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Old 27th December 2012, 06:21 PM   #691
bcmbob is offline bcmbob  United States
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Rudi, I'm confused. I thought the FC-100 was Class A. How do you classify it?
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Old 28th December 2012, 08:02 AM   #692
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Talking All right now....

Hi friends,

I have now resolved my problem. I had on hand a pair of Fostex FE83en loudspeakers and I tried them. Absolutely fantastic sound!!!

There is a small amount of lacking bass but this is speaker fault. Now I am in the way to build a better FR with the CSS EL70 drivers.

Thank you all for your suggestions.

Happy new year!!!

Regards
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Old 28th December 2012, 03:18 PM   #693
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My first try, thank you Rudi!

http://www.abload.de/image.php?img=acapcbtdj6e.jpg

Last edited by clayman0403; 28th December 2012 at 03:43 PM.
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Old 28th December 2012, 10:33 PM   #694
mikje is offline mikje  United States
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I probably missed it somewhere in the thread, but what's the status on future amp camp amps? I'd like to try the class A route and this is affordable and has a solid name behind it.
Any more amps going to be offered in the future? I signed up for the mailing list, but am wondering if there's a time frame estimate.
Thanks,
Mike
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Last edited by mikje; 28th December 2012 at 10:35 PM.
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Old 29th December 2012, 02:31 AM   #695
Variac is offline Variac  United States
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We'll have more kits in about a month , more boards in 2 weeks
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Old 29th December 2012, 12:57 PM   #696
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Default Q1 set at 10 volts DC

Hello

My ACA is also running
But i think i will run it at higher Rail voltage, because my psu deliver a bit more than 19V.
Burning down the Voltage with resistor to desired level will produce a lot of heat -wanted to avoid this.

Now i dont know should i also set Q1 at 10V or is it different at higer Rail voltages?
Ive read the artikle but i already dont know why there are 10V?

Help needed thanks
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Old 29th December 2012, 11:08 PM   #697
bcmbob is offline bcmbob  United States
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General question

I'm curious about how many are using a preamp/gain stage with the ACA as opposed to a pot or other attenuation device for volume control.
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Old 29th December 2012, 11:43 PM   #698
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Right now, I am using the ACA in my office, connecting the RCA outs from a M-Audio 2496 sound card on my computer, using the M-Audio app to control the volume. Works real well, sounds great with my Zaph|Audio ZA5.2s. Try Dead Can Dance "Into the Labyrinth" as a test album!
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Old 30th December 2012, 02:05 AM   #699
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Quote:
Originally Posted by Danger Mouse View Post
Hello

My ACA is also running
But i think i will run it at higher Rail voltage, because my psu deliver a bit more than 19V.
Burning down the Voltage with resistor to desired level will produce a lot of heat -wanted to avoid this.

Now i dont know should i also set Q1 at 10V or is it different at higer Rail voltages?
Ive read the artikle but i already dont know why there are 10V?

Help needed thanks
Generally the voltage is set to give maximum output before clipping. Because the ACA is not totally symmetrical, the voltage is not exactly half the power supply voltage. Experiments have shown that the higher the voltage is set, the less dramatic the 1 Watt distortion raise is at higher frequencies. I posted a plot of this in post 576 of this thread. I theorize that this is because the gain starts to fall off as the output voltage swings positive and the effect and amount of Q1's non-linear gate capacitance is also increasing. If you don't have an oscilloscope, start at half the supply voltage and try small changes to see if you can preceive a tonal change. Note that the voltage set by P1 does not change if the supply voltage changes, only a small temperature drift.
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Old 30th December 2012, 04:34 AM   #700
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Quote:
Originally Posted by Danger Mouse View Post
But i think i will run it at higher Rail voltage, because my psu deliver a bit more than 19V.
Burning down the Voltage with resistor to desired level will produce a lot of heat -wanted to avoid this.
There's lots of margin in this design. As long as your original voltage is
not really much larger, I suggest you use it, and set the Drain voltage
at approximately 1/2 of the supply.

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