Aca 1.6 noise at start up
Ok I have let it burn in for awhile and at start up I get this sound like something is winding up. Zrrrrrrr and stops. Like a cap is loading charge or something. No issues playing music and no noise while playing. Thoughts.
It comes from speaker driver not inside of amplifier.
Jon
Ok I have let it burn in for awhile and at start up I get this sound like something is winding up. Zrrrrrrr and stops. Like a cap is loading charge or something. No issues playing music and no noise while playing. Thoughts.
It comes from speaker driver not inside of amplifier.
Jon
Sorry, I know this is a really long thread, but this has been discussed ad nauseam.
It's the cap charging up. Normal.
It's the cap charging up. Normal.
Surprise happy end
Whilst making the measurements that Mooly suggested on both boards, I noticed that R11 on the left board was loose.
This threw me for a spin because the left board was working fine, leading me to believe that the problem should be in the right board.
I took the left board out, and touched up all joints for good measure.
Put everything back together, hooked the amp up and..... music! in Stereo!!!
Thanks to everyone and especially Alan4411 and Mooly for your help and patience.
One more question though, there is a noticeable "thump" in the speakers when I turn the amp off (you can see the cones move).
Is this expected behaviour?
Thanks,
Laurens
Whilst making the measurements that Mooly suggested on both boards, I noticed that R11 on the left board was loose.
This threw me for a spin because the left board was working fine, leading me to believe that the problem should be in the right board.
I took the left board out, and touched up all joints for good measure.
Put everything back together, hooked the amp up and..... music! in Stereo!!!
Thanks to everyone and especially Alan4411 and Mooly for your help and patience.
One more question though, there is a noticeable "thump" in the speakers when I turn the amp off (you can see the cones move).
Is this expected behaviour?
Thanks,
Laurens
The movement in the cones is the reverse of the Brzzzzzzzzt noise on start-up, meaning that the noise it the coupling cap charging, and movement is the coupling cap discharging.
Nothing to worry about, amp operating normally.
Nothing to worry about, amp operating normally.
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Pleased to hear you found your fault 
Yes, the thump is normal, as it is on most AC coupled amps such as this. When you switch on the output of the amp rises almost instantly to 12 volts. That voltage allows the cap to charge via the speaker.
Its just the same as taking your speaker and connecting via a 3300uF cap across a 12v car battery. The speaker will make a loud pop/thump.
Edit... oh, I see its when you switch off 🙂 So charge your 3300uF cap to 12 volts and then discharge it across the speaker. Loud thump.
Yes, the thump is normal, as it is on most AC coupled amps such as this. When you switch on the output of the amp rises almost instantly to 12 volts. That voltage allows the cap to charge via the speaker.
Its just the same as taking your speaker and connecting via a 3300uF cap across a 12v car battery. The speaker will make a loud pop/thump.
Edit... oh, I see its when you switch off 🙂 So charge your 3300uF cap to 12 volts and then discharge it across the speaker. Loud thump.
Mr Cheese (Laurens),
Very pleased to hear it is all working.
Thanks for the voltage table, that will help others in the future I'm sure.
So go and enjoy now.
Alan
Very pleased to hear it is all working.
Thanks for the voltage table, that will help others in the future I'm sure.
So go and enjoy now.
Alan
Thanks everyone for confirming that the "thump" at shutdown is normal and is nothing to be concerned about.
Enjoying Ben Patterson through ACA / FHXL as we speak
Enjoying Ben Patterson through ACA / FHXL as we speak
Dear All & Jason,6L6, etc...
I think the cap charge/discharge characteristic needs to be explained/mentioned in both the 1.5 and 1.6 guides if not already done. Moreover, this is present in those solid state amplifier designs (particularly of the SE variety) where there is a cap on the output and no relay protection installed. You can implement that protection scheme, but it seems overly complicated and perhaps unnecessary given the budget and simplistic nature of this ACA product.
Personally, I like/love the sound. It sounds like glorious flatulence!
On another note, it behooves me to remind all newbies who have never soldered to practice first on some simple inexpensive eBay pcb's along with liquid flux, Kester solder and a temperature controlled iron. It will save you all A LOT of grief in the future.
Best,
Anadn.
I think the cap charge/discharge characteristic needs to be explained/mentioned in both the 1.5 and 1.6 guides if not already done. Moreover, this is present in those solid state amplifier designs (particularly of the SE variety) where there is a cap on the output and no relay protection installed. You can implement that protection scheme, but it seems overly complicated and perhaps unnecessary given the budget and simplistic nature of this ACA product.
Personally, I like/love the sound. It sounds like glorious flatulence!
On another note, it behooves me to remind all newbies who have never soldered to practice first on some simple inexpensive eBay pcb's along with liquid flux, Kester solder and a temperature controlled iron. It will save you all A LOT of grief in the future.
Best,
Anadn.
They’ve been done for about two weeks, the FW M2 was back in the chain for a few days to help me compare, and now the ACA’s have their own home, and new cables for easy swapping. I am very happy with them. They’re rather remarkable in general. Really amazing sound, and nothing about their looks says “kit”. These may have just made me catch the diy audio bug. Thanks to everyone for their help, and of course thanks to Nelson for creating all these works of art.
Ok sorry for my ineptness. Then why does it only happen on one channel ?? Not both.
Dudeisms, those look great next to the big speakers.
How would you compare the sound of the ACA vs the M2? Do they share common characteristics at all (descending from the same genetic father 🙂 ) or are they simply in completely different leagues?
Thanks,
Rafa.
How would you compare the sound of the ACA vs the M2? Do they share common characteristics at all (descending from the same genetic father 🙂 ) or are they simply in completely different leagues?
Thanks,
Rafa.
Hi Iain,
as promised, here is the PDF. It has two pages, one with the outlines and holes, and one without. The one without you need for the engraving, printing, lasering. There is a small dot in the left corner of the drawing (you will see it when you zoom in to approx 400% and more). This dot indicates the top left corner of the back panel so your laser company can use it to position the backpanel.
You can convert this pdf to any other file. I used PDF because of the embedded font capabilities.
If you have any questions, please ask!
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... ohh, forgot to mention, it will be really great to hear from you how the CM performs under load once you've got everything settled in, especially in light of this comment:
Yeah, that's what my eyes tell me but I was just wanting to check I hadn't missed anything.
Hi Iain,
The ACA's preform very well! I love them for the money. As others also stated with the CM in place, it has a very nice holographic music representation.
I connected the ground directly to the amp pcb's and the CM. They all share the same common ground. The CM board also shares a common ground from input to output. There is no use in wiring the common first to the CM and afterwards to the amp boards.
The Allo board use nice thick tracks. It's also capable of supplying 32V @5 Amps. Enough power I guess.
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No pro or con, it's an aesthetic choice.
I prefer flush -
Agreed. However the choice of in or out is best made at build time. It's not the sort of thing that lends itself to a change of mind once all the solder has had time to freeze. Might be worth making a note along those lines in the v1.6 build guide.
Cheers and big thanks for that. Yep, I can see the dot. In blue, right? Looks like there are various ways to convert pdf to dxf, so I should be good. I take it that the scale is 1:1? Looks like it is from a quick check.
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Just my opinion here... I have a FW M2, and I bought my folks a FW J2 (but I got to spend 6 months with the J2). So the M2, has the ends of the frequency spectrum sorta rounded off, kinda like a tube amp, but without the philosophical drawbacks of tube. At least with my speakers and everything else in the chain, the M2 has a very organic aspect to it, I call it the sonic hug, very warm sounding. There is almost something mythical or magical to the M2. But combo’d with the speakers, things sound like they are happening in the room with you.
The J2 while still warm sounding is perhaps more analytical, certainly more bass and crystal highs in comparison.
I personally find the ACA leans in having more in common with the J2. The ACA has more bass than the M2, more crystal highs... and more lively at lower volume than the M2. In my setup the M2 seems to like to stretch its legs a bit more. And the J2 just plain has more gain.
But they all sound incredible, I feel very lucky and thankful to be able to listen and enjoy any of these amps. Mr Pass is offering us all these slightly different “flavors” of sound, and that unto itself is fun to hear.
it strongly depends of nature of power brick used
however , nothing to worry about , there is a capacitor on output
however , nothing to worry about , there is a capacitor on output
The ACA has "only" 12V across the gain transistor, so it is a fair bit short of that 24-25V limit, which results in rounding-off of the top end. It has 10K input impedance, but this can be compensated if a reasonably specced pre-amp is used. What I also found is that ACA does not like, not a single bit, a highish-capacitance speaker cables, like ribbons of any kind...
But still, it sounds very nice, relaxed, spacious, with an outstanding bottom-end definition. It is, after all, supposed to be an introduction to Pass amplifiers.