Does volume control bring noise


#1

hello,

I wanted to try connecting my amps directly to the DS using its volume control.

but doing that adds a lot of noise to the picture… A hiss, definitely bothering.

I use Y cables to connect 2 amps to each channel for bi-amp, is the impedence too low?

amps are Emotiva XPA-1 connected in XLR

do you experience the same using the volume control?


#2

No, but it means the speakers connected to the amps are more sensitive than the chosen setting on DS. Go into the menu and use the low output setting and the hiss goes away.


#3

Forgot about that settings! Thanks, it worked!

bypassimg my preamp is much better, now either I get a better preamp or rewire the system each time I switch from stereo to home cinema…

Choices choices!


#4

tested this morning before going to work, it works wonders in stereo

but the integration of HC is not easy

I used the coax input to connect to the HC preamp repeater output, this resulted in a downmix of the multichannel into the FL and FR handled by the DS.

So the center and surrounds were replicated on FR and FL, which didn’t sound too good…

Is there a way to ask the DS to decode only the FL and FR channels out of the multichannel instead of downmixing all channels?


#5

The DS just thinks it’s getting a regular stereo signal, which is the only thing it knows. This would have to be dealt with by the pre-amp settings. It sounds like your “repeater” is doing a lot more than repeating what comes in.


#6

no such settings on my preamp unfortunately

digital output on the pream gets 5.1 in and sends 5.1 out which makes sense, nothing else than repeating here.

I’d like to find a way for the DS to only care about the FL and FL parts!

(adding an extra device between the two defeats the simplification effort)


#7

Your prior post said it was down-mixing 5.1 to stereo. That’s not just “repeating.” Maybe one of the guys who use DSs for multichannel has a suggestion.


#8

The DS isn’t down mixing - it’s a stereo only device. Most 5.1 sources have a setup to just put out stereo and most home theater preamps that pass digital have options to send out just stereo as well.


#9

By “it” I meant his preamp was doing the down mixing.


#10

Sorry, I was replying to him, trying to emphasize your earlier point that if a mixdown was happening that it was from something upstream.


#11

My bad. I read your response too quickly. It was perfectly clear.


#12

Thanks for the confirmation, I wasn’t sure where the downmixing was happening.

I ll have to see with the hc preamp then!


#13

I’m running my DS direct into a pair of Luxman M600-A amps and can hear hiss from 12’ away when using the normal gain setting on the DS. It bothers me a bit but when I use the -20db setting it sounds terrible - almost like putting a blanket over my speakers. The speakers are a bit efficient at 93-94 db and the amps when run in bridged mode have 35db gain (very high I know) and .55mv input sensitivity. I also have a pair of tube amps that have less gain and sens. and don’t produce hiss but then I run out of volume (sometimes) on the DS in normal gain setting. I’m using the RCA output to the amps and XLR to the speaker subs (Hypex DS8). Any idea why the DS doesn’t sound good at the -20 gain setting? I’m wondering if a low/0 gain preamp might be a solution? I can get rid of the hiss using Rothwell attenuators but that looses transparency too. I realize my Luxman are probably a bad match with my speakers but would like to find some solution…

Thanks for any advice.

Tony


#14

Do you have some lower capacitance interconnect cables?

The transformer output on the DS interacts with higher cable capacitance:

  • With the high gain setting rising cable capacitance raises the frequency response at the very high end
  • With the low gain setting rising cable capacitance rolls off the frequency response at the very high end.
Having two sets of interconnects (roughly) doubles the capacitance and hence exaggerates the above effects.

I suspect that either some lower capacitance interconnects (or much shorter interconnects) will help but also using a preamp (and hence only one set of interconnects) on the DS would also help.


#15

Hi Ted, I’m using HiDiamond D9 IC’s at 1.5M to the amps and Canare Star Quad XLR 10’. Thanks for your reply.

Specs for HiDiamond:

Technical characteristics: External jacket mm. 19; Number of cond. 4; Cond. Graphite/Copper (4VRC); Capacity max. 83nf/km.; Conductor Resistance: 16 Ohm/km; Shield Resistance: 12 Ohm/Km.

Specs for Canare:

Model Cond. D.C.R.

ohm/1000ft
(ohm/100m)

Shield D.C.R.

ohm/1000ft
(ohm/100m)

Nom. Cap. *** pF/m Nom. Cap. † pF/m Nom. Imp.

(ohm)

Nom. Atten.

V/1000ft
(V/100m)

Group Delay Time nS/ft (nS/m)
L-4E6S <29.9 (<9.8) <9.1 (<3.0) 150 185 44 0.9 (0.3) 1.80 (5.9)

#16

You can definitely hear 1nF of capacitance on the output of the DS. Also many companies don’t tell you what the capacitance loading of the connectors (and their bonding to the cables ends) are on interconnects - it’s often non trivial.

For comparison to the above, Belden’s new ICONOCLAST interconnects are about 11 or 12pF / ft connectors included compared to the 50pF (or 60pF) / foot for the long cable and the 28pF / foot for the short cable you mention above.

Does disconnecting the Canare make the kind of difference you need to the sound quality? (I know that dropping the bass makes that a little harder to tell, but the effects of the extra capacitance are probably exactly what you are experiencing.)


#17

Hi Ted, disconnecting the XLR did make a difference! The sound quality between -20 and normal wasn’t as big and was almost as open sounding at -20db. I need to adjust the DS volume by about 50 to equal sound levels so it’s not an instant comparison. I think I will get some lower cap. XLR in mean time and see how that works. Any idea when the Belkin will be available? I would prefer not using -20 because if I understand correctly the signal is going through a bunch of resistors. I think ultimately I need a pre with adjustable input gain and also a master volume control for output. That way I will be set with both my SS and tube amps.

thanks for the advice

tony


#18

Random thoughts:

I think a preamp is the way to go (I too have way too much gain in my system - I usually watch TV down 60dB from full level…

Using the -20dB attenuator adds 15 Ohm shunts to ground on the outputs. That’s about as benign as it gets considering how many other resistors the audio’s been thru. They are good sounding thin film, high precision resistors (as are all of the resistors in the audio path.) It is true that there are 3 resistors in parallel for each 15 Ohm shunt, but that’s good, not bad.

40 ticks of the volume control is the same difference as using the -20dB attenuator.