Wow. In checking the value I now see I ordered 90.9 ohm instead of 90.9K ohm resistors. Thanks for seeing this.
I appear to have two choices at Mouser right now. They appear to be almost the same outside of PPM. Which of the two should I choose?
https://www.mouser.com/ProductDetail/71-RN60D-F-90.9K
https://www.mouser.com/ProductDetail/71-RN60C9092F
I appear to have two choices at Mouser right now. They appear to be almost the same outside of PPM. Which of the two should I choose?
https://www.mouser.com/ProductDetail/71-RN60D-F-90.9K
https://www.mouser.com/ProductDetail/71-RN60C9092F
RN60C, according to spec sheet, is 50 ppm TC, while RN60D is 100 ppm TC. Otherwise they appear to be the same physical shape, size and other relevant electrical characteristics including 1% tolerance. But the 50ppm part is cheaper so I would go with that.
@Ben Mah I want to personally thank you for figuring out what I did wrong. Today the correct resistors arrived, and after being installed, I was amazed to hear the amp that Mr. Pass designed. I would say it is the best thing that happened today, but as a 50+ year NY Mets fan it is number 2. To get a Mets playoff series win AND this amp working in one day is pretty special. Thanks again!
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You're welcome.
Next project, use your multimeter and measure the resistors and compare them to the schematic before installing them on the PCB. Measure and check twice, at least. The time spent is much less than the time that would be spent on trouble shooting. 🤓
Next project, use your multimeter and measure the resistors and compare them to the schematic before installing them on the PCB. Measure and check twice, at least. The time spent is much less than the time that would be spent on trouble shooting. 🤓
That is sound advice. I will say that I did test all resistors that came with the kit, but I did not test the premium parts that I purchased directly. 🙁 What my logic was, I don't know, but lesson learned. I am I totally surprised how good the ACA amp is. I now understand why there are so many threads surrounding this kit. Makes me wonder how much better the F5M will sound once I get to building it. I wouldn't start that until I finished the ACA.
Here is the BOM of my build with Mouser part numbers. Hopefully it will help others. It sounds just divine with these parts.
Code:
Designation Mouser No. Per board
Std R1, R2 2019-MOSX3CT631RR47JCT-ND 2
Prem R3 2019-MOSX3CT631RR68JCT-ND 1
Prem R4 WW3FTR500TR-ND 1
Std R5, R6 660-MF1/4DCT52R1000F 2
Std R7, R13 660-MF1/4DL1002F 2
Std R8, R14 660-MF1/4DCT52R1001F 2
Std R9 660-MF1/4DCT52R1211F 1
Std R10 660-MF1/2DC3323F 1
Prem R11 71-RN65C-F-20K 1
Prem R12 71-RN60C9092F 1
Std R15 660-MS1/4DCT52R2211 1
Prem R16 660-MF1/4LCT52R201G 1
Prem C1 493-16235-ND 1
Prem C2 647-RNL1C102MDS1 1
Prem C3 555-RFS50V100MG3#5 1
Prem C4 647-RL81V101MDN1KX 1
Prem C101 80-C315C100KCR 1
Prem Q1, Q2 844-IRFP140PBF 2
Std Q3 ZTX450-ND 1
Std Q4 2SK170BL 1
Std P1 5K Preset Pot of your choice 1hi TA
Can you give me a hint please where the pcb from Rudi can be found. you refered in post 1385?
is here a PCB -gerber available about ACA with TA mods?
sound after amyalice -SMPS filter:
i want to share my experience with this SMPS filter:
my setup is still small. i use a meanwell LRS 24V/150W SMPS brick in a seperate housing. I filtered every channel with this filter. the rail on the amp pcb is 24V and the DC point is 12,5V. i use the zerozone pcb with TA mods in a small chineses housing with 1,5A bias . MOSFETS are IRF044N and i am happy with the darkness of the tuning.
you should try this !!
SMPS Filter - AmyAlice
chris
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Hi everyone!
I just finished my two ACA that I'm using as monoblocks on XLR connected to an iFi Audio NEO iDSD DAC (https://ifi-audio.com/products/neo-idsd/) with a pair of Heco Direkt Einklang (94dB coax, ported, down-firing: https://www.whathifi.com/heco/direkt-einklang/review) and love the speed, clarity and amazing soundstage.. BUT (unlike many other commenters I've seen) they really lack bass and mid-bass (and overall punch). I'm using the provided Meanwell 24v SMPS and set the DC balance at as close to 12v (12.01x).
My main amp is a KT88 PP tube amp at 30W (ChiFi, but w/ upgraded caps, pots, etc.) that pushes a lot of bass even at very low volumes - so much so, that I calibrated the room with Dirac and reduced bass (before you ask, I did disable Dirac for my tests with the ACA - and will attempt a calibration for them this weekend). I also have a Yamaha A-S500 that I mainly use as a phono preamp (so also solid-state https://europe.yamaha.com/en/products/audio_visual/hifi_components/a-s500/index.html) and while it doesn't have the ACA soundstage or highs detail, it still pushes a lot of bass.
I'll also mention I'm not a "bass-head", don't want my whiskey glass rattling - but the ACAs in their current state are unlisteneable for voices and unimpressive for instrumental.
So.. a few questions:
Bonus question: I also have a (very) cheap DIY oscilloscope and a signal generator (built from AliExpress kits) - any tests I could run with these? (not asking for step by step instructions, just a pointer for further reading).
Thanks everyone for your time and advice!
Raz
I just finished my two ACA that I'm using as monoblocks on XLR connected to an iFi Audio NEO iDSD DAC (https://ifi-audio.com/products/neo-idsd/) with a pair of Heco Direkt Einklang (94dB coax, ported, down-firing: https://www.whathifi.com/heco/direkt-einklang/review) and love the speed, clarity and amazing soundstage.. BUT (unlike many other commenters I've seen) they really lack bass and mid-bass (and overall punch). I'm using the provided Meanwell 24v SMPS and set the DC balance at as close to 12v (12.01x).
My main amp is a KT88 PP tube amp at 30W (ChiFi, but w/ upgraded caps, pots, etc.) that pushes a lot of bass even at very low volumes - so much so, that I calibrated the room with Dirac and reduced bass (before you ask, I did disable Dirac for my tests with the ACA - and will attempt a calibration for them this weekend). I also have a Yamaha A-S500 that I mainly use as a phono preamp (so also solid-state https://europe.yamaha.com/en/products/audio_visual/hifi_components/a-s500/index.html) and while it doesn't have the ACA soundstage or highs detail, it still pushes a lot of bass.
I'll also mention I'm not a "bass-head", don't want my whiskey glass rattling - but the ACAs in their current state are unlisteneable for voices and unimpressive for instrumental.
So.. a few questions:
- Could it be something I did / didn't do while building / balancing? Anything specific I could check? (I will go through the resistance check, I admit I didn't do it yet)
- Will upgrading the caps help with bass response? I'm also having a hard time finding the Nichicon Golds, so what should I look for in cap specs?
- Are the resistors also a requirement?
- Does changing Q1 / Q2 help in this regard?
- Any recommended resistor swaps to improve this area?
- Would a higher voltage PSU help? If so, what should I get? (I was thinking of buying / building a linear PSU, but at the same time the noise floor is already very low, so not sure linear would add too much to the experience?)
- And finally: what's your workflow for swapping parts? Do you take everything fully apart? My lazy idea would be to just remove the rads and work on the back of the boards. I'm also thinking of getting additional boards - any suggestions for sellers / providers in EU? (or get them custom made locally, but where does one get the schematics?)
Bonus question: I also have a (very) cheap DIY oscilloscope and a signal generator (built from AliExpress kits) - any tests I could run with these? (not asking for step by step instructions, just a pointer for further reading).
Thanks everyone for your time and advice!
Raz
Attachments
If the bass is so faint that it’s hard to listen to a voice, I‘d guess there’s an issue somewhere. Sorry but I can’t help on this.
Have you ever tried the other modes of the ACA, like bridged or plain default? Could at least be fun. (Here’s a little, subjective characterization: https://www.diyaudio.com/community/threads/amp-camp-amp-aca.215392/page-527#post-6735809 )
Have you ever tried the other modes of the ACA, like bridged or plain default? Could at least be fun. (Here’s a little, subjective characterization: https://www.diyaudio.com/community/threads/amp-camp-amp-aca.215392/page-527#post-6735809 )
Use your scope to make sure both sides are producing output from the XLR input.
@myleftear - that's what I suspect, I might've done something wrong, since everyone else raves about bass reproduction 🙁 (I'll dig a bit deeper on the forums or post in the build thread as well)
@Loudthud - thank you, will do!
@Loudthud - thank you, will do!
What components did you use, as that can make a big difference?
Compare to the list of components in post #1546. The ones marked "Prem" are the important ones.
Compare to the list of components in post #1546. The ones marked "Prem" are the important ones.
I just completed my prem part upgrades after reg ACAs being used for 5yrs or so without a hitch. Like yours and others comments etc., and trying to figure out what's wrong with the sound (or lack thereof), I'd suggest looking at the way either the inputs or ESPECIALLY the output wiring is done. I've yet to enjoy my upgrades yet, due to lack of sleep and overworking; but it seems I had similar results (yet knowing it couldn't be correct after owning them as standard status, paralleled monos, or even reg stereo usage, etc for that matter)............only for me to realize I screwed up the wiring to the speaker outputs in reverse!! I suppose it's been so long since I made a single change to them, that I didn't notice when reconnecting those wires. To top it off, I've previously spotted the same error on 2 others' ACAs a couple of years ago, yet did it to mine after adding all my premium parts.....that ol red speaker post has a habit of throwing such a simple wrench sometimes, even when one already knows about how the amps inverts polarity and that the "red" outputs are grounded, etc etc. ANyway, if one is severely disappointed with the ACAs sound, I find that input and esp output wiring is usually in reverse. Unfortunately, with build guide pics vs differences in actual received kit wires and/or other's own independent wires, it can make it harder to realize or easily in one post, correct or point out the wiring mistake, even by others in the various threads. I mean heck, I built both my ACAs originally 5yrs ago without incident, and therefore wasted hours analyzing what I did wrong this time, even risking part damage from OCD reworking soldering connections, etc. 
Seeing that these are your first ACA's, you should be made aware that the preamp you drive them with is very important. You really need some gain in the preamp, ideally 10dB or more. The speakers are equally important. I suggest minimum 96dB sensitivity if you want decent SPL.
Edit: I see you use Heco Direkt speakers with 96dB sensitivity. That's on the low side, but they should work ok. That means you preamp may not be driving the ACA's to their max.
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I was going to say the exact same thing, people really underestimate the quality of preamp needed to get the best out of the ACA. I use the Pass designed Adcom GFP-750. It works fantastic, so much better than driving from a dac or other device.
Hi all! Thank you so much for the advice, it really helps.
First off, even a bit of burn-in seems to have helped: I left them on for about 24h and the bass warmed up a bit on XLR too. Which is why I posted in this thread - as I feel at least a recap and burn-in will help tremendously.
@myleftear - switching to parallel RCA did the trick (sort of): the bass and mid-bass is back to where I expected it for these speakers, but now I'm missing some of the detail in the highs, and imaging is less vivid. But the overall "listenability" is far superior (now I can listen to opera, whereas on XLR there was no way). I also have a loss of volume, but I'm not throwing raves, so all good here.
My two reasons for wanting to use XLR are noise floor and cable length (I want them near the speakers, on the floor - but at the same time they're dead silent on RCA as well) and laziness (my DAC outputs on both RCA and XLR, so I wanted to keep both the ACAs and my tube amp connected and just switch speaker cables). So at the end of the day nothing blocking.
But is there a way to get "the both of both worlds"? Could I rewire the back panel to use XLR in parallel mode? (I'm thinking not, w/o some extra components, because of the inverted phases?)
Oh, and at volumes over about 50% on XLR, I can hear some distortion in the highs as well (none on RCA).
@Loudthud - I've yet to hook it up to the scope (I first need to figure out how to even use it), so I'll keep investigating that as well.
@Skylar88 - this is a stock build ATM, I was asking if upgrading would bring my bass back. So now I know it wasn't this, and I'll go on to the upgrade anyway. Which brings back this question: what's your workflow for the upgrade? Take everything apart, or is there a better way to go about it? (you may notice laziness is a theme here)
@Ericc1 - at your recommendation, I triple checked everything with all the build pics, and all seems fine. Plus it's now much better on RCA parallel, so I'm guessing they're connected right.
@Skylar88 (again) - I couldn't find a lot of specs for the output of my specific DAC, but I could also try running it through my other solid-state amp (Yamaha A-S500). It does have a "pure direct" mode, but I feel that would add unnecessary complication to my signal path. Worth a test, though.
I'll also be building an EAR834 soon, so we'll see how it pairs with that one as well.
@Zamjazz27 - well, why not? I'll add one to my project list 🙂
I'll run some more tests over the weekend, and re-calibrate the room on Dirac for the ACAs as well and will follow up.
Thanks again, great being here 🙂
First off, even a bit of burn-in seems to have helped: I left them on for about 24h and the bass warmed up a bit on XLR too. Which is why I posted in this thread - as I feel at least a recap and burn-in will help tremendously.
@myleftear - switching to parallel RCA did the trick (sort of): the bass and mid-bass is back to where I expected it for these speakers, but now I'm missing some of the detail in the highs, and imaging is less vivid. But the overall "listenability" is far superior (now I can listen to opera, whereas on XLR there was no way). I also have a loss of volume, but I'm not throwing raves, so all good here.
My two reasons for wanting to use XLR are noise floor and cable length (I want them near the speakers, on the floor - but at the same time they're dead silent on RCA as well) and laziness (my DAC outputs on both RCA and XLR, so I wanted to keep both the ACAs and my tube amp connected and just switch speaker cables). So at the end of the day nothing blocking.
But is there a way to get "the both of both worlds"? Could I rewire the back panel to use XLR in parallel mode? (I'm thinking not, w/o some extra components, because of the inverted phases?)
Oh, and at volumes over about 50% on XLR, I can hear some distortion in the highs as well (none on RCA).
@Loudthud - I've yet to hook it up to the scope (I first need to figure out how to even use it), so I'll keep investigating that as well.
@Skylar88 - this is a stock build ATM, I was asking if upgrading would bring my bass back. So now I know it wasn't this, and I'll go on to the upgrade anyway. Which brings back this question: what's your workflow for the upgrade? Take everything apart, or is there a better way to go about it? (you may notice laziness is a theme here)
@Ericc1 - at your recommendation, I triple checked everything with all the build pics, and all seems fine. Plus it's now much better on RCA parallel, so I'm guessing they're connected right.
@Skylar88 (again) - I couldn't find a lot of specs for the output of my specific DAC, but I could also try running it through my other solid-state amp (Yamaha A-S500). It does have a "pure direct" mode, but I feel that would add unnecessary complication to my signal path. Worth a test, though.
I'll also be building an EAR834 soon, so we'll see how it pairs with that one as well.
@Zamjazz27 - well, why not? I'll add one to my project list 🙂
I'll run some more tests over the weekend, and re-calibrate the room on Dirac for the ACAs as well and will follow up.
Thanks again, great being here 🙂
When I did the upgrade, I used new boards. I hate unsoldering components.
That is a good option @razvanbrates. I used boards that I've designed myself in 2017, because the store had none in stock. I still had 2 left and used those.
I just ordered a pair for myself......in order to complete a 2nd ACA for parallel monoblocks. I initially even bought a very highly reviewed solder sucker, but just ended up using my blue weller brand one on my 1st attempt at giving one aca the tungsten audio treatment. Consider it a lesson learned, I'll never waste so much time/effort and risk to components attempting such upgrades......especially when one can order virgin pcbs for 10 bucks. I may just add even more new parts this time. I upgraded my other other current aca last weekend, and of course I'm having this exact same issue!! I'll wait to ask for help on it though, as I'm sure it's a resistor related issue. I didn't add R16 (or the one aka the resistor installed after cutting the pcb trace).....or not as of yet. I think I also just used two 0.5 2 watt resistors in place of the .68k resistors when I should have just used one 0.5 resistor and left the other original resistor/value. But regardless, doing the 2nd one will take 1/3 the time to upgrade even without the new boards, but my goodness....for 10-15bucks it should go lightening quick.
Most of my used time was caused directly from the result of not having touched the internals of an ACA in almost 6 years For awhile I was worried that it was because I took the boards off by just unscrewing them and the fets from the heatsinks and then carefully screwing them back on......and not knowing if the faint sounds were a result of not using new keratherm pads. But I've been told anyway, that it should be fine. I might just leave them on the heatsink next time since I'kll be using blank boards. But yeah, having the clean slate/blank canvas is so much easier than having to remove all the solder, and cleaning flux etc.