Just had a short session using the Xonar Essence on all outputs. No hum whatsoever on the line arrays. As I was in the vicinity I put my ears to the subs as well. A very faint hum there.
But I guess this confirms prior suspicions, the DAC lets go at higher listening levels. The Xonar was good and able to still sound good. Be it, that it did seem to sound a little different (aargh..)
I do realize that I need to redo all processing again to have a valid reference. However all indications point to the DAC being the weak link here.
If I have some time left, I will put the pré-amp in there at 6 dB gain with the Asus feeding it. Just as an indication if it makes sense to go out and get me some buffers to feed my long lines.
But I guess this confirms prior suspicions, the DAC lets go at higher listening levels. The Xonar was good and able to still sound good. Be it, that it did seem to sound a little different (aargh..)
I do realize that I need to redo all processing again to have a valid reference. However all indications point to the DAC being the weak link here.
If I have some time left, I will put the pré-amp in there at 6 dB gain with the Asus feeding it. Just as an indication if it makes sense to go out and get me some buffers to feed my long lines.
Shute, that didn't take long. Inserted the Atom with 6 dB gain, reduced internal level within JRiver with 6 dB. Boom. I prefer it with the Atom.
I should insert the Atom with no gain to be precise, only using it as a line driver, but I had marked the 6 dB level so this was easier.
I can't believe those little nuances that can be so different.
I started my listening session with a headache, had it before anything was turned on. I even feel better now, but going crazy from these nuance changes.
With Atom = more alive sound, more real. More open, more sparkle, ah heck, I need to learn the Audiophile language to express myself.
PC -> Xonar Essence ST -> Atom -> Long cable -> Goldmund clone
I prefer this, heck if I know the M1 DAC was doing better.
I should insert the Atom with no gain to be precise, only using it as a line driver, but I had marked the 6 dB level so this was easier.
I can't believe those little nuances that can be so different.
I started my listening session with a headache, had it before anything was turned on. I even feel better now, but going crazy from these nuance changes.
With Atom = more alive sound, more real. More open, more sparkle, ah heck, I need to learn the Audiophile language to express myself.
PC -> Xonar Essence ST -> Atom -> Long cable -> Goldmund clone
I prefer this, heck if I know the M1 DAC was doing better.
As I'm rambling already, the headache was the result of saying up way to late to read that Goldmund Memesis thread.
Not sure if that brought me anything.
I've listened some more, didn't have the room to myself any longer but my son thoroughly enjoyed the listening session with me. He started dancing to the music, suggesting a few songs and having a good time. This was with the JDS Atom in there at 6 dB gain. The Xonar Essence ST being the DAC for all channels.
It makes me think to buy the Universal Buffers to drive the long lines. An opportunity to convert the sub lines to balanced making the subs balanced in as they were meant to be. Still leaves the question if I need gain and if I do, how much?
I'm pretty sure once I measure and adjust everything all over again this setup could really rock as it is right now. However I don't want the Atom there, as it has no power button, you're supposed to turn it off with the volume control. That volume control isn't super, as I've had a few positions give me a skewed image. Not at the 6 dB mark though.
I played a lot of varied material, all from close mic-ed voices to Audiophile classics like Hotel California (Hell Freezes Over) to Devin Townsend with Awake (representing a wall of sound). Even though the balance can't be where it's supposed to be, it sure did sound good.
Not sure if that brought me anything.
I've listened some more, didn't have the room to myself any longer but my son thoroughly enjoyed the listening session with me. He started dancing to the music, suggesting a few songs and having a good time. This was with the JDS Atom in there at 6 dB gain. The Xonar Essence ST being the DAC for all channels.
It makes me think to buy the Universal Buffers to drive the long lines. An opportunity to convert the sub lines to balanced making the subs balanced in as they were meant to be. Still leaves the question if I need gain and if I do, how much?
I'm pretty sure once I measure and adjust everything all over again this setup could really rock as it is right now. However I don't want the Atom there, as it has no power button, you're supposed to turn it off with the volume control. That volume control isn't super, as I've had a few positions give me a skewed image. Not at the 6 dB mark though.
I played a lot of varied material, all from close mic-ed voices to Audiophile classics like Hotel California (Hell Freezes Over) to Devin Townsend with Awake (representing a wall of sound). Even though the balance can't be where it's supposed to be, it sure did sound good.
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Very interesting, but I wouldn't say it is all that surprising to me. First of all it is not surprising that such a "high-end" system is sensitive to small things. Second, I would be a bit nervous using the same chain from the computer to the amplifier. DACs, RCA Cables and pre-amps can all introduce issues (well, small issues). My prejudice (and experience) would lead me to avoiding such a setup.
I would imagine, given a good power supply and a decent motherboard, the interference to your sound card could be almost eliminated (the audible part that is). Is it a PCI-express card?
I am sure you have thought about all this before, but what is the reason for not shortening the chain and outputting directly from the Xonar, analogue? It should be able to perform adequately as such (I am aware of the issues that surround internal soundcards - as well as steps that can be taken to avoid most of them).
I hope I don't sound pedantic or anything like that, I am very interested in the subject and it is something I have been thinking about myself. Please don't take this the wrong way.
I would imagine, given a good power supply and a decent motherboard, the interference to your sound card could be almost eliminated (the audible part that is). Is it a PCI-express card?
I am sure you have thought about all this before, but what is the reason for not shortening the chain and outputting directly from the Xonar, analogue? It should be able to perform adequately as such (I am aware of the issues that surround internal soundcards - as well as steps that can be taken to avoid most of them).
I hope I don't sound pedantic or anything like that, I am very interested in the subject and it is something I have been thinking about myself. Please don't take this the wrong way.
Hi Wesayso,
a quick backwards look didn't find full specs for the Goldmund amp, so the following is pretty much spitballing....
...but it sounds like the analog output of the DAC, and the input sensitivity of the amp aren't mating well. Specifically that the input sensitivity of the amp is too low (needs a higher voltage to drive to full power.)
i've run into this using mindsp dacs with their 2.0Vrms consumer output, trying to drive pro amps with +26dB constant gain.
Monitoring the DAC's meter doesn't show clipping, because the digital input ..the meter, isn't clipping.
But where are the meters on the DAC's analog output capability? Nowhere !
Anyway, if your amp is relatively insensitive, this may well be the issue....DAC analog clipping when trying to play loud. It would kill bass first, and just get worse with more volume.
The amp is consumer isn't it? RCA inputs only? Usually consumer amps have the necessary input sensitivity to easily handle a good consumer DAC's output, like you have.
But then again, consumer amps aren't usually spec'ed as constant gain.
So like said, without more amp specs...just spitballin
a quick backwards look didn't find full specs for the Goldmund amp, so the following is pretty much spitballing....
...but it sounds like the analog output of the DAC, and the input sensitivity of the amp aren't mating well. Specifically that the input sensitivity of the amp is too low (needs a higher voltage to drive to full power.)
i've run into this using mindsp dacs with their 2.0Vrms consumer output, trying to drive pro amps with +26dB constant gain.
Monitoring the DAC's meter doesn't show clipping, because the digital input ..the meter, isn't clipping.
But where are the meters on the DAC's analog output capability? Nowhere !
Anyway, if your amp is relatively insensitive, this may well be the issue....DAC analog clipping when trying to play loud. It would kill bass first, and just get worse with more volume.
The amp is consumer isn't it? RCA inputs only? Usually consumer amps have the necessary input sensitivity to easily handle a good consumer DAC's output, like you have.
But then again, consumer amps aren't usually spec'ed as constant gain.
So like said, without more amp specs...just spitballin
I welcome the discussion, no problem. Even though my keyboard and monitor are in the same room as my setup, the PC is in my corridor, leaving all nasty sounds it can make with fans and hard drives there . So I needed something to cover the distance from the corridor all the way to the other side of my living room.
The card is an Asus Sonar Essence ST (PCI model with separate molex power receptor) It has an Xonar H6 extension card for 8 channels in total.
This system grew over the years, so some compromises had to be made. Ideally you would be right, but I still wouldn't love the idea of having the PC in the room. As I also use it for video (Home Theatre) and let the graphics card do the rendering I don't want to substitute it for a (probably more silent) NUC.
From all I could find about it, the ST cards were pretty good with stellar timing vs the latter STX PCIE cards. That made me stick with it. I even have a reserve if anything happens to it (thanks to a kind member here).
When I started out, I never thought it would lead to 6 channels of amplification. So that's when I bought the DAC to be able to use optical in.
As it turns out, the DAC does fine at lower drive levels. That's why I never (consciously) bumped into problems with my previous amplifier.
The DAC was daisy chained off of the SP/Diff out of the Xonar. Not ideal perhaps, but running it full range I never experienced any problems.
I did notice the DAC sounding different. However looking at loop back measurements and adjusting the Asio buffer made that difference go away.
The DAC is a Musical Fidelity M1 DAC, which is an upsampling DAC. In all honesty, at that time I was quite pleased with the sound of the Xonar card, except for it's hum problem at that time. A ground look isolator solved that, but showed raised distortion at bass frequencies in my measurements. The M1 DAC through optical was clean as a whistle.
Anyway, this above shows you go from one point to another, which brings new things to light during its course. Always hoping for improvement, but as it seems, sometimes you might lose something to.
Prior to running the DAC at higher levels it has always done a satisfactory job. All of the reviews that are linked on the first page were with this DAC.
So I can't call it bad, it just falls apart at higher volumes when driving long cables. Or something like that.
. So I needed something to cover the distance from the corridor all the way to the other side of my living room.The card is an Asus Sonar Essence ST (PCI model with separate molex power receptor) It has an Xonar H6 extension card for 8 channels in total.
This system grew over the years, so some compromises had to be made. Ideally you would be right, but I still wouldn't love the idea of having the PC in the room. As I also use it for video (Home Theatre) and let the graphics card do the rendering I don't want to substitute it for a (probably more silent) NUC.
From all I could find about it, the ST cards were pretty good with stellar timing vs the latter STX PCIE cards. That made me stick with it. I even have a reserve if anything happens to it (thanks to a kind member here
).When I started out, I never thought it would lead to 6 channels of amplification. So that's when I bought the DAC to be able to use optical in.
As it turns out, the DAC does fine at lower drive levels. That's why I never (consciously) bumped into problems with my previous amplifier.
The DAC was daisy chained off of the SP/Diff out of the Xonar. Not ideal perhaps, but running it full range I never experienced any problems.
I did notice the DAC sounding different. However looking at loop back measurements and adjusting the Asio buffer made that difference go away.
The DAC is a Musical Fidelity M1 DAC, which is an upsampling DAC. In all honesty, at that time I was quite pleased with the sound of the Xonar card, except for it's hum problem at that time. A ground look isolator solved that, but showed raised distortion at bass frequencies in my measurements. The M1 DAC through optical was clean as a whistle.
Anyway, this above shows you go from one point to another, which brings new things to light during its course. Always hoping for improvement, but as it seems, sometimes you might lose something to.
Prior to running the DAC at higher levels it has always done a satisfactory job. All of the reviews that are linked on the first page were with this DAC.
So I can't call it bad, it just falls apart at higher volumes when driving long cables. Or something like that
.
Hi Wesayso,
a quick backwards look didn't find full specs for the Goldmund amp, so the following is pretty much spitballing....
...but it sounds like the analog output of the DAC, and the input sensitivity of the amp aren't mating well. Specifically that the input sensitivity of the amp is too low (needs a higher voltage to drive to full power.)
i've run into this using mindsp dacs with their 2.0Vrms consumer output, trying to drive pro amps with +26dB constant gain.
Monitoring the DAC's meter doesn't show clipping, because the digital input ..the meter, isn't clipping.
But where are the meters on the DAC's analog output capability? Nowhere !
Anyway, if your amp is relatively insensitive, this may well be the issue....DAC analog clipping when trying to play loud. It would kill bass first, and just get worse with more volume.
The amp is consumer isn't it? RCA inputs only? Usually consumer amps have the necessary input sensitivity to easily handle a good consumer DAC's output, like you have.
But then again, consumer amps aren't usually spec'ed as constant gain.
So like said, without more amp specs...just spitballin
It will be somewhere in between this one: Goldmund - Telos 350
and this one: https://web.archive.org/web/20081202053450/http://www.goldmund.com/aproducts/telos600/telos600_datasheet.pdf
Can't find the exact model yet due to them changing the site ever so often.
It is a DIY clone of a Goldmund Telos 400, consisting of 2 monoblocks in one chassis. With the omission of the build in pré-amp. However all schematics between models were largely the same. Each one is build upon prior series with small improvements to each new model etc.
I found some of it, within the waybackmachine dating back to 2007:
GOLDMUND - Products - Telos 400
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Nice stuff Goldmund is
Comments are based from looking primarly at the Telos 400 wayback sheet, which shows an input sensitivity of 1.45 V, with > 10dB of attenuation available.
Also see under Rear panel Connectors and Controls that the unit had an input attenuator: 7 x 3dB steps. Along with balanced inputs.
The adjustable attenuation is nice, when using pro level line gear.
Is there any chance your clone has some adjustable attenuation applied?
Probably not, but if so, yay ! Get rid of it !
If not, here's the best-bet problem possibility i think..
The Telos 400 spec sheet no doubt includes the built-in pre-amp, which you say the clone doesn't have.
My pure guess says the pre-amp has to have at least 3 dB of gain, or why bother with it at all.
3dB of missing gain would raise input sensitivity voltage to 2.05V (1.45V x 1.414) Now it's beginning to get marginal.
But the pre-amp having just 3dB gain is doubtful, probably at least 6dB gain, which would take sens to 2.9V. (1.45V x 2)
Definitely marginal at best for use with a consumer DAC.
Hope that made sense and I'm not just barking up a tree...
Comments are based from looking primarly at the Telos 400 wayback sheet, which shows an input sensitivity of 1.45 V, with > 10dB of attenuation available.
Also see under Rear panel Connectors and Controls that the unit had an input attenuator: 7 x 3dB steps. Along with balanced inputs.
The adjustable attenuation is nice, when using pro level line gear.
Is there any chance your clone has some adjustable attenuation applied?
Probably not, but if so, yay ! Get rid of it !
If not, here's the best-bet problem possibility i think..
The Telos 400 spec sheet no doubt includes the built-in pre-amp, which you say the clone doesn't have.
My pure guess says the pre-amp has to have at least 3 dB of gain, or why bother with it at all.
3dB of missing gain would raise input sensitivity voltage to 2.05V (1.45V x 1.414) Now it's beginning to get marginal.
But the pre-amp having just 3dB gain is doubtful, probably at least 6dB gain, which would take sens to 2.9V. (1.45V x 2)
Definitely marginal at best for use with a consumer DAC.
Hope that made sense and I'm not just barking up a tree...
Indeed, nice stuff it is! especially for someone that is interested in phase flat as a pancake throughout its entire range.
You're thinking is similar to mine. The back side of the real deal has that dial making gain adjustable from -9 to +9 dB.
If koldby is sure about the 26 dB gain, the total gain as factory has put it on the spec sheet is 29 dB. So that would make the pré-amp section 3 dB gain.
No, the clone does not feature the attenuation circuitry.
The way I look at it, I'm thinking of getting a pré-am with fixed 6 dB gain (Universal Buffer from tomchr, Neurochrome). Or I could fit a volume pot to it making it adjustable.
Seeing the backside of the Telos 400, it would make sense to me if the pré-section is the 9 dB that is adjustable in steps? In that case overall gain would only be 20 dB.
You're thinking is similar to mine. The back side of the real deal has that dial making gain adjustable from -9 to +9 dB.
If koldby is sure about the 26 dB gain, the total gain as factory has put it on the spec sheet is 29 dB. So that would make the pré-amp section 3 dB gain.
No, the clone does not feature the attenuation circuitry.
The way I look at it, I'm thinking of getting a pré-am with fixed 6 dB gain (Universal Buffer from tomchr, Neurochrome). Or I could fit a volume pot to it making it adjustable.
Seeing the backside of the Telos 400, it would make sense to me if the pré-section is the 9 dB that is adjustable in steps? In that case overall gain would only be 20 dB.
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yep, thoughts are together ...
since the back panel level control spans 18 dB, it seems to me it has to be attenuating the combined pre-amp and amp gain.....unless the pre-amp has a full 18dB gain by itself.
you know, just for certainty's sake, and maybe for better knowing what pre-amp gain you want....i'd stop and measure the amp gain...
it's easy with nothing more than a half decent voltmeter.
use an AC line freq sine wave, 50 or 60Hz, or any freq if you have a super true rms voltmeter
Measure the output of whatever is feeding the amp input, disconnected from the amp. Dial in a voltage around .5 to 1V.
Then reconnect the amp, and measure the amps' output, without any load.
Use calculator to figure gain.Calculation voltage and power - gain and loss - sengpielaudio Sengpiel Berlin
Some few amps have circuitry to mute them when there is no load.
If you find you have no amp output unloaded, I'd get an electric water heater element and use it as a load. They are easy to find at 8-16 ohms and are cheap
Do be aware not to leave power on for real long (many minutes at full power)...they can get hot . Or put them in a bucket of water.
Whatever the gain the amp has doesn't really matter, since gain doesn't limit full power. Personally, i like +20 to +26dB for good gain staging
since the back panel level control spans 18 dB, it seems to me it has to be attenuating the combined pre-amp and amp gain.....unless the pre-amp has a full 18dB gain by itself.
you know, just for certainty's sake, and maybe for better knowing what pre-amp gain you want....i'd stop and measure the amp gain...
it's easy with nothing more than a half decent voltmeter.
use an AC line freq sine wave, 50 or 60Hz, or any freq if you have a super true rms voltmeter
Measure the output of whatever is feeding the amp input, disconnected from the amp. Dial in a voltage around .5 to 1V.
Then reconnect the amp, and measure the amps' output, without any load.
Use calculator to figure gain.Calculation voltage and power - gain and loss - sengpielaudio Sengpiel Berlin
Some few amps have circuitry to mute them when there is no load.
If you find you have no amp output unloaded, I'd get an electric water heater element and use it as a load. They are easy to find at 8-16 ohms and are cheap
Do be aware not to leave power on for real long (many minutes at full power)...they can get hot . Or put them in a bucket of water.
Whatever the gain the amp has doesn't really matter, since gain doesn't limit full power. Personally, i like +20 to +26dB for good gain staging
yep, thoughts are together ...
since the back panel level control spans 18 dB, it seems to me it has to be attenuating the combined pre-amp and amp gain.....unless the pre-amp has a full 18dB gain by itself.
you know, just for certainty's sake, and maybe for better knowing what pre-amp gain you want....i'd stop and measure the amp gain...
it's easy with nothing more than a half decent voltmeter.
use an AC line freq sine wave, 50 or 60Hz, or any freq if you have a super true rms voltmeter
Measure the output of whatever is feeding the amp input, disconnected from the amp. Dial in a voltage around .5 to 1V.
Then reconnect the amp, and measure the amps' output, without any load.
Use calculator to figure gain.Calculation voltage and power - gain and loss - sengpielaudio Sengpiel Berlin
Some few amps have circuitry to mute them when there is no load.
If you find you have no amp output unloaded, I'd get an electric water heater element and use it as a load. They are easy to find at 8-16 ohms and are cheap
Do be aware not to leave power on for real long (many minutes at full power)...they can get hot . Or put them in a bucket of water.
Whatever the gain the amp has doesn't really matter, since gain doesn't limit full power. Personally, i like +20 to +26dB for good gain staging
Or calculate it from the schematics. I will try to look my schematic up and do that. It is very easy in a feedback amp. It is the ratio between the resistor going from the output to the inverting input of the diff stage and the resistor going from the non inverting input to ground!
Same with the preamp stage.
"The way I look at it, I'm thinking of getting a pré-am with fixed 6 dB gain (Universal Buffer from tomchr, Neurochrome). Or I could fit a volume pot to it making it adjustable."
Buffers are the most useful when they are before long cable runs. I doesn't help to amplify a degraded signal.
Buffers are the most useful when they are before long cable runs. I doesn't help to amplify a degraded signal.
Which is what it would do, inserted before the long RCA and after the DAC (with short RCA's from DAC to Universal Buffer).
As long as the M1 DAC isn't up in volume it is clean sounding. The Xonar DAC is clean, even higher up in volume it seems to do better than the M1 DAC.
I preferred to have the JDS Atom pré amp before the long RCA, it was set at 6 dB gain. All I meant to say is I could get gain adjustable with a volume control.
The function of the universal buffer would be to drive the long RCA cable runs. Fixed gain would work.
As long as the M1 DAC isn't up in volume it is clean sounding. The Xonar DAC is clean, even higher up in volume it seems to do better than the M1 DAC.
I preferred to have the JDS Atom pré amp before the long RCA, it was set at 6 dB gain. All I meant to say is I could get gain adjustable with a volume control.
The function of the universal buffer would be to drive the long RCA cable runs. Fixed gain would work.
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Ronald, why not measure actual voltage at your speaker terminals with Pano's test? No reason you can't start with JRiver at -20dB to be safe.
Hi guys see some discussions on gain and ability to drive long cables is blamed why wesayso sensed a difference at our meeting, may i mix me up in discusion now i hope i remember everything right and my speculation for how koldby ended trim Telos clone is spot on, else give me a size 45 in my back end .
Lets analyze what happened, kolby brought a bunch of power amps with him at the meeting to test on towers and i brought Neurochrome HP-1 headphone amp with 0,5Ω output impedance to test with some head phones and that HP-1 we used as PRE to test think it was 7 power amps because it could dial in the acoustic weighted SPL using wesayso's nice handhold meter to take precaution for varius gain and sensivity numbers power amps between.
Me and koldby drove from Denmark in his nice car so we had tons of audio talk 700 kilometers along, and he told which power amp he thought was the best sound and wesayso probably would prefer that one, under the listening test think remember it was the last DUT and that Telos clone had played 30 seconds or so there was a big wau feeling, we could hear it immediately all three of us including koldby, but where me and wesayso had never heard that amp before and just used our ears this was a winner then koldby did agree for sound performance it was the winner here but he was surprised at same or a big quostion about what happened, and he turned that outcome around tons of times on our 700km drive home.
Because i told previos part with so many nonsense little things or details is because if i'm right then koldby never heard that Telos clone before in its right trim with a close to zero impedance as its source as that HP-1 used as PRE. Also will imagine that M1 DAC can swing absolute perfect voltage over long cables, it has 47Ω output impedance probably technical to protect itself from nasty parasitic loads and also imagine its AC coupled because know wesayso had measure it for DC offset, also its not a cheap unit. Also will say think wesayso have fantastic ears or skills because he told ever since via PM that he missed signature of HP-1 as PRE for Telos clone but myself can't know because i never heard Telos clone without HP-1 but would normal think that less is more so wondered a bit about that.
Few time ago wesayso in PM techtalk again was around he missed that HP-1 as PRE for Telos clone and we did agree maybe it could be a good thing try that JDS Labs ATOM headphone amp because on paper its as transperant as HP-1 at cost that is to laugh at, and output impedance is a very low 0,1Ω.
Objective reason i think wesayso prefer a PRE for Telos clone and why koldby never heard it in close to best trim other than at our meeting using a 0,5Ω source in HP-1 is in below schematic.
As i informed koldby build it without PRE probably thinking less is more and the 52,5kΩ we see there for VAS stage named "INPUT 1" is a perfect input impedance number for a power amp and agree so far looking direction source to load.
Looking the other direction from load to source, below circuit is the PRE that is omitted (modelled in TI TINA, btw gain is +6dB, -3dB point at 4,3mHz, and DC servo feature handle up to +150/-160mV offset on input) and wired directly to "INPUT 1" of above VAS stage, its a zero impedance source and my bet is VAS stage operating point and ballance will tilt a bit not seeing a 100% stable zero impedance source but instead will have to look through a non stiff 10-15 meter cable before it can see 47Ω of M1.
Another never ending story and of course critic or input is welcome but hope i'm not way off in above analyze find a good objective reason why a PRE here makes a difference for sensitive ears, know 47Ω plus some cable is relative low but actual its huge if VAS stage was designed to see a zero Ω stiff impedance as source. If it holds water imagine best thing wesayso can do if he get universal buffer boards from Tom is build it into Telos Clone and then its win win situation change output on M1 DAC from RCA to its native XLR and run ballanced cable to new ballanced input buffer in Telos clone.
now i hope i remember everything right and my speculation for how koldby ended trim Telos clone is spot on, else give me a size 45 in my back end .Lets analyze what happened, kolby brought a bunch of power amps with him at the meeting to test on towers and i brought Neurochrome HP-1 headphone amp with 0,5Ω output impedance to test with some head phones and that HP-1 we used as PRE to test think it was 7 power amps because it could dial in the acoustic weighted SPL using wesayso's nice handhold meter to take precaution for varius gain and sensivity numbers power amps between.
Me and koldby drove from Denmark in his nice car so we had tons of audio talk 700 kilometers along, and he told which power amp he thought was the best sound and wesayso probably would prefer that one, under the listening test think remember it was the last DUT and that Telos clone had played 30 seconds or so there was a big wau feeling, we could hear it immediately all three of us including koldby, but where me and wesayso had never heard that amp before and just used our ears this was a winner then koldby did agree for sound performance it was the winner here but he was surprised at same or a big quostion about what happened, and he turned that outcome around tons of times on our 700km drive home.
Because i told previos part with so many nonsense little things or details is because if i'm right then koldby never heard that Telos clone before in its right trim with a close to zero impedance as its source as that HP-1 used as PRE. Also will imagine that M1 DAC can swing absolute perfect voltage over long cables, it has 47Ω output impedance probably technical to protect itself from nasty parasitic loads and also imagine its AC coupled because know wesayso had measure it for DC offset, also its not a cheap unit. Also will say think wesayso have fantastic ears or skills because he told ever since via PM that he missed signature of HP-1 as PRE for Telos clone but myself can't know because i never heard Telos clone without HP-1 but would normal think that less is more so wondered a bit about that.
Few time ago wesayso in PM techtalk again was around he missed that HP-1 as PRE for Telos clone and we did agree maybe it could be a good thing try that JDS Labs ATOM headphone amp because on paper its as transperant as HP-1 at cost that is to laugh at, and output impedance is a very low 0,1Ω.
Objective reason i think wesayso prefer a PRE for Telos clone and why koldby never heard it in close to best trim other than at our meeting using a 0,5Ω source in HP-1 is in below schematic.
As i informed koldby build it without PRE probably thinking less is more and the 52,5kΩ we see there for VAS stage named "INPUT 1" is a perfect input impedance number for a power amp and agree so far looking direction source to load.
Looking the other direction from load to source, below circuit is the PRE that is omitted (modelled in TI TINA, btw gain is +6dB, -3dB point at 4,3mHz, and DC servo feature handle up to +150/-160mV offset on input) and wired directly to "INPUT 1" of above VAS stage, its a zero impedance source and my bet is VAS stage operating point and ballance will tilt a bit not seeing a 100% stable zero impedance source but instead will have to look through a non stiff 10-15 meter cable before it can see 47Ω of M1.
Another never ending story and of course critic or input is welcome but hope i'm not way off in above analyze find a good objective reason why a PRE here makes a difference for sensitive ears, know 47Ω plus some cable is relative low but actual its huge if VAS stage was designed to see a zero Ω stiff impedance as source. If it holds water imagine best thing wesayso can do if he get universal buffer boards from Tom is build it into Telos Clone and then its win win situation change output on M1 DAC from RCA to its native XLR and run ballanced cable to new ballanced input buffer in Telos clone.
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From the schematic we have a feedback resistor : 7,5 KOhms and a resistor to ground 270 Ohms.The gain is : (7500/270) = 27,78 times.
In dB this is 20xlog(27,78) = 28,8 dB.
The reason it is a little higher than normal is that the normal input voltage for poweramps to have full power output is 2 Volts and as the Goldmund is a 350 Watt amp it has to have more gain to achieve that than a 100 Watt amp.
The input stage of the original Telos has no gain. R feedback is 2k2 and the R to ground is also 2K2. It is only a buffer that drives the attenautor between this input buffer and the power stage.
In dB this is 20xlog(27,78) = 28,8 dB.
The reason it is a little higher than normal is that the normal input voltage for poweramps to have full power output is 2 Volts and as the Goldmund is a 350 Watt amp it has to have more gain to achieve that than a 100 Watt amp.
The input stage of the original Telos has no gain. R feedback is 2k2 and the R to ground is also 2K2. It is only a buffer that drives the attenautor between this input buffer and the power stage.
I really think your conclusions are wrong. One thing is that it is not the VAS stage that is the input of the Telos clone . The VAS stage is the FTZ transistors whereas the DIFF (diferential) stage is the double fet 2N5556. This is a standard input stage (refined by Goldmund, I will return to this later) and is seen in 90% of all poweramps without any input buffer.Hi guys see some discussions on gain and ability to drive long cables is blamed why wesayso sensed a difference at our meeting, may i mix me up in discusion
Lets analyze what happened, kolby brought a bunch of power amps with him at the meeting to test on towers and i brought Neurochrome HP-1 headphone amp with 0,5Ω output impedance to test with some head phones and that HP-1 we used as PRE to test think it was 7 power amps because it could dial in the acoustic weighted SPL using wesayso's nice handhold meter to take precaution for varius gain and sensivity numbers power amps between.
Me and koldby drove from Denmark in his nice car so we had tons of audio talk 700 kilometers along, and he told which power amp he thought was the best sound and wesayso probably would prefer that one, under the listening test think remember it was the last DUT and that Telos clone had played 30 seconds or so there was a big wau feeling, we could hear it immediately all three of us including koldby, but where me and wesayso had never heard that amp before and just used our ears this was a winner then koldby did agree for sound performance it was the winner here but he was surprised at same or a big quostion about what happened, and he turned that outcome around tons of times on our 700km drive home.
Because i told previos part with so many nonsense little things or details is because if i'm right then koldby never heard that Telos clone before in its right trim with a close to zero impedance as its source as that HP-1 used as PRE. Also will imagine that M1 DAC can swing absolute perfect voltage over long cables, it has 47Ω output impedance probably technical to protect itself from nasty parasitic loads and also imagine its AC coupled because know wesayso had measure it for DC offset, also its not a cheap unit. Also will say think wesayso have fantastic ears or skills because he told ever since via PM that he missed signature of HP-1 as PRE for Telos clone but myself can't know because i never heard Telos clone without HP-1 but would normal think that less is more so wondered a bit about that.
Few time ago wesayso in PM techtalk again was around he missed that HP-1 as PRE for Telos clone and we did agree maybe it could be a good thing try that JDS Labs ATOM headphone amp because on paper its as transperant as HP-1 at cost that is to laugh at, and output impedance is a very low 0,1Ω.
Objective reason i think wesayso prefer a PRE for Telos clone and why koldby never heard it in close to best trim other than at our meeting using a 0,5Ω source in HP-1 is in below schematic.
As i informed koldby build it without PRE probably thinking less is more and the 52,5kΩ we see there for VAS stage named "INPUT 1" is a perfect input impedance number for a power amp and agree so far looking direction source to load.
Looking the other direction from load to source, below circuit is the PRE that is omitted (modelled in TI TINA, btw gain is +6dB, -3dB point at 4,3mHz, and DC servo feature handle up to +150/-160mV offset on input) and wired directly to "INPUT 1" of above VAS stage, its a zero impedance source and my bet is VAS stage operating point and ballance will tilt a bit not seeing a 100% stable zero impedance source but instead will have to look through a non stiff 10-15 meter cable before it can see 47Ω of M1.
Another never ending story and of course critic or input is welcome but hope i'm not way off in above analyze find a good objective reason why a PRE here makes a difference for sensitive ears, know 47Ω plus some cable is relative low but actual its huge if VAS stage was designed to see a zero Ω stiff impedance as source. If it holds water imagine best thing wesayso can do if he get universal buffer boards from Tom is build it into Telos Clone and then its win win situation change output on M1 DAC from RCA to its native XLR and run ballanced cable to new ballanced input buffer in Telos clone.
The only reason the original Telos has a input buffer is that it also have a gain setting attenuator, and this calls for a buffer, not the input stage.
And I think I have heard the full potential of the Goldmund chez moi, as I have no problems with driving cables from my preamp. The difference between the three first amps was exactly what I expected. What puzzeled me was that the last candidate underperformed . But I think it was partly because Wesayso are compensating his Line Arrays all the way down and mine are attenuated under 35 Hz or so. This could lead to the last candidate, beeing the least powerfull of the three, would struggle more . I am not at all sure that this was the case as it was also noticeable in more quite passages. I am still puzzled.