Grado HP-1000 > Great, but not with my amp.

davstev

Well-Known Member
Hello and Happy New Year!

I have a very nice pair of Grado HP-1000 drivers in custom black walnut cups. I'm using an Accuphase C200 preamp to amplify them. Both of these pieces are excellent, but I wonder how well mated they are. I have to turn the volume up to the 1 o'clock position just to get it to a normal volume. When I want to crank it, it's in the 3 or 4 o'clock position. In other words, there's just not a lot of power, not enough power, coming from the preamp, toward these rather inefficient headphones. However, I can't complain about the sonics, they are lovely. It just bothers me to have to crank it so much just to get a normal volume. There's not much headroom.

I've read from a reliable source that for my Accuphase pre, the voltage supply to the headphone amp is only about 4.5V. I also know that HP-1000's are rated at about 40 ohms.

If I wanted to purchase a new pair of phones that would mate well with this low-output preamp, what ohm value would be ideal? What other specifications matter here? Any recommendations for headphones that would mate well?

Btw, I'm not really considering a different amplification source, for reasons of cost.

Thanks !
 
I've read from a reliable source that for my Accuphase pre, the voltage supply to the headphone amp is only about 4.5V. I also know that HP-1000's are rated at about 40 ohms.
Is this the actual supply voltage internally or is this the spec for the headphone output? If it's the output, what load is specified for that output voltage?
Generally, HP amps with low output voltage swings work pretty well with low Z phones - unless the sensitivity of the phones is also low. I don't know anything about your Grados as far as sensitivity goes - perhaps check the manual to determine what it is.

Buying headphones based on how they mesh with your amp characteristics has a number of pitfalls. Fit, comfort and most importantly how they sound to you should probably be at the top of the list.

Anyway, good luck with your endeavor.
 
Hello and Happy New Year!
I've read from a reliable source that for my Accuphase pre, the voltage supply to the headphone amp is only about 4.5V. I also know that HP-1000's are rated at about 40 ohms.

Thanks !

the C200 manual here http://www.accuphase.com/cat/pcten.pdf
gives the spec for the headphone amp as a very respectable 0.3 ohm output impedance, and 0.4 V output.

If the specs given here https://www.stereophile.com/content/grado-hp-1-headphones-specifications apply, the sensitivity is 96 db / mwatt - and the preamp is generating 4 mwatt into that impedance, so yeah, you're not going to have a lot of headroom there.

There are a lot of cans that are 10 or even 15 db more sensitive than the HP1 - but if you like the sound of those, equalling it is probably going to cost you more than adding a decent headphone amp to your setup will. Basically, my guess is you can hit diminishing returns more cheaply on the amp side than on the headphone side.
 
Fellas,

Thanks for the research and good input. Sorry for the delay, I've been too busy of late.

Based on your advice olderroust, i should investigate what options there might be for a headphone amp. It would have to be fairly inexpensive and really well matched to the Grados in terms of having fantastic sonics and providing higher output levels. I would say that the C200 and HP-1000 combo sounds really very good, but I dislike the background noise that is inevitably added when you turn your amp to 1/2 or 3/4 of its maximum capacity just to achieve a normal listening volume.

Alternately I might start investigating headphones with higher sensitivity, maybe in the 105-110 db range, just to see what's out there. I can probably sell my HP-1000's for enough to fund a new purchase.

Thanks again,
David
 
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