[flyte3333]

I’ve problems one and two, well the only real problem is the channel imbalance, using XLR input and low impedance dynamic headphones in gain 1. I don’t think the crosstalk is audible but for me the amp sounds best using balanced output.

Hi, thanks for the reply.

So these cons you noted were with balanced XLR input - but on the headphone cable side, were these cons with balanced output too or single ended output headphone cable?

 

[elira]

Hi, thanks for the reply.

So these cons you noted were with balanced XLR input - but on the headphone cable side, were these cons with balanced output too or single ended output headphone cable?

Mainly with the balanced output, single ended it has less gain and that helps to get the pot to a better position.

 

[flyte3333]

Mainly with the balanced output, single ended it has less gain and that helps to get the pot to a better position.

Thanks. I may have missed it earlier, but can you remind me which low impedance cans? Or was it IEMs?

 

[elira]

Thanks. I may have missed it earlier, but can you remind me which low impedance cans? Or was it IEMs?

Grado GS2000e and Cleer Next. With the HD58X or LCD2C I don't have problems.

 

[flyte3333]

Mainly with the balanced output, single ended it has less gain and that helps to get the pot to a better position.

Is it under 12 o'clock on the volume knob where you see/hear your issues with Gain #1 ? Where over 12 o'clock is ok? Or problems even show up above 12 o'clock also?

i.e. what's the pot position where things cross from good to bad with gain #1 for you?

 

[elira]

Is it under 12 o'clock on the volume knob where you see/hear your issues with Gain #1 ? Where over 12 o'clock is ok? Or problems even show up above 12 o'clock also?

i.e. what's the pot position where things cross from good to bad with gain #1 for you?

At ~9 o'clock it starts to be balanced. At 12 o'clock there are definitely not issues but it's too loud. It also depends on the output of the DAC, mine outputs 5V, which is +16dBu.

 

[flyte3333]

At ~9 o'clock it starts to be balanced. At 12 o'clock there are definitely not issues but it's too loud. It also depends on the output of the DAC, mine outputs 5V, which is +16dBu.

Have you tried RCA input cables on the THX789 instead of balanced - and does it help at all?

Or does your DAC only have balanced XLR outputs?

 

[elira]

Have you tried RCA input cables on the THX789 instead of balanced - and does it help at all?

Or does your DAC only have balanced XLR outputs?

I haven't tried the RCA outputs of my DAC. I tested using a Bifrost Multibit but it sounded dull in comparison to my R2R-1, not sure if it's because of the single ended input of the amp or because of the DAC. But definitely there was less gain.

 

[AndrewM888]

Not if you wire it like this. Here the shield isn't connected to the RCA cable at all:

Your diagram and description is a bit hazy. What connector and what shield termination are you making at the two ends of your cable?
Remember, CM current from the various mechanisms behaves mostly like a current source. It will find a path to flow. So it's a matter of either making sure it doesn't flow on a path that's corruptable, or minimizing the Vdrop if it does.

 

[Yviena]

@AndrewM888 Hmm my soekris dac1541 measures better single ended but i loose 3dB SNR, would this cable https://benchmarkmedia.com/collections/cables/products/benchmark-rca-to-xlrm-adapter-cable# be a good rca-xlr cable for the THX 789 to minimize CM noise?

 

[AndrewM888]

@AndrewM888 Hmm my soekris dac1541 measures better single ended but i loose 3dB SNR, would this cable https://benchmarkmedia.com/collections/cables/products/benchmark-rca-to-xlrm-adapter-cable# be a good rca-xlr cable for the THX 789 to minimize CM noise?

Yes exactly! Good find, and good price.

 

[AndrewM888]

Your diagram and description is a bit hazy. What connector and what shield termination are you making at the two ends of your cable?
Remember, CM current from the various mechanisms behaves mostly like a current source. It will find a path to flow. So it's a matter of either making sure it doesn't flow on a path that's corruptable, or minimizing the Vdrop if it does.

See the RCA to XLR Benchmark cable Yviena found. That's how it's done properly.
Your 1 side floating shield approach doesn't provide a separate path for CM current to flow. In your setup, CM current will flow in your star quad negative wire, adding ground bounce that'll manifest as noise/hum.

Your diagram and description is a bit hazy. What connector and what shield termination are you making at the two ends of your cable?
Remember, CM current from the various mechanisms behaves mostly like a current source. It will find a path to flow. So it's a matter of either making sure it doesn't flow on a path that's corruptable, or minimizing the Vdrop if it does.

Check out the Benchmark RCA to XLR cable Yviena found. That's how to cover Ll the bases.

 

[Yviena]

I really like that the amplifier has adjustable gain, gain 2 would be too much for my HD800 running balanced if the dac is also using balanced out, as it is with SE out from DAC to XLR in amp i still find it too loud on some music where it's approaching 9 o'clock even with -4dBFS in my software player to account for inter-sample peaks, no way would i be able to run gain 1/2 if i ran the dac through the balanced outs, or setting the software volume to 0dBFS, ideally i would have wanted a even lower gain.

 

[TheLastZealot]

Anyone used this amp for Senn HD800? Any impressions?

I've heard that HD800 is not suited for solid state amps. But other than listening to music I also do some recordings, so I'd like this set-up to be good for monitoring as well. I'm not sure about going into tube amps

 

[Arctia]

Yeah I use HD800 with mine. You either used to treble or you're not. IMO you really need to mod the HD800, or EQ it, regardless of amp.