AKG K702 + Phil Jones HA-2 = Overpriced Garbage

MrUsefulAlien

MrUsefulAlien

Jun 10, 2011
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www.rotherbassworks.com
#1
I set out to replace my aging Vox Amplug Bass and found what I thought were second hand gems in the portable practice rig market.
- Phil Jones HA-2 Bighead Pro - €170 shipped
- AKG K702 (62ohm) - €60 shipped

My verdict is that this combo is severely underwhelming.
The AKG have less punch than the Sennheiser HD280 pro they replaced, although what they lack in bass presence is made up for in a natural and wide sound (vs. the boxy Sennheisers.)
The PBJ headphone amp is less loud and does an outright poor job of amplifying a bass. The literal example of "you only had one job", I needed full Vol and full Gain plus 75% and 75% treble to get a decent sound that keeps up with a backing track (Indie pop, rock, prog rock, disco songs). It struggles, and does so at a high price tag.

I teste the setup with a variety of basses: MIM P with G&L MFD, US Std. P, Lakland 55AJ, and Lakland DJ4.

What I would have liked to have, is similar volume and presence as the Rolls PM351 in a wall-wart-free package, but I have been undone by my ignorance of reading spec sheets and maybe having unrealistic expectations.

I have read that the HA-1 had issues driving headphones, and I get the sense the Ha-2 suffers the same shortcomings. After much research I landed on the AKG K702, but a tiny bit more research illumined their 'current hungry nature' and a need to have an amp despite the low Ohmage.

Needless to say I am frustrated, as I have a big production to prepare for and this duo is an expensive lateral step to my previous setup, plus the time waste of research + buying is an exacerbating fact.

Have others had similar issues? Can this be solved with another pair of 'cans'?
I need to have the ability to practice away from a power source, so anything wired will not work.

PXL_20230222_210848175.jpg
 
#2
I previously had the PJB HA-1 Bighead and currently have the PJB HA-2 Bighead Pro. I think it's a fantastic headphone amp and preamp, very clean. I've only used it with Sony MDR-7506 headphones and get plenty of volume for me although I've never used it with the aux so I can't provide any feedback for that use. I haven't used it in a while so I just tried it with several basses and guitars to try to provide proper feedback here.

Volume and Gain all the way up, Bass and Treble controls flat: With my Fender AVRI and CS passive P and J basses, the volume is fine, not thundering, but I really wouldn't want it louder. With my active Rob Allen and Rick Turner basses, and Godin Multiac guitars, I had to turn the volume down on the instruments quite a bit because it got so loud.

I've not tried your AKG headphones, but I've tried other headphones in the past, (including Sennheiser and Velodyne). I like the Sony 7506 best for bass and guitar practice. But I don't think this helps you much because I can't compare the volume difference between the AKGs and Sonys. Let me know if you have any questions I can try to help with.
 
#3
Thanks for the response, I called Phil Jones and I've posted on Head-Fi to get an idea of what the situation is.

For whomever needs to read this, here is some helpful info:
The guys at Phil Jones told me that despite the stated resistance ratings (16-64ohm) the HA-2 is designed for 32-38ohm; 32, 64, 80, 250, 600 are the usual resistance options.
The 300mW ratings are nonsense, and the guy I talked to on the phone couldn't tell me at which resistance that is and actual RMS numbers.

The guys at the Head-Fi forum cautioned that even if my 64ohm AKG and Sennheiser were the correct ohmage, they would still be underpowered due to their low sensitivity, AKG is rated about 96dB/1mW.
It is fairly disappointing that at that price point there wouldn't be an amp section for the headphones. It's just a normal port needing low resistance, whereas an amp driving at least 64 or 80ohm would expand our options to open eared headphones in the 64, 80 and maybe even 250ohm range.

Long story short, if you want to get good volume out of the HA-2, get headphones meant for laptops/smart phone/mp3 players, rated 32ohm and more than 103dB sensitivity.
I myself will get the AKG K371, rated at a highly sensitive 114dB/1mW and 32ohm.
 
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#5
Something's wrong here, but I don't know what. The Bighead should have more than enough volume on tap. If I cranked mine up all the way, I think my ears would explode. For me, it's been a great practice tool and done everything I wanted it to do. My only criticism is that it's so clean to the point of feeling sterile. I guess I like a more colored sound, but I can always put a pedal in front of it. In my experience, it nails it as an ultra clean headphone amp with plenty of headroom.
 
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#6
MrUsefulAlien said:
Thanks for the response, I called Phil Jones and I've posted on Head-Fi to get an idea of what the situation is.

For whomever needs to read this, here is some helpful info:
The guys at Phil Jones told me that despite the stated resistance ratings (16-64ohm) the HA-2 is designed for 32-38ohm; 32, 64, 80, 250, 600 are the usual resistance options.
The 300mW ratings are nonsense, and the guy I talked to on the phone couldn't tell me at which resistance that is and actual RMS numbers.

The guys at the Head-Fi forum cautioned that even if my 64ohm AKG and Sennheiser were the correct ohmage, they would still be underpowered due to their low sensitivity, AKG is rated about 96dB/1mW.
It is fairly disappointing that at that price point there wouldn't be an amp section for the headphones. It's just a normal port needing low resistance, whereas an amp driving at least 64 or 80ohm would expand our options to open eared headphones in the 64, 80 and maybe even 250ohm range.

Long story short, if you want to get good volume out of the HA-2, get headphones meant for laptops/smart phone/mp3 players, rated 32ohm and more than 103dB sensitivity.
I myself will get the AKG K371, rated at a highly sensitive 114dB/1mW and 32ohm.
Click to expand...

Have you tried a different set of headphones with your PJB amp, or tried your AKGs with a different amplifier?

You might be able to use the process of elimination to figure out which component is causing which problems.

Good luck! :)
 
#7
Kenan said:
Something's wrong here, but I don't know what. The Bighead should have more than enough volume on tap. If I cranked mine up all the way, I think my ears would explode. For me, it's been a great practice tool and done everything I wanted it to do. My only criticism is that it's so clean to the point of feeling sterile. I guess I like a more colored sound, but I can always put a pedal in front of it. In my experience, it nails it as an ultra clean headphone amp with plenty of headroom.
Click to expand...

I've read rave reviews on TB lauding the excellence of the headphone signal provided by Mesa's amplifiers.
 
#8
Kenan said:
Something's wrong here, but I don't know what. The Bighead should have more than enough volume on tap. If I cranked mine up all the way, I think my ears would explode. For me, it's been a great practice tool and done everything I wanted it to do. My only criticism is that it's so clean to the point of feeling sterile. I guess I like a more colored sound, but I can always put a pedal in front of it. In my experience, it nails it as an ultra clean headphone amp with plenty of headroom.
Click to expand...
It works fine with earbuds and IEM, but it cannot power headphones with higher ohms and for sure not ones with low sensitivity. The Sennheiser somehow still work, but the bass is not present unless I boost via the EQ, but then I lose mids.
The sad part, the truly sad part, is that my junk Vox Amplug has enough current for the bigger headphones. It's just that it sounds horrible. I cannot understand why we wouldn't have more headroom on the PJ. It's the only thing that matters, to hear the bass. Super frustrating.
 
#9
Jazzdogg said:
Have you tried a different set of headphones with your PJB amp, or tried your AKGs with a different amplifier?

You might be able to use the process of elimination to figure out which component is causing which problems.

Good luck! :)
Click to expand...
Yes, Sennheiser HD280 Pro, 64ohm. Same issue.
No issue with the amplug.
RHA earbuds, KZ pro, and UM custom shells. Their sensitivity is super high, so they worked.
I do not want to practice for 3-4hrs with earbuds though.
I've tested the AKG with my laptop and the Amplug, they work fine. They are, however, considered power hungry and it's recommended to use a headphone amp with them for use with mp3 players or phones. I found that out after the fact. I also found out after the fact that the HA-2 has slightly misrepresented power and resistance figures.
 
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#11
Jazzdogg said:
I've read rave reviews on TB lauding the excellence of the headphone signal provided by Mesa's amplifiers.
Click to expand...

Yes, I can confirm. I have a D800 that works great with headphones. It also has an aux in which can be used to pipe in other audio. The only advantage the Bighead really has is the ultra portable size and battery power (one less cord to worry about). The Mesa has a more colored sound of course, which is either a plus or a minus depending on what you're looking for.
 
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#12
MrUsefulAlien said:
I'll update once I get the K371.
Your Sony headphones have the right sensitivity, but the fact that you need to max the gain and volume suggests we're kinda in the same boat.
Click to expand...

As I stated in my post, the volume is fine on the Bighead Pro with the bass and treble flat and the volume and gain at max...I wouldn't want it any louder at all (and I like it loud). I had to turn down the volume considerably on the other basses and the Godin guitars with the same setup. We're not in the same boat as you state. The sensitivity of the headphones we are using is completely different. I'm trying to be helpful here but it seems that you are frustrated with your experience, which I understand, but you are trashing a product that works really well in the right configuration. Additionally, I had the Amplug many years ago and, although it fits its purpose at that price point, it doesn't even come close to the quality of the PJB Bighead products so I don't really understand the comparison here.
 
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#14
porterbass said:
As I stated in my post, the volume is fine on the Bighead Pro with the bass and treble flat and the volume and gain at max...I wouldn't want it any louder at all (and I like it loud). I had to turn down the volume considerably on the other basses and the Godin guitars with the same setup. We're not in the same boat as you state. The sensitivity of the headphones we are using is completely different. I'm trying to be helpful here but it seems that you are frustrated with your experience, which I understand, but you are trashing a product that works really well in the right configuration. Additionally, I had the Amplug many years ago and, although it fits its purpose at that price point, it doesn't even come close to the quality of the PJB Bighead products so I don't really understand the comparison here.
Click to expand...
If you have to max out the volume and gain then we are not in that different a situation, @Kenan mentions how if he turned up it would be too loud.
Don't try to gaslight and make it seem I'm a frustrated loon, the HA-2 has a design flaw if it cannot drive something more than the most sensitive of consumer headphones.
As you're struggling to piece things together here let me help you with the Amplug comp, the Amplug doesn't display the same volume issues. Of course the HA-2 is in a different galaxy quality wise, it just lacks the volume capabilities you'd expect at that price point. Specifically, it should be delivering more than 300mW at unspecified resistance, also maybe not state a range of 16-64ohm, when it's squarely meant for 32.
 
#15
ddnidd1 said:
AKG K701's and K702's are the same headphones (other than the chords and the colors). Neither one is a great choice for bass guitar. There just isn't much low-end at all. Just too thin sounding for enjoyable bass.
Click to expand...
There is some nice low end extension, but yes, they turned out to be anemic. I didn't do a good enough job finding the right set of cans. I should've looked at the specs and read a bit more, here on TB some members were effusive about them.
I think the K371 will work much better.
Still, the issue is that the bass itself maxed out pretty quickly, the mp3 source was amplifying just fine and was in fact too loud at 80%. The bass guitar, not so much.
 
#17
I think I spot the issue here...

MrUsefulAlien said:
There is some nice low end extension, but yes, they turned out to be anemic. I didn't do a good enough job finding the right set of cans. I should've looked at the specs and read a bit more, here on TB some members were effusive about them.
I think the K371 will work much better.
Still, the issue is that the bass itself maxed out pretty quickly, the mp3 source was amplifying just fine and was in fact too loud at 80%. The bass guitar, not so much.
Click to expand...


Don't lump me into your bashing a product to justify your position. As I've now stated twice, the Bighead Pro works great for me as it does for many others.
 
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#20
If it's any help, the headphones that I'm using with the Bighead are Sony MDR-V700. They're nothing special, but have been getting it done for me for about 20 years now. I'm sure many others will work great as well.
 
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