ACA amp with premium parts

[Dneu2011]

Is adding r16 as simple as cutting the trace on the PCB that goes from V+ to the positive of C4 and the D of Q4? Then adding a 499 ohm resistor from V+ to the positive of C4?

I circled it on the image below.

 

[dfoulk]

I did cut that trace on one set of 1.6 boards to insert the resistor. When I built up
another set of 1.6 boards, I just soldered the resistor to the drain leg and left the

trace intact. Either way worked fine for me🙂

 

[Dneu2011]

Ok. Much easier than I thought. I was under the impression I had to cut some traces and risk screwing up.

So, I will solder one end of the 499 ohm resistor to V+, then extend it to connect to the drain on Q4? No traces needing to be cut.

Just making sure so I can easily make the modification.

 

[dfoulk]

I snipped the drain leg of Q4 off a bit, and just soldered it to the leg of Q4, then

soldered Q4 into place on the board. Just don't overheat Q4 when soldering the resistor to the end of the leg. If I can find the picture I took of mine, I will post it.
Den

 

[Dneu2011]

Oh. Makes complete sense. Should be easy to do as I’m not having to modify an already stuffed board.

Thank you so much for clarifying.

 

[dfoulk]

Sure!
I can't find the picture I took of the resistor altered leg, but you understand🙂
The only other thing I did was slip a little piece of heatshrink over the leg to make sure it didn't touch the middle leg, but that is not really necessary.

 

[Dneu2011]

One can never be too safe! Thanks.

 

[dfoulk]

I tend to think that way too

 

[heavysugar]

Would someone be willing to help me get all the parts I need for the "TungstenAudio" upgrade? I have tried reaching out to him more than once with no luck. I already have two of the ACA amps and just want to make sure I'm getting the right parts in my cart.
I'm not even sure where I should be ordering these parts from.
I will Venmo or PayPal you a couple bucks for your time and trouble. Thanks in advance.
Raymond

 

[Dneu2011]

So, here is an update to my attempt at building an external power supply for a pair of amp camps to replace the 24V power supplies.

I am using 4 of Rudi’s CapMX power supply boards with 24V 200va secondaries showing 28V on the rails. I made all the modifications from Tungenstenaudios schematic including the 499 ohm resistor 16 and irfp140s on Q1 and Q2. I’ve tested all 4 boards on a large heatsink and they all test fine. Now I need to try wiring all of them up for a test to see how they sound.

Goal is to cut the heatsinks down but have them at least 40% larger than the aca chassis heatsinks to handle the higher voltages and heat. I biased all the boards to 14V which I hope isn’t too high.

Any more feedback on this build would be great!

 

[6L6]

The pot does not set bias, it's DC balance. Set to 1/2 the rail voltage like you've got it. 🙂

 

[Dneu2011]

Aw.... got it! Thanks.

 

[twocents]

Would someone be willing to help me get all the parts I need for the "TungstenAudio" upgrade? I have tried reaching out to him more than once with no luck. I already have two of the ACA amps and just want to make sure I'm getting the right parts in my cart.
I'm not even sure where I should be ordering these parts from.
I will Venmo or PayPal you a couple bucks for your time and trouble. Thanks in advance.
Raymond

Hi Raymond. I was planning to pimp my ACA with some premium parts last year, but never pulled the trigger since I am no longer using my ACA. My pimping plan was based on going through this thread and making notes of the modifications made by members TungstenAudio, JOIMONF and dfoulk. Here is a spreadsheet with the TungstenAudio modifications and the Mouser part numbers of the parts that I would have ordered. I hope it helps you, but I take no responsibility if the listed parts are incorrect or does not bring the desired results.

We can discuss PayPal bucks once your ACA amps sound so much better after the mods. 😀

 

[jdb996]

Has anybody look at the PS-3N35 PS-3N35 - 300W 35V Power Supply - AnTek Products Corp As a possible internal PS?

 

[TungstenAudio]

^ Those power supplies are intended for industrial motor / servo applications. Probably not a good choice for audio. The ACA responds well to a good linear PSU, such as CRC, CRCRC, or possibly CLCRC. I haven't found any benefit from using integrated 3-pin regulataors, but low Vf diode bridges do help.

 

[chermann]

Hi


i started with my ACA before Christmas with the zerozone clone pcb. i read all of the ACA thread...

before i do my 2nd ACA with modded parts i read all pages of this premium part thread. hopefully i get everything in my head..😉


my second boards are nearly ready and i did most of the modification but i do not order some other MOSFET. before i ordered i did an overview of all "facts" of the power MOSFET i think they are important. be patient with me because i am not sure i miss some datas.😉


first questions
is it wrong to think that the CCS Q2 should be a low Rds on to deliver better/faster the current?

View attachment ACA_MOSFET_Compare_v01.pdf

chris


edit
upload again..typo

 

[Loudthud]

Rds(on) has little effect. Input capacitance and the Gate stoppers have a much bigger influence on THD above 5KHz or so. More capacitance equals more THD.

 

[NBPK402]

Is there a addon for remote start?

 

[chermann]

Rds(on) has little effect. Input capacitance and the Gate stoppers have a much bigger influence on THD above 5KHz or so. More capacitance equals more THD.

thank you for your explanation.
i will update the not listed MOSFET IX....etc.

 

[Stanislav]

Hi


i started with my ACA before Christmas with the zerozone clone pcb. i read all of the ACA thread...

Don't think some of the data in your file, especially for IRFP044 & 150 is correct.
The datasheets I've got state :
Ciss 044 - 2500pF
150 - 1900pF
Maybe you have parts from different manufacturers.