Or just cut off the leads soldered in, and a dual pot to the leads hanging out. Safe
If we knew the value Or cut off the leads on one and solder it to the other??
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Yes, you probably want a better quality pot or attenuator in there. Probably 10k. Space may be an issue, because it's right behind the front panel. I would put a fixed resistor there in place of the pot, and use it as a power amplifier. Does the preamp seem to have much gain? Any noise at full volume setting?
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No noise at 3/4 volume, but my setup is a HT setup, so hardly audiophile. 3/4 is about as much as I can take
, But the sound compared to the 3225 is comparable, but not the volume level. You have to crank this thing up a bit. Slightly harsh on the highs.... only slightly...Can someone explain what is this unique "impedance is changing with frequency" behaviour of the ICEpower modules? I mean I have a desktop DAC with 200 Ohm output (+ an integrated headphone amp if that helps), and I'm thinking about simply bypassing the preamp / input buffer stage. Wouldn't it make a better sound?
It has a volume knob which also affects the line out, or I can use digital volume controls. Would that work with the 125ASX2 or I'll have trouble because of the "changing impedance" thing? Here are two pics from my DAC:
pic1
pic2
It has a volume knob which also affects the line out, or I can use digital volume controls. Would that work with the 125ASX2 or I'll have trouble because of the "changing impedance" thing? Here are two pics from my DAC:
pic1
pic2
The 125ASX2 manual states: "The input impedance of the signal input section is approximately 8k over the audio bandwidth, which is an
acceptable loading condition for most pre-amps, active crossover outputs etc." Standard line level impedence is 10k, so the 8k figure kind of stands out.
200 Ohm output impedence is very good. You should have no problems. Your DAC has a very good output opamp. I think the least amount of components in the signal path, the better. In my setup, I go straight from the DAC to the amp. You may need to determine the sound quality of the digital volume control. There are different ways to implement this. If the DAC chip has a hardware volume control, and you can control it, it's probably good.
The output impedence of the amp increases with frequency, because of the required filter on the output to attenuate switching noise. I think all Class D amps have this filter.
acceptable loading condition for most pre-amps, active crossover outputs etc." Standard line level impedence is 10k, so the 8k figure kind of stands out.
200 Ohm output impedence is very good. You should have no problems. Your DAC has a very good output opamp. I think the least amount of components in the signal path, the better. In my setup, I go straight from the DAC to the amp. You may need to determine the sound quality of the digital volume control. There are different ways to implement this. If the DAC chip has a hardware volume control, and you can control it, it's probably good.
The output impedence of the amp increases with frequency, because of the required filter on the output to attenuate switching noise. I think all Class D amps have this filter.
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hifiamps, thanks a lot for the explanation, I'll mod it to bypass the input buffer then.
The only thing which is not clear to me is that people said that using a potentiometer would not work with these amps. So if my DAC has a potentiometer (as well as hardware volume control). So is the pot usually at the input stage, before the op-amps?
The only thing which is not clear to me is that people said that using a potentiometer would not work with these amps. So if my DAC has a potentiometer (as well as hardware volume control). So is the pot usually at the input stage, before the op-amps?
The 125ASX2 can take single ended inputs in stereo mode. Your DAC has low enough impedence to drive it. The potentiometer is before the opamp buffer. In mono BTL mode, the 125ASX2 needs a balanced input.
Thanks, yes, I realised this would only work in SE mode, luckily I only ordered one board only.
I have some questions about the Vocopro FA-500. Is the preamp noninverting? How are left and right connected to channel one and two of the 125ASX2? In bridged mode, do I connect the + speaker lead to the left + output, and the - speaker lead to the right + output, or is it the other way around. The manual isn't clear. I don't want the output inverted at the speaker.
I made a little tests with single ended input, using 3.5mm jack, driving a sealed 15" subwoofer from my AVR LFE output. Gain is not much, and subwoofer seemed a little anemic, even with the gain knobs at top and +10db on my AVR setup.
Switched to balanced input thru a ART CleanBox Pro II and it was much better. Then tested BTL mode in the FA-500, which leads to a much better level and power. Definitely the kind of power I was looking to my subwoofer.
Switched to balanced input thru a ART CleanBox Pro II and it was much better. Then tested BTL mode in the FA-500, which leads to a much better level and power. Definitely the kind of power I was looking to my subwoofer.
Just received the amps and listening to them now. Initial listening impression is very good.
I am now more confused about speaker connections in BTL mode. On my back panels, left and right are opposite from the manual, and BTL speaker polarity is not labeled. This is critically important information. I may need to scope it to know for sure.
The dimensions of the box without the front panel and not including volume knobs or binding posts/jacks is : 260mmx110mmx52mm. Build quality is very good, but the power LED near the switch is out on one of the amps. The blue accent stripes are not as bold in normal room light as in the photos (good).
I am now more confused about speaker connections in BTL mode. On my back panels, left and right are opposite from the manual, and BTL speaker polarity is not labeled. This is critically important information. I may need to scope it to know for sure.
The dimensions of the box without the front panel and not including volume knobs or binding posts/jacks is : 260mmx110mmx52mm. Build quality is very good, but the power LED near the switch is out on one of the amps. The blue accent stripes are not as bold in normal room light as in the photos (good).
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I connected my SW in BTL using the Left + (the binding posts near the external border of the amp) as BTL(+) and the Right + (the binding post near the AC connector) as BTL(-)
In response to the OP's original question, deal or not? Definitely a deal, probably a steal. I would like to raise my glass in a salute of thanks to mga2009 for bringing this deal to my attention.
This amp sounds very similar to the 500ASP in general. The treble isn't as refined, but it may smooth out with break-in. Very enjoyable. Initial mod would be to dump the volume pots. Sensitivity through the TRS inputs seems normal line level. If one could swing getting two, monoblocks is the way to go, at least with my 86dB sensitivity Harbeths.
This amp sounds very similar to the 500ASP in general. The treble isn't as refined, but it may smooth out with break-in. Very enjoyable. Initial mod would be to dump the volume pots. Sensitivity through the TRS inputs seems normal line level. If one could swing getting two, monoblocks is the way to go, at least with my 86dB sensitivity Harbeths.
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