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Old 18th March 2009, 09:29 AM   #1
Skorpio is offline Skorpio  Denmark
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Default ICE input sensitivity

I have to much gain in my system, so my preamps volume control is only used i the area from 8 to 9 o'clock. In the manual (Parasound) it is stated that best performance are percived if the volume are around 12 o'clock in normal listening mode.

I would also like better "resolution" when using remote, so the volume is less sensitive...

I was considering lowering the gain in the preamp, but then an alternative came up:

My poweramp is an ICEpower DIY based on ICEpower 200ASC modules. The input seems to be an opamp in virtuel ground mode. Input resistance is 10kOhm in unbalanced mode.

If I put a resistor in series with the input (direct on input jack) I would increase input resistance and lower sensivity? If i ex. uses i 10k in series would I not lower gain by 6db?

Is there any problems with this solution? Other than the fact that my preamp must deliver a higher voltagesving?

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Old 18th March 2009, 12:19 PM   #2
bwaslo is offline bwaslo  United States
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Seems like a good plan. 6dB isn't a lot though, you might want to add 30k to drop 12dB instead.
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Old 18th March 2009, 01:19 PM   #3
Skorpio is offline Skorpio  Denmark
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Ok, I will try that....thank you for the response
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Old 18th March 2009, 05:16 PM   #4
Skorpio is offline Skorpio  Denmark
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Just tried with both 10k and 22k and sensitivity was reduced as was the sound quality!

Bas was reduced downwards, now sounding funny and image and dynamics was gone for good...

Back to normal, everything was nice again (exept level ).....

Don't waste your energy on this little trix
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Old 23rd October 2014, 04:37 PM   #5
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Does anybody know the input sensitivity of the 200ASC?
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Old 23rd October 2014, 08:14 PM   #6
Nisbeth is offline Nisbeth  Denmark
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Around 1.3V for full output I believe (200W/4R and 26.8 dB gain).

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Old 2nd November 2014, 01:52 PM   #7
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i have the same problem with my arcustic reality 202ref (which use 200asc modules). too much gain. If you find a suitable solution i'm very interested in getting the info.
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Old 8th November 2014, 09:52 AM   #8
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Because of the relative low input impedance of amp you need low output impedance driver. You can use pre-amp with low output impedance or imo best solution TVC (transformer volume control). .

I faced the same issue with L15D Pro modules which have 3.3kOhm input impedance. Also tried resistance devider in front, which reduces gain but also affects audio quality. So a potmeter (passive Pre) will not work (high output impedance compared to the low input impedance of amp).

I tried several active pre-amps designs (tubes, Fets for very low output impedance) but was not satisfied. Then I decided to use step-down transformers because they will lower the output impedance by square times voltage division (I.e. voltage divided by 2 means impedance lowered 4 times). I ordered Sowter attenuators type 9150 which gives steps of -10 dB. Well, this works! Great sound not affected by attenuation as with potmeter.

In my case I use Logitech streaming device with provides volume control, so with the Sowter I can adjust the volume in rough -10 dB steps and fine volume control with Logitech. In case you want complete volume control you can consider TVC's (transformer volume control) which are unfortenately very expensive (>€500 mfr Tribute NL), but it's a great passive pre-amplifier and the best option i experienced over all these years.
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