It is more about the driver & box than the size. I have 2 stereo diyA kits and one of the earlier 5w ones.
Either drive my 87ish dB WAWs (with a pssive XO) fine, a pair bridged have tow high an output impedance (lets lose the term damping), than optimal (bass gets wooly), i haven’t tried a pair in parallel, which should halve the output impedance (and the direction you would wan tot go with 4Ω speakers).
What are your FR/box?
dave
The reason there's no startup fart/switch off thump in balanced mode is the fact that speakers' outputs are not referenced to the ground - no charge up/discharge of the capacitors through the speakers, and into the ground.
There's no potential difference between two ACA PCB's / two outputs (minuses) at any point in time during turn on/ turn off - this is a characteristic of ALL ACA's operated in balanced mode.
So.... nothing special about your builds, it seems... but don't let a bit of technical knowledge/truth discourage you from believing you do indeed have special builds.
i have built more than 100 boards, most of it single ended ACA,
an about a few bridged amps, never had any problem you mentioned...
what i know is that the smps psu we used have a soft start feature...
and they were of the cheap variety....an NTC in series with the line with a cold resistance of about 10 ohms is good to use here..
ACA Parallel mono configuration, close amp matching needed?
Hi,
according to the ACA V1.6 Operation modes (link below) the parallel mono configuration would fit my needs the best with more power into 4 ohms and less distorsion. However, I understand that parallel mono may require the amplifiers to be closely matched (e.g. gain and DC offset) to work well. Close matching does not seem to be required when the amp use current drive.
Can anyone please explain current drive in the context of the ACA?
Does the ACA 1.6 use current drive or do the amps need to be closely match using the parallel mono configuration?
https://cdn.shopify.com/s/files/1/1006/5046/files/ACA_Monoblock_Operation_RevA.pdf
Regards,
M
Hi,
according to the ACA V1.6 Operation modes (link below) the parallel mono configuration would fit my needs the best with more power into 4 ohms and less distorsion. However, I understand that parallel mono may require the amplifiers to be closely matched (e.g. gain and DC offset) to work well. Close matching does not seem to be required when the amp use current drive.
Can anyone please explain current drive in the context of the ACA?
Does the ACA 1.6 use current drive or do the amps need to be closely match using the parallel mono configuration?
https://cdn.shopify.com/s/files/1/1006/5046/files/ACA_Monoblock_Operation_RevA.pdf
Regards,
M
The ACA always has zero DC offset by default... it is AC coupled. So no problem there.
Amplifiers with high damping factor/low output impedance do require good gain matching and also some form of current sharing (such as low value series output resistors) for parallel operation.
As far as I am aware, the ACA's low damping factor/high output impedance render such precautions as unnecessary.
The ACA would be classed as voltage drive, however the high output impedance means that the output voltage is subject to being altered significantly by the impedance of the connected load.
Amplifiers with high damping factor/low output impedance do require good gain matching and also some form of current sharing (such as low value series output resistors) for parallel operation.
As far as I am aware, the ACA's low damping factor/high output impedance render such precautions as unnecessary.
The ACA would be classed as voltage drive, however the high output impedance means that the output voltage is subject to being altered significantly by the impedance of the connected load.
It usually means a trans-conductance type of amplifier. Look how the feedback is arranged in the first two diagrams:
Amplifier topologies for current-drive | Current-Drive - The Natural Way of Loudspeaker Operation
http://www.firstwatt.com/pdf/art_cs_amps.pdf
Joe Rasmussen "Trans-Amp" - 40 Watt Transconductance "Current Amplifier"
Sorry
, bad wording on my part (and lack of knowledge). I was referring to type of amplifier and topology.