What the output impedance of the headphone socket on a TD module?

[jweaver]

When i got my TD3 I bought the Sennheiser HD-215 headphone and was quite happy.. But the more time I spend with them, the more I realise that they are not that great.

The aren't particularly bassy and they arn't all that loud either. Don't get me wrong, they are loud enough, but I have to run them at almost full volume.

So I have decided to upgrade.. After doing extensive searches, I have decided on the Beyer Dynamic DT770s, but I am worried as they are 250ohm, and considering my HD-215s are 32ohm, there is a major difference and I don't know whats best.

I know that the DT770s have an 80 ohm option, but I don't know what to go for... This is especially confusing as anyother highly recommended headphone (Sony MDR-7509) are only 24 ohms.

I have looked in the manuals for all the TD modules and the only quoted 'output' is 1Kohms, but I am assuming that this is the 'amp' output and not the headphones.

So, basically, I just want to know what the impedence of the headphone output is on a TD (Specifcally TD8) and what would happen if I get the impedence wrong?

Jon

[Hercules]

Hi Jon,

This may sound like a bit of a pain, but, how about going into the headphones shop with your module and one pad and testing the phones?

Check out the Beyer website - there is a good explanation and a .pdf that you can download. The ones I saw were the 770M models which have a volume control and are listed at 80Ohms and specifically for drum monitoring, so I don't think you'd go wrong with these.

[Michael Render]

You will not damage anything with the "wrong" impedence. But it will have an effect on overall volume. generally, the lower the impedence, the higher the volume. My recommendation is to get a high-quality, low-impedence pair. The Sonys are good - I also like the ATH-M50s.

[foofoo]

the reason for the higher ohms in some of the headphone models is that it allows an amp to drive several pairs efficiently.pro recording studios use them more often. stick with the lower stuff. i like the akg 240 studio version. its 55 ohms compared to 600 ohms for the original 240 version.i gotta try those audio technicas some day!

[jweaver]

Hi Jon,

This may sound like a bit of a pain, but, how about going into the headphones shop with your module and one pad and testing the phones?

Check out the Beyer website - there is a good explanation and a .pdf that you can download. The ones I saw were the 770M models which have a volume control and are listed at 80Ohms and specifically for drum monitoring, so I don't think you'd go wrong with these.

I would love to, but in my part of the world (infact my part of the country) I don't have this luxury

Jon

[jweaver]

You will not damage anything with the "wrong" impedence. But it will have an effect on overall volume. generally, the lower the impedence, the higher the volume. My recommendation is to get a high-quality, low-impedence pair. The Sonys are good - I also like the ATH-M50s.

I realise that I won't damage anything.. But I want to get it right, to get the best 'efficiency' out of the headphones.

Like you, I always thought that lower impedance = louder.. But I have since spoken to some experts, who went on to talk about "Power Transfer" and I glazed over.

It seems that the best efficiency is if you closely match the impedance.. So, putting 32ohm headpones into an output designed for 250ohms, is just as bad as putting 250ohm headpones into a 32ohm output.

The problem is that I don't know what the TD output is.. Since the Roland headphones are 65ohms, this could indicate something.. And as such, using Sony 24ohm headphones may not be ideal either!

Not sure what to do now.. If I do go for the DT770s I don't know whether to go 250 or 80 ohms!

Also, with the ATH-M50s, I looked at the spec and on paper, the ATH-M40s go lower.. Is this really the case?

Jon

[Michael Render]

Output amps don't have a specific impedence. They have a range of impedences they can handle. Too high and you get no volume. Too low can burn out the amp. But by too low, I mean really low. Like less than 8 Ohms.

foofoo is spot on for the reason they have very high impedence cans. It's to share an output. Run two headphones in parallel and you half the impedence. If you use 4 250 Ohm pairs, you get a 62.5 Ohm load.

The ATH-M40fs is rated at 60 Ohms.
The ATM-M50 is 35 Ohms.

Bottom line is you want the lowest impedence on a good pair of headphones. But don't let impedence be your only guide. Given the choice between say, the AKG 240M and the 240S, take the S because it is lower imepedence. But better sounding headphones are more important. And there are a lot of great sounding cans with low impedence.