6080 OTL Headphone amp

[Nick]

I have been reminding myself about the OTL phone amp I have been playing with. I am unsure (not being a long time headphone amp user) if it produces enough power to be useful. Hopefully those out there who use phones will let me know if this power outputs are any use or not.

Impedance - RMS voltage - Power out 1kHz two chan

300 ohm - 13.1v - 0.57W
150 ohm - 8.9v - 0.53W
64 ohm - 5.5v - 0.48W
32 ohm - 2.9v - 0.26W
16 ohm - 1.4v - 0.124W

Output impedance is 13 ohm

[Toppsy]

Nick, not sure, but I use the WAD HD83 to drive my Sennheiser HD650 headphones, which are 300-ohm.

Here are the specs for these: http://www.sennheiser.co.uk/uk/home_en. ... nes_009969

May help.

You are welcome to borrow the HD650's for experimental purposes.

Colin

[Nick]

Yes, it would be helpfull to borrow them some time Colin. Thanks.

I will measure the amp at 150 and 300 ohm for reference.

[Mike H]

Guess it depends what headphones, but for "ordinary" ones I've noticed tends to be about 45mV.

'Least that's what's written in the service manual for my cassette recorder IIRC, as an example.



 

[Nick]

I have updated the original post to add 150 and 300 ohm

[cressy]

hi nick, i can send you up my big old sony headphones if you want them, ive no use for them (been replaced) and id assume they were pretty average in terms of specs if you want them

cheers ant

[Toppsy]

Yes, it would be helpfull to borrow them some time Colin. Thanks.

Nick,

I could bring them over one day/evening next week, if that's OK?

I can collect and pay for the Start-up boards at the same time, hey

[colin.hepburn]

There’s the Spec for my Headphone Amp if it helps I Use my Sennheiser HD650 /300 ohms with it

[Nick]

Thanks for the offer Ant, I may take you up on that later, I have the ones that were the free giveaway from HFW some time ago (second pair, Dave donated his to me).

Colin H, thats very useful. Looks like the voltage into 32 ohm is ok then, good, I will carry on trying to get the diag into a state and then write some text for it.

Colin T, That would be great, given you have found a excuse to come over . Any evening will be good for me.

[colin.hepburn]

Hi Nick
Here’s a Link to the 6AS7 Headphone amp I was intending to build some time ago but it is still on the back burner of projects to build it give some measurements that my be of help its about half way down the the page http://gilmore2.chem.northwestern.edu/p ... e1_prj.htm

[Nick]

Yes, that also helps Colin, its good to have comparisons. I feel better about the power output of what I have now, seems to be enough. Sounds nice anyway. Cristal clear in that OTL way. I will look forward to seeing how it works with Colin T's better cans.

The circuit I have is more complex that the one you linked, but I wanted to play with a push pull sort of OTL stage as a alternative to the cathode follower type you linked to. Its two ECC83's and two 6080's +- 200v and +- 120v power supplies.

[Blagdon75]

I have been reminding myself about the OTL phone amp I have been playing with. I am unsure (not being a long time headphone amp user) if it produces enough power to be useful. Hopefully those out there who use phones will let me know if this power outputs are any use or not.
...

My advice to you is you can try using it though you are not so sure about it. We don’t like to lose a headphone or amp. Best thing to do is to read the manual of the amp before using it.

[Nick]

Err, Maybe reading the thread would help. I was talking about the design of a amp.

Anyhow, Colin has kindly lent me his high impedance headphones, so I have tried both ends of the range. Still writing up the text for it at the moment, next is to add some schematics.

[Nick]

The doc with the design is up now

http://www.hificollective.co.uk/pdf/otl_head.pdf

Thanks to those who helped with the proof reading.

[Mike H]

Whoo, cool.