A bridged should go louder than non bridged (either normal single channel or parallel mono) because there is twice the voltage swing available but depending on the gain set up within the amp it may or may not be louder for a given volume setting if that makes sense. The ability to go louder is there though.
Its difficult to say on your ACA without seeing the connectivity of it all but I wouldn't have thought any normal combination of configurations should make it quieter.
Random thought, I wonder if you were feeding one working channel into a non working (as in no audio present) because of some connectivity issue... would have to see measurements to know 🙂
Its difficult to say on your ACA without seeing the connectivity of it all but I wouldn't have thought any normal combination of configurations should make it quieter.
Random thought, I wonder if you were feeding one working channel into a non working (as in no audio present) because of some connectivity issue... would have to see measurements to know 🙂
Yes, I was wondering something like that as the XLR has Pin1 Shield/Grd connected to the Buss Pin 2 +/hot to R Phono Pin3 -/Cold to L Phono. I left these connected when trying the unbalanced bridged method, but now wonder whether I should have removed the XLR connections to the RCA sockets. I will remove them tomorrow and see what that brings. Could it be that the pukka Diyaudio boards are different in operation to mine?
More Fiddling. I use my mobile phone with YT as a test source, not ideal but I wasted 2 MP3 players some years ago when I used to use them to test my P2P Gainclone creations. I should have learnt how to make a DC blocker as a first step.
I found that if I use YT on my laptop and phone the phone does not show a volume control so I have to use the laptop to alter the volume😡 some tracks are of course louder than others which may have been the problem yesterday.
I have put together 2 bridged ACAs using the RCA with 34-39k resistor fed back to the output. In my main system the volume is slightly lower than in stereo mode but not massively so. If the volume is increased to higher than I would find comfortable to listen at it seems to have greater headroom and there is no sign of strain or distortion. I will evaluate them further over the next few days.
I did not desolder any of the wires from the XLR to the Phonos as I could not really see why there might be a need to do so. I did plug in an XLR (not connected to anything else) to see what happened and the volume decreased slightly.
I found that if I use YT on my laptop and phone the phone does not show a volume control so I have to use the laptop to alter the volume😡 some tracks are of course louder than others which may have been the problem yesterday.
I have put together 2 bridged ACAs using the RCA with 34-39k resistor fed back to the output. In my main system the volume is slightly lower than in stereo mode but not massively so. If the volume is increased to higher than I would find comfortable to listen at it seems to have greater headroom and there is no sign of strain or distortion. I will evaluate them further over the next few days.
I did not desolder any of the wires from the XLR to the Phonos as I could not really see why there might be a need to do so. I did plug in an XLR (not connected to anything else) to see what happened and the volume decreased slightly.
Yesterday I listened to both amps in bridged mode. Sounded fine, but to me some of the magic that I have with just one was missing. Tried them bi-amped and this was definitely not for me and sounded artificial. So I have a spare if I need it. With the first amp with linear PS I played with the bias and I will have a tweak of this one now.
I would have to have one in front of me to tell tbh. Wiring and connectivity issues are really difficult to diagnose without having it in front of you unless you have a two channel scope and can do simple tests to see what the inputs to the two amps are showing and what the outputs are showing.
That's quite possible.
Lets try and explain this simply 🙂
The thing with the ACA is that it has a very high output impedance and that means that anything other than a resistive load will modulate the output level depending on frequency. In other words the output level of the ACA varies in accordance with the impedance curve of a real speaker. That's not necessarily a bad thing and it is one of the facets of the ACA that contributes to the subjective sound quality result.
The problem is that if we take that modulated output and feed it to the second channel of the ACA then not only does that second channel add the same characteristic but that channel is also being fed with an input signal that has already seen that characteristic applied.
I think so.
Post #5980 shows how the output is pulled around by a reactive load such as a speaker. So you can imagine using this as an input signal.
https://www.diyaudio.com/community/threads/amp-camp-amp-aca.215392/post-5548842
Post #5980 shows how the output is pulled around by a reactive load such as a speaker. So you can imagine using this as an input signal.
https://www.diyaudio.com/community/threads/amp-camp-amp-aca.215392/post-5548842
Horizontal as this is how I have always done it. However I see that there is Vertical too. You learn something every day.
Wow! Thanks for posting that. I've got 4 boards to build a stereo pair to power my mids and tweeters. Would you recommend putting a zobel on them, even though the xo is digital (before the amps) ?
(Tweeters are on horns so impedance curve is all over the shop without)
Thanks,
Rob.
Hey all,
sorry if this question may have been raised prior but i tried to search and can't seem to find - possible that i'm using wrong verbiage as i'm most certain a novice at this hobby. I built 2 ACA's in order to run as monoblocks....was running on some older speakers, and they perform perfectly, but just attached to a new pair of crites cornscala's....they sound great, but at idle one of the amps produce static crackling. i've switched them and it appears to be the amp, not the speakers or the preamp. Have checked the solders seem solid. Any thoughts on how best to trouble shoot - its not very loud, but noticeable when close. Thank in advance!!
sorry if this question may have been raised prior but i tried to search and can't seem to find - possible that i'm using wrong verbiage as i'm most certain a novice at this hobby. I built 2 ACA's in order to run as monoblocks....was running on some older speakers, and they perform perfectly, but just attached to a new pair of crites cornscala's....they sound great, but at idle one of the amps produce static crackling. i've switched them and it appears to be the amp, not the speakers or the preamp. Have checked the solders seem solid. Any thoughts on how best to trouble shoot - its not very loud, but noticeable when close. Thank in advance!!
I had the same problem with my first amp I built. I spent hours trying to track it down. Finally took the advice of most on here and re-flowed the solder to both boards, (mine looked fine too). Has never reared it's ugly head ever again.
I've always said that 88% of the problems with the ACA can be solved with a reflow...
The ACA is what I would call 'unconditionally stable' meaning it is never going to have any issues that would need a traditional Zobel network.
If you mean using a network to try and flatten the impedance curve of the drivers (which is outside my experience of doing anything like that) then I suspect you would have your work cut out to design a suitable network specific to your drivers.
I can't imagine the mid and tweeter drivers dip all that low... do they?
Even if the impedance is all over the place it is really the ratio of the minimum impedance compared to the output impedance of the ACA that is going to be the over riding factor.
For example if the output impedance is 0.7 ohms and you have a speaker that dips to 3 ohms then that 0.7 ohms is going to make a big difference, however if the speaker driver minimum is say 15 ohms then it makes much less of a difference.
There is really a difference between bridged XLR and bridged RCA mode. In XLR mode with real symmetrical signal instead of the output signal of one amp the ACA sings, in RCA mode with the "used" signal it is as with the handbrake not fully unlocked.
I will try the XLR bridged mode but I have suffered a set back in the last 2 days. I contracted Covid in October last year and amongst other things my mild Tinnitus got worse. Where as I used to be able to zone out of it (mostly) it is now there 24/7. Since Tuesday it seems that I have much less hearing in my left ear and far more high pitched whistling. It must have been getting worse whilst I was playing with the amps and getting them wired up for the RCA bridged mode. Probably why it all sounded off.
I have just finished a few months of tests for other problems :Joints, Skin rashes and itching, potential heart murmur all known Covid hang-ons and am due to see the Doc soon. I hope to be put on one of the programmes that monitor long covid.
Will report back when I have tried the XLR bridged.
I have just finished a few months of tests for other problems :Joints, Skin rashes and itching, potential heart murmur all known Covid hang-ons and am due to see the Doc soon. I hope to be put on one of the programmes that monitor long covid.
Will report back when I have tried the XLR bridged.
Mine stay above 8 ohms in the passband (1050Hz xo) Red trace in attachment.
Thanks,
Rob.
Attachments
I can believe the two setups do sound very different. This shows the voltage output of a bridged ACA where one channel output feeds the input of the second. You can see the effect does double up as expected looking at the output of each side. Ignore the opamp... that was added to get perfect DC balance of the two sides and allow DC coupling.
I'm really sorry to hear that news 🙁 Hope things soon start looking up for you 🙂
It is much more mild an impedance curve than the B&W 703's I have and use in the sim (they go down to around 3 ohm) but even so it will still significantly pull the voltage around... but as I've said, that is one of the ACA's design features that definitely contributes to the subjective sound quality.
Hi
I built a pair of ACA v 1.8. These are currently driving a full ranger OB, 8 Ohm speakers in bridged mono (all my sources are SE).
As per the table published in ACA guides, with 8 Ohm the output is 15W and 4 Ohm it is 5W in bridged mono. If I were to get a new set of speakers 6 Ohm impedance, what would be the output? Does it remain at 5W?
I built a pair of ACA v 1.8. These are currently driving a full ranger OB, 8 Ohm speakers in bridged mono (all my sources are SE).
As per the table published in ACA guides, with 8 Ohm the output is 15W and 4 Ohm it is 5W in bridged mono. If I were to get a new set of speakers 6 Ohm impedance, what would be the output? Does it remain at 5W?