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Cheap portable headphone amp that is NOT noisy?

post #1 of 26
12/8/03 at 12:58am
Thread Starter 
Back when I was using personal tape players the volume was more
than adequate to drive a mid-market pair of headphones, like the
Sennheiser 457's. But now I'm using tapes less and less (arent we all)
and I find my MD portable
(Sony MD-MZN505) to be lacking in volume. If I crank the vol past 28
there starts to be distortion. I think the amps in most personal
portables are at only 5mw to save on battery power, but audio quality
suffers.
I have both the Koss EQ 30 AND 50. For those that never heard of them
they take 2 AAA batteries are are about half the size of a cassette
tape. The battery life is excellent (usally well over 50 hours).The
older model, the 30, has better controls but both seem to be kind of
noisy. It seems they pick up high frequency noise from TV stations,
power lines, and cell phones very easily.
Poor sheilding I guess. Anyway I'm wondering if the Radio Shack 3-way
volume booster (cat 33-1109) is any better than the Koss EQ's.
It would be nice to get a nice portable amp without hearing the loud
splatter from cell phones (which are just about everywhere now) and
the hash and beeps from power lines.
I dont think power lines are even supposed to emit high frequency
noise but they do. I dunno if its from utility equipment or not.
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post #2 of 26
12/8/03 at 1:02am
please do not buy radio shack's volume booster, that thing is awful, just like all cheap volume boosters (aka, "amp").
spend about $25+ and build yourself a cMoy, cheap, quality, good sounding amp that will blow any volume booster away in term of sound quality

welcome to head-fi my friend
http://www.tangentsoft.net/audio/cmoy-tutorial/
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post #3 of 26
12/8/03 at 1:52am
Thread Starter 
Quote:
Originally posted by ProFingerSk8er
please do not buy radio shack's volume booster, that thing is awful, just like all cheap volume boosters (aka, "amp").
spend about $25+ and build yourself a cMoy, cheap, quality, good sounding amp that will blow any volume booster away in term of sound quality

welcome to head-fi my friend
http://www.tangentsoft.net/audio/cmoy-tutorial/
Problem is I dont have all that equipment neccesary to build a project like that. It also sounds quite time consuming.
Isn't there any way I can just modify my existing amps so that the noise is screened out?
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post #4 of 26
12/8/03 at 5:23am
I can understand you not wanting to spend the time to build an amp and not wanting to spend a fortune to buy one.

The Radio shack model you mentioned is also known as the boostaroo and they've come out with a new model that is supposed to have less hiss. I owned the original model and for $20.00 it did the job and allowed two headphones to plug into it at the same time. There is hiss which was only really obvious when the music was either off or low volume tracks. Okay, it is a bit of a joke when you compare it to any half way decent amp out there, but if all you are looking for is something that gives you a 20% or 30% boost in volume or two headphones into one unit then $20.00 isn't too unreasonable.

The price is up to $30.00 for the new one, but there is no way I'm going to be the guinea pig to find out if it's improved any by buying it. I'd still like to know if it's a step up from the original though.

www.boostaroo.com
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post #5 of 26
12/8/03 at 5:47am
Having used the Koss EQ50, and found the hiss to be unbearable, I recently bought a Boosteroo from Sound Professionals, and found it to be not bad at all, in fact rather good. There's no perceptible hiss, and it sounds clear and loud enough with my Sony MDs (5mW x 2) and also my 0.5mW x 2 D-EJ2000!. It only lacks a volume control, so no line out usage, but for $24 I'd say it's worth it. I'll buy/make a better amp later on, but for now it's fine.
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post #6 of 26
12/8/03 at 6:46am
I'm sure you could find someone out there willing to quickly whip up a cmoy amp for you for less than 30 bucks..

Try the DIY forum?
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post #7 of 26
12/8/03 at 9:45am
Anyone in the UK want to do one for me...?
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post #8 of 26
12/8/03 at 4:47pm
Might I suggest the regular Airhead (not the 2003 version) which is under $100 and quiet, even when driving really hard to drive cans such as the HD600. If you are using the old airhead (3 AAAs) with a pair of really bright phones and you listen very loud you will hear noise.

Also consider the 2003 airhead, that thing was dead silent for me out of an iriver 400 powering PX100s at ridiculously high volumes. Thats about $150 or so.

Both amps have an excellent crossfeed processor which greatly improves the sound. Once you have heard that, you'll never go back to non-crossfeed headphone listening.

Cheers,
Geek
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post #9 of 26
12/8/03 at 4:51pm
I would have to disagree about the crossfeed... it is a very subtle effect..

I doubt you would be able to A-B the difference on normal tracks.. it just reduces fatigue made from long listening sessions.

Anyhow.. if you do a search on the amps forum, you'll see the many DIY amps heavily favoured over the Airhead.. at any price point.
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post #10 of 26
12/9/03 at 2:44am
Thread Starter 

Boostaroo

Hmm, the Boostaroo sounds like an option. But I want to make sure the thing wont pick up interference from power lines and cellphones (which are all over the place here on suburban Long Island).
I'd also be more likely to get the "generic" at Radio Shack, as long as its not inferior in quality to the actual Boostaroo. I always usually prefer buying from a "brick and mortar" establishment and would like to avoid paying extra for shipping.
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post #11 of 26
12/9/03 at 4:31am
I speak for most people when I say PLEASE do not get the boostaroo....

It is definitely not worth it.. I may not have a lot of post counts but I've read a LOT of posts.. make a thread on the amp forum..

I don't remember one person liking the boostaroo..

[edit: People have even tried modding it.. to no success.]
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post #12 of 26
12/9/03 at 12:05pm
A used Airhead would probably set you back $50 or less.
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post #13 of 26
12/9/03 at 12:26pm
The radio shack booster provided approximately 6db of gain. I have tested the unit and it did not add any appreciable noise levels. Arny Kruegar has measured this unit, and found it to have distortion levels far below human threshold, as well as confirmed good signal/noise behaviour. Here is an excerpt from http://www.realcaraudio.com/forums/a...opic/7525.html :

Quote:
Finally, for the benefit people who find that the headphone jack of their
portable equipment lacks "oomph", I investigated the Radio Shack part number
330-1109 3-Way Headphone Volume Booster. This device runs off of 2 AA cells
and provides 3 headphone jacks. I ran some measurements on it and find that
it has approximately 6 dB gain, 0.003% THD @ 1 KHz full output,
approximately 90 dB SNR and frequency response 20-20 KHz +0, - 0.3 dB.
I should add that the unit works well with Alkaline or other 1.5v batteries, but 1.2v batteries such as NiMH rechargables reduced the gain perceptibly(as in I believe i could percieve the volume difference in spite of the difficult comparision where it takes time to chane batteries, and no protocol established to do the test blind or other bias removing method).

-Chris
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post #14 of 26
12/9/03 at 6:14pm
Quote:
Originally posted by WmAx
The radio shack booster provided approximately 6db of gain. I have tested the unit and it did not add any appreciable noise levels. Arny Kruegar has measured this unit, and found it to have distortion levels far below human threshold, as well as confirmed good signal/noise behaviour. Here is an excerpt from http://www.realcaraudio.com/forums/a...opic/7525.html :
I've talked to this Arny Krueger guy before on Usenet... the guy is not only clueless when it comes to audio, but he's a habitual flamer and troll. In many ways he makes "Merton" look like a genius. Believe his spoutings at your own peril.
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post #15 of 26
12/9/03 at 8:00pm
contact head-fi guru jmt or post in our diy section, save a little money and have a budget, and tell him what kind of headphones you use, etc., and you can get a nicely built, powerful but quiet amp like the cha47 (for example).
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