hi all,
Sorry for the noob question. I successfully completed ACA for a while now. The amp just keeps sounding better and better everyday. My speaker sensitivity level is 90db, 8 ohm . I've read that Class A amp will sound better with high efficiency speaker.
I'm thinking to upgrade my system to Zu speakers with 100 db efficiency. However, Zu speaker input impedances are either 16 ohm or 12 ohm. It's not a standard 8 ohm.
Will ACA be able to drive 16 and 12 ohm impedance speakers ? Do you know any paper that explain the speaker impedance synergy with amplifier ?
Do any of you know the output impedance of ACA amp ? is it Rout = (R1//R2) + (R3//R4) ?
In general rule, speaker with higher input impedance will have easier load for amplifier to drive since amplifier is expected to have low output impedance? is it the right assumption ?
Thanks,
Tom
Sorry for the noob question. I successfully completed ACA for a while now. The amp just keeps sounding better and better everyday. My speaker sensitivity level is 90db, 8 ohm . I've read that Class A amp will sound better with high efficiency speaker.
I'm thinking to upgrade my system to Zu speakers with 100 db efficiency. However, Zu speaker input impedances are either 16 ohm or 12 ohm. It's not a standard 8 ohm.
Will ACA be able to drive 16 and 12 ohm impedance speakers ? Do you know any paper that explain the speaker impedance synergy with amplifier ?
Do any of you know the output impedance of ACA amp ? is it Rout = (R1//R2) + (R3//R4) ?
In general rule, speaker with higher input impedance will have easier load for amplifier to drive since amplifier is expected to have low output impedance? is it the right assumption ?
Thanks,
Tom
My simplistic view of the world:
Higher impedance => easier load but less output power; power comes from voltage swing and current. Voltage swing is determined by your PS rails; current (provided the amp can deliver it) depends (through Ohm's law) on the impedance of the speaker. So the speaker will demand less current and deliver less power. Probably not that important because you wil l upgrade from 90dB speakers to 100dB.
Higher impedance => easier load but less output power; power comes from voltage swing and current. Voltage swing is determined by your PS rails; current (provided the amp can deliver it) depends (through Ohm's law) on the impedance of the speaker. So the speaker will demand less current and deliver less power. Probably not that important because you wil l upgrade from 90dB speakers to 100dB.
The ACA does have a significant turn off thump. Could this damage a fragile tweeter? I'd hate to say no and then have to buy you new tweeter. Such a tweeter would be really cheap or very expensive. To be on the safe side, a smaller output cap could be used, perhaps one that is a little more transparent to high frequencies.
Can someone comment on this please. Not sure things are running optimally.
Heat sink is 3U, 40mm thick, 300mm deep, wave profile.
Also, R15 is 2.67. Mod is 2.21k. Could this be source of cool running amp?
Thanks,
Vince
About 25 Watt is not a challenge for such a big heatsink.
My ACA runs at 24V, has resistor mod and lives in a 2 U 300mm box. It never gets really hot dissipating almost 35 W. Conclusion, bigger sink, less power, cool amp.
Cheers
I do remember reading about it in this thread before but search didn't bring up the right results. Do you know which page the relevant info is on?
Also what is this I hear about the ZM 1.7amp bias?
