[birdie00]

So, after doing some research over here I think I've decided on the beyer DT 880 /PRO 600 ohm, but I wanted to know if these can be driven by a kenwood HD60GD9 with the gold plating using a sr71, or is it just wishfull thinking?
My main music I listen to is classical, and cantorial. I'm not too concerned with detail as much as the musical entertainment. If you guys have any other reccommendations, I'm all ears. BTW I will probably recable as well I just haven't figured out with what( still researching). Also after doing some research I still can't figure out the difference between the regular, and the pro if someone can help?

 

[ericj]

I don't think there's any reason the SR71 wouldn't work.

If you don't mind my asking, what's the gold for in that kenwood? Best i can think of is that it might prevent corrosion of the internal frame if you spend a lot of time near the ocean.

 

[ericj]

Actually scratch that. Ray Samuels says the gain of the SR71 is 6db - which is pathetically low for high-Z cans. Also seems like a waste of a 2x9v power supply.

Unless he doesn't know the difference between decibels and voltage gain, and meant to say that it has a voltage gain of 6, which would be 15.6db.

I built my mini3v2 with a voltage gain of 8, which is about 18db. Paired with my iRiver H120, this seems to be enough for 600-ohm headphones.

It is extremely likely that the kenwood has a voltage output similar to the iRiver. Especially with that 10mw output rating -- which kinda demands that you have an external amp.

Perhaps you should ask him for clarification, and see if you can get a higher-gain custom configuration if he really does mean 6db (which is a voltage gain of 2).

 

[birdie00]

The Gold is supposed to enhance the SQ. BTW which other HP come in 600ohm ?

 

[nikongod]

im PRETTY sure the sr-71 has gain of 6db (like 2) which is AMPLE for most listeners and IEM's and low-impedance headphones. as far as the 2X9V supply, its not about the 18v, its about the quality of them.... yeppo.

anyways, i have driven my AKG k-240 (the 600-ohm version you want to have sextett with) from the sr-71 with good results, but i generally listen quietly. the SQ was as you probably guess very good.

for the more power hungry of us, the sr-71 may leave you wanting more. i would call ray and ask for the high gain option, that should do you well.

 

[ericj]

Quote:

Originally Posted by birdie00 /img/forum/go_quote.gif The Gold is supposed to enhance the SQ. BTW which other HP come in 600ohm ?

I don't see how the gold plating could have any effect on the SQ.

Where they've used it, it doesn't even lower the impedance of the ground rail. It is certainly not in the signal path. Perhaps they hope that as shielding it will hasten the passage of RF noise to the ground rail?

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif as far as the 2X9V supply, its not about the 18v, its about the quality of them.... yeppo.

How could that be?

Most opamps that you'd use in a portable amp can swing to within about 1 volt of each power rail. Some, like both opamp choices in the mini3v2, swing almost to the rail, and are essentially basically true rail-to-rail parts.

Nearly all portable devices are going to swing about 2.4vpp on the output strictly because of the limitations of a 3.6v supply. You MIGHT get some devices swinging 3vpp.

So lets say 3vpp line-out, times two, 6 volts peak to peak on the output of your SR71.

Unless you have some opamp that gets really cranky with low voltge power supplies, like an opa2107, at a gain of 2, your source is clipping long before the amp is clipping with a single 9v battery.

Some parts, like the ad8397, actually behave worse with an 18v supply than they do with a 9v supply.

Without knowing what chips are used in the SR71, it's impossible to say whether they benefit from a higher voltage supply. If he had built it with relatively high gain, I wouldn't have thought anything of it. My suspicion is that he's using chips that perform well at 8.4v and that the 2nd battery is just more weight and bulk.