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REVIEW: Yulong Sabre A18 Reference headphone amp - Page 8

post #106 of 177

Just finished cleaning the scratchy volume pot on my A18. Man, this knob is so buttery smooth! With it off, Im finding excuses just to turn the pot all the way left and right lol. Not a hint of scratching or grain, very close to the feeling of a warm or hot knife going through a brick of butter.

 

Also, if Im hearing correctly; It sounds as if cleaning the pot has really refined the sound. The responsiveness of the slightest pinch of movement on the knob gives me excellent control. Really feels like Ive just received a brand-new A18, burned in :D

post #107 of 177

Ok Im starting to think that prior to cleaning my A18 there were some serious problems that I was not aware of. This is no placebo effect, there is definitely change in the sq for the better. I'm literally knocked on my a**, such a effortless and breathtaking sound. I knew potentiometers had a big role in amps, but I honestly was not expecting a change to this degree. As embarrassed as I am saying this, I honestly feel like my entire time spent with the A18 was a complete waste and I am just now listening to the A18. How can this be  -___-.

 

Some of the things I did while I had the A18 open were cleaning/lubricating the volume pot (literally spent about 30mins just turning the knob from 0 to max with very small shots of DeoxIT in between until any scratching and graininess was eliminated), air blasted the entire internal chamber, cleaning/lubricated all inputs rca,xlr,etc.

post #108 of 177
Quote:
Originally Posted by DarKen23 View Post
 

Ok Im starting to think that prior to cleaning my A18 there were some serious problems that I was not aware of. This is no placebo effect, there is definitely change in the sq for the better. I'm literally knocked on my a**, such a effortless and breathtaking sound. I knew potentiometers had a big role in amps, but I honestly was not expecting a change to this degree. As embarrassed as I am saying this, I honestly feel like my entire time spent with the A18 was a complete waste and I am just now listening to the A18. How can this be  -___-.

 

Some of the things I did while I had the A18 open were cleaning/lubricating the volume pot (literally spent about 30mins just turning the knob from 0 to max with very small shots of DeoxIT in between until any scratching and graininess was eliminated), air blasted the entire internal chamber, cleaning/lubricated all inputs rca,xlr,etc.

Sounds like you did an excellent job cleaning. Yeah I too have been amazed with how much of a difference a volume pot or preamp makes. The LDR preamp a.ka. "lightspeed" has been a real ear opener and will never underestimate its importance ever again :)

post #109 of 177
Quote:
Originally Posted by brunk View Post
 
Quote:
Originally Posted by DarKen23 View Post
 

Ok Im starting to think that prior to cleaning my A18 there were some serious problems that I was not aware of. This is no placebo effect, there is definitely change in the sq for the better. I'm literally knocked on my a**, such a effortless and breathtaking sound. I knew potentiometers had a big role in amps, but I honestly was not expecting a change to this degree. As embarrassed as I am saying this, I honestly feel like my entire time spent with the A18 was a complete waste and I am just now listening to the A18. How can this be  -___-.

 

Some of the things I did while I had the A18 open were cleaning/lubricating the volume pot (literally spent about 30mins just turning the knob from 0 to max with very small shots of DeoxIT in between until any scratching and graininess was eliminated), air blasted the entire internal chamber, cleaning/lubricated all inputs rca,xlr,etc.

Sounds like you did an excellent job cleaning. Yeah I too have been amazed with how much of a difference a volume pot or preamp makes. The LDR preamp a.ka. "lightspeed" has been a real ear opener and will never underestimate its importance ever again :)

Man, I just cannot believe the difference Im hearing..The transparency is through the roof and the bass is literally epic.

post #110 of 177
Quote:
Originally Posted by DarKen23 View Post
 

Man, I just cannot believe the difference Im hearing..The transparency is through the roof and the bass is literally epic.

:beerchug:

post #111 of 177
Quote:
Originally Posted by DarKen23 View Post
 

Man, I just cannot believe the difference Im hearing..The transparency is through the roof and the bass is literally epic.

Here's something interesting. I think I have the same pot you do, except mine is for hardwiring, not a PCB. I was originally going to install this in my BH Crack, but am using a pre instead. I took it out of its bag, put it to my ear and guess what? I hear some light scratches, but mostly a constant rubbing sound like two pieces of paper being rubbed together. Definitely a weak link and am glad i never used it.

post #112 of 177
Quote:
Originally Posted by brunk View Post
 

Here's something interesting. I think I have the same pot you do, except mine is for hardwiring, not a PCB. I was originally going to install this in my BH Crack, but am using a pre instead. I took it out of its bag, put it to my ear and guess what? I hear some light scratches, but mostly a constant rubbing sound like two pieces of paper being rubbed together. Definitely a weak link and am glad i never used it.

 

Yours was used as well? The only difference with the 2 is the numbers, mine being 120g and yours 247g. I assume the numbers are different due to the fact that yours is for hardwiring applications?

post #113 of 177
Quote:
Originally Posted by DarKen23 View Post
 

Yours was used as well? The only difference with the 2 is the numbers, mine being 120g and yours 247g. I assume the numbers are different due to the fact that yours is for hardwiring applications?

No that pot i showed is brand new unused. Their both a 50k stereo logarithmic pot, going off the top of my head i think the first set of numbers determines pcb/hardwire and shaft length.

post #114 of 177
Quote:
Originally Posted by brunk View Post
 
Quote:
Originally Posted by DarKen23 View Post
 

Yours was used as well? The only difference with the 2 is the numbers, mine being 120g and yours 247g. I assume the numbers are different due to the fact that yours is for hardwiring applications?

No that pot i showed is brand new unused. Their both a 50k stereo logarithmic pot, going off the top of my head i think the first set of numbers determines pcb/hardwire and shaft length.

I see. Man I really wish I knew the output impedance of the A18 to determine weather or not a lightspeed attenuation control can be added. 

post #115 of 177
Quote:
Originally Posted by DarKen23 View Post
 

I see. Man I really wish I knew the output input impedance of the A18 to determine weather or not a lightspeed attenuation control can be added. 

Seeing that it has a 50k pot, that solves the question. The input impedance is 50k ohms, which barely qualifies for a passive pre. In order for a passive pre to outshine an active pre in most systems, the input impedance must be 47k or higher. You my friend do indeed have that option. You can go two routes with the ALPS pot. 1) Turn it all the way up which will effectively disable the pot, but the signal will still pass through it. 2) Remove it completely,tap the RCA jacks and add 50k+ resistors (i did 68k with my BH Crack) to L/R signal lines and jumper PCB path with wire where the pot was.

 

Side note, the lower the input impedance, the lower the potential for noise. However this makes it much harder for your source to drive it (bad for passive system). The higher the input impedance, the higher the potential for noise, but it makes it much easier for your source to drive (good for passive system). You will typically see input impedances anywhere from 47k to 100k. There are of course several amps with much lower input impedances, but those are not the norm.


Edited by brunk - 10/25/13 at 1:40pm
post #116 of 177
Quote:
Originally Posted by brunk View Post
 
Quote:
Originally Posted by DarKen23 View Post
 

I see. Man I really wish I knew the output input impedance of the A18 to determine weather or not a lightspeed attenuation control can be added. 

Seeing that it has a 50k pot, that solves the question. The input impedance is 50k ohms, which barely qualifies for a passive pre. In order for a passive pre to outshine an active pre in most systems, the input impedance must be 47k or higher. You my friend do indeed have that option. You can go two routes with the ALPS pot. 1) Turn it all the way up which will effectively disable the pot, but the signal will still pass through it. 2) Remove it completely,tap the RCA jacks and add 50k+ resistors (i did 68k with my BH Crack) to L/R signal lines and jumper PCB path with wire where the pot was.

 

Side note, the lower the input impedance, the lower the potential for noise. However this makes it much harder for your source to drive it (bad for passive system). The higher the input impedance, the higher the potential for noise, but it makes it much easier for your source to drive (good for passive system). You will typically see input impedances anywhere from 47k to 100k. There are of course several amps with much lower input impedances, but those are not the norm.

Nice! So it looks like I may very well get a external passive pre. Given my input impedance is 50k, would you say that I would get a significant gain?

 

Id like to add something like this to the A18 :basshead:


Edited by DarKen23 - 10/25/13 at 2:04pm
post #117 of 177
Quote:
Originally Posted by DarKen23 View Post
 

Nice! So it looks like I may very well get a external passive pre. Given my input impedance is 50k, would you say that I would get a significant gain?

More than likely yes. A passive pre will always be better when the system qualifies for it. Especially a lightspeed over the ALPS blue velvet.

post #118 of 177

I hate head-fi :o

post #119 of 177

Btw Brunk, Im also thinking about building some speakers. Ill messages you later with the details

 

Cant get over that speaker youve built using the Fostex super tweeter *drool*


Edited by DarKen23 - 10/25/13 at 2:14pm
post #120 of 177
Quote:
Originally Posted by DarKen23 View Post
 

Btw Brunk, Im also thinking about building some speakers. Ill messages you later with the details

 

Cant get over that speaker youve built using the Fostex super tweeter *drool*

I'll be more than happy to help :)

:beerchug:

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