Hello everybody,
I hope I'm on the right forum/section, since I'm not really involved in DIY stuff but I'm a owner of a Pass Labs preamp and I'm looking for a place where I can find answers to some questions.
Well, so, I noticed something strange about my X0.2 preamplifier outputs.
This preamp is connected alternatively to Coda CX monoblocks or to a Stax SRM 727A headphone amplifier (with preamp stage disabled).
To connect this stuff, I have the choice between two cables I own, some Transparent Musiclink super XLR cables, and Mogami 2549 RCA cables.
I've been using XLR cables for a long time but I often noticed strange changes in sound quality (sometimes sounding quite dry, sometimes sounding very fluid and generous in the bottom), that I often thought was due to a bad current in my house. But recently, I noticed that I could stop the "dry periods" sometimes by disconnecting and reconnecting the XLR cables, or by turning off the preamp (by disconnecting of the mains, since it doesn't have a power button).
When using the Mogamis, it looks like the sound is continuously good, no dry periods.
So I did some test, and I noticed that if I have the Mogamis (RCA) connected on the output of the preamp to an amplifier (for example the Codas) and the Transparent XLR to another (for example the Stax), the sound changes from the situation where the XLR are not connected at all, or just connected to the preamp (and fall on the floor, for example).
In the situation where the preamp is connected to both the Codas and the Stax, using RCA and XLR cables, the output volume is quite lowered and the bottoms are quite different (more fluid but less bandwidth; the feeling).
Actualy, I have a bigger volume using RCA alone cables at the output of the X0.2 than using XLR alone or both XLR and RCA cables. No difference if connected all on output 1, 2 or one on output 1 and the other on output 2.
In the user manual, Pass doesn't say anything about this. It's just said that XLR outputs are advised.
So, is this normal or not? If not, can this be due to the Trasparent cables? I don't own another pair of XLR interconnects or another preamp to make other test.
I hope my explanations are understandable, please forgive me for my approximative English, it isn't my former language (I'm French).
Best regards.
I hope I'm on the right forum/section, since I'm not really involved in DIY stuff but I'm a owner of a Pass Labs preamp and I'm looking for a place where I can find answers to some questions.
Well, so, I noticed something strange about my X0.2 preamplifier outputs.
This preamp is connected alternatively to Coda CX monoblocks or to a Stax SRM 727A headphone amplifier (with preamp stage disabled).
To connect this stuff, I have the choice between two cables I own, some Transparent Musiclink super XLR cables, and Mogami 2549 RCA cables.
I've been using XLR cables for a long time but I often noticed strange changes in sound quality (sometimes sounding quite dry, sometimes sounding very fluid and generous in the bottom), that I often thought was due to a bad current in my house. But recently, I noticed that I could stop the "dry periods" sometimes by disconnecting and reconnecting the XLR cables, or by turning off the preamp (by disconnecting of the mains, since it doesn't have a power button).
When using the Mogamis, it looks like the sound is continuously good, no dry periods.
So I did some test, and I noticed that if I have the Mogamis (RCA) connected on the output of the preamp to an amplifier (for example the Codas) and the Transparent XLR to another (for example the Stax), the sound changes from the situation where the XLR are not connected at all, or just connected to the preamp (and fall on the floor, for example).
In the situation where the preamp is connected to both the Codas and the Stax, using RCA and XLR cables, the output volume is quite lowered and the bottoms are quite different (more fluid but less bandwidth; the feeling).
Actualy, I have a bigger volume using RCA alone cables at the output of the X0.2 than using XLR alone or both XLR and RCA cables. No difference if connected all on output 1, 2 or one on output 1 and the other on output 2.
In the user manual, Pass doesn't say anything about this. It's just said that XLR outputs are advised.
So, is this normal or not? If not, can this be due to the Trasparent cables? I don't own another pair of XLR interconnects or another preamp to make other test.
I hope my explanations are understandable, please forgive me for my approximative English, it isn't my former language (I'm French).
Best regards.
Last edited:
I have not heard of this before. The indication is that when you connect the
balanced cables to an amplifier the sound changes dramatically.
There is nothing in the X0.2 circuit which should give rise to this. The + output
on the RCA is the same as Pin 2 of the XLR.
It is not clear if you can drive both the Coda and Stax with balanced lines.
Offhand, I would check the input arrangement on the balanced inputs of the
amplifier being used. It is possible that pin 2 or 3 is grounded, which would
make for a dramatic difference in the sound of the preamp.
😎
balanced cables to an amplifier the sound changes dramatically.
There is nothing in the X0.2 circuit which should give rise to this. The + output
on the RCA is the same as Pin 2 of the XLR.
It is not clear if you can drive both the Coda and Stax with balanced lines.
Offhand, I would check the input arrangement on the balanced inputs of the
amplifier being used. It is possible that pin 2 or 3 is grounded, which would
make for a dramatic difference in the sound of the preamp.
😎
Thank you for your fast answer!
I can't drive both the Coda and Stax with balanced lines. I only can drive one with balanced and one with single ended. My only other balanced cable is between the DAC and the preamp. What I used to do was to disconnect the balanced cables to one amplifier and connect them to the other(s) when I wanted to use the other. I recently tried to connect one with XLR and one with RCA because I was tired to go behind my hifi gear all the time! 😀
I can't tell you anything about the inputs of the Coda but you have the informations about the inputs of the Stax on this picture: here. Coda and Stax amplifiers seem to have the same behavior regarding this problem: periods of "good and fluid sound" and periods of dry sound. It's been like this for more than one year (when I bought the preamp).
I've also reproduced the test of switching from XLR to RCA between the preamp and amplifier (any of them): the sound is louder when I have only the RCA connected. When I have the XLR connected to the other amp, the volume decreases. I think it's quite strange.
This evening I tried to intervert the XLR between DAC/preamp and between preamp/amplifiers. I never tried this test. The sound is quite different (quite darker, and I'd say a little better). Same thing happens when I replace the XLR between preamp and amp by RCA: the volume increases (is this normal?).
I'll see if I also get "dry sound periods" in this configuration. If I don't (which I hope), it will mean that the Transparent cable didn't like to be between the preamp and and amps, and the X0.2 isn't concerned. I'll go back and tell you.
By the way, I just had to tell that I'm very, very impressed to see a superstar amplifier engineer like you answering to my little questions, even if I'm an owner of your (fabulous) preamplifier. 🙂
I can't drive both the Coda and Stax with balanced lines. I only can drive one with balanced and one with single ended. My only other balanced cable is between the DAC and the preamp. What I used to do was to disconnect the balanced cables to one amplifier and connect them to the other(s) when I wanted to use the other. I recently tried to connect one with XLR and one with RCA because I was tired to go behind my hifi gear all the time! 😀
I can't tell you anything about the inputs of the Coda but you have the informations about the inputs of the Stax on this picture: here. Coda and Stax amplifiers seem to have the same behavior regarding this problem: periods of "good and fluid sound" and periods of dry sound. It's been like this for more than one year (when I bought the preamp).
I've also reproduced the test of switching from XLR to RCA between the preamp and amplifier (any of them): the sound is louder when I have only the RCA connected. When I have the XLR connected to the other amp, the volume decreases. I think it's quite strange.
This evening I tried to intervert the XLR between DAC/preamp and between preamp/amplifiers. I never tried this test. The sound is quite different (quite darker, and I'd say a little better). Same thing happens when I replace the XLR between preamp and amp by RCA: the volume increases (is this normal?).
I'll see if I also get "dry sound periods" in this configuration. If I don't (which I hope), it will mean that the Transparent cable didn't like to be between the preamp and and amps, and the X0.2 isn't concerned. I'll go back and tell you.
By the way, I just had to tell that I'm very, very impressed to see a superstar amplifier engineer like you answering to my little questions, even if I'm an owner of your (fabulous) preamplifier. 🙂
The Stax picture doesn't tell us much, but since both it and the Coda were
designed by competent people we will assume that they are following
normal convention for wiring.
The outputs of the X0.2 have internal attenuators on jumpers for different
gain settings. You might check to see that they are set to the same values
for both channels and such.
Also, the X0.2 has a higher output impedance than most other preamps -
as high as 1.5K depending on attenuator settings. If the XLR cables have
loading networks on them then this might show up, and you should then
try maximal attenuation (minimum gain) settings to see if that does anything.
😎
designed by competent people we will assume that they are following
normal convention for wiring.
The outputs of the X0.2 have internal attenuators on jumpers for different
gain settings. You might check to see that they are set to the same values
for both channels and such.
Also, the X0.2 has a higher output impedance than most other preamps -
as high as 1.5K depending on attenuator settings. If the XLR cables have
loading networks on them then this might show up, and you should then
try maximal attenuation (minimum gain) settings to see if that does anything.
😎
Ok, I think I have progressed...
This morning, when I woke up and tested the system, I again had a dry sound.
The Transparent cables were between the DAC and the preamp. It was not *very* dry, but enough to make me feel that something was not right. The more I listened, the more it was dry.
I swapped the cables between the X0.2 and the amps (Harmonic Technology Magic link 2 XLR to Mogami RCA): not better. Not satisfying.
So then I disconnected the Transparent cables from the preamp output for several seconds, and then reconnected them. I didn'jt touch to the outputs. The sound was now ok.
I think the problem is identified: the Transparent cables seem to have a strange behaviour.
I'm not sure what you're meaning about "loading networks" on the cables, but Transparent uses what they call networks on their cables (it's inside the little box all of their cables have). They don't tell what is inside these boxes but there are some photos on the web done by people who have opened these boxes, like here. I'm not a technician at all but apparently it's something very cheap. I wonder if this kind of thing can be the origin of what I noticed... And if these cables can change their behaviour from times to times... Maybe something like they could be sensitive to RF, or anything like that.
What is strange is that I had used these cables for years before buying the X0.2 and they had always been good. Maybe a problem of compatibility or synergy between the components?
I'll spend some time now totally without the Transparent cables (my Harmonic Technology and the Mogamis only), and see the sound gets dry now. But I'm almost sure it won't. I should receive some XLR cables at home next week for test. I'll tell on the forum what happens.
I don't think there is a problem with the internal attenuators on the outputs of the X0.2: when connected to my Stax amp, the soundstage is perfect with no balance problem between left and right. Since there isn't any acoustic problem when listening to headphones, I'm confident about the value of the attenuation for both channels.
One more time, thank you for taking the time to answer me!
This morning, when I woke up and tested the system, I again had a dry sound.
The Transparent cables were between the DAC and the preamp. It was not *very* dry, but enough to make me feel that something was not right. The more I listened, the more it was dry.
I swapped the cables between the X0.2 and the amps (Harmonic Technology Magic link 2 XLR to Mogami RCA): not better. Not satisfying.
So then I disconnected the Transparent cables from the preamp output for several seconds, and then reconnected them. I didn'jt touch to the outputs. The sound was now ok.
I think the problem is identified: the Transparent cables seem to have a strange behaviour.
I'm not sure what you're meaning about "loading networks" on the cables, but Transparent uses what they call networks on their cables (it's inside the little box all of their cables have). They don't tell what is inside these boxes but there are some photos on the web done by people who have opened these boxes, like here. I'm not a technician at all but apparently it's something very cheap. I wonder if this kind of thing can be the origin of what I noticed... And if these cables can change their behaviour from times to times... Maybe something like they could be sensitive to RF, or anything like that.
What is strange is that I had used these cables for years before buying the X0.2 and they had always been good. Maybe a problem of compatibility or synergy between the components?
I'll spend some time now totally without the Transparent cables (my Harmonic Technology and the Mogamis only), and see the sound gets dry now. But I'm almost sure it won't. I should receive some XLR cables at home next week for test. I'll tell on the forum what happens.
I don't think there is a problem with the internal attenuators on the outputs of the X0.2: when connected to my Stax amp, the soundstage is perfect with no balance problem between left and right. Since there isn't any acoustic problem when listening to headphones, I'm confident about the value of the attenuation for both channels.
One more time, thank you for taking the time to answer me!
Ok, I'm back after some days of test.
First: yes, Transparent Cables were crap. I'm afraid when thinking I've spent almost five years with them whereas I had my Mogamis sleeping and they were far better than the Transparent.
But, problem not solved. Or I should say, it changed when using the Mogamis instead of the Transparents.
Now this is what I noticed: after having plugged the cables for some time (usually several days), the sound is becoming quite dry too. Not as dry as with the Transparent cables, there is still some bass, but it's not as satisfying, the bass are less liquid, and mediums and highs sound too sharp, the sound is overall less bold, it has less body and sounds less natural.
First I was not sure about it, but now I am. And the difference is evident, I know from the very first seconds if it's right or not.
So I did some tests to find what can systematically make the "right" sound back with no doubt.
Disconnecting and reconnecting the cables between the X0.2 and the monoblocks doesn't help. Even with a long time before reconnecting them. Turning off the X0.2 and the monoblocks (by disconnecting them from the mains) doesn't help either. Same sound after turning them on again.
My completely absurd solution is to connect my cables (I'm still talking about the RCA Mogamis, I don't use the Transparent anymore) to my headphone amplifier (Stax), play some music, and reconnect them to the monoblocks. And now suddenly it sounds right.
I can't explain this, I don't know anything in electricity, but I tried it 3 times (couldn't test it more because it takes several days to have the dry sound back after this) and it always worked.
Only tried it one time but also worked: plug at the same time RCA and XLR cables on the outputs of the X0.2. The RCA are connected to the inputs of the monoblocks, the XLR are not connected, they lay down to the floor. When the dry sound comes, change the RCA for the XLR, play some music, and reconnect the RCA. It sounds right. But I shoud make the test more times to be sure it works.
I'm not sure if playing music before reconecting the RCA is necessary. I just did it each time I did the test.
Is there some logic behind this strange problem?
I have to tell that my system is located in an attic, just under the roof, near to the antenna of the house, and really close to an electric pillar. I don't know if this can have an influence to the behaviour of the system.
Nothing dramatic about this, I can plug and unplug the cables in several seconds when the dry sound happens so I can "heal" the system when it needs it, but I'd be happy if I wouldn't have to do that, or if I just was able to understand what is happening here.
First: yes, Transparent Cables were crap. I'm afraid when thinking I've spent almost five years with them whereas I had my Mogamis sleeping and they were far better than the Transparent.
But, problem not solved. Or I should say, it changed when using the Mogamis instead of the Transparents.
Now this is what I noticed: after having plugged the cables for some time (usually several days), the sound is becoming quite dry too. Not as dry as with the Transparent cables, there is still some bass, but it's not as satisfying, the bass are less liquid, and mediums and highs sound too sharp, the sound is overall less bold, it has less body and sounds less natural.
First I was not sure about it, but now I am. And the difference is evident, I know from the very first seconds if it's right or not.
So I did some tests to find what can systematically make the "right" sound back with no doubt.
Disconnecting and reconnecting the cables between the X0.2 and the monoblocks doesn't help. Even with a long time before reconnecting them. Turning off the X0.2 and the monoblocks (by disconnecting them from the mains) doesn't help either. Same sound after turning them on again.
My completely absurd solution is to connect my cables (I'm still talking about the RCA Mogamis, I don't use the Transparent anymore) to my headphone amplifier (Stax), play some music, and reconnect them to the monoblocks. And now suddenly it sounds right.
I can't explain this, I don't know anything in electricity, but I tried it 3 times (couldn't test it more because it takes several days to have the dry sound back after this) and it always worked.
Only tried it one time but also worked: plug at the same time RCA and XLR cables on the outputs of the X0.2. The RCA are connected to the inputs of the monoblocks, the XLR are not connected, they lay down to the floor. When the dry sound comes, change the RCA for the XLR, play some music, and reconnect the RCA. It sounds right. But I shoud make the test more times to be sure it works.
I'm not sure if playing music before reconecting the RCA is necessary. I just did it each time I did the test.
Is there some logic behind this strange problem?
I have to tell that my system is located in an attic, just under the roof, near to the antenna of the house, and really close to an electric pillar. I don't know if this can have an influence to the behaviour of the system.
Nothing dramatic about this, I can plug and unplug the cables in several seconds when the dry sound happens so I can "heal" the system when it needs it, but I'd be happy if I wouldn't have to do that, or if I just was able to understand what is happening here.
are they (amps,preamp) properly grounded , I'm thinking of safety ground in house mains circuit ?
is there any corelation with preamp constantly powered On ?
is there any corelation with preamp constantly powered On ?
I don't think so.
I use a Gigawatt PC4 EVO power conditionner and it has a red led on its back panel, which shows if it detects a problem of phase or ground. The red led is off.
Before you ask, I already had this problem before buying the power conditionner (I had it with no conditionner, and with a Gigawatt PC2, and now with PC4). So the conditionner isn't the source of the problem.
But, maybe the Gigawatt conditionners have a bad detection of ground and phase problems, this could be possible.
I don't think so. Today I had the dry sound again, I tried to turn off the preamp and the amps (it's not the first time I try) and it didn't help. But, I clearly remember that some time ago, it worked, one time, but only one...
Maybe this could help: after a thunderstorm, when reconnecting everything (I always disconnect my gear during a thunderstorm), the sound is always ok, never dry. For several years I've had this problem, it has always been true.
Actually I feel I'm going to get mad about this...
The day before, I had also the dry sound, and just disconnecting a power plug of a gear that I wasn't using from the mains, and replugging it solved the problem. It was effective two times.
But today it isn't. Actually, I wasn't able today to make the dry sound stop, although I used all the "tricks" I thought were effective. Changing the RCA for the XLR and reconnect RCA, disconnect something from the mains and reconnect it, etc. Nothing worked.
Now I'm thinking it has nothing to do with the outputs of the preamp, but I was able to use these outputs to "solve" the problem several times and this made me think it was the preamp's fault.
I'm completely lost... I'm thinking about a ground problem which could affect some items in the system, but I can't find it. It happened even when I'm using only XLR cables, the chassis of my elements don't touch each other... It happens even when I'm only using toslink as digital connexion so there is no electrical interference coming from the source...
I'm really thick of this and the system seem to be working fine only by chance...
I just feel the desire to throw everything by the window... Stop me please!
try other preamp in combo , or other power amp(s) , just to determine in which box culprit (possibly ) lies
however , if you decide to toss them through the window , you know how ppl in civilized countries are doing that ....... you can count on OPLDF services
however , if you decide to toss them through the window , you know how ppl in civilized countries are doing that ....... you can count on OPLDF services
Clean all contacts at amps and cables and speakers with contact cleaner such as Deoxit. Could help.
Hello everybody and first of all, I wish you a happy new year!
Well I'm back here after 4 months, because I... I think I solved the problem and wanted to share my adventure with you guys who took some time to help me.
So, no more suspense: it was not the X0.2's fault!
Actually, there was no culprit in my different hifi gears. The culprit was my computer, which I use as a source for playing music, connected by Toslink to my DAC (Weiss Medea+), or by Firewire to my DAC with a Weiss INT202 but I don't use it anymore, I prefer the sound by the toslink cable. I had bad results with Firewire (using a firewire card) on my last computers, I don't know why.
So well, what's bad with the computer?
Actually, I was quite surprised because I had the occasion to build a second system recently, using another computer (a laptop), a 3D Lab Millenium MK2 Dac, a NAD 304 amp and Focal 907BE speakers, and Stax SRM-727+SR007 headphone system... The problem was still here.
I recently bought a Viva Audio Egoista 845 headphone amp, and a JPS Labs Abyss headphones, and the problem was still here...
Even in another place!!
At this time I was going to get completely mad and started to wonder if my ears were ill or something like that.
And so, actually the problem is that when the volume is set at 100% in the Windows volume setting (and/or in the Foobar player), the problem occurs. Same thing with laptop or with desktop computer. Same thing with Daphile or Windows. When the output volume from the computer is high (not necessarily 100%), the problem occurs. But when it is low and I max the volume from the amp or the preamp, the sound is fine.
Here are the symptoms when the problem occurs and the sound becomes "dry":
- Bad spatialisation, the sound "sticks" to the speakers and is flat
- No bandwidth, the bass is almost missing, the highs don't get high at all
- The mediums are to "thin", they have no depth
- Global sensation that the music is played too bright, the system sings out of tune
Turning down the volume from the computer makes the problem disappear, always. I have no explanation since it only digital signal coming out from the computer, 0 and 1s! I can understand it from the laptop which has the same output (jack 3.5mm) for digital and analog output, but same thing with the desktop computer which has a dedicated toslink output.
Furthermore, I have always read that it is mandatory to play music at 100% volume in the digital devices in order to have no loss in the digital signal transmitted. Maybe I do have a little loss now, but the sound is just 1000 times better now. It's actually now a normal sound and I re-discover my hifi system now... The fact that I sometimes got a good sound at 100% volume, and sometimes not, is a mystery for me too. But at a volume, let's say, 35%, I always get a good sound.
I discovered this completely randomly, because my NAD amplifier doesn't have a remote control and I was tired to stand up to change the volume, so I changed it in the foobar player, and when the volume was low, the sound was strangely better.
What I don't understand is why, when the sound became "dry", I sometimes tried to listen from my CD player and the sound stayed dry. Same thing with the Totaldac server I had for some days at home in summer. But the Totaldac is actually a very optimised computer. I don't know for the CD player, it maybe just have a dry sound as a transport, it was just an entry-level Marantz player.
Maybe some DACs don't like a too high volume in their inputs...? But how is it even possible, it's only 0 and 1s!
Since my problem is solved, I'm just happy and will now take some heavenly good time with my hifi system (and my beloved X0.2 preamp!). I re-discover my system, speakers and headphones, they just have never sounded so good... But I'd like to know if you see some kind of sense, of logic, in my story. Since you're into DIY stuff, I suppose you have a big experience and knowledge in electronics.
Well I'm back here after 4 months, because I... I think I solved the problem and wanted to share my adventure with you guys who took some time to help me.
So, no more suspense: it was not the X0.2's fault!
Actually, there was no culprit in my different hifi gears. The culprit was my computer, which I use as a source for playing music, connected by Toslink to my DAC (Weiss Medea+), or by Firewire to my DAC with a Weiss INT202 but I don't use it anymore, I prefer the sound by the toslink cable. I had bad results with Firewire (using a firewire card) on my last computers, I don't know why.
So well, what's bad with the computer?
Actually, I was quite surprised because I had the occasion to build a second system recently, using another computer (a laptop), a 3D Lab Millenium MK2 Dac, a NAD 304 amp and Focal 907BE speakers, and Stax SRM-727+SR007 headphone system... The problem was still here.
I recently bought a Viva Audio Egoista 845 headphone amp, and a JPS Labs Abyss headphones, and the problem was still here...
Even in another place!!
At this time I was going to get completely mad and started to wonder if my ears were ill or something like that.
And so, actually the problem is that when the volume is set at 100% in the Windows volume setting (and/or in the Foobar player), the problem occurs. Same thing with laptop or with desktop computer. Same thing with Daphile or Windows. When the output volume from the computer is high (not necessarily 100%), the problem occurs. But when it is low and I max the volume from the amp or the preamp, the sound is fine.
Here are the symptoms when the problem occurs and the sound becomes "dry":
- Bad spatialisation, the sound "sticks" to the speakers and is flat
- No bandwidth, the bass is almost missing, the highs don't get high at all
- The mediums are to "thin", they have no depth
- Global sensation that the music is played too bright, the system sings out of tune
Turning down the volume from the computer makes the problem disappear, always. I have no explanation since it only digital signal coming out from the computer, 0 and 1s! I can understand it from the laptop which has the same output (jack 3.5mm) for digital and analog output, but same thing with the desktop computer which has a dedicated toslink output.
Furthermore, I have always read that it is mandatory to play music at 100% volume in the digital devices in order to have no loss in the digital signal transmitted. Maybe I do have a little loss now, but the sound is just 1000 times better now. It's actually now a normal sound and I re-discover my hifi system now... The fact that I sometimes got a good sound at 100% volume, and sometimes not, is a mystery for me too. But at a volume, let's say, 35%, I always get a good sound.
I discovered this completely randomly, because my NAD amplifier doesn't have a remote control and I was tired to stand up to change the volume, so I changed it in the foobar player, and when the volume was low, the sound was strangely better.
What I don't understand is why, when the sound became "dry", I sometimes tried to listen from my CD player and the sound stayed dry. Same thing with the Totaldac server I had for some days at home in summer. But the Totaldac is actually a very optimised computer. I don't know for the CD player, it maybe just have a dry sound as a transport, it was just an entry-level Marantz player.
Maybe some DACs don't like a too high volume in their inputs...? But how is it even possible, it's only 0 and 1s!
Since my problem is solved, I'm just happy and will now take some heavenly good time with my hifi system (and my beloved X0.2 preamp!). I re-discover my system, speakers and headphones, they just have never sounded so good... But I'd like to know if you see some kind of sense, of logic, in my story. Since you're into DIY stuff, I suppose you have a big experience and knowledge in electronics.
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