[donato]

So I've been trying to troubleshoot my white noise and buzzing with my Pass XP-12 pre and X150.5 amp when using less power hungry headphones. It's fine for use with my more power hungry headphones (susvara, LCD-4 (marginally)), but definitely not with the more less power hungry ones (HEK SE, VO). I tried a bunch of things - different power cables, different power conditioners (also direct into wall), different interconnects. I even tried building a partial faraday cage around my pre using faraday fabric. It looks like the white noise is actually coming from the preamp and not the amp. If I only have the amp on, I don't hear the white noise, but I still hear buzzing (AC power supply noise?). If I have the preamp connected on mute, I don't hear the white noise (but still buzzing). But if the preamp is not on mute, even at volume 0, I get the noise. So I thought all along it was the amp that was making the noise, but it seems I was wrong about that. I have a message into pass labs about this, but I suppose I shouldn't be surprised when dealing with milliwatt sensitivity for headphones using stereo equipment designed to drive over 100+ watts I also have an XA25 on the way next week, but I don't really expect this to change things if it's the pre. Regardless, the buzzing is louder than the white noise anyway and if I can't clear that up, it doesn't matter about the noise.

 

[donato]

So I've been trying to troubleshoot my white noise and buzzing with my Pass XP-12 pre and X150.5 amp when using less power hungry headphones. It's fine for use with my more power hungry headphones (susvara, LCD-4 (marginally)), but definitely not with the more less power hungry ones (HEK SE, VO). I tried a bunch of things - different power cables, different power conditioners (also direct into wall), different interconnects. I even tried building a partial faraday cage around my pre using faraday fabric. It looks like the white noise is actually coming from the preamp and not the amp. If I only have the amp on, I don't hear the white noise, but I still hear buzzing (AC power supply noise?). If I have the preamp connected on mute, I don't hear the white noise (but still buzzing). But if the preamp is not on mute, even at volume 0, I get the noise. So I thought all along it was the amp that was making the noise, but it seems I was wrong about that. I have a message into pass labs about this, but I suppose I shouldn't be surprised when dealing with milliwatt sensitivity for headphones using stereo equipment designed to drive over 100+ watts I also have an XA25 on the way next week, but I don't really expect this to change things if it's the pre. Regardless, the buzzing is louder than the white noise anyway and if I can't clear that up, it doesn't matter about the noise.

FWIW, I also tried using the preamp functionality of my V281 and it also generates some white noise when connected to the amp. I suppose line level attenuators out of the preamp could help.

 

[Sajid Amit]

FWIW, I also tried using the preamp functionality of my V281 and it also generates some white noise when connected to the amp. I suppose line level attenuators out of the preamp could help.

Interesting. So when I use my Cayin Pre-Amp and Roksan K3 power amp, I get a buzzing noise on my Auteur, but not my Susvara. Susvara is quite silent, for obvious reasons. So my work around for this was to use the Cayin Pre-Amp and the Roksan K3 Integrated amp. This way, even on my Auteur, I don't get any noise at all, until I turn the volume up of my Integrated amp to 1 'o clock or more, which I would never need to anyway. So instead of a pre and power, and I am using a pre and integrated, and doing gain control on both the pre and the integrated. It's not as cumbersome as it sounds, and I am quite pleased with the results.

Meanwhile, I have tried the Auteur with an Accuphase E-380, and there was just a marginal noise after connecting which promptly disappeared. Of course, it was dead silent with my Susvaras. So in this case, of course, credit goes to Accuphase amp and their awesome design and implementation.

Just sharing my experiences with noise, in case it helps.

 

[donato]

Interesting. So when I use my Cayin Pre-Amp and Roksan K3 power amp, I get a buzzing noise on my Auteur, but not my Susvara. Susvara is quite silent, for obvious reasons. So my work around for this was to use the Cayin Pre-Amp and the Roksan K3 Integrated amp. This way, even on my Auteur, I don't get any noise at all, until I turn the volume up of my Integrated amp to 1 'o clock or more, which I would never need to anyway. So instead of a pre and power, and I am using a pre and integrated, and doing gain control on both the pre and the integrated. It's not as cumbersome as it sounds, and I am quite pleased with the results.

Meanwhile, I have tried the Auteur with an Accuphase E-380, and there was just a marginal noise after connecting which promptly disappeared. Of course, it was dead silent with my Susvaras. So in this case, of course, credit goes to Accuphase amp and their awesome design and implementation.

Just sharing my experiences with noise, in case it helps.

That's also interesting. When you run only out of the Roksan integrated (i.e. no Cayin pre), do you get buzzing? I'm guessing no which means the buzzing was upstream from that which you were able to attenuate with the gain setting on the Cayin.

In my case, with the X150.5, I get buzzing just from the amp alone. Doing a little research, I do see that the specs for noise on the X150.5 is 200uV per the Pass web site. On the XA25 (mine is supposedly arriving today!) is only 50uv per hometheaterreview.com. Pass Labs support did also mention this lower noise floor to me on the XA25 vs. the 150.5. As an FYI (since I know you'll be testing out some of these too), per hometheaterreview.com, XA30.8 is also 200uv and the FirstWatt J2 is at 100uv per the firstwatt website.

 

[Bonesy Jonesy]

Just reporting on this forum that I am getting fantastic results powering my Hifiman Susvara's from my Chord Electronics Mezzo 140 Speaker Power Amp speaker taps which is connected to my Chord DAVE and DAVE to Chord M Scaler and M Scaler to Chord Blu MK1. All connected via balanced XLR, using the stock Susvara cable and a CustomCans XLR to banana speaker tapping connectors adapter.

From the Chord Electronics website; https://chordelectronics.co.uk/product/mezzo140/ ;
The Mezzo 140 connected to speakers push out 140W RMS per channel with 0.016% distortion @ 4 Ohms and a frequency range of 5Hz to 100kHz +/- 0.5dB (which nicely covers the Susvara spec of 7Hz to 65kHz).

There are other websites that have reviewed the Mezzo140 and quoted the Mezzo 140 providing 120W with 0.03% distortion @ 8 Ohms.

Therefore from the above specs, the Chorrd Mezzo 140 will give the Susvara's (with an impedence of 60 Ohms) anything from 9.33 Watts (from the Chord website for values at 4 Ohms) to 16 Watts (for specs at 8 Ohms from other websites).

Chord don't make the Mezzo 140 (nor the Mezzo 50) anymore with both of them being replaced by the new Chord Etude. However occasionally the Mezzo 140 (and 50) come up on the internet second hand for around £1.5 to 1.8k for the 140 which considering the new price a few years back for the 140 was £4+k and the specification and build quality is quite a bargain especially of you also have the other Chord Choral products to connect to it an have them all mounted on a Chord Aspire Rack (also not made anymore and rarely come up for sale).

 

[donato]

So I've been trying to troubleshoot my white noise and buzzing with my Pass XP-12 pre and X150.5 amp when using less power hungry headphones. It's fine for use with my more power hungry headphones (susvara, LCD-4 (marginally)), but definitely not with the more less power hungry ones (HEK SE, VO). I tried a bunch of things - different power cables, different power conditioners (also direct into wall), different interconnects. I even tried building a partial faraday cage around my pre using faraday fabric. It looks like the white noise is actually coming from the preamp and not the amp. If I only have the amp on, I don't hear the white noise, but I still hear buzzing (AC power supply noise?). If I have the preamp connected on mute, I don't hear the white noise (but still buzzing). But if the preamp is not on mute, even at volume 0, I get the noise. So I thought all along it was the amp that was making the noise, but it seems I was wrong about that. I have a message into pass labs about this, but I suppose I shouldn't be surprised when dealing with milliwatt sensitivity for headphones using stereo equipment designed to drive over 100+ watts I also have an XA25 on the way next week, but I don't really expect this to change things if it's the pre. Regardless, the buzzing is louder than the white noise anyway and if I can't clear that up, it doesn't matter about the noise.

I just hooked up the XA25...no noise or buzzing from my HEK SE or my Verite Open!

 

[drc73rp]

I just hooked up the XA25...no noise or buzzing from my HEK SE or my Verite Open!

Will be waiting for your comparison of the XA25 vs X150.5.

 

[ra990]

Yes @donato we're all waiting to hear more about the XA25, don't keep us waiting too long!

 

[donato]

Will be waiting for your comparison of the XA25 vs X150.5.

Yes @donato we're all waiting to hear more about the XA25, don't keep us waiting too long!

Sorry guys, I got lost in listening for hours yesterday and again this morning

I'm already having to come from memory comparing to the X150.5 because I'm not likely to try to switch back and forth. First off, the X150.5 weighs 62 lbs and the XA25 a much more manageable 45 lbs. I pulled out the still warm X150.5 out of the bottom shelf of my rack and put the still cold-from-being-in-UPS-warehouse-and-delivery-vehicle. But I know you weren't asking about the weight and temperature of the amps (although interestingly the XA25 seems to run slightly cooler that I remember the X150.5. With an infrared thermometer, the XA25 runs about 120 degrees as measured in the middle cooling fins).

On first listen , the word that came to mind was "glowing" but that doesn't quite explain...all the produced sound just seemed more vivid. I'm not sure if it was because there was a blacker background; I wasn't consciously aware of noise on the X150.5, but I've previously mentioned that due to noise/buzzing the X150.5 worked best with the Susvara and somewhat the LCD-4, but my other HPs were unusable with the X150.5, but the XA25 is quiet with all of my HPs. It made think that when you see a stage production with spotlights on a performers and the performers stand out that much more from the black background around them. From memory, the 150.5 seemed warmer more lush, but of course less distinct.

Upon more extended listening ("extended" being relative since I've only owned this for about 24 hours) and with the amp fully warmed up (I also left it on overnight)...ok, this is all going to sound like audio/new equipment cliche, but it's the best I can describe...the most striking thing is how natural this all sounds...for one, the timbre is intoxicating...every sounds like it's supposed to sound whether it's piano, woodwinds, massed strings, guitar, drumstick on a cowbell or most any other percussion instrument sounds...right. There's harmonic richness and density, but not overly so. I think some of this is due to greater detail and every part of a sounds being produced, the attach, sustain, decay just all being so clean. Hearing the microdynamics in vocal vibrato sometimes made me feel like I could see into the performers throat and see their tonsils. Reproduced audio is all an illusion and this illusion works for me...so many of the clues that betray reality...sibilance, compression, thinness/clinical/analytical sound were minimized compared with the X150.5.

After dinner last night, I asked my wife to listen with the Susvaras while I listened along using my HEK SE on my HPA-1. I try not to ever ask her to listen to "equipment" but I wanted to play the Pas de Deus part of The Nutcracker, performed by Mariinsky Theatre Orchestra conducted by Valery Gergiev, which for me is my favorite movement and this performance is so expressive. She calls this one the "sad" one and listening on this setup had her in tears. While listening, she would call out the instruments as the melody was handed off from oboe to clarinet or comment on the harps in the background. She then wanted to hear all of her favorite movements from The Nutcracker. It was as much of a validation as I would have expected from someone who wasn't into gear/equipment at all.

So you may have to excuse my effusive descriptions since I've been like a kid on Christmas (oh wait, it is Christmas day...). The XA25 was a significant upgrade in my playback system (XP-12, XA25, Susvara. DAC is currently Holo Spring KTE, but Santa is coming back for an encore on Monday with a Holo May KTE DAC...) and it's hard for me to imagine looking to upgrade this (ha, famous last words...). The X150.5 was my first attempt at using a speaker amp (i.e. the one I had on hand) and that certainly opened up my experience with my Susvara, but the XA25 was the component that I picked with the intent of using it to power headphones and I couldn't be happier with it.

 

[BassicScience]

Interesting. So when I use my Cayin Pre-Amp and Roksan K3 power amp, I get a buzzing noise on my Auteur, but not my Susvara. Susvara is quite silent, for obvious reasons. So my work around for this was to use the Cayin Pre-Amp and the Roksan K3 Integrated amp. This way, even on my Auteur, I don't get any noise at all, until I turn the volume up of my Integrated amp to 1 'o clock or more, which I would never need to anyway. So instead of a pre and power, and I am using a pre and integrated, and doing gain control on both the pre and the integrated. It's not as cumbersome as it sounds, and I am quite pleased with the results.

Meanwhile, I have tried the Auteur with an Accuphase E-380, and there was just a marginal noise after connecting which promptly disappeared. Of course, it was dead silent with my Susvaras. So in this case, of course, credit goes to Accuphase amp and their awesome design and implementation.

Just sharing my experiences with noise, in case it helps.

Another solution to driving different headphones with widely divergent sensitivity from the same power (or integrated) amp is to get one with a variable gain switch. I generally like to avoid having two volume controls in series, although have done it in certain circumstances.

 

[ra990]

Sorry guys, I got lost in listening for hours yesterday and again this morning

I'm already having to come from memory comparing to the X150.5 because I'm not likely to try to switch back and forth. First off, the X150.5 weighs 62 lbs and the XA25 a much more manageable 45 lbs. I pulled out the still warm X150.5 out of the bottom shelf of my rack and put the still cold-from-being-in-UPS-warehouse-and-delivery-vehicle. But I know you weren't asking about the weight and temperature of the amps (although interestingly the XA25 seems to run slightly cooler that I remember the X150.5. With an infrared thermometer, the XA25 runs about 120 degrees as measured in the middle cooling fins).

On first listen , the word that came to mind was "glowing" but that doesn't quite explain...all the produced sound just seemed more vivid. I'm not sure if it was because there was a blacker background; I wasn't consciously aware of noise on the X150.5, but I've previously mentioned that due to noise/buzzing the X150.5 worked best with the Susvara and somewhat the LCD-4, but my other HPs were unusable with the X150.5, but the XA25 is quiet with all of my HPs. It made think that when you see a stage production with spotlights on a performers and the performers stand out that much more from the black background around them. From memory, the 150.5 seemed warmer more lush, but of course less distinct.

Upon more extended listening ("extended" being relative since I've only owned this for about 24 hours) and with the amp fully warmed up (I also left it on overnight)...ok, this is all going to sound like audio/new equipment cliche, but it's the best I can describe...the most striking thing is how natural this all sounds...for one, the timbre is intoxicating...every sounds like it's supposed to sound whether it's piano, woodwinds, massed strings, guitar, drumstick on a cowbell or most any other percussion instrument sounds...right. There's harmonic richness and density, but not overly so. I think some of this is due to greater detail and every part of a sounds being produced, the attach, sustain, decay just all being so clean. Hearing the microdynamics in vocal vibrato sometimes made me feel like I could see into the performers throat and see their tonsils. Reproduced audio is all an illusion and this illusion works for me...so many of the clues that betray reality...sibilance, compression, thinness/clinical/analytical sound were minimized compared with the X150.5.

After dinner last night, I asked my wife to listen with the Susvaras while I listened along using my HEK SE on my HPA-1. I try not to ever ask her to listen to "equipment" but I wanted to play the Pas de Deus part of The Nutcracker, performed by Mariinsky Theatre Orchestra conducted by Valery Gergiev, which for me is my favorite movement and this performance is so expressive. She calls this one the "sad" one and listening on this setup had her in tears. While listening, she would call out the instruments as the melody was handed off from oboe to clarinet or comment on the harps in the background. She then wanted to hear all of her favorite movements from The Nutcracker. It was as much of a validation as I would have expected from someone who wasn't into gear/equipment at all.

So you may have to excuse my effusive descriptions since I've been like a kid on Christmas (oh wait, it is Christmas day...). The XA25 was a significant upgrade in my playback system (XP-12, XA25, Susvara. DAC is currently Holo Spring KTE, but Santa is coming back for an encore on Monday with a Holo May KTE DAC...) and it's hard for me to imagine looking to upgrade this (ha, famous last words...). The X150.5 was my first attempt at using a speaker amp (i.e. the one I had on hand) and that certainly opened up my experience with my Susvara, but the XA25 was the component that I picked with the intent of using it to power headphones and I couldn't be happier with it.

Great, so glad you're enjoying it! I can't wait to get my hands on it.

 

[Sajid Amit]

Sorry guys, I got lost in listening for hours yesterday and again this morning

I'm already having to come from memory comparing to the X150.5 because I'm not likely to try to switch back and forth. First off, the X150.5 weighs 62 lbs and the XA25 a much more manageable 45 lbs. I pulled out the still warm X150.5 out of the bottom shelf of my rack and put the still cold-from-being-in-UPS-warehouse-and-delivery-vehicle. But I know you weren't asking about the weight and temperature of the amps (although interestingly the XA25 seems to run slightly cooler that I remember the X150.5. With an infrared thermometer, the XA25 runs about 120 degrees as measured in the middle cooling fins).

On first listen , the word that came to mind was "glowing" but that doesn't quite explain...all the produced sound just seemed more vivid. I'm not sure if it was because there was a blacker background; I wasn't consciously aware of noise on the X150.5, but I've previously mentioned that due to noise/buzzing the X150.5 worked best with the Susvara and somewhat the LCD-4, but my other HPs were unusable with the X150.5, but the XA25 is quiet with all of my HPs. It made think that when you see a stage production with spotlights on a performers and the performers stand out that much more from the black background around them. From memory, the 150.5 seemed warmer more lush, but of course less distinct.

Upon more extended listening ("extended" being relative since I've only owned this for about 24 hours) and with the amp fully warmed up (I also left it on overnight)...ok, this is all going to sound like audio/new equipment cliche, but it's the best I can describe...the most striking thing is how natural this all sounds...for one, the timbre is intoxicating...every sounds like it's supposed to sound whether it's piano, woodwinds, massed strings, guitar, drumstick on a cowbell or most any other percussion instrument sounds...right. There's harmonic richness and density, but not overly so. I think some of this is due to greater detail and every part of a sounds being produced, the attach, sustain, decay just all being so clean. Hearing the microdynamics in vocal vibrato sometimes made me feel like I could see into the performers throat and see their tonsils. Reproduced audio is all an illusion and this illusion works for me...so many of the clues that betray reality...sibilance, compression, thinness/clinical/analytical sound were minimized compared with the X150.5.

After dinner last night, I asked my wife to listen with the Susvaras while I listened along using my HEK SE on my HPA-1. I try not to ever ask her to listen to "equipment" but I wanted to play the Pas de Deus part of The Nutcracker, performed by Mariinsky Theatre Orchestra conducted by Valery Gergiev, which for me is my favorite movement and this performance is so expressive. She calls this one the "sad" one and listening on this setup had her in tears. While listening, she would call out the instruments as the melody was handed off from oboe to clarinet or comment on the harps in the background. She then wanted to hear all of her favorite movements from The Nutcracker. It was as much of a validation as I would have expected from someone who wasn't into gear/equipment at all.

So you may have to excuse my effusive descriptions since I've been like a kid on Christmas (oh wait, it is Christmas day...). The XA25 was a significant upgrade in my playback system (XP-12, XA25, Susvara. DAC is currently Holo Spring KTE, but Santa is coming back for an encore on Monday with a Holo May KTE DAC...) and it's hard for me to imagine looking to upgrade this (ha, famous last words...). The X150.5 was my first attempt at using a speaker amp (i.e. the one I had on hand) and that certainly opened up my experience with my Susvara, but the XA25 was the component that I picked with the intent of using it to power headphones and I couldn't be happier with it.

You write well, my friend. Hope to see more impressions in the future of your listening experiences. I am going to audition an XP12 and an XA25 tonight. The XP12 is already with me.

 

[donato]

You write well, my friend. Hope to see more impressions in the future of your listening experiences. I am going to audition an XP12 and an XA25 tonight. The XP12 is already with me.

Oh fantastic. I can't wait to hear what your impressions are!

Side note, there is a slight buzzing I notice with my Verite Open and my HEK SE. I only gave them a very quick check when I first received the XA25. Much quieter than the X150.5 was, but still a little bit of buzzing.

 

[Sajid Amit]

Oh fantastic. I can't wait to hear what your impressions are!

Side note, there is a slight buzzing I notice with my Verite Open and my HEK SE. I only gave them a very quick check when I first received the XA25. Much quieter than the X150.5 was, but still a little bit of buzzing.

Thanks for mentioning!

But you seem to be quite moved by the XA25's sonic qualities in general, so as long as it can do the same (or similar) for me with Susvara, I am happy to drive my sensitive HPs off my other amps! Fingers crossed.

 

[Roasty]

Oh fantastic. I can't wait to hear what your impressions are!

Side note, there is a slight buzzing I notice with my Verite Open and my HEK SE. I only gave them a very quick check when I first received the XA25. Much quieter than the X150.5 was, but still a little bit of buzzing.

Any idea what is the cause of the buzzing?

If you can't find the cause, are you going to get the items replaced, or just live with it?

I think it would drive me crazy haha