Bottlehead Repro Output

[Grant99]

Hi all, this is more a comment/question than some kind of complaint.  Earlier this year, my preamp was out for service (more like "restoration"!) so I wasn't able to listen to my LPs...so I figured I do lots of tape listening.  So I hooked up my Repro directly to my headphone amp...well it just didn't sound right.  There was some kind of distortion, at higher frequencies.  I have never heard this before.

So...my question is: isn't the output from the repro a standard line stage output?  Or is there some mismatch between feeding the repro directly into the headphone amp?

The headphones being used are Stax OAIIs...if there's any distortion/discolouring of the sound, you'll hear it with them...

Since I've got my preamp back everything is back to normal.  I did listen to my tuner and some cassette dubs (don't laugh) at the time and didn't hear any distortion.  If anyone has any insights on this, I would love hear them....thanks

[docb]

Since the problem does not occur with a preamp in between it sounds like an issue of the interface between the Repro and the headphone amp. Or maybe you just have some tubes that are getting long in the tooth and the headphones helped you to hear it.

Which output of the Repro did you use? The single ended RCA outputs are around -10dbV. The output impedance is 4K ohms, so if the amp the Repro is running into has a very low input impedance like 600 ohms ( not likely) it could affect the sound. The true balanced XLR output has an output level of around +4dBm ( which is of course trimable on the front) and the output impedance is 500 ohms, thus less sensitive to loading.

[ironbut]

Hey Grant,

If you were using the EA-8 which is in your signature, I can pretty much assure you that the amp is the problem.
If you're hearing "clipping" type distortion on peaks, it's a design issue with that amp.
The design of that amp was for the more efficient electrostatic headphones and certainly not for the Omega ll.
You can minimize the distortion by using the balanced output of your Repro but the issue will remain (just less obvious).

[Grant99]

Thank you both for your comments...I'm still puzzled though.  I don't think the EA-8 was clipping, though, as the distortion wasn't in louder passages only....BUT, if it was, why don't I hear it when the repro is routed through my preamp?  I always thought shortening the path of your signal would improve sonics...you know, the "minimum path rule".

I am currently using the XLR outputs of the repro, they go through these "American Recorder" XLR-to-RCA adaptors, then go through Atlas interconnects.  Perhaps my preamp is masking the problem when I use it?

The preamp is currently sounding great, I have had the RCAs at the back all replaced, new caps, and a new selector & gain pots.

But thanks again for the comments...Steve, would you be OK I sent you a PM about this?

In any event...thanks!

[docb]

If you are trying to use the minimum path you should forego the XLR-RCA adapters and plug the RCA interconnects into the single ended outputs. That eliminates not only an adapter but also a triode and a transformer.

Are you listening to the preamp thru the headphone amp? Or are you saying the headphone amp sounded worse than the preamp does through your speaker system?

[ironbut]

Hey Grant,

It's not that it's clipping but the distortion kind of has a similar sound (kind of fuzzes out ).
I'd be happy to go into more details if you wish to PM me.
But IMHO, the EA-8 just isn't a very good amp for some headphones.

[Grant99]

Are you listening to the preamp thru the headphone amp? Or are you saying the headphone amp sounded worse than the preamp does through your speaker system?

  My comparison was repro directly to headphone amp (some distortion as I indicated) compared to repro to preamp to headphone amp...the amp I use for my speakers doesn't come into as I can't run the repro directly to my power amp without a preamp (no vol. control).

I've never heard any of this distortion through my speakers...thanks

[docb]

If the headphone amp happens to have a gain stage ahead of its volume control that could be the issue.  That input stage could be overdriven by the Repro balanced output, and the preamp would be creating a way to cut that signal before it gets to the headphone amp. It's not particularly likely that is how the headphone amp is designed, but it's the only scenario that comes to mind. You could try trimming the pots on the Repro and see if that helps. Or just try using the single ended output as I suggested before.