[OzarkTom]

WOW!

Just got a look at this thing, and had been contemplating a high quality tube buffer for my system.
The boy's at AMR have gotten the iFi line right!
It's great to see a company, that is well renowned for reference gear, bring that technology to budget gear. 
Without it being some watered down, cheepo, under-performing version with their name on it, just for profit! 
I had the iPhono and the thing was amazing and performed waaay above it's price point.
I will buy another one when my listening room is rebuilt. 

Will be looking for one of these units when it hit's the market! 

Any idea of the tube used?

I was told, but forgot.

I believe it starts with the number 5. is four numbers, and is a NOS tube. Definitely is not some junk tube. But I don't believe it is a 5751 tube, but maybe so. Itube also has adjustable gain in case you need it. The holographic circuit will even enhance audio systems that costs over $100K, so you may see a lot of people using the Itube..

That Thorsten of Ifi and AMR is a genious. He himself is the ultimate tweekster.

[wisnon]

It launches Aug 16. Triple play become quadruple play, i.e., iUSB  via Gemini to iLink to iTube.

Details at the FB page, but you have to dig for it as this was mentioned weeks ago.

[rodge827]

It launches Aug 16. Triple play become quadruple play, i.e., iUSB  via Gemini to iLink to iTube.

Details at the FB page, but you have to dig for it as this was mentioned weeks ago.

Very nice!
Hope to get one when they hit the US. 

[wisnon]

Then contact Bonnie and Darrell Censullo at Avatar Acoustics in GA.

[roscoeiii]

Continuing our OT diuscussion of the iTube. Here is the first review of the unit I have found:

http://www.audiostream.com/content/ifi-itube-active-tube-bufferpreamplifier

Hardly an across-the-board rave. Seemed to be pretty system dependent, with the greatest benefit coming with the Audioquest Dragonfly, and minimal benefit when used with the Mytek DAC.  As always, synergy is everything.

[OzarkTom]

Continuing our OT diuscussion of the iTube. Here is the first review of the unit I have found:

http://www.audiostream.com/content/ifi-itube-active-tube-bufferpreamplifier

Hardly an across-the-board rave. Seemed to be pretty system dependent, with the greatest benefit coming with the Audioquest Dragonfly, and minimal benefit when used with the Mytek DAC.  As always, synergy is everything.

Even with the Mytek, the 3D circuit was said to benefit the sound in the review.

[roscoeiii]

Even with the Mytek, the 3D circuit was said to benefit the sound in the review.

From the article: "With the Mytek DAC there was minimal benefit,the most dramatic difference being the 3D HologrpahicSound providing a larger and more natural sound image"

[Freo-1]

Is this a re-hash of the Carver "Sonic Holograph" circuit?

[OzarkTom]

Is this a re-hash of the Carver "Sonic Holograph" circuit?

I doubt it, but this is the latest link from IFI's website describing it.

http://ifi-audio.com/en/iTube.html

[rodge827]

Found this review of the iTube over on Head-Fi:

http://www.head-fi.org/products/ifi-audio-itube/reviews/9473

and Enjoy The Music:

http://www.enjoythemusic.com/magazine/equipment/0913/ifi_micro_itube_review.htm

Thought this was an appropriate OT post, will keep to the TBI Amp in the future.

[zilch0md]

Hi everyone!

This is my first post at AC, having heard about this thread a few weeks ago at Head-Fi.  I've just today finished reading the entire thread and have to say I really enjoyed everyone's contributions.

I took delivery of a TBI MG3 about a week ago and have been enchanted, no... make that infatuated, no... obsessed, ever since.   

I had ordered the MG3 with the intention of using it as a headphone amp, as others have before me.  But while waiting for an impedance match that Jan Plummer is making for my 50-Ohm Audeze LCD-2 headphones, I decided to connect my 8-Ohm, 90 dB, Definitive Technology SM45 monitors - another big bang for the buck product that was very favorably reviewed by Chris Martens of TAS, in April of this year:

http://www.theabsolutesound.com/articles/definitive-technology-studiomonitorsm-45-loudspeakers-hi-fi/

After spending nearly every available free minute of my life for the past week listening to the MG3 > SM45s, I'm not so sure I'll ever be able to experience anything nearly as wonderful with my LCD-2 headphones.  I had previously used a $189 Emotiva Mini-X a-100 (50-Wpc) integrated amp to drive my $320/pair SM45s, but there is no comparison.  It's as if the SM45s have been unshackled by the MG3.  This combo has great synergy, for lack of a better word.   The MG3 is so musical compared to any other amp I've ever heard.

Here's a picture I took a couple of days ago of my audio workbench (the dining table!)  And yes, I have a truly wonderful wife, who puts up with a lot! 



More later...

[rodge827]

zilch0md
Very nice desk table top set up!
What is the gizmo to the right of the MG3? Card reader?

Chris
 

[zilch0md]

Hi,

That's an RC hobbyist's four-cell, 1000 mAh LiPo battery, rated at 14.8V nominal (which translates to 16.8V when fully charged and 12.0V when discharged).  It's about $10.00 at HobbyPartz.com



LiPo batteries are very light and energy dense relative to something like SLA, especially.  That little battery will power the MG3 for about six hours but experiences a substantial voltage drop, and therefore, a substantial drop in Watts rms to the speakers, as it discharges (from 16.8V to 12.0V), but the discharge curve is very flat, with most of the drop to 12.0V occurring in the last few minutes of use. 

These batteries have two leads (+ and -) for discharging, but another set of leads that allow a so-called "balance charger" to charge each cell independently, in parallel, instead of charging them in series, where a cell that's lagging behind its siblings could cause healthier cells to be damaged by over-voltage.   Here's the balance charger I use - a Thunder AC6 , that can handle all manner of battery charging needs, very intelligently.  It's called a "Dual Power" charger because it will operate from either 120V AC or from 12V DC.  Yes, it has a DC-to-DC converter that allows charging of up to 25.2V six-cell LiPo packs from your vehicle's 12V accessory socket, for example!  It's about $45 at HobyPartz.com:



When not on the charger, the balance-charging  leads can be connected to various monitoring devices, such as the one that's displaying 15.0 (Volts) in the first photo, above.  This thing can be programmed to sound an audible alarm (it's loud - just like a smoke detector) at a user-specified voltage in the range 2.7V to 3.7V.  The factory default it 3.3V - giving the pilots of RC aircraft time to get their planes back on the ground (or those of RC boats to get them back to shore) before the battery would be damaged due to discharge below 3.0V per cell.  I've got mine set to 3.0V, as it takes no time at all for me to turn off an amplifier.   

This one is called the Integy C23212 Lipo Voltage Checker/Warning Buzzer and it's available at Amazon for about $10:



Since taking that picture of my dining table, I've switched to using a 3600 mAh 6-cell LiPo pack, rated at 22.2V nominal (25.2V when fully charged, falling to 18.0V when discharged.)  This one is much larger - about the same length as the MG3 is from front to rear, but not quite as wide.   I've used it for about 20 hours and it has only lost about 0.25 V from its fully charged voltage.  It's likely to last 100 hours or more, but I really have no idea at this point.  Called the Venom 25C 6S 3600mAh 22.2 LiPO Battery, it's $99 at Amazon:



Jan Plummer has assured me that I don't need to concern myself with the fact that these batteries can deliver crazy amounts of current.  The 1000 mAh four-cell LiPo, mentioned above, has a maximum continuous discharge rating of "20C."  Doing the math, one takes the mAh rating (1000 mAh) and multiplies by the maximum discharge rate (20C) to get the maximum continuous load it can handle (without overheating) of 20,000 mA (or 20A).   If that sounds like a lot of current, try the same calculation with the 3600 mAh six-cell LiPo, which has a discharge rate of 25C...   3600mAh * 25 = 90,000 mA (or 90A)!

When selecting LiPo packs for this purpose (not for RC toys), pay attention to the "C" rating - selecting as low a rating as possible for the voltage your're seeking (i.e. 20C or 25C, not 30C to 70C) and also remember that the voltage shown for a LiPo pack will always be the "nominal" voltage (3.7V per cell), not the fully charged voltage (4.2V per cell).

UPDATE:  Jan Plummer says that a supply voltage of 27.5V can cause the MG3 to demand currents exceeding 4A - enough to blow the fuse, so don't try to use 7-cell LiPo packs that would produce 29.4V when fully charged.  Stick with 6-cell LiPo packs (25.5V) or less.

Gotta run for now!

Mike

[zilch0md]

I just now found this page that does a good job with covering the basics of using LiPo batteries:

http://revolution-robotics.com/articles/lithium_polymer_lipo_battery_guide

It includes this graph that has me rethinking my current strategy of discharging the batteries all the way to 3.0V per cell for use with the MG3.



It shows that in the last 1/9th of the total time required to discharge each cell of a 6-cell LiPo pack from 4.2V down to 3.0V, the voltage drops from 3.43V to 3.0V.  For the first 8/9ths of the total time it takes to discharge to 3.0V, the curve is fairly flat. 

Thus, if a 6-cell battery of a given mAh rating were to last a total of 9 hours with a given load, the first 8 hours would be "flat" with the voltage dropping no lower than 3.43V per cell, or 20.6V for a 6-cell pack.  In the last hour of 9 hours, said 6-cell pack under said load would drop from 20.6V to 18V, which for the MG3 would translate to a corresponding, precipitous drop in Watts rms per channel (in the 9th hour). 

Moral of the story:  I'm going to reprogram my voltage alarm to sound at 3.4V per cell, instead of at 3.0V per cell.

 

Mike

[rodge827]

 Mike,
Thanks for the very informational threads using a LiPo battery looks like a good idea, and is very cost effective.

Have you listened to the amp powered by other power supplies, and is there a sound quality difference?

Chris

[zilch0md]

Thanks Chris,

To date, since getting the MG3 only 10 days ago, I've only "auditioned" the following power sources:

1)  The 24V 2.7A switch-mode PSU that comes with the MG3

2)  A 3-cell 2200 mAh (12.6V max.) LiPo pack

3)  A 4-cell 1000 mAh (16.8V max.) LiPo pack

4)  A 6-cell 3600 mAh (25.2V max.) LiPo pack

5) An Energizer XP8000 2000mAh Li-Ion battery (which, at 18-months of age, is delivering only 19.5V when fully charged).

6)  8 AA (standard) 1.5V Duracell Alkalines (in the battery compartment)

7)  8 AA 1.5V Energizer e² Lithium-Ion (in the battery compartment)

Across all seven solutions, I have no issues with noise that could be attributed to the power supply, per se.  I can, however, hear a very faint hiss with #1 and #4, prior to playing a track, but I have to hold my ear against a speaker grill to hear it, and it's there, no matter where I set the MG3 volume control - even turned all the way down.  I attribute this hiss to the higher voltage of #1 and #4, nothing more.  I just think my 90 dB sensitivity speakers require a little less gain.  Interestingly, when I first got the MG3, the hiss on 24V was worse than it has become after just a few hours of break-in.  My noise floor is inky black now - allowing lots of micro details to come through, beautifully - no matter what voltage I use (in the permissible range of 10 to 27V). 

Note that I sit with each ear at about 20-inches from its respective speaker, so I get plenty of SPL with the MG3 coasting along at a volume setting of about 7:30 or 8 o'clock, at most.  I mean it's plenty loud at 8 o'clock - that's tops.

Of #'s 2, 3, and 4, I prefer the six-cell 25.2V LiPo pack, because the MG3 offers more headroom (and all that comes with it) at 24V (or thereabout).  Dynamics are spectacular with 24V power (translating to 32W into 8-Ohm), as is bass control and, I don't think I'm imagining this, but mids and treble seem to be a little better defined, too.

#6 and #7 fail to excite me, simply because they start at 12V and decay from there with use - I found the sound to be lackluster at 12V.  Perhaps if I had more efficient speakers or headphones - I'm still waiting for Jan Plummer to finish an impedance match he's building for my 50-Ohm Audeze LCD-2 - which suffer a lot of hiss during playback if I connect them directly to the MG3's binding posts.

My Audeze LCD-2 are gathering dust at the moment. 

#5 is a solution that I feel most comfortable recommending to anyone who wants a lot more convenience than fussing with the RC-style LiPo packs and balance chargers.  I'm not an RC enthusiast - I've never worked with these batteries for any purpose other than audio applications, beginning with the Meier Audio Corda Stepdance portable, single-ended headphone amp, and later, the iBasso PB2 Pelican, balanced headphone amp, in each case enjoying greater power output to the headphones by driving the amp at higher voltages than is possible using its internal battery.

Even though I've become familiar with using the Thunder AC6 charger with RC-style LiPo batteries, learning how to do it correctly and safely is a discipline I wouldn't expect everyone to readily embrace.  It's a pain in the rear, to be honest, but I've grown to enjoy the ritual of it - like grinding coffee beans right before french pressing, and then having to clean the press afterwards  - the music just "tastes better" when more work is involved - a labor of love.   

#5, the Energizer XP8000 Li-Ion battery is very nicely "consumerized" - automating the whole process of charging (and avoiding excessive discharge) while also providing taps for for multiple voltages, including a 5V USB port. 

For the MG3, there's a problem with the Energizer XP8000, however - potentially insufficient amperage.

Note the specs for current version of the XP8000, known as the Energizer XP8000A:



http://www.energizerpowerpacks.com/products/xp8000a/

Rated Output Current at 19V is only 2000mA  (vs. the 4000 mAh the MG3 can pull to blow a fuse with supply voltage exceeding 27.5 Amps - per Jan Plummer.)

Now, at the SPL I desire with my 90 dB 8-Ohm speakers only 20 inches from my ears, I doubt the MG3 is pulling even 500 mA continuous, and I can say that my XP8000 sounds absolutely fine with the MG3.  I can't really say I can hear a difference in dynamics or any other sonic trait vs. running the 25.2V 6-cell LiPo pack or the 24V PSU.   There's surely a reduction in Watts rms with only 19V supplied by the XP8000 vs. 24 or more, but again, I can't hear so subtle a difference, where I can when taking the voltage all the way down to 12V with internal AA batteries or with the 3-Cell LiPo pack (where the Watts rms falls to 10Wpc).

So here comes my recommendation, which is at best a hunch, given that I haven't tested it...  Check out the specs of the larger Energizer XP18000A (available in black or white versions):



http://www.energizerpowerpacks.com/products/xp18000a/

Rated Output Current at 19V is 3500 mA - Now we're talking!   That's a much better match to the 3.7A capacity of the 24V PSU.



I think this would make an ideal solution for anyone who wants a "transportable" MG3, or even for those who just want truly clean desktop power.  It's way more convenient than the RC LiPo packs I'm using, but with an 18,000 mAh capacity, this thing is relatively large (7.1 x 4.3 x 0.8 inches) and heavy (18.2 ounces).  Then again, this means it will hold a high voltage all the longer with the greater capacity.  (I would charge it every night, just the same, instead of deep-cycling it.)

http://www.amazon.com/Energizer-XP18000AB-Universal-External-Smartphones/dp/B00CFHBV5E

http://www.xpalpower.us/2012/manuals/xp18000a.pdf

By the way, I'll add that when I've tried to charge my XP8000 while using it to power my headphone amps, I can hear a faint buzzing if using sensitive IEMs (instead of fullsize headphones) - I've not tried doing that with the MG3, but why bother?

Here's a YouTube video on the XP18000A:  http://youtu.be/UjFLXhLlhyI

At 36-seconds into the video you will briefly see a cable with blue tips at both ends - this is all you'll need to connect the XP18000A or (XP8000A) to an MG3's power jack.

Who wants to take the plunge and let us know how it sounds on an MG3?  

Meanwhile, I'm all set with my 6-cell LiPo pack, for desktop and "transportable" use:



Mike

[wushuliu]

Thanks, all good recommendations. I believe I mentioned the Energizer early in the thread and it bears mentioning again as an ezpz solution.

[zilch0md]

The Energizer XP18000 is definitely a no-thinking-required way to operate, and there's something else that I should have mentioned above...

It's intrinsically safer than using a battery pack that's capable of supplying 90 Amps continuous!   

Jan Plummer says if anything shorts inside the MG3, the 4A fuse will blow, but I'm still a little nervous hooking up so powerful a battery.  I can imagine arcs jumping across traces on a PCB, but I just have to remind myself that a battery can't force a load to accept more amps than its pulling.   I've been using these high-current LiPo's with audio gear for over two years, with no problems thus far, but the lower rating of the XP8000/XP18000 just seems like the better way to go, not to mention the aforementioned convenience factor.

Mike

[rodge827]

Mike,
Thanks for answering my question.
I see you have put a lot of thought into using LiPo packs and sharing your experience is most appreciated. 
There are many on this thread who may take you up on your suggestions.

Would this battery unit be OK or is the amp level, 3a @ 19v, to low?

http://www.amazon.com/Anker-Ultra-High-Multi-Voltage-Notebooks-Compatible/dp/B00B45EOYS/ref=pd_sim_e_1

or this one?

http://www.amazon.com/Capacity-33600mAh-Portable-External-Notebooks/dp/B0063KXZQ2/ref=pd_sim_sbs_pc_3

Chris

[zilch0md]

Before ordering the Energizer XP18000A for the MG3, another option to consider is the less expensive Anker Astro Pro 2, as discussed in the three posts beginning here, at Head-Fi:

http://www.head-fi.org/t/649107/speaker-amps-for-headphones/915#post_9764910

Mike