OK, the wires are untwisted, so that may help. Thanks for that. I will try twisting 5&6 and 7&8. I don't hear noise or hum from the amps, but maybe injected RF is affecting the sound. I'm not giving up on this preamp board yet. It would be nice if it sounds good.
Going to the site, they do have shielded cables for the "Pro" harness.
Going to the site, they do have shielded cables for the "Pro" harness.
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I agree upon that. I once worked with assembling ICE modules into proprietary chasis with input buffer. Shielded input wiring and twisted speaker wires were mandatory to keep the noise as low as possible. Remote preamps w/ bluetooth come cheap on the bay these days making it possible to "fake" an integrated amp in an easy way.
I'm checking the Ghent audio kit and the signal cable seems to be some kind of a smaller coax, is this the best choice for an upgrade here?
ghentaudio --- DIY Hifi Cable-Set for ICEpower 125ASX2/250ASX2 module
ghentaudio --- DIY Hifi Cable-Set for ICEpower 125ASX2/250ASX2 module
So I hooked one amp from preamp out to 125 input with Alpha milspec teflon shielded signal wire and the other with twisted pairs 5&6 and 7&8. I not sure how it compares to previously, not a significant difference. Both channels sound about the same with similar distortion. I'm fairly certain the preamp board needs to go.
Another thing I discovered is that there was only about 5-10% contact between the 125 heat sink and the chassis.
Another thing I discovered is that there was only about 5-10% contact between the 125 heat sink and the chassis.
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So about internal cabling, what are exactly the recommended cables for power, signal and speakers? I have some questions.
- power: I don't understand why is it better twisted than straight. In the walls, in the power cords, it's always just parallel cables, why should we twist it once it enters the amplifier chassis.
- signal: for unbalanced, I've read that coaxial is the right choice. But do I need a special solid core coax cable, or I can just cut and reuse any RCA interconnect?
- speakers: I was thinking about using the very same wire (11 AWG) I'm using for the external speaker cables, untwisted. What is the point in using thinner wires but twisting them inside the chassis?
- power: I don't understand why is it better twisted than straight. In the walls, in the power cords, it's always just parallel cables, why should we twist it once it enters the amplifier chassis.
- signal: for unbalanced, I've read that coaxial is the right choice. But do I need a special solid core coax cable, or I can just cut and reuse any RCA interconnect?
- speakers: I was thinking about using the very same wire (11 AWG) I'm using for the external speaker cables, untwisted. What is the point in using thinner wires but twisting them inside the chassis?
So what would be a good replacement for the preamp? The Icepower 125ASX2 needs an input source with an impedance of around 1 ohm from what I've read. Poking around the DIYAudio site, the DCB1 preamp looks like it would be a good match, but it would require me to bone up on my soldering, so that I don't leave little silver goobers all over the board. Is the DCB1 a reasonable project for someone with very basic soldering skills?
Would a prebuilt JC2 preamp board like this one from YuanJing work?
Would a prebuilt JC2 preamp board like this one from YuanJing work?
Why not a 3E audio DSP? Maybe not the best option if you are leaning towards critical listening... I use them for HT.
Input impedence is 8k. If you are using it stereo, you may not need much of a preamp. It takes single ended inputs in stereo. If your DAC has volume control and output impedence 1k, I would try it without preamp. Just go straight into the 125 inputs.
In BTL, you need a balanced input. Most consumer DACs are unbalanced (single ended), so you need an input transformer (balun, decent ones are expensive), or an active unbalanced to balanced line driver to the input of the 125 and connect ground to BTL pin.
In BTL, you need a balanced input. Most consumer DACs are unbalanced (single ended), so you need an input transformer (balun, decent ones are expensive), or an active unbalanced to balanced line driver to the input of the 125 and connect ground to BTL pin.
Yeah, I went back and re-read the postings and it said that the low end of input impedance was 8k, so someone recommended a buffer or preamp stage with around 1k (not 1!).
I'm thinking that something like a Topping DX3pro or a Yamaha WXC-50 connected directly to the 125 inputs should be pretty good.
I'm thinking that something like a Topping DX3pro or a Yamaha WXC-50 connected directly to the 125 inputs should be pretty good.
Can I just slap XLR inputs on the amp board and have a true balanced power amp? This is great,l price and I already have two preamps and I just need a balanced power amp. In thinking I buy this, get the amp board out and buy the Ghent audio harness fur XLR and call it a day? Am I missing something?
Edit: I just want a good cheap true balanced power amp, who do I have to screw to get that? What is btl mode? Is it like running two boards in dual mono?
Edit: I just want a good cheap true balanced power amp, who do I have to screw to get that? What is btl mode? Is it like running two boards in dual mono?
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I don't have any experience with Ghent.
The existing extruded Al case that came with the amp is good enough.
That's why I ordered another unit.
Might paint top plate to cover weird graphics.
If I want to put in another case later I would make a wooden case and mount 2 existing cases inside. So I won't have to worry about burning my wooden case.
The existing extruded Al case that came with the amp is good enough.
That's why I ordered another unit.
Might paint top plate to cover weird graphics.
If I want to put in another case later I would make a wooden case and mount 2 existing cases inside. So I won't have to worry about burning my wooden case.
The FA-500 takes two balanced inputs (TRS not XLR), and can run as a stereo amp or in BTL (mono) mode it mixes the two channels (proportioned by the volume controls) and you have a mono amp.
Unfortunately, the quality of the preamp board in the FA-500 is not close to the sound quality of the Icepower 125ASX2 module. If you think the FA-500 sounds fine stock, you are done. If not, you can do the following:
The 125 takes two single ended (unbalanced) inputs for stereo. You could take the XLR balanced outputs and connect the (-) to GND (converting balance to unbalanced) and use it that way as a stereo amp. But, since you have a balanced output, you could use the included FA-500 signal input connector, cut the 8 pin preamp out connector, twist the channel 1/ground pair and channel 2/ground pair and solder to XLR jack with proper (+) , (-) and GND connections as described in the 125 manual, with BTL pin connected to ground. That gives you a mono amp with 225W into 8 ohms and 450W into 4 ohms, and you don't need to purchase any additional harness. Use the FA-500 case by removing the FA-500 preamp board and fan, and solder the speaker wires(you just need the red and white wires pins 1 and 4, remove the two black wires) to binding posts (red-red and white-black) and XLR jack to the fan panel by drilling/punching holes.
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Correction: balanced so no need to twist inputs to 125. Connect Channel 1 (pin 8) input to (-) XLR and Channel 2 (pin 5) input to (+) XLR. Connect Ground XLR to two ground inputs (pins 6 and 7) and BTL input (pin 1). See Fig 17 in the 125 manual. It shows unbalanced input with inverting opamp on Channel 1. But (-) XLR replaces inverting opamp.
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