Interview with ALO and GR9 about the ALO Rx, music and everything


Recently, TouchMyApps had the good fortune to review the excellent ALO Rx portable headphone amp. As you can read in my review, the amp is a driving champion, supplying power and flat frequency response for a very wide variety of headphones. The Rx isn’t only your “prescription for sound”, it is also a partner product from the newly formed team, ALO and GR9. Both Ken Ball (ALO) and Matt MacBeth (GR9) have had years in their respective industries, and if I may be so bold, left indelible marks on each. Naturally, I was intrigued about their philosophies, goals, and good ol’ fashioned teamwork. By the way, Matt’s often detailed answers are a great reference for what is possible via the iPhone. Yes, his answers were typed 100% on a virtual keyboard.

For reference, please take a look at TMA’s ALO Rx review and follow any links in the text.

Questions and comments from me will be bolded; Matt will have a nice ‘M’ in front of his name, whist Ken will be fixed with a ‘K’ in front of his.

1. Gentlemen, both of you are benchmark players in the audio world, having founded or worked in amazing, pivotal companies; how is it that you decided to hook up? Whose idea was it and how has the partnership worked out?

M: We actually met waiting for a shuttle bus at LAX on the way to CANJAM ’08.  This was my first “headphone” show & I didn’t know anyone in this industry, or many of the products.  We started chatting & I found out he was the guy who makes the really nice iPod line out cables.  So during the show, we continued to chat & we began discussing my iPod transport project & I also showed him some of my other projects, like the ultra high-end iPod speaker dock.

We eventually got around to discussing the possibility of working together on a portable amp for the ALO brand.  We’re both very easy going & figured that we should give it a shot, so we began to make a headphone amp.

K: This is my favorite story.

Ok I have a table at the international Head-fi shows every year. I get off the plane at LAX and get on the shuttle going to the hotel. On my hand carry I have a ALO cable sticker and this guy sitting right next to me asks me “hey are you going to the headphone show?” I said yes and he asks what I do, I say that I own a cable making company, with my main cable is a ipod dock connector cable. What do you do I ask he (Matt) 😉 says Oh i have a device that takes the digital off an ipod! the rest is history I was bugging Matt the whole weekend.

2. Describe how you work together. Who is the bigger visionary? Who is the bigger blood-and-guts designer?

M: For this project, I’d say Ken is the marketing visionary & I’m the engineering visionary.  We took a look at the competitive landscape, and found a void that together we could fill.  Ken knew what this amp should be & I knew how to get us there.

K: Matt is the man with the digi chopps, I just told him what it should look like and add some hints on what it sounds like. I am just a cable maker with some business points. For the Rx it was all Matt. I was responsible for (asking for) the double Li-Ion battery, listening and making some suggestions. Headphone amps are ALL about the battery.

3. How are your audio philosophies entwined? How much compromising have you had to do to combine both of your goals/visions/dreams?

M: Our personalities combine very well, and we both have a passion for providing the utmost in audio quality and product support – I don’t think this project could have gone any better.  Because of our instant synergy, I don’t feel that I had to compromise anything to realise Ken’s vision for this amp.  The ALO Rx amp is the perfect combination of size (just right for iPod Classic, Touch, and iPhone), power (drives anything from a 4-ohm subwoofer to 600 ohm cans), battery life (I typically get over 30 hours per charge), control (likely the first portable amp on the market with an analog stepped attenuator audio chip), and reliability (the Rx has a real battery conditioning/charge supervisory circuit for the lithium-ion batteries to ensure the batteries are always safe and “well fed”).

K: It was pretty easy for the Rx we wanted something to pair up well for the iPhone it was really pretty easy Matt know exactly what I was after. I think we both have the same goals of course there are business parts that make some things we want to do no possible but we both really look forward to coming up with new things to bring to the market.

4. How did you decide on the name Rx for the amp and audio accessory brand?

M: This one’s all Ken… I still think it’s pretty cool; especially the “prescribed by ALO” on the back panel.

K: That was my gimmick 😉 I really see being “a portable audiophile” much like an addiction, a real one. The amp I wanted Matt to develop was to be like a drug, to ease the addiction.. hence the Rx. I think its a potent prescription that we are both super proud of.

5. What is the one internal component or technology which you are most proud of?

M: This one’s a toss-up of the volume controller & the battery chip.

I first used this volume control chip back around 1999; it’s a real dual stepped attenuator that’s designed specifically for audio.  There are many other stepped attenuator chips available, but they’re designed for microprocessor interfacing of signals and sensors, not audio fidelity.  This chip gives the tracking performance of a digital chip, and the audio quality of discrete thin-film resistors.  The ALO Rx amp is the only portable headphone amp to use this volume controller.

As far as the other technology, The Rx is actually the very first product on the market to use this lithium-ion battery charge/supervisor circuit.  This circuit constantly monitors voltage/current/and temperature of the battery circuit, and determines the best combination of current and voltage necessary to charge the battery.  If the battery is mostly full, the circuit does not allow the battery to charge, until the battery level gets lower; this greatly extends the life of the battery.  Lithium-ion batteries are very powerful and require careful attention to the voltage & current from the load AND the charger.  If the battery level gets too low in this circuit, the battery will automatically disconnect from the circuit to prevent damage to the battery AND the rest of the amp.  Plugging the charger into the amp will engage the charging/supervisory circuit and safely bring the battery back up to full charge.

K: Thats Matts baby

6: I hate blood and guts, but I reckon that TMA readers aren’t. Any tidbits about the guts you might share with us?

M: I’m a minimalist in all aspects of audio design, and many of my designs defy “conventional wisdom” in the world of very high-end audio.  But in the world of extremely high-resolution medical video devices and unlimited budgets, my designs make perfect sense.  Basically I’ve experienced electronic design philosophies ranging from medical imaging to PC microprocessors & motherboards to the tweakiest of audiophile products.  I pick what sounds the best, no matter where or when it was conceived.

Specifically for the Rx it’s a basic op-amp circuit that’s very similar to a high-res video circuit.  Nothing fancy, just the right combination of a chip and thin-film resistors.  The schematic and parts list is actually very boring, but We don’t listen to schematics or bill-of-materials, do we?

K: Matt

7. In designing the Rx (apart from sound quality), what was the crux of your design plan? Did it work? Do you think anyone else could have done it? If not, tell me why GR9 and ALO have been able to achieve the impossible.

M: The non-audio design goals were to mimic the size & shape of the most popular iPods and use a good/reliable rechargable power supply.  We accomplished these goals without compromise in any way.

Could any else have done this?  Sure, but the early development of the Rx used pre-production silicon, so they would have had to wait a bit.  We’re not rocket scientists, but we’re quite good at what we do – but more importantly – we work very well together and have common interests and goals.  This amp is the result of unselfish teamwork.

K: Again for me its all about the power supply, Matt nailed it.

8. What sort of headphones did you design the ALO to drive? And, what headphones personally do you listen to when you are not ‘critically listening’ to new gear or competitor’s stuff? What portable audio equipment do you carry around?

M: for big cans, I use Sennheiser HD650’s and some other stuff I have in the works; for single-armature IEMs, I use Klipsch Image X5’s (one of my projects when I was at Klipsch, so I’m extremely familiar with them); for complex load IEMs I’m switching over to JH13Pro’s (after hearing them with the Rx amp at RMAF).  For battery/power supply/output stage testing I use a pair of big ‘ol 12″ 4 ohm subwoofers; I figure if the Rx can push two 12’s, it can handle any headphone.

I use just about everything as a test source, from 24/96 wav to YouTube clips.  I design with test tones, but tweak with music; final tweak is always with TV news – the best source of various vocal sounds anywhere (if a system can measure well, sound good with music, AND sound natural/neutral with voices; you really have something good!)  For fun/exercise, I typically listen to Pandora and concert clips on YouTube via iPhone with IEMs.

My iPhone is the centre of my portable audio world, and is always within reach – I’m still amazed that I’m almost never more that 30 seconds away from any song that I want to hear!

K: When I was listening to the prototypes I was using a pair of Ultrasone Edition 9s and a modified Grado GS1000.

RE: And, what headphones personally do you listen to when you are not ‘critically testing or listening’ to new gear or competitor’s stuff?

Currently HD800s with the ALO aftermarket HD800 cable.

RE: What portable audio do you carry around?

iPhone and 3 Nanos, one loaded with hip hop/ downbeat , one with classical and the other rock

9. Ken, you’ve been involved in creating some of the nicest looking, phattest line out iPod cables since… well since a long time. What do you think of the iPod/iPhone/iPod touch as an audio source?

K: I guess its about the music really, and how it aids and or effects the users life. I mean sure the iPod is not some super uber high end audio device like a $50,000 CD play can be. Its about the availability and usage and how that effect work on us. The ipod is in many respects a gigantic audio mile stone, and amazing audio enabler. Even the more snobby home audio audiophile can not discount the iPod. So yeah as a music source its amazing, and soon to me even more amazing with new technologies and larger flash drives.

10. What other plans do you have to revolutionise the market? Anything that you can ‘leak’ here or do you need to take a few minutes, send over a beat team who will sew my lips together and my fingers into my ribs?

M: The only comments I can make are that the Rx is just the beginning of the “revolution” and the iPhone will soon be the standard-bearer for portable audio fidelity.

Here’s my visionary statement: It is quite possible by this time next year for small portable audio products to meet or exceed the performance of the most esoteric high-end home audio products, forcing the home audio guys to start playing catch-up with the portable guys!

K: I’m mum…

11. Gentlemen, what would you as designers say to the portable audio community in general in closing? Any non-partisan hints to help them enjoy our music better?

M: It all boils down to enjoying the music; I’d rather watch/listen to an awesome concert on my iPhone via YouTube than listen to a perfect reproduction of something that does not interest me.

K: For me its an exciting time to be a portable audio enthusiasts, I think there are a lot of very interesting developments by larger audio companies jumping into the “high end” portable, headphone and earphone market and we will all enjoy this!

Thank you gentlemen. If you have anything you would like to add, I will be happy to put it together. Also, if you have photos (nice mug shots) for instance, please attach them.


Ken Ball has recently opened up a new brick and mortar audio shop: 32 OHM Audio which complements his web store: ALO Audio.

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