These have a serious potential to sound fabulous. You see, these do not have any hook-up wiring to degrade the performance. The only limiting factor is the power supply's quality, and its phase margin.I've wanted to build the ACA amps ever since they came out but life gets in the way. Well I'm going to build these!!!
I've never heard them before and don't know if they need a preamp.
Any thoughts
I was able to drive the 86dB efficient Dynaudios with standard ACA to a very satisfying level. The sound was beautiful.
Re: pre-amp... it is a good idea if you need more gain and source selection and volume control. However, you will be introducing the contact resistances, volume control... additional capacitors in a signal path, interconnects... hook-up wiring; in other words, have a look at the first paragraph (you'll be using a simplistic approach no frills amplifier), and then consider what your priorities are.
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Great news! The first batch of kits are complete. Just in time for Burning Amp build camp too 😉
30 builders put their kits together at the event in San Francisco over the course of 3 hours. Organizing a build like this is new for me but I had a great time and I'd venture to say the builders did too.
The remaining kits are currently in my garage except for one that I sent to 6L6 who generously offered to make a build guide. I'm excited about that for two reasons, it's one less thing I need to do for the kits, and, more importantly, he makes excellent guides!
Not so good news. The kits as they are currently packed are not ready for shipping. The parts move around too much in the box and I want to avoid them banging around and getting damaged. Anyone willing to make the trip to San Francisco, send me an email at acaredux@gmail.com and we can schedule a time for pickup. All others, sit tight, I'll be working toward a new packing solution that properly protects the kits in shipping.
30 builders put their kits together at the event in San Francisco over the course of 3 hours. Organizing a build like this is new for me but I had a great time and I'd venture to say the builders did too.
The remaining kits are currently in my garage except for one that I sent to 6L6 who generously offered to make a build guide. I'm excited about that for two reasons, it's one less thing I need to do for the kits, and, more importantly, he makes excellent guides!
Not so good news. The kits as they are currently packed are not ready for shipping. The parts move around too much in the box and I want to avoid them banging around and getting damaged. Anyone willing to make the trip to San Francisco, send me an email at acaredux@gmail.com and we can schedule a time for pickup. All others, sit tight, I'll be working toward a new packing solution that properly protects the kits in shipping.
Great news! The first batch of kits are complete. Just in time for Burning Amp build camp too 😉
30 builders put their kits together at the event in San Francisco over the course of 3 hours. Organizing a build like this is new for me but I had a great time and I'd venture to say the builders did too.
The remaining kits are currently in my garage except for one that I sent to 6L6 who generously offered to make a build guide. I'm excited about that for two reasons, it's one less thing I need to do for the kits, and, more importantly, he makes excellent guides!
Not so good news. The kits as they are currently packed are not ready for shipping. The parts move around too much in the box and I want to avoid them banging around and getting damaged. Anyone willing to make the trip to San Francisco, send me an email at acaredux@gmail.com and we can schedule a time for pickup. All others, sit tight, I'll be working toward a new packing solution that properly protects the kits in shipping.
Hmm... how can we order them? I can wait for you to get around to shipping. Would definitely make a great Christmas vacation project.
SF is an 8 hour drive, so I can wait.
I will happy to repair just in case....😉 you can ship to me as is if possibleGreat news! The first batch of kits are complete. Just in time for Burning Amp build camp too 😉
30 builders put their kits together at the event in San Francisco over the course of 3 hours. Organizing a build like this is new for me but I had a great time and I'd venture to say the builders did too.
The remaining kits are currently in my garage except for one that I sent to 6L6 who generously offered to make a build guide. I'm excited about that for two reasons, it's one less thing I need to do for the kits, and, more importantly, he makes excellent guides!
Not so good news. The kits as they are currently packed are not ready for shipping. The parts move around too much in the box and I want to avoid them banging around and getting damaged. Anyone willing to make the trip to San Francisco, send me an email at acaredux@gmail.com and we can schedule a time for pickup. All others, sit tight, I'll be working toward a new packing solution that properly protects the kits in shipping.

I've opened orders for ACA Redux kits! I think I contacted everyone who filled out the interest form so far, so check your emails.
Mr. Pass (the other Nelson
) was kind enough to provide 2SK370 and IRFP048 from his not so secret stash for these kits. Thank you again!
Take a look at the beauty pics courtesy of 6L6. Thank you too!
I should have expected this, but costs add up. The final price per kit is $220 plus actual shipping cost. Sorry for the tease, I'm new to this, but that's part of why I didn't take pre-orders.
If you were waiting, now's the time to fill out the order form. When I run out of kits I'll stop taking orders and start gauging interest in another run of kits.
Mr. Pass (the other Nelson

Take a look at the beauty pics courtesy of 6L6. Thank you too!
I should have expected this, but costs add up. The final price per kit is $220 plus actual shipping cost. Sorry for the tease, I'm new to this, but that's part of why I didn't take pre-orders.
If you were waiting, now's the time to fill out the order form. When I run out of kits I'll stop taking orders and start gauging interest in another run of kits.
Attachments
I've opened orders for ACA Redux kits! I think I contacted everyone who filled out the interest form so far, so check your emails.
Mr. Pass (the other Nelson) was kind enough to provide 2SK370 and IRFP048 from his not so secret stash for these kits. Thank you again!
Take a look at the beauty pics courtesy of 6L6. Thank you too!
I should have expected this, but costs add up. The final price per kit is $220 plus actual shipping cost. Sorry for the tease, I'm new to this, but that's part of why I didn't take pre-orders.
If you were waiting, now's the time to fill out the order form. When I run out of kits I'll stop taking orders and start gauging interest in another run of kits.
Hmm, I didn't get an email. I'm pretty sure I filled out the interest form a while back. Where is it?
Just checked and you're not in my response list. I hope google hasn't been dropping responses some how. Can you try submitting the form again?Hmm, I didn't get an email. I'm pretty sure I filled out the interest form a while back. Where is it?
Hey, Nelson, I was at the BAF build (we moseyed in after everyone started). Where did you source those groovy multi-colored LEDs? I love them. Thanks.
Where is the form?Just checked and you're not in my response list. I hope google hasn't been dropping responses some how. Can you try submitting the form again?
mini kit like pcb Nelson active part ? to UE is a bit prices adding at 50$min shipping the 28% import taxI've opened orders for ACA Redux kits! I think I contacted everyone who filled out the interest form so far, so check your emails.
Mr. Pass (the other Nelson) was kind enough to provide 2SK370 and IRFP048 from his not so secret stash for these kits. Thank you again!
Take a look at the beauty pics courtesy of 6L6. Thank you too!
I should have expected this, but costs add up. The final price per kit is $220 plus actual shipping cost. Sorry for the tease, I'm new to this, but that's part of why I didn't take pre-orders.
If you were waiting, now's the time to fill out the order form. When I run out of kits I'll stop taking orders and start gauging interest in another run of kits.
You can find them on ebay, AliExpress and the like by searching for "slow color change LED". They make a fast flashing version too but they're... overstimulating.Hey, Nelson, I was at the BAF build (we moseyed in after everyone started). Where did you source those groovy multi-colored LEDs? I love them. Thanks.
I'm only offering compete kits at this time. I've considered selling bare PCBs, but even that is a little complicated for this design. The holes on the heatsink need to line up with the PCB, so if you source your own there's no guarantee they'll match and if you bought from my local USA source you'd have the same import problems.mini kit like pcb Nelson active part ? to UE is a bit prices adding at 50$min shipping the 28% import tax
If you're interested in an ACA with more customization (for skilled diy's), I'd recommend you check out this premium ACA thread. TungstenAudio gave me an extra set of the PCBs by Rudi_Ratlos that I'd be willing to send you for the cost of shipping.Ok tnx ,btw but bare pcb+mosfet is for skilled diy's 😉
Hi Folks,
I'm having some issues sending emails with similar content to everyone that filled out the interest form. Looks like spam to the email systems.
Rather than try to make email work, I've created a new google form for submitting orders. I'll reach out to those that filled out the form previously, but anyone who wants a kit will need to fill out the new form. Sorry for any confusion this may have caused.
ACA Redux Order Form
I'm having some issues sending emails with similar content to everyone that filled out the interest form. Looks like spam to the email systems.
Rather than try to make email work, I've created a new google form for submitting orders. I'll reach out to those that filled out the form previously, but anyone who wants a kit will need to fill out the new form. Sorry for any confusion this may have caused.
ACA Redux Order Form
I am in receipt of my ACA Redux order. The kits are really solidly packed and arrived without a scratch and quickly after ordering - thanks Nelson!
For those who might be interested in the nature of some of the key parts included, beyond what Nelson said in post #226, a quick survey gives the following:
1000µF/25V caps — Rubycon PX series
10µF/25V caps — Elna Silmic II
IRFP048N — actual International Rectifier parts (have the I🖤R logo molded in)
Silpads for the above — pale lavender colored
24V PS (2 units) — Jameco ReliaPro; output rated at 24V 2.5A 60W, UL Listed
For those who might be interested in the nature of some of the key parts included, beyond what Nelson said in post #226, a quick survey gives the following:
1000µF/25V caps — Rubycon PX series
10µF/25V caps — Elna Silmic II
IRFP048N — actual International Rectifier parts (have the I🖤R logo molded in)
Silpads for the above — pale lavender colored
24V PS (2 units) — Jameco ReliaPro; output rated at 24V 2.5A 60W, UL Listed
Hi Folks,
I'm having some issues sending emails with similar content to everyone that filled out the interest form. Looks like spam to the email systems.
Rather than try to make email work, I've created a new google form for submitting orders. I'll reach out to those that filled out the form previously, but anyone who wants a kit will need to fill out the new form. Sorry for any confusion this may have caused.
ACA Redux Order Form
I guess... hmm... do I have to reorder or am I golden on this?
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