15 replies to this topic

[aechmea]

I have an old ME25 pre-amp and a couple of pairs of vintage headphones (Stax SR3 and Sennheiser HD420). I have read that the ME25 makes a very good headphone amp, so thought that I might blow the dust off and get them all working again.

Of course the ME25 has RCA output and the headphones don't. Is it simply a matter of finding the right adaptor? Do such adaptors exist or is it a DIY job?

[The Stax has hi-level speaker connections: The Senns have a line level stereo phono plug]

I'm pretty sure that the ME25 has a really high output of something like 6v when wound up, so should be able to drive the electrostatics directly.

Thanks.

[Zaphod Beeblebrox]

I have an old ME25 pre-amp and a couple of pairs of vintage headphones (Stax SR3 and Sennheiser HD420). I have read that the ME25 makes a very good headphone amp, so thought that I might blow the dust off and get them all working again.

Not quite correct. The ME25 makes the best headphone amp. Assuming you have the latest version of the ME25, that is. If not, then what you have will merely be a brilliant headphone amp.

Of course the ME25 has RCA output and the headphones don't. Is it simply a matter of finding the right adaptor? Do such adaptors exist or is it a DIY job?

I usually make adapters from a pair of RCA leads and fit a 6.5mm socket to the other end. Simple, cheap and quick. Soldering required, of course.

[The Stax has hi-level speaker connections: The Senns have a line level stereo phono plug]

I'm pretty sure that the ME25 has a really high output of something like 6v when wound up, so should be able to drive the electrostatics directly.

Thanks.

Touch and go, with the Stax. The Senns will work a treat. Try it with both. You are unlikely to cause any damage. Maximum output of the ME25 is approximately 10 Volts RMS. Output impedance is 2 Ohms (open loop).

Edited by Zaphod Beeblebrox, 06 September 2011 - 03:47 PM.
Brain fart

[aechmea]

Thanks ZB.

Pretty much what I thought. We'll see what happens with the electrostatics [if they still work at all! Has to be 25-30 years since they've had electrons running through them]

[braddo]

here ya go..........

If you feel you need to upgrade/change phones, go for it, the ME with pass with flying colours.

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Edited by braddo, 06 September 2011 - 04:47 PM.

[vinilink]

braddo, is the other end is balanced? I am planning to get a hd600/650

[Zaphod Beeblebrox]

braddo, is the other end is balanced? I am planning to get a hd600/650

It doesn't matter. Headphones can be operated from balanced or unbalanced sources. The most important thing to consider is the output impedance of the source. The ME preamp has an extremely low output impedance, making it perfectly suited to any headphone.

[MultiplexMan]

I need to get/make one of these cables to try with my ME25.

Anyone recommend a suitable headphone socket for connecting to the end an RCA pair?

[Zaphod Beeblebrox]

I need to get/make one of these cables to try with my ME25.

Anyone recommend a suitable headphone socket for connecting to the end an RCA pair?

Neutrik make an excellent connector. If you can't locate one, le tme know. Element 14 stocks them.

[aechmea]

Noticed that my thread has been resurrected ...

Nothing quite worked for me.

The ME25 by itself wouldn't drive the Stax electrostatics to a reasonable enough level. Power amp required.

I bought a pre-made RCA male to TRS female cable but somehow I manage to get Left plus Right channels in the Left earpiece and Right in the right earpiece. The headphones are fine and work OK when used without the cable, so there is something incompatible in the cable/connector somewhere. I am assuming that it won't matter if the plug is 6.5mm (metric) and the socket is 1/4inch (imperial). It seems that the tip or the ring or the sleeve are touching somewhere.

Too hard for me. I gave up at that point.

[MultiplexMan]

@zb Thanks - looks like there is a bit of choice...

http://au.element14....3way/dp/1804844

http://au.element14....cking/dp/212179

http://au.element14....black/dp/212210


@ aechmea - did you check the cable for correct wiring? I've had preassembled cables assembled incorrectly in the past.

Edited by MultiplexMan, 08 April 2012 - 09:41 AM.

[aechmea]

Yes it has to be the adapter cable wired the wrong way. I specified it as Tip = positive, Ring = positive other channel, Sleeve = earth.

I have just checked the setup again. There is something odd going on suggesting cross wiring.

With the phones plugged into the adapter cable, I checked continuity from the RCA end.
Earth to earth = zero ohms = expected
Earth to positive = .58ohm (not sure where the decimal point goes!)
Earth to other positive = 1.17ohm = continuity through both voice coils via the earth? Suggests earth and one positive reversed (I think!!!)
Which is why one channel is twice as loud as the other.

Just to make sure that the phones are 'normal', I checked continuity of the plug on the phones.
Sleeve to ring = .58ohm = expected
Sleeve to tip = .59ohm = expected
Ring to tip = 1.17ohm = expected (once I thought about it a lot!!).

So I reckon that I need to swap one positive with the earth inside the female RTS.

Thanks for forcing me to re-investigate. Now which end of the soldering iron gets hot again .....

[Catostylus]

Now which end of the soldering iron gets hot again .....

The other end.

[Zaphod Beeblebrox]

Noticed that my thread has been resurrected ...

Nothing quite worked for me.

The ME25 by itself wouldn't drive the Stax electrostatics to a reasonable enough level. Power amp required.

I bought a pre-made RCA male to TRS female cable but somehow I manage to get Left plus Right channels in the Left earpiece and Right in the right earpiece. The headphones are fine and work OK when used without the cable, so there is something incompatible in the cable/connector somewhere. I am assuming that it won't matter if the plug is 6.5mm (metric) and the socket is 1/4inch (imperial). It seems that the tip or the ring or the sleeve are touching somewhere.

Too hard for me. I gave up at that point.

If you want a professionally made pair of leads (by myself), I'll send a pair to you. You try them and send them back, if you're not happy. You pay for postage both ways. Sound fair?

[aechmea]

The other end.

I was very lucky - I guessed right first time. 50-50 chance!

[aechmea]

If you want a professionally made pair of leads (by myself), I'll send a pair to you. You try them and send them back, if you're not happy. You pay for postage both ways. Sound fair?

Thanks ZB. A very generous offer. I did however manage to disassemble the lead that I had, and after working out what wire went to what tab, I resoldered the crook positive and the ground the other way around. Works fine.

[Only a couple of panics along the way. The spring on the locking socket disappeared onto the floor at some point. Eventually found it when I trod on it. I needed 4 hands to do the soldering (one for the iron, one for the solder, one for the socket and one for the cable). I presume that there is some smart technique to do this by oneself. Anyway Mrs A lent a hand or 2 , so to speak. The wire snapped off when I twisted it to get it into position so had to strip all the wires back and start again. It was ridiculously difficult to unravel the shielding to form the earth wire. Mrs A suggested that it was probably easier to buy another cable.]

Yes it does work. I can't really comment on the sound Q as I have nothing to compare it to. I think that it is subdued in the treble compared to the speakers but maybe thats just because the preamp is as it was in 1983 and could do with a tart-up and the headphones are 1977-ish and I was using the analogue out from the CD player rather than digital out plus DEQX fiddling via the speakers. Apples and oranges. As proof of concept though, it works fine.

[Zaphod Beeblebrox]

Thanks ZB. A very generous offer. I did however manage to disassemble the lead that I had, and after working out what wire went to what tab, I resoldered the crook positive and the ground the other way around. Works fine.

[Only a couple of panics along the way. The spring on the locking socket disappeared onto the floor at some point. Eventually found it when I trod on it. I needed 4 hands to do the soldering (one for the iron, one for the solder, one for the socket and one for the cable). I presume that there is some smart technique to do this by oneself. Anyway Mrs A lent a hand or 2 , so to speak. The wire snapped off when I twisted it to get it into position so had to strip all the wires back and start again. It was ridiculously difficult to unravel the shielding to form the earth wire. Mrs A suggested that it was probably easier to buy another cable.]

Yes it does work. I can't really comment on the sound Q as I have nothing to compare it to. I think that it is subdued in the treble compared to the speakers but maybe thats just because the preamp is as it was in 1983 and could do with a tart-up and the headphones are 1977-ish and I was using the analogue out from the CD player rather than digital out plus DEQX fiddling via the speakers. Apples and oranges. As proof of concept though, it works fine.

All good then. Even an old ME preamp should perform quite well, though the later models are a big improvement.