Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Questyle CMA800 Current Mode amp
New Posts  All Forums:Forum Nav:

Questyle CMA800 Current Mode amp - Page 39

post #571 of 614
Quote:
Originally Posted by gsr108 View Post

Just wanted to post that I had a VERY good experience with Bruce Ball and questyle in general. I brought a used CMA800R. One of the screws on the top plate wasn't fitting correctly and looked out of place. Amp was working fine. I contacted questyle initially to get a replacement screw and they decided to replace the whole unit for me for free. I should be getting the unit today. Great customer service in my book!


Another update.  So I received the amp back.  Instead of sending me a new one they either sent me a refurbished model or replaced the screw on my old amp.  I can tell because the amp that was sent back seems to be an older model (the faceplate is slightly different).  This is after Mr Ball emailed me and offered to exchange my old amp for a new amp due to the faulty screw.  I've emailed him multiple times in the past 4 days without any replies.  Hopefully he will email me back soon but, so far, I feel let down by their customer service. 


Edited by gsr108 - 8/1/14 at 10:31am
post #572 of 614
Quote:
Originally Posted by gsr108 View Post
 
Quote:
Originally Posted by gsr108 View Post

Just wanted to post that I had a VERY good experience with Bruce Ball and questyle in general. I brought a used CMA800R. One of the screws on the top plate wasn't fitting correctly and looked out of place. Amp was working fine. I contacted questyle initially to get a replacement screw and they decided to replace the whole unit for me for free. I should be getting the unit today. Great customer service in my book!


Another update.  So I received the amp back.  Instead of sending me a new one they either sent me a refurbished model or replaced the screw on my old amp.  I can tell because the amp that was sent back seems to be an older model (the faceplate is slightly different).  This is after Mr Ball emailed me and offered to exchange my old amp for a new amp due to the faulty screw.  I've emailed him multiple times in the past 4 days without any replies.  Hopefully he will email me back soon but, so far, I feel let down by their customer service. 

Is there a problem with the replacement amp? Can you post a pic of the faceplate?

post #573 of 614


You can tell the one on top is older due to the bevels around the lights.  There was an issue with the amp I'm trying to figure out right now - could be due to my system also.  Basically, when I emailed Bruce Ball about the issue - he asked me where I got the amp.  My reply was that this is the amp he sent back to me - which should have been a new unit.  I've asked if he just replaced the screw or sent me a refurbished unit.  That was on Monday.  Multiple emails since that time have gone unanswered.  My issue is that he misrepresented what he was going to do.  Instead of a new unit I have a possibly refurbished unit that may have some issue with it (still trying to figure that out). 

post #574 of 614

Those bevels were used on the original CMA800 model but all the CMA800R examples I've seen have the smoother design. I wonder if they repurposed one of the older chassis they had laying around? 

 

How are the sides of that front panel? Do they have a sort of angle to them?

post #575 of 614
Quote:
Originally Posted by gsr108 View Post
 


You can tell the one on top is older due to the bevels around the lights.  There was an issue with the amp I'm trying to figure out right now - could be due to my system also.  Basically, when I emailed Bruce Ball about the issue - he asked me where I got the amp.  My reply was that this is the amp he sent back to me - which should have been a new unit.  I've asked if he just replaced the screw or sent me a refurbished unit.  That was on Monday.  Multiple emails since that time have gone unanswered.  My issue is that he misrepresented what he was going to do.  Instead of a new unit I have a possibly refurbished unit that may have some issue with it (still trying to figure that out). 

 

 

It looks like it was from a different production run. That would be annoying if you wanted a matched pair.


Edited by Sanlitun - 8/2/14 at 3:14pm
post #576 of 614
Oh Man! All for a screw...

Sent from my Samsung Note 3 using Tapatalk Pro
Edited by m-i-c-k-e-y - 8/2/14 at 8:49am
post #577 of 614

So Mr. Ball has emailed me back.  He states that the one he sent me was a new amp, and that he did not have any old amps in stock.  Even though he was the one to mention that the amp on top looked like an older style.  He's trying to make this right by fixing my old amp and sending it back, which he states is the smoother style like the amp on bottom.  Unfortunately I don't remember if the old amp was the older beveled style or the newer smooth style amp.  When I first received both amps I did not have a dual 3 pin XLR adapter and did not pay that much attention to the differences between the two.  I think the old amp had the beveled style lights also, but could be wrong.  Regardless there are some discrepancies between what has been stated between us.  If everything turns out okay I won't hold any grudges.  And for my LCD 3f's the dual mono setup is REALLY nice. 

 

For those interested, the issue with the amp is that its volume control seems different between the two amps.  If I place the bottom amp's volume at 25%, the top amp's volume has to be has to be a little higher - say 28-30% to level match the two.  But if I place both amps volume at 50% - they seem pretty even at that time.  I've tried running both at 100% - but then it seems like the amp on tops volume decreases as the amp gets hotter.  It just makes it hard to level match between the two.  I'm using a NAD M51 as a preamp.  The DAC has also been switched since I got the amp back, so I don't believe it is DAC related (exchanged a silver M51 for a black M51, problem persists on both).  I've also switched XLR connecters since I've noticed the volume issue - without improvement.  If anyone has any suggestions I'd be happy to listen to them. 


Edited by gsr108 - 8/2/14 at 10:25am
post #578 of 614

Mine are pretty closely matched but I bet if I was able to somehow label them precisely, I'd find a slight difference as well. Same thing with the NuForce HA-200 in monoblock mode. It's basically the nature of a potentiometer to have slight variation from one to the next - even for really nice ones. 

 

This is why I prefer to use DAC volume control (or a preamp, if that better fits your system). 

post #579 of 614

I was wondering if anyone can answer this question for me - is it safe to just turn both amps up to max volume when using both in dual mono mode?  A NAD M51 will be used to control volume.  Any chance of overheating? 

post #580 of 614
No problem, these are monoblocks.
That is the way I (try) to use them, and permanently "on".
But I desperate to find a preamp which respects the amazing transparency of the amps.
I tried with several ones, even a passive, once it introduces noise or sound purity is affected.
Tell me your impressions with the Nad.
post #581 of 614

Cranking to full volume on both in monoblock mode seems to be the intent of the design, so it should be fine. That's how I use mine and it's been great. You just need to use a high quality DAC or preamp in the chain that won't detract from the transparency of these amps. 

post #582 of 614

Quick question - do you guys think my volume imbalance issue could be related to burn in?  When I initially got the new amp it was very obvious that the volume level was less on the new amp compared to the older one throughout the volume range.  Now I'm not too sure.  At 25% volume on both amps, I notice the new amp to play slightly less loud - which pretty much resolves by 50% volume on both amps.  The other thing that happened was that I am no longer running the XLR connections through a loop out - the dynahi I had between the NAD and CMA800R's is currently being fixed. 

post #583 of 614
Quote:
Originally Posted by gsr108 View Post
 

Quick question - do you guys think my volume imbalance issue could be related to burn in?  When I initially got the new amp it was very obvious that the volume level was less on the new amp compared to the older one throughout the volume range.  Now I'm not too sure.  At 25% volume on both amps, I notice the new amp to play slightly less loud - which pretty much resolves by 50% volume on both amps.  The other thing that happened was that I am no longer running the XLR connections through a loop out - the dynahi I had between the NAD and CMA800R's is currently being fixed. 

If you have volume control through your DAC or use a preamp I'd do what project does and set both amps to max then control volume with the DAC/preamp and see if you notice an imbalance then.

post #584 of 614
Quote:
Originally Posted by BydoEmpire View Post

If you have volume control through your DAC or use a preamp I'd do what project does and set both amps to max then control volume with the DAC/preamp and see if you notice an imbalance then.

That's how I run them. What I was trying to say is that when I first received the other amp. I definitely heard a imbalance between the two throughout the volume range (voices appeared to image more towards the amp that was louder). Now I don't. The only things that have change are the amp has "burned in." And I took out the XLR loopout between the NAD M51 and the CMA800Rs. Could either of those two things been causing the difference I heard?
Edited by gsr108 - 8/6/14 at 7:39am
post #585 of 614

For anyone interested, and also to clear questyles north america's name.  I think I figured out why I was hearing the channel imbalance at low volumes but not high volumes.  Really stupid really.  The new amp is from a different product run and the volume knobs do not line up completely.  So what I thought was 1/4 way on the knob was actually less than that on the new amp vs the old one.  Which explains why I heard the imbalance at low volumes, but as I turned it up, the imbalance went away.  DUH. 

 

For those with dual monos, I added a tripp lite UPS the other day and it seems to have made a very positive impact.  Especially noticeable to me when running my modded HE-6's (grill, fuzzor, vegan pads).  First time I listened to them with the UPS added, I immediately noticed that soundstage was very holographic, 3D.  Bass also seemed improved.  I brought the UPS because I thought my system seemed to sound slightly better at night but its made a significant difference.  As always YMMV, etc. 

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Questyle CMA800 Current Mode amp