So Confused: Amps for Low Imp .Phones? (Grado 125s)

[caballo]

I have two friends. One keeps pushing me to get an amp. Says even though I've lived with my Grado SR-125s for years unamped, I'll just be blown away.

My other friend says it's idiotic to buy an amp for phones with such a low (32) impedence. All it will do is make noise and I'll only be able to turn the volume up about .03% before it blows my head off.

I primarily listen to these phones at home on the computer and also through a reciever. Although I do listen to my work headphones (Sennheiser PX100s in a iMac) a lot more, hour-wise. So it might be nice to have a portable amp to run my Koss Sportapros (commuting phones), my PX100s and even my Grados (when traveling).

I've looked into

Shellbrook Maxi Moys
JMT Portable PIMETAs
Fixup SuperMacros
Airhead/Total Airheads
some random cheapo CMoy

I've done research but my problem is that most people seem to have Sennheisers and those reviews don't really tell me anything.

I don't really plan on upgrading my headphones. I like the Grados and I'm only wondering if there's some untapped well of sound I'm missing since I'm unamped

So which head amp would be good for me and what sorts of modifications or custom work should I ask for to make it work well with Grado 125s. Would the PX100s see any benefit from an amp?

(Also, if you're an amp builder and have some great custom idea, go ahead and pitch it to me. I'm trying to stay below $200 though.)

 

[atx]

Quote:

My other friend says it's idiotic to buy an amp for phones with such a low (32) impedence

An amp changes the signature of the sound. It's not just for increasing volume. You'll notice more refined bass, greater clarity, differences in soundstage, etc, etc depending on the type of amp (and how much it costs

).

For the majority of people who don't pay attention to detail, the difference between amp and unamped is so small, it makes no sense to spend any money on it. On the other extreme of the spectrum, there are people who spend thousands and thousands of dollars just to get the sound "just right"-- there's a delay in the decay of the notes in the cymbals, lets spend another $500 to get that decay JUST RIGHT. Call that extremity or stupidity, it's your call.

But to make an informed opinion, you should probably try out one of the more expensive amps (with a money back guarantee) and see if its worth the money. If so, you'll probably end up poorer but happier for it.

My first headphone is a Grado SR 125 just like yours. My second is a Sennheiser HD580. I enjoy the 580 more than the Grado, and is my primary cans for any music. It's not redundant to own both because they sound very different, and you may choose one headphone over another depending on the music material.

 

[gsferrari]

EE 101


Let us assume Impedance = Z
Resistance = R
Inductance = L
Capacitance = C
X = Reactance (XL and XC - Inductive/Capacitive Reactance)
Current = I
Voltage = V

Impedance Z is a combination of R, XL and XC

POWER = I * I * Z OR V * V / Z
V = I * Z

When Z is low (Low impedance)
I draw is high

When Z is high
I draw is low


Therefore it is important to have an amplifier capable of delivering high currents in the case of low impedance headphones - AND - an amplifier capable of high voltage output in the case of high impedance headphones.

SO - amplification is important...

Ever wonder why you need such powerful amps for those 2/4 and 8 Ohm subwoofer drivers?

 

[caballo]

Quote:

Originally Posted by gsferrari EE 101

I see. So which amps give the best current for low impedence cans? I take it I don't need much gain.

 

[recstar24]

Well, the gilmore lite pretty much fits that bill. Its output impedance is extremely low, i believe its close to 0, and with the power supply there is massive amounts of current, which works well with the grados. There are some other options as well, i have an hr-2, works wonderfully, a little high on the gain side, but i don't mind it a bit, i figured they are good enough to drive 8 ohm speakers, 32 ohms is a piece of cake!

 

[gradeo]

I've been asking this same question in various forms for a while. Still, I have no idea what high current, low impedence amps are out there, other than the Apheared 47.

How about the CMoy, META, PiMeta, MINT, and PPA? Does anyone know how they would do with Grados?

 

[atx]

Quote:

EE 101 Let us assume Impedance = Z

So what causes hiss in low impedance headphones with some amps? Too much current?

 

[EdipisReks]

my corda works really well with low impedance cans. with my grados i keep the volume around 9-10 o'clock, and with my etys or with CD3000's the volume stays around 8-9 o'clock. there is absolutely no hiss using this amp with low impedance cans.

 

[gsferrari]

Quote:

Originally Posted by caballo I see. So which amps give the best current for low impedence cans? I take it I don't need much gain.

You dont need much voltage gain...you need more current gain...

As for why low impedance headphones hiss more than high impedance headphones - this can also be because of poor impedance matching between the amp and the headphone...

 

[MD1032]

Like gsferrari said, it's all about current. Grados, while low-impedance, will take a lot of current, and this extra current really fills things in and improves the sound a lot.

 

[caballo]

OK. So it sounds like the Gilmore Lite is really one of the only amps for Grados.

I guess I got some saving to do before I can buy one.

Thanks for all the help and anyone interested in selling a Gilmore can contact me at the_caballo at hotmail.

 

[recstar24]

dont forget about the sr-71 or any other of ray's amps, those things have enough current to drive 8 ohm speakers, so 32 is like nothing.

 

[errorich]

You can DIY an amp or have one built thats made specifically for low impedance phones. My PPA has an extra opamp and jack for low impedance and my primary jack is set to run high impedance phones.

 

[chillysalsa]

In my experience, if the amp is not providing the adequate amount of current, the bass will be weak, and highs will become grainy.

The Gilmore amps do a fantastic job with Grados because they provide more than the required current. The hiss is extremely low with these too, allowing a silky-black background which is otherwise hard to achieve with Grados because they are so sensitive.

 

[Imyourzero]

Quote:

Originally Posted by caballo OK. So it sounds like the Gilmore Lite is really one of the only amps for Grados. I guess I got some saving to do before I can buy one. Thanks for all the help and anyone interested in selling a Gilmore can contact me at the_caballo at hotmail.

While the Gilmore Lite is probably one of the best amps to use with Grados, I wouldn't say it is "really one of the only amps for Grados." I noticed a huge improvement in the sound of my SR225 and MS-2 just by adding a Headsave Go-Vibe, which uses a 9v battery and doesn't even use an AC adapter or external PSU. I think one reason I experienced such a great improvement is because I was previously driving my headphones directly from my sound cards (AV-710 and E-MU 0404) which do not have enough current to drive Grados properly. If someone was using their Grados with the headphone out of a stereo receiver, the improvement seen by adding a dedicated headphone amp might be less than what I experienced.