why most designs avoid them altogether. I will say that removing the C1 cap is the biggest pita mod, they are a pain to get out.
Which Rubycon are you using?
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Thanks for the help have an order in for the following to upgrade my existing Version 1.8 Monoblock running Bridged Single Ended. Single 24V Meanwell Power Supplies on each.
Did I miss anything or am I about to do anything stupid?
C1: 4700 uF, 35V; Nichicon KG series "Gold Tune"
C2: 1000 uF, 16V; Nichicon RNL series Aluminum Organic Polymer
C4: 100 uF, 35V; Nichicon RL8 series Aluminum Organic Polymer
R11: 20 kOhm, 1/4W, 1% metal film
R12: 90.9 kOhm, 1/4W, 1% metal film
FQH44N10 - After reading through the forum, planning on using in Q1 positions on my monoblocks
68.1K bridge Resistor to replace the stock 30k
.5ohm 3W to replace stock R4 resistor, instead of using the 2.0 in parallel
System is 2021 Bluesound stream/dac, Elekit 8500 preamp, ACA 1.8 monos, Klipsch RF5000f
All looks good so far.
One possible addition might be what I’ve called R16, a resistor between the power rail and the drain of the input JFet. It is not required here with the 24V PSU, but acts as a noise filter in conjunction with C4. Requires some minor surgery with an Xacto knife to add.
One possible addition might be what I’ve called R16, a resistor between the power rail and the drain of the input JFet. It is not required here with the 24V PSU, but acts as a noise filter in conjunction with C4. Requires some minor surgery with an Xacto knife to add.
K170 works better @ ~7-8V Vds due to increasing gate current leakage at higher Vds. Size your R16 appropriately.
Has anyone experimented with going larger than 4700 on C1? I think the bass response is pretty spot on with that value.
There is no reason not to use a larger cap for C1, as long as it fits on the board. The Rubycon part mentioned above is a good choice; it has a smaller diameter and sounds fine once it has had some time to play.
On the VFET amp OS boards, the big electrolytic coupling caps have Wima 0.33 uF Polypropylene connected in parallel. Similar 0.47 uF caps would work just as well. There is not a place for these on the ACA boards, unless one wants to get really creative.
On the VFET amp OS boards, the big electrolytic coupling caps have Wima 0.33 uF Polypropylene connected in parallel. Similar 0.47 uF caps would work just as well. There is not a place for these on the ACA boards, unless one wants to get really creative.
I agree, would be pretty tough to get a bypass in there, running off 36v and biased at 18.5 what voltage rating do you think I should stick with for C1?
35V for C1. Pay attention to the diameter. It needs to fit within the other components that have been selected for adjacent locations. That's partly why I like the Aluminum-polymer cap for C2; it is smaller than most in diameter.
@Zamjazz27, interesting update on C1 with Mundorf Mlytic cap. But once you have replaced that, isnt the input cap now the bottle neck? Will you still hear the improvements with input cap being the same and just changing the output cap to Mundorf?
Thanks
Thanks
I have done all of the upgrades that Tungsten has provided so those input caps have been upgraded, maybe not to a crazy level. I know that the output coupling cap is pretty important from a sound quality standpoint which is why I chose to try a new one in that spot. It would be interesting to think about what you could do there. I do think that with this last upgrade and running on 36v that I have achieved a really high level of extension, bass definition, I listen to a lot of acoustic jazz and I notice myself really following the rhythmic momentum of the walking bass lines and really hearing the definition of the attack of different players. The stock ACA sounds very veiled by comparison with a more over ripe and bloated bass.
I don't know how much more punishment my boards can take as far as part switching, those boards are so robust! but maybe the bug will bite me again and I'll put some 6800-10,000uf caps on the output coupling and look out those other caps, but I don't think they are holding things back...