crymsonsunset
New Head-Fier
- Joined
- Jun 6, 2002
- Posts
- 17
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A few weeks ago I posted an article detailing my impressions of the Headroom Airhead 4.5V portable headphone amp.
Overall, my negative review was not popular, but it was honest and my opinions about the AH have not changed from the original post.
I returned the amp to Headroom and after doing some searching and reading on this and the HeadWize forums, decided to commission JMT to build me a CHA-47 in a wintergreen Altoid tin with the following upgrades to his standard configuration:
Despite my dissapointment with the AH, I was optimistic. JMT was highly spoken of and highly recommended. After communicating with him through e-mail, it was clear to me that he understood what I was looking for, and he was willing to accomodate and explain the pros and cons of the customizations I inquired about.
After receiving the amp, I connected it to my PCDP's line-out (*NOT* headphone jack), plugged in my Koss KSC-35s and again selected Dream Theater's Six Degrees of Inner Turbulence Disc 2 for testing.
Immediately, I was impressed by the smooth, extended response. Every aspect of the music was represented with crystal clarity - from the lowest bass notes and kick drum beats to the highest cymbal crashes and synthesizer effects.
The sound stayed smooth as I turned up the volume. With a single 9V NiMH battery, the amp pushed my headphones to their physical limits of operation, and introduced no distortion. Loud volume was one of my goals in putting together a portable rig, and I got far more than I ever expected out of JMT's little amp. Unbelievable.
Now, I want to address a common misconception that some posters seemed to promote in my previous thread about the Headroom AH. I mentioned at the outset that I was looking for high volume. Not at the sacrifice of SQ, that was the number one priority. But overall volume was and still is important to me. I said that my benchmark for volume (and minimum benchmark for SQ) was the headphone output of my Yamaha RX-995 A/V receiver.
Because I made that comment, it seemed like a lot of people got on my case about hearing loss. Some even seemed to be suggesting that my hearing may have already been damaged, and that I therefore wouldn't be able to distinguish good sound. (If I've misinterpreted what someone intended, I apologize in advance). That's hogwash. I never stated that I intended to listen to the amp at excessive volume levels frequently or for hours and hours at a time. I do however, like loud music, and wanted an amp that had that ability when I really wanted it.
Back on track. The JMT CHA-47, in stark contrast to the Headroom AH, easily meets or exceeds the aforementioned A/V receiver in terms of SQ. It also has more volume potential than even I was looking for, not that this is a bad thing.
Most of the time, I listen to the amp at moderate levels at work, and I've spent a few weeks now enjoying it while being simultaneously amazed by it.
There is tremendous musical clarity, with excellent separation of instruments. Dynamics are good. The amp seems to faithfully reproduce the mix, never flattening it out but never exaggerating it either.
Another point that I was impressed by was the amp's silent operation. There is no audible hiss and no noise when operating the volume control.
The amp's construction is meticulous and solid. It goes without saying that portability is excellent. Incidentally, I took a trip recently and was curious to see, as some had joked or suggested, whether or not the amp would raise eyebrows at airport security. It did not. At one point, I was singled out for a random security check/bag search at the terminal gate. I thought for sure they would at least ask what the deal with all the electronic parts and wires inside the Altoid tin was. But they didn't.
All things considered, the JMT CHA-47 is a tremendous value. I was asked to keep costs confidential, and I intend to fully respect that wish. I will say, however, that the contribution JMT asks for is unbelievably reasonable. It is easily worth double the cost of the standard Headroom AH as it outperforms the AH hands down in every way.
To anyone considering the purchase of a portable headphone amp, you simply cannot go wrong with JMT CHA-47!
Overall, my negative review was not popular, but it was honest and my opinions about the AH have not changed from the original post.
I returned the amp to Headroom and after doing some searching and reading on this and the HeadWize forums, decided to commission JMT to build me a CHA-47 in a wintergreen Altoid tin with the following upgrades to his standard configuration:
- 470µF/16v PS caps
- Vishay/Dale resistors
Despite my dissapointment with the AH, I was optimistic. JMT was highly spoken of and highly recommended. After communicating with him through e-mail, it was clear to me that he understood what I was looking for, and he was willing to accomodate and explain the pros and cons of the customizations I inquired about.
After receiving the amp, I connected it to my PCDP's line-out (*NOT* headphone jack), plugged in my Koss KSC-35s and again selected Dream Theater's Six Degrees of Inner Turbulence Disc 2 for testing.
Immediately, I was impressed by the smooth, extended response. Every aspect of the music was represented with crystal clarity - from the lowest bass notes and kick drum beats to the highest cymbal crashes and synthesizer effects.
The sound stayed smooth as I turned up the volume. With a single 9V NiMH battery, the amp pushed my headphones to their physical limits of operation, and introduced no distortion. Loud volume was one of my goals in putting together a portable rig, and I got far more than I ever expected out of JMT's little amp. Unbelievable.
Now, I want to address a common misconception that some posters seemed to promote in my previous thread about the Headroom AH. I mentioned at the outset that I was looking for high volume. Not at the sacrifice of SQ, that was the number one priority. But overall volume was and still is important to me. I said that my benchmark for volume (and minimum benchmark for SQ) was the headphone output of my Yamaha RX-995 A/V receiver.
Because I made that comment, it seemed like a lot of people got on my case about hearing loss. Some even seemed to be suggesting that my hearing may have already been damaged, and that I therefore wouldn't be able to distinguish good sound. (If I've misinterpreted what someone intended, I apologize in advance). That's hogwash. I never stated that I intended to listen to the amp at excessive volume levels frequently or for hours and hours at a time. I do however, like loud music, and wanted an amp that had that ability when I really wanted it.
Back on track. The JMT CHA-47, in stark contrast to the Headroom AH, easily meets or exceeds the aforementioned A/V receiver in terms of SQ. It also has more volume potential than even I was looking for, not that this is a bad thing.
Most of the time, I listen to the amp at moderate levels at work, and I've spent a few weeks now enjoying it while being simultaneously amazed by it.
There is tremendous musical clarity, with excellent separation of instruments. Dynamics are good. The amp seems to faithfully reproduce the mix, never flattening it out but never exaggerating it either.
Another point that I was impressed by was the amp's silent operation. There is no audible hiss and no noise when operating the volume control.
The amp's construction is meticulous and solid. It goes without saying that portability is excellent. Incidentally, I took a trip recently and was curious to see, as some had joked or suggested, whether or not the amp would raise eyebrows at airport security. It did not. At one point, I was singled out for a random security check/bag search at the terminal gate. I thought for sure they would at least ask what the deal with all the electronic parts and wires inside the Altoid tin was. But they didn't.
All things considered, the JMT CHA-47 is a tremendous value. I was asked to keep costs confidential, and I intend to fully respect that wish. I will say, however, that the contribution JMT asks for is unbelievably reasonable. It is easily worth double the cost of the standard Headroom AH as it outperforms the AH hands down in every way.
To anyone considering the purchase of a portable headphone amp, you simply cannot go wrong with JMT CHA-47!