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Speaker amps for headphones - Page 57

post #841 of 2846

I don't know if it has been mentioned in this thread before, but the MG3 is a so-called "chip amp."  This may not be accurate, but I read at the AudioCircle forum that It's built around a Texas Instruments TPA3100D2.

 

 

Quote:
The TPA3100D2 is a 20-W (per channel) efficient, Class-D audio power amplifier for driving bridged-tied stereo speakers. The TPA3100D2 can drive stereo speakers as low as 4 Omega.gif. The high efficiency of the TPA3100D2, 92%, eliminates the need for an external heat sink when playing music.

 

http://www.ti.com/product/tpa3100d2

 

http://www.ti.com/lit/ds/symlink/tpa3100d2.pdf

 

Everything I've read makes it clear that Jan Plummer has taken this diamond in the rough and worked wonders with it.  

 

Knowing that this TBI giant-killer of an amp is just a "chimp amp" at heart, makes me like it all the more.  It's the antithesis of a Burson Soloist's design, for example, which uses discrete components - but the MG3 sounds so much better.

 

tongue.gif

 

Mike

post #842 of 2846

Chip amps actually sounds damn nice when done properly.  Not really giant killers or world beaters in any ways but very competent for the price. Especially T-amps, I don't think you can build any amps around 200 bucks that is remarkbly better than a good Ta2020 amp =p.

 

My two favorites are some implementations of the TA2020 and the Gainclone.

post #843 of 2846
Quote:
Originally Posted by zilch0md View Post

I don't know if it has been mentioned in this thread before, but the MG3 is a so-called "chip amp."  This may not be accurate, but I read at the AudioCircle forum that It's built around a Texas Instruments TPA3100D2.

 

 

 

http://www.ti.com/product/tpa3100d2

 

http://www.ti.com/lit/ds/symlink/tpa3100d2.pdf

 

Everything I've read makes it clear that Jan Plummer has taken this diamond in the rough and worked wonders with it.  

 

Knowing that this TBI giant-killer of an amp is just a "chimp amp" at heart, makes me like it all the more.  It's the antithesis of a Burson Soloist's design, for example, which uses discrete components - but the MG3 sounds so much better.

 

tongue.gif

 

Mike

I am about to display my ignorance of voltages vis a vis power adapters, etc., but Mike, if 15 volts (either ac or dc) is the sweet spot sonicly for the Millenia (at least, in terms of what you prefer) is there available an ac 15 volt power adapter that would work with it, instead of the 24 volt one that comes with it? If so, would that solve the problem of a more constant voltage, at least on ac, and at 15volts?

post #844 of 2846

From diyaudio, you can even buy an eval board from digikey for the TI TPA3100D2.

 

http://www.ti.com/lit/ug/slou179a/slou179a.pdf

 

http://www.diyaudio.com/forums/class-d/217903-ti-tpa3100d2-amazing-class-d-amp.html


Edited by wuwhere - 8/24/13 at 5:09pm
post #845 of 2846

Here is more action on the Millenia. I am including a link here because there is much discussion about battery power. Seems like the guys on Audiocircle have discovered Head-Fi! Jan must be very busy.....

 

http://www.audiocircle.com/index.php?topic=115309.0

post #846 of 2846
Quote:
Originally Posted by SMG52 View Post

Here is more action on the Millenia. I am including a link here because there is much discussion about battery power. Seems like the guys on Audiocircle have discovered Head-Fi! Jan must be very busy.....

 

http://www.audiocircle.com/index.php?topic=115309.0


That thread was where I got the idea of using a bench-top power supply.  I then did some research, and if you watch a few video reviews of various power supplies you can actually hear the damned fans pretty clearly.  No way that would work for audio. 

 

I find it amazing that they are sending that little amp around the country.  I guess I'm not that generous.  I'm willing to bring it to the Head-Fi meet in VA next weekend, but I'm not lettin' anybody else take it home with them!!!!! 

post #847 of 2846

I hear you Gary.  And you have to babysit your gear at the meets, too!  

 

[I'm omitting a rant I just wrote about scratches applied to my Burson Soloist at the Dallas meet, through shear negligence. You would think that everyone attending a Head-Fi meet would be able to stick a TRS plug into a TRS jack without leaving scratches all over the place.  There I go starting my rant again. The End]

 

Mike

post #848 of 2846

Hey Stew,

Quote:
Originally Posted by SMG52 View Post

I am about to display my ignorance of voltages vis a vis power adapters, etc., but Mike, if 15 volts (either ac or dc) is the sweet spot sonicly for the Millenia (at least, in terms of what you prefer) is there available an ac 15 volt power adapter that would work with it, instead of the 24 volt one that comes with it? If so, would that solve the problem of a more constant voltage, at least on ac, and at 15volts?

 

For sure!  What you're looking for is "a linear regulated DC power supply" rated at your voltage of choice with at least a 3-Amp current capacity (higher is better because you can't always trust the ratings) - with heat sinks - no fans (thanks Gary!)   

 

I can't say that 15V is going to be the sweet spot for my headphones once I try them with the forthcoming impedance match, but 15V sure great with my speakers.  I don't know how you would go about discerning which voltage gives you the sound you want with your transducers of choice, without having a way to power the MG3 at different voltages (in the range 10V to 26V, per the Texas Instruments datasheet).  

 

But once you do figure out which voltage you want, here are some examples of fixed-output linear regulated DC power supplies having at least a 3Amp capacity:

 

13.8V  6A  http://www.amazon.com/Pyramid-PS8KX-Amp-Power-Supply/dp/B000A896GG

 

Get one of these, too:

 

http://www.amazon.com/2-1mm-5-5mm-11-2mm-Plug-Cord/dp/B0002KRCRW

 

Unfortunately, it's hard to these in fixed voltages other than 12V (or 13.8V).

 

You might try a switch-mode regulated power supply (as opposed to linear regulated power supply), but switch-mode power supplies can induce noise. The only way to know for sure is to test it and see if you can hear any noise in the signal.  Amazon allows returns.......

 

Here are examples you might want to try (they've got the correct sized plug, plenty of amps, ready to go):

 

15V 5A  http://www.amazon.com/Power-Supply-2-5mm-Regulated-Adapter/dp/B006QZUSPA

 

18V 4A  http://www.amazon.com/Power-Adapter-2-1mm-Regulated-Supply/dp/B006QZZ00I

 

 

If you just bought these last two (and hope that they aren't noisy), you'd be able to compare them to 12V internal AA's and the 24V power supply that came with the MG3.  

 

12, 15, 18, and 24 would be a nice spread to test.  Send back anything you don't want to keep.

 

:-)

 

Mike

post #849 of 2846

What size is the external power jack on the MG3?  I can't seem to find reference to it in my allergy induced fog...

 

Thanks, 

 

michael

post #850 of 2846

2.5mm inner diameter, 6.3mm outer diameter.  Pretty standard I think...

post #851 of 2846
Hey Gary,
Quote:
Originally Posted by Gary in MD View Post

2.5mm inner diameter, 6.3mm outer diameter.  Pretty standard I think...

It's actually 2.1mm x 5.5mm (more common still).

UPDATE: The MG3 jack is meant for 6.3mm x 2.5mm plugs, just as Gary said, but the AC adapter Jan Plummer shipped with my MG3 is equipped with a 2.1mm x 5.5mm plug! See my post below at http://www.head-fi.org/t/649107/speaker-amps-for-headphones/840_20#post_9742018

Since the size is not documented in the MG3 manual, I just measured the outside diameter of the DC power plug that's on the 2.7A 24V AC-to-DC adapter that came with my MG3, using vernier calipers: 5.5mm

This will work:

http://www.amazon.com/2-1mm-5-5mm-11-2mm-Plug-Cord/dp/B0002KRCRW


And if you want to run a heavier gauge wire of any length of your choosing you can solder to one of these:

http://www.amazon.com/Amico-Black-2-1mm-5-5mm-Adapter/dp/B008OTKDNS

Or, if soldering is not your thing, you can use one of these:

http://www.amazon.com/Gino-5-5mm-Power-Connector-Camera/dp/B008AGUI8K

Mike
Edited by zilch0md - 8/25/13 at 8:25am
post #852 of 2846

Great!  Thanks, guys!

post #853 of 2846
Quote:
Originally Posted by zilch0md View Post

Hey Gary,

 

It's actually 2.1mm x 5.5mm (more common still).

 

Since the size is not documented in the MG3 manual, I just measured the outside diameter of the DC power plug that's on the 2.7A 24V AC-to-DC adapter that came with my MG3, using vernier calipers: 5.5mm

 

This will work:

 

http://www.amazon.com/2-1mm-5-5mm-11-2mm-Plug-Cord/dp/B0002KRCRW

 

And if you want to run a heavier gauge wire of any length of your choosing you can solder to one of these:

 

http://www.amazon.com/Amico-Black-2-1mm-5-5mm-Adapter/dp/B008OTKDNS

 

Or, if soldering is not your thing, you can use one of these:

 

http://www.amazon.com/Gino-5-5mm-Power-Connector-Camera/dp/B008AGUI8K

 

Mike


Mike:

 

There's a diagram on the back of the amp that has the numbers I quoted.  Does it mean something other than what I thought?  Wouldn't be the first time I misinterpreted electronical hieroglyphics...

 

Gary

post #854 of 2846
Quote:
Originally Posted by Gary in MD View Post


Mike:

 

There's a diagram on the back of the amp that has the numbers I quoted.  Does it mean something other than what I thought?  Wouldn't be the first time I misinterpreted electronical hieroglyphics...

 

Gary

 

Wow!  No kidding!  I just looked at the back of my amp and there it is, a diagram showing 6.3mm outside and 2.5mm inside diameter!   Thanks for catching that, Gary.

 

But..  the AC adapter that Jan shipped with my MG3 measures precisely 5.5mm outside diameter and I'm using a 5.5mm x 2.1mm plug for my battery packs (same as Jan's AC adapter) and it's working fine.

 

I suppose either size will work.  Take your pick, but I had noticed that both Jan's AC adapter plug and my plug are a bit wobbly in the jack, though secure, so I think Jan really is installing a 6.3mm x 2.5mm jack in the MG3, just as it says on the back of the MG3, even though his AC adapter has the more common 5.5 x 2.1mm plug.  

 

So... I'd have to recommend that we use the 6.3mm x 2.5mm, when building cables, as Gary originally stated.  smile.gif  

 

Here's a picture I just took of my MG3 doing its thing:

 

 

WAV > Foobar 2000 WASAPI event mode > USB > Moon Audio Blue Dragon USB cable > CEntrance DACmini CX  Line Out > Emotiva RCA interconnects > TBI Millenia MG3 > KnuKonceptz Kord 10-AWG 462-strand OFC > Definitive Technology SM45 monitors (with the MG3 powered by a four-cell 1000 mAh LiPo pack that produces 16.8V at full charge, requiring recharge at 12.0V)

 

Oops!   I forgot this is a headphone forum.  Where did I leave those LCD-2, anyway?  They're around here somewhere...

 

redface.gif


Edited by zilch0md - 8/25/13 at 9:30am
post #855 of 2846
Quote:
Originally Posted by zilch0md View Post

 

Wow!  No kidding!  I just looked at the back of my amp and there it is, a diagram showing 6.3mm outside and 2.5mm inside diameter!   Thanks for catching that, Gary.

 

... snip ....

 

So... I'd have to recommend that we use the 6.3mm x 2.5mm, when building cables, as Gary originally stated.  smile.gif  

 

... snip ....

redface.gif

 

Any chance that's a misprint on the silkscreen on the back of the MG3?  I'm not sure the power jack would even make contact with a 5.5mm barrel in a 6.5mm jack...  Somethings not adding up here....

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