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Speaker amps for headphones - Page 64

post #946 of 2599

On another note - anyone pairing their HE-6 or other Can with the Audio-gd Precision 1 amp?

post #947 of 2599
Quote:
Originally Posted by zilch0md View Post
 

[snip]

 

Oh, back to Head-Fi...  It occurred to me today, that I could omit four binding posts and four banana plugs from my signal path to the LCD-2, by asking Jan if he would allow me to send him two 14-inch lengths of my favorite speaker wire to pass through holes on the MG3 side of the match box for a soldered connection to a terminal strip inside, such that the match box will have only four binding posts on top (instead of eight) - into which only banana plugs from the headphones will go.  The speaker wire pig tails will be terminated with banana plugs that go to the MG3's binding posts.  Jan agreed to do this, no problem, with no difference in price.  So I've got 28-inches of KnuKonceptz 10-AWG 462-strand OFC speaker wire ready to Priority Mail to Jan tomorrow morning in a bubble pack.  

 

[snip]

 

Mike

 

I called Jan today to ask how my impedance match is coming.  He's very accessible - seems to have all the patience in the world to explain things.  :D

 

He recommended I go with eight binding posts, similar to Gary's impedance match, rather than trying to solder the 10AWG 462-strand OFC wire I'd sent him, to terminal strips inside the box.  He explained that the wire is just too large to get a good solder, and so, I'll be using binding posts to get to the MG3, instead.  

 

He also explained that I should use the smallest gauge wire sufficient for the amount of current expected vs. the distance to the speakers, for example.  There's a table of recommended values that I'd previously seen in the MG3 owner's manual.  He said that high frequencies can actually end up arriving at the transducer (whether speaker or headphone), slightly late relative to lower frequencies, by nature of their much shorter wavelengths allowing them to take indirect paths around a wire of excessively large diameter.  How about that?   Makes sense to me!

 

So, I'll be getting the same box that Gary got (the first one, for which Gary preferred the sound - vs. the one with Mills resistors).

 

Tick, tock, tick, tock...

 

Mike

post #948 of 2599

Did he say what value resistors he found to be optimal for the HD-800?

Quote:

Originally Posted by zilch0md View Post
 

 

I called Jan today to ask how my impedance match is coming.  He's very accessible - seems to have all the patience in the world to explain things.  :D

 

He recommended I go with eight binding posts, similar to Gary's impedance match, rather than trying to solder the 10AWG 462-strand OFC wire I'd sent him, to terminal strips inside the box.  He explained that the wire is just too large to get a good solder, and so, I'll be using binding posts to get to the MG3, instead.  

 

He also explained that I should use the smallest gauge wire sufficient for the amount of current expected vs. the distance to the speakers, for example.  There's a table of recommended values that I'd previously seen in the MG3 owner's manual.  He said that high frequencies can actually end up arriving at the transducer (whether speaker or headphone), slightly late relative to lower frequencies, by nature of their much shorter wavelengths allowing them to take indirect paths around a wire of excessively large diameter.  How about that?   Makes sense to me!

 

So, I'll be getting the same box that Gary got (the first one, for which Gary preferred the sound - vs. the one with Mills resistors).

 

Tick, tock, tick, tock...

 

Mike

post #949 of 2599
Quote:
Originally Posted by brunk View Post
Did he say what value resistors he found to be optimal for the HD-800?

 

No, he only briefly mentioned that the HD-800 is more sensitive than the LCD-3 or LCD-2 and that the sensitivity of the driver is of greater concern than the impedance when selecting values for the resistor.  He had said this on the heels of my having asked him if he was going to use the same values for my 50-Ohm LCD-2 as for Gary's 45-Ohm LCD-3.  He made it clear that he's more curious about any difference in sensitivity between the LCD-2 and LCD-3, at which point I told him that the LCD-2 is only slightly more sensitive than the LCD-3, from what I've heard, but not by taking measurements.  

 

We then got into a discussion about how I just want to get rid of the hiss I hear with the LCD-2 in the absence of resistors, without taking down the power any further than necessary.  He emphasized that headphones (with no qualification as to which) really don't need but a fraction of the power the MG3 can provide, in essence saying (I'm paraphrasing here), that it would be better to over-do the attenuation in the match box than to go easy and not have a pitch black noise floor.  I countered that Audeze support has written that the LCD-2 can handle up to 13-Watts rms into 50-Ohm - the equivalent of 81 Watts into 8-Ohm, even though they sound "loud enough" on only 30mW from the amp section of an iPod.  

 

I told him that although I want the hiss to go away, obviously, I also want as much of the the dynamics and bass control as possible that come with more power - that, ideally, I wouldn't want to do anything more than take the hiss away.  He didn't seem to buy into there being any benefit to having a lot of excess headroom - that if you can develop an SPL of 90 dB at the headphones with 30mW, then an amplifier capable of one full Watt would be plenty of headroom (even if Audeze says the LCD-2 can handle 13 Watts).  He repeated that doubling the power raises the SPL 3 dB, and thus...  there's no need for concern about the possibility of overdoing the resistance values a little bit?  There will be plenty of dynamics with the headroom had with only one Watt.  (Again, I'm paraphrasing, but that's the essence of his argument.)   

 

I know that Audeze recommends a minimum of 2 Watts per channel into 50-Ohms, but the attenuation Jan will be applying isn't likely to threaten that, when we're starting out with 32 Watts into 8-Ohms (or about 5 Watts into 50-Ohm) with the MG3 on 24V power.  So, I ended up admitting that ultimately, I'd rather trust his decisions than try to do the designing for him!   :o   And thus, he will be building an impedance match identical to the one that Gary prefers (of the two he tested). My slightly more sensitive LCD-2 will be a little bit more vulnerable to hiss than Gary's LCD-3, but Jan said I could send it all back to him for further tweaking, if necessary.

 

On the subject of hiss, without my having mentioned my experience with the MG3 > Definitive Technology SM45 (8-Ohm monitors), when he was talking to me about finding that balance between hiss elimination and retaining as much gain as possible, he said (again, paraphrasing):  "It's just right for the sensitivity of any given speaker if you can hear a slight hiss with your ear right up against the speaker grill."   I laughed, telling him that this is exactly what I'm getting with my 8-Ohm SM45s with the MG3 on 24V power - but that at my normal (near-field) listening distance of about 20 inches, I can't hear any hiss at all and my noise floor is pitch black during the silent portions of music that's playing - with good recordings, of course.

 

I didn't say this to him during the call, but I should think one wouldn't want to hear ANY hiss in a headphone (because your ear is always against the grill, so to speak.)

 

So... like it or not, without sending Jan your headphones and allowing him (paying him extra?) to spend several hours trying to finely tune the hiss away with various resistor values, you're going to end up with what Gary and I have - an impedance match that's pretty much assumed to have excess resistance, but...   With plenty of headroom to spare, we shouldn't fret over it.  Getting rid of the hiss is the goal, more than having gain so excessive it can't be put to good use.

 

Jan said he expects to ship my impedance match in a couple of days. (I should have it next week some time.)

 

UPDATE:  Let me add that my DACmini CX, which puts out about 680mW rms into 50-Ohm, offers superb dynamics, and thanks to a more forward presentation, vs. the 10th-row-seating of the laid-back Burson Soloist, I find the DACmini CX to offer slightly more "slam" and solid "hits" than does the Burson Soloist - which itself only delivers 1.28 Watts rms into 50-Ohms.   So...  two points here:  1) I don't really know, but I doubt that Jan's impedance match is going to reduce the output power from 5.12 Watts into 50-Ohm (MG3 speaker taps) to anywhere near as low as 680mW into 50-Ohm (DACmini CX headphone out), and 2) I suspect that the impression one can have of great dynamics, can come as much from an amplifier's design traits other than rated power output, as from raw power - not to mention just how dynamic a given recording is, as that would be a constant in any such comparison.

 

Mike


Edited by zilch0md - 9/3/13 at 3:43pm
post #950 of 2599

Yeah I agree that hiss elimination is the #1 concern. There's almost always too much gain (I wonder how many gain stages the MG3 has) in a typical setup anyway. Like he said, there shouldn't be a problem killing the extra power as heat from the resistors because these headphones are not power hungry at all. The exception being the HE-6 which I'm sure is no problem for a direct connection. I was under the impression that you were getting a box made for the HD-800, or was that someone else? Looking forward to your impressions Mike.

 

Regards,

Brunk

Quote:

Originally Posted by zilch0md View Post
  Mike's conversation with Jan (Click to show)

No, he only briefly mentioned that the HD-800 is more sensitive than the LCD-3 or LCD-2 and that the sensitivity of the driver is of greater concern than the impedance when selecting values for the resistor.  He had said this on the heels of my having asked him if he was going to use the same values for my 50-Ohm LCD-2 as for Gary's 45-Ohm LCD-3.  He made it clear that he's more curious about any difference in sensitivity between the LCD-2 and LCD-3, at which point I told him that the LCD-2 is only slightly more sensitive than the LCD-3, from what I've heard, but not by taking measurements.  

 

We then got into a discussion about how I just want to get rid of the hiss I hear with the LCD-2 in the absence of resistors, without taking down the power any further than necessary.  He emphasized that headphones (with no qualification as to which) really don't need but a fraction of the power the MG3 can provide, in essence saying (I'm paraphrasing here), that it would be better to over-do the attenuation in the match box than to go easy and not have a pitch black noise floor.  I countered that Audeze support has written that the LCD-2 can handle up to 13-Watts rms into 50-Ohm - the equivalent of 81 Watts into 8-Ohm, even though they sound "loud enough" on only 30mW from the amp section of an iPod.  

 

I told him that although I want the hiss to go away, obviously, I also want as much of the the dynamics and bass control as possible that come with more power - that, ideally, I wouldn't want to do anything more than take the hiss away.  He didn't seem to buy into there being any benefit to having a lot of excess headroom - that if you can develop an SPL of 90 dB at the headphones with 30mW, then an amplifier capable of one full Watt would be plenty of headroom (even if Audeze says the LCD-2 can handle 13 Watts).  He repeated that doubling the power raises the SPL 3 dB, and thus...  there's no need for concern about the possibility of overdoing the resistance values a little bit?  There will be plenty of dynamics with the headroom had with only one Watt.  (Again, I'm paraphrasing, but that's the essence of his argument.)   

 

I know that Audeze recommends a minimum of 2 Watts per channel into 50-Ohms, but the attenuation Jan will be applying isn't likely to threaten that, when we're starting out with 32 Watts into 8-Ohms (or about 5 Watts into 50-Ohm) with the MG3 on 24V power.  So, I ended up admitting that ultimately, I'd rather trust his decisions than try to do the designing for him!   :o   And thus, he will be building an impedance match identical to the one that Gary prefers (of the two he tested). My slightly more sensitive LCD-2 will be a little bit more vulnerable to hiss than Gary's LCD-3, but Jan said I could send it all back to him for further tweaking, if necessary.

 

On the subject of hiss, without my having mentioned my experience with the MG3 > Definitive Technology SM45 (8-Ohm monitors), when he was talking to me about finding that balance between hiss elimination and retaining as much gain as possible, he said (again, paraphrasing):  "It's just right for the sensitivity of any given speaker if you can hear a slight hiss with your ear right up against the speaker grill."   I laughed, telling him that this is exactly what I'm getting with my 8-Ohm SM45s with the MG3 on 24V power - but that at my normal (near-field) listening distance of about 20 inches, I can't hear any hiss at all and my noise floor is pitch black during the silent portions of music that's playing - with good recordings, of course.

 

I didn't say this to him during the call, but I should think one wouldn't want to hear ANY hiss in a headphone (because your ear is always against the grill, so to speak.)

 

So... like it or not, without sending Jan your headphones and allowing him (paying him extra?) to spend several hours trying to finely tune the hiss away with various resistor values, you're going to end up with what Gary and I have - an impedance match that's pretty much assumed to have excess resistance, but...   With plenty of headroom to spare, we shouldn't fret over it.  Getting rid of the hiss is the goal, more than having gain so excessive it can't be put to good use.

 

Jan said he expects to ship my impedance match in a couple of days. (I should have it next week some time.)

 

UPDATE:  Let me add that my DACmini CX, which puts out about 680mW rms into 50-Ohm, offers superb dynamics, and thanks to a more forward presentation, vs. the 10th-row-seating of the laid-back Burson Soloist, I find the DACmini CX to offer slightly more "slam" and solid "hits" than does the Burson Soloist - which itself only delivers 1.28 Watts rms into 50-Ohms.   So...  two points here:  1) I don't really know, but I doubt that Jan's impedance match is going to reduce the output power from 5.12 Watts into 50-Ohm (MG3 speaker taps) to anywhere near as low as 680mW into 50-Ohm (DACmini CX headphone out), and 2) I suspect that the impression one can have of great dynamics, can come as much from an amplifier's design traits other than rated power output, as from raw power - not to mention just how dynamic a given recording is, as that would be a constant in any such comparison.

 

Mike

 

post #951 of 2599
Originally Posted by brunk View Post
I was under the impression that you were getting a box made for the HD-800, or was that someone else? Looking forward to your impressions Mike.

 

That would be me... and I'll have the Millenia, (HD800-friendly) resistor box, and my HD800 back a week from today.  If it works out, I'll get at Jan for the schematic.

post #952 of 2599
Quote:
Originally Posted by FlySweep View Post
 

 

That would be me... and I'll have the Millenia, (HD800-friendly) resistor box, and my HD800 back a week from today.  If it works out, I'll get at Jan for the schematic.

Cool! I hope it sounds great! :popcorn:

post #953 of 2599

Folks:

 

All I can say about the MG3 with resistor-boxes driving the LCD-3 is that I've never had it past ~10 o'clock on the dial, even with AA batteries.  Normal listening for my old ears is usually just short of 9 o'clock, though at the meet this past weekend some of the young guys were pushing it to ~12, and those of us not wearing the LCDs could clearly hear what was being played, as if it was being played on speakers at moderate volume.  It's a wonder that these guys aren't totally deaf, and my guess is that a number of them will be by the time they reach ~35.  If they reach that age.  Youth surely is wasted on the young... 

 

But back to my point (hey, I'm old, my mind wanders... ):  whatever attenuation Jan is putting in the box is not sucking away too much power.  It isn't at all like what Michael P was experiencing with the HE-6s and his resistor box -- pushing the volume control well past 12 o'clock.  There is plenty of headroom with the LCDs using Jan's box designs.  And I'm guessing that with the HD800s' greater sensitivity, folk will get plenty of dynamics even with the higher resistor values that he's going to use to knock down the hiss.  Of course, the fact that different headphone designs will require use of different resistor boxes (or no resistor box, for the HE-6) makes Jan's life a bit tougher, but once he has a chance to work up designs for the most popular headphone groupings it will get easier.  And I think he is probably enjoying the challenge... at least a bit. 

 

But one thing for sure:  there is nobody on this planet who understands that particular amp design and its implications for the rest of the chain better than Jan, so I would just trust that whatever he ends up sending you is going to be the best choice, even if he has to use some trial and error up front to dial in the perfect balance.  Actually Flysweep had the right idea to send him the cans to do the experimenting on site, instead of possibly having the trial and error done long distance.  But hey, UPS/FedEx guys have to make a living too, and patience is a virtue (... no I don't really believe that... but it is a necessity in some cases if you want the right ending...).

post #954 of 2599
I really like this, Gary!

"Youth surely is wasted on the young... "

:-)
post #955 of 2599

One of the interesting experiences for me when I demoed the LCD2s last week was that I was actually finding myself turning down the volume level as compared with my Paradox. I attributed this to possibly looking for a fuller sound in turning up the Paradox. The Audeze have that fuller sound and plenty of detail even at lower levels. Good to be able to enjoy music at somewhat lower rather than higher levels; we do want to preserve our hearing.....and avoid tinnitus, right? In terms of levels needed to attain approximately the same volume level, I found the Audeze to be more sensitive (requiring less level) than the Paradox. But, I was using the same resistor box. Worked perfectly for both phones (impedance are pretty close, and sensitivity likely is not THAT far off from each other). Hopefully, to keep things simple and preserve Jans' sanity, he'll find a couple (2, 3 or so) resistor configurations that will work with a range of headphones' impedance and sensitivities.

post #956 of 2599
Quote:
Originally Posted by zilch0md View Post

I really like this, Gary!

"Youth surely is wasted on the young... "

:-)

I certainly didn't invent the phrase... In fact I think the person who did invent it was the first human to reach middle age...

post #957 of 2599

Hmmm... the T50RPs are spec'ed at 98dBs per mW, the LCDs at 91... The mods that Paradox does probably drop the sensitivity some, but it could be that you are craving parts of the spectrum that the Paradox rolls off... or the LCDs accentuate.  Either way, you need to be working on strengthening your skull so that you can enjoy the LCDs without feeling the pain.  I'm sure if you google "skull strengthening exercises" somebody will have something to sell you...:biggrin:

 

I'm guessing that Jan will have to have more than a couple of resistor configurations.  There's SE vs. Balanced to start, and then impedance ranging from the few tens of ohms for planars to a few hundreds for dynamics... and seemingly everything in between.  Sensitivities then put limits on how much attenuation a given headphone can handle... The end result is likely more than 2-3 circuit designs.

 

The difficulty with the resistor boxes really drives home the point that every amp designer has to choose a particular type of circuitry to suit a relatively small group of transducers (particularly headphones, but also true of speakers) and that some combinations are going to work and some are not. 

 

Which makes it clear that all opinions on a particular piece of equipment need to be understood within the context of the rest of the hardware chain, plus the individual's particular hearing and taste. 

 

Which in turn has led me to use personal demos as much as possible to choose my equipment. 

 

Which in turn reinforces my opinion that the hifi audio business is a really tough one these days, since people can't just go to their local hifi store and listen. As a result, since a large percentage of folks don't like the idea of trying stuff via in-home comparisons and would rather just search for reviews on the internet, equipment sellers are highly dependent on opinions stated on blogs or forums or Amazon, often without context or understanding of the individual's hearing or taste. 

 

So next time you read a review on Head-Fi, a blog, or Amazon, consider that the person writing it could be mostly deaf, or at least mostly tone deaf, after listening to nothing but really bad heavy-metal garage bands for 25 years, and that this person could be using totally mismatched components in the rest of the chain.  And think about the fact that the success or failure of a product or company could be totally dependent on this person's opinion, which could snowball into either the flavor-of-the-month (year) or "worst product ever" ratings.  Pretty damned scary if you are in the trade, huh?

 

Okay, now it's time for me to put in my hearing aids and go listen to my "Unknown Heavy Metal Garage Bands of the 70s-80s" cassette tape at max volume on my Walkman knock-off feeding the MG3, into my Beats...:darthsmile:

post #958 of 2599
Quote:
Originally Posted by Gary in MD View Post
 

Hmmm... the T50RPs are spec'ed at 98dBs per mW, the LCDs at 91... The mods that Paradox does probably drop the sensitivity some, but it could be that you are craving parts of the spectrum that the Paradox rolls off... or the LCDs accentuate.  Either way, you need to be working on strengthening your skull so that you can enjoy the LCDs without feeling the pain.  I'm sure if you google "skull strengthening exercises" somebody will have something to sell you...:biggrin:

 

I'm guessing that Jan will have to have more than a couple of resistor configurations.  There's SE vs. Balanced to start, and then impedance ranging from the few tens of ohms for planars to a few hundreds for dynamics... and seemingly everything in between.  Sensitivities then put limits on how much attenuation a given headphone can handle... The end result is likely more than 2-3 circuit designs.

 

The difficulty with the resistor boxes really drives home the point that every amp designer has to choose a particular type of circuitry to suit a relatively small group of transducers (particularly headphones, but also true of speakers) and that some combinations are going to work and some are not. 

 

Which makes it clear that all opinions on a particular piece of equipment need to be understood within the context of the rest of the hardware chain, plus the individual's particular hearing and taste. 

 

Which in turn has led me to use personal demos as much as possible to choose my equipment. 

 

Which in turn reinforces my opinion that the hifi audio business is a really tough one these days, since people can't just go to their local hifi store and listen. As a result, since a large percentage of folks don't like the idea of trying stuff via in-home comparisons and would rather just search for reviews on the internet, equipment sellers are highly dependent on opinions stated on blogs or forums or Amazon, often without context or understanding of the individual's hearing or taste. 

 

So next time you read a review on Head-Fi, a blog, or Amazon, consider that the person writing it could be mostly deaf, or at least mostly tone deaf, after listening to nothing but really bad heavy-metal garage bands for 25 years, and that this person could be using totally mismatched components in the rest of the chain.  And think about the fact that the success or failure of a product or company could be totally dependent on this person's opinion, which could snowball into either the flavor-of-the-month (year) or "worst product ever" ratings.  Pretty damned scary if you are in the trade, huh?

 

Okay, now it's time for me to put in my hearing aids and go listen to my "Unknown Heavy Metal Garage Bands of the 70s-80s" cassette tape at max volume on my Walkman knock-off feeding the MG3, into my Beats...:darthsmile:

Yes, not sure what is at work with relation to my needing to turn up the Paradox from what I was using for the Audeze. Could be that efficiency differences of the headphones were not at play.

 

And yes, a pair of Audezes may still be in my future. It's not really the neck muscles, it's the clamping force, and hardness of the earpads. But Audeze said that the LCD3 pads may be more to my liking, so that is a possibility as is stretching out that headband some more. What I am particularly waiting on now is the appearance of the closed back design, as that would eliminate some of the background noise that I need to deal with, as well as other factors. They should be released pretty soon, I believe. If they are MUCH more expensive than the LCD2s, they may not then be in the running anyway. We'll see......

 

As for the rest of your entry, I couldn't agree with you more Gary. Used to be back in the day, Stereophile writers didn't even mention what their system components were, unless it appeared in the article. Now at least most reviewers spell out their associated equipment, and it's helpful to know what their biases are if one is going to take anything at all away from the article. But, an in-home audition is the way to go, unless one doesn't mind becoming a used hi fi sales person, and then purchasing off of Audiogon is an alternative, without  taking too much of a loss. 

 

Stew

post #959 of 2599

Stew:

 

Just for you I googled "Skull strengthening" and believe it or not, unlike every other thing in the universe, nobody in the top 100 or so results was selling anything that would strengthen your skull.  Hard for me to believe that given all of the "products" and advice available on the web, but I guess you're just SOL regarding Audeze products, unless the softer pads or stretched out headband work. 

 

Of course, as an alternative there's all sorts of stuff available to deaden the pain... not that I've ever tried any or anything... but some folks say it also helps them enjoy the music more... or at least gives them an appreciation of what some of the rock musicians were hearing (or thought they were hearing) when they made the recording, if you know what I mean...

post #960 of 2599
Quote:
Originally Posted by Gary in MD View Post
 

Stew:

 

Just for you I googled "Skull strengthening" and believe it or not, unlike every other thing in the universe, nobody in the top 100 or so results was selling anything that would strengthen your skull.  Hard for me to believe that given all of the "products" and advice available on the web, but I guess you're just SOL regarding Audeze products, unless the softer pads or stretched out headband work. 

 

Of course, as an alternative there's all sorts of stuff available to deaden the pain... not that I've ever tried any or anything... but some folks say it also helps them enjoy the music more... or at least gives them an appreciation of what some of the rock musicians were hearing (or thought they were hearing) when they made the recording, if you know what I mean...

Actually I do know what you mean.....but those days are long gone. I don't even tolerate alcohol very well; 1/2 a beer and I'm done. :D

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