Head-Fi.org › Forums › Summit-Fi (High-End Audio) › High-end Audio Forum › Speaker amps for headphones
New Posts  All Forums:Forum Nav:

Speaker amps for headphones - Page 20

post #286 of 2599
Quote:
Originally Posted by zilch0md View Post

Hey Gary,

 

Reading all of your posts to this thread, again this morning, it has struck me that you've never expressed why you've chosen to insert the Adcom GFP-555 pre-amp between the Emotiva XDA-1 (USB DAC) and the various amps you'll be testing, but I can see from you latest post, that you're adjusting the pre-amp's gain to regulate the signal strength coming into the Emotiva Mini-X. 

 

It turns out that when I'm using my LCD-2 with the Mini-X, with my DAC providing a 2V rms signal directly to the Mini-X RCA inputs (without a pre-amp), I measure a SPL of 85 dB between the ear pads with the Mini-X volume control at 9 o'clock.   I don't know what SPL you're achieving at the LCD-3 ear pads when your Adcom pre-amp is at 12-o'clock and the Mini-X is at 9-o'clock, but I'm guessing it would be somewhere around 85 dB, given that you find those gain settings to provide a reasonable auditioning volume.

 

Making a lot of assumptions in above paragraph as to output voltage of your DAC (being the same as my DAC), efficiency of the LCD-3 (being the same as my LCD-2 rev.1), and SPL at the ear pads (being the same as I measure with the JL Audio iPhone app and the lapel mic I'm using)...   I can nevertheless propose that when your Adcom gain is set at 12-o'clock, you might actually be at or near unity gain - where the Vrms leaving the pre-amp is the same as the Vrms coming in from the DAC.   Can you confirm this through documentation or measurement?

 

I ask because I'm concerned about the impact that your Adcom is going to have on all of your impressions, even if you were to leave its gain fixed as you compare one amp to another, due to injection of the Adcom's deviations from perfect neutrality and transparency (no matter how subtle).  But I'm also very concerned that if, for any reason, you vary the signal strength coming out of the Adcom as you compare amps, you could significantly alter the dynamics or weight of what's heard at the headphones vs. setting the Adcom at unity gain.

 

In the Owner's Manual of the Decware ZSTAGE (single-tube triode gain stage) Steve Deckert writes that one can reduce the dynamics and weight of a DAC/amp combo, by inserting the ZSTAGE between them and adjusting the ZSTAGE gain to something less than unity gain, while simultaneously increasing the gain at the amp to maintain a constant SPL at the headphones or speakers.  

 

Conversely, he writes that the ZSTAGE (which is really just a tube pre-amp with a single pair of RCA inputs and outputs), can be used to increase the the Vrms going into the amp (up to about 5 Vrms, depending on the tube you've selected).  When the amp sees a stronger signal than what the DAC would provide directly (greater than 2Vrms, for example), dynamics and weight can be increased, while maintaining a constant SPL at the headphones by simultaneously decreasing the amp's gain.

 

 

 

I can attest that I've experienced this ability to customize dynamics, first hand, using the ZSTAGE to either increase or decrease the gain seen by the amp (above or below the 2Vrms provided by my DACmini CX DAC section).  And last night, just by inserting a pair of Harrison Labs 6dB inline attenuators between the DACmini CX and Emotiva Mini-X (reducing the incoming signal from 2Vrms to 1Vrms), I could hear a reduction in dynamics.  

 

 

 

So, with tremendous respect, I'd like to propose that you remove the Adcom from your test environment when using amps that have their own volume control - opting instead to compare these amps with a direct signal from the XDA-1 DAC.   This could make volume adjustments tricky for the more powerful amps, but it would rule out any sonic traits imparted by the Adcom even if it were fixed at unity gain, and would also rule out the impact on dynamics that can be imposed with variations to either side of unity gain.

 

What do you think?

 

Thanks,

 

Mike

 

 

Great stuff Mike..

post #287 of 2599

Guys:

 

I thought about pulling the Adcom out of the system, but it was ~11 PM when I first opened the Emo box, and the Adcom was already set up and... I think you understand.  I should be able to get it all rearranged today/tonight, and I'll see if I think there is any difference.  While all electronics add/subtract something from the sound, the Adcom has a reputation of being pretty transparent.  But we'll see.

 

By the way, the Emo at idle produces unmeasurable heat.  I'd love to have it not be idling, but I'm supposed to be working.tongue.gif

 

Gary

post #288 of 2599
Mike, well put and I've agreed with your assessment. It's Gary's test and I didn't want to mention this issue but since it's out, less is best. Adding a pre has been negative with all I've tried (prepro's new toy exception).
post #289 of 2599
Quote:
Originally Posted by Gary in MD View Post

Guys:

 

I thought about pulling the Adcom out of the system, but it was ~11 PM when I first opened the Emo box, and the Adcom was already set up and... I think you understand.  I should be able to get it all rearranged today/tonight, and I'll see if I think there is any difference.  While all electronics add/subtract something from the sound, the Adcom has a reputation of being pretty transparent.  But we'll see.

 

By the way, the Emo at idle produces unmeasurable heat.  I'd love to have it not be idling, but I'm supposed to be working.tongue.gif

 

Gary

 

 

Yeah - The a-100 will not put out a high amount of heat, even after a few hours of play.  Is the cyclops as pure Class A amp?  If so then that will heat your room up - Like my First Watt.

post #290 of 2599

What new toy - My new pre ampbiggrin.gif

 

 

 

 

 

 

post #291 of 2599

Folks:

 

The Adcom pre-amp is out of the loop and Mike was right -- depending on the recording, rock is at about the right volume at 9 o'clock on your listening dial, maybe 8:30 for some stuff, 9:30 for others.  Reasonably easily modulated, though it does get pretty loud pretty fast -- you get maybe an hour on the clock each way before it gets too loud or soft.

 

Sound quality-wise, the sound is richer and fuller without the pre-amp... or perhaps without the really cheapo-crappo interconnects I was using, since I didn't really think ahead about how I would be connecting all of these components (there's always something I forget to think about ahead of time).  Not that the ones I'm using now are anything special, but they are at least more substantial than what I used last night (hey, it was late, I was tired, didn't want to start rewiring everything, wah, wah, wah).  In any case, I would call the setup without the pre-amp a slight improvement, as the depth and realism is improved, but the high end is still a bit more prominent/sizzly than I would like.  Certainly no "veiled" LCD-3s with this setup.

 

I think the TBI Millennia comes out next.  That might not be until Thursday, believe it or not.  I have orchard work to do now (the Montmorency cherries are ripe... I either pick 'em now or just feed the bugs again), then out early and home late Wednesday.  That's better than last week's schedule, which is why I had the stuff arrive this week, but next week I'm taking off from work, so should have lots more time to play.

post #292 of 2599

Hey Gary,

 

I apologize for making suggestions so early in the game.  I'll be more patient.  I certainly don't want to squelch your enthusiasm for posting first impressions.  

 

I know that, in the end, a guy like you will have everything sorted out very smartly.  

 

Picking cherries, eh?  That sounds like a lot of work - but fruitful.  biggrin.gif

 

Mike

post #293 of 2599

Mike:

 

Don't worry about it, I'm just winging it here.  I thought about pulling the Adcom last night, was too tired, so didn't.  Your suggestion gave me a bit of a push, which I needed.  I might stick the pre-amp back in the mix at some point, just as a switch between amps (it has lots of outputs), but it's not really that much harder to move the one set of interconnects around between the amps instead.  Of course, the Burson has its own DAC, which makes things even more interesting... then I have to connect it to the computer, either USB  or optical (which is currently connected to the Emotiva DAC)... And then maybe use its DAC out to the other amps... This place is gonna be a mess for a while...but it'll be fun...

 

That's all for tonite, off to bed so I can get to work early enough and maybe even get home in time to play... though not likely.

post #294 of 2599
Quote:
Originally Posted by preproman View Post

What new toy - My new pre ampbiggrin.gif

 

 

 

 

 

 

 

Hey Preep, a bit OT, but if you end up posting your thoughts on this (or if you've posted them already and I'm blind), definitely let me know... I've been curious about the A20 since seeing it on the AMB site. 

 

@Gary: man, this is like a Head-Fi Game of Thrones or something... I come home excited to see what the next installment's gonna be!! Great work so far man, keep it up!! beerchug.gif

post #295 of 2599

Hey Theo,

 

Great little pre amp.   Done by SWA.  This one is balanced so no SE inputs or outputs.  You can have it built anyway you want.  It's a very transparent pre.  I can pick between 3 gains.  2X, 3X and 4X.  I find it works better that the pre amps in my DAC - the PWD mkII.  My Master 7 don't have a pre - that's the main reason I got it made - for DACs with no pre amps.  I really liked the pre amp section in the NAD M51 though - one of the better ones I've heard. 

post #296 of 2599

The best result I can get with mine headphone are french tube amplifier, an audiomat prelude reference 20. It justs beat in everything the SRM600, KGSS, Beta 22 3ch, Super 7. 

 

All frequencies are more integrated. The bass are more extended and tighter. The treble are also more extended and more thick. The medium are more smooth. The soundstage are larger and more holographic. 

post #297 of 2599
Quote:
Originally Posted by preproman View Post

Hey Theo,

 

Great little pre amp.   Done by SWA.  This one is balanced so no SE inputs or outputs.  You can have it built anyway you want.  It's a very transparent pre.  I can pick between 3 gains.  2X, 3X and 4X.  I find it works better that the pre amps in my DAC - the PWD mkII.  My Master 7 don't have a pre - that's the main reason I got it made - for DACs with no pre amps.  I really liked the pre amp section in the NAD M51 though - one of the better ones I've heard. 

 

Sounds killer man. I know I'm not the only guy living vicariously through your signature gear list, so anytime you feel like dropping a few impressions on us, color me interested ;). Thanks for the reply!!

post #298 of 2599

Folks:

 

Here's a teaser for the next episode:  the TBI MIllennia is up and running, a king might die, and Danaerys might get naked.  

 

In the amp comparison part of the show, I'm holding the good stuff for tomorrow when I will get more head time, but I will reveal that without the magic resistor box the Millennia has a VERY audible hiss at zero volume, whereas the mini-x is dead silent.  However, add the resistor box, and voila, the TBI's hiss is gone.  If I've understood what I've read here and on AVS over the past month, that must mean that the gain/sensitivity on the TBI is significantly greater than the Emo.  Right?

 

Also, the TBI is not easily controllable without the magic box.  You go from low volume and poor balance to too loud very quickly.  With the box, prime listening volume is around 9 o'clock, and the amp is very easy to control.  So Jan Plummer definitely knows his amp, and it definitely needs a magic box to perform properly with headphones, or at least with the LCD-3s.

 

And finally, anybody who says amps all sound alike is deaf.  The Emo and TBI sound very different, and the differences aren't subtle or slight.

 

More on that after I've listened for more than half an hour, and when I'm not as tired as I am now. 

 

Sorry, sometimes you just have to wait for the good stuff.  Except that Danaerys is pretty much always naked, or near naked, for those of us who are into that sort of thing.

 

Gary

post #299 of 2599

Cliffhanger!   

 

biggrin.gif

post #300 of 2599

Looking forward to further impressions Gary. 

 

BYW, I just wonna plug First Watt F3 here. I liked it with my M51 but PWD mk2 completed the package for me. It just raised the level of musicality by a little bit, turning it into something I am now considering my end game set up for a while. I am using it primarily with HE6 and I am super happy with it! It is also a gem for HD800. As such, I bet it would work nicely with Audezes. I am really curious to compare it to the GSX when it gets here.

 

 

anyway, back to you Gary.

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: High-end Audio Forum
Head-Fi.org › Forums › Summit-Fi (High-End Audio) › High-end Audio Forum › Speaker amps for headphones