The Official Guide to Converting your Quickie for Headphone Use

[musiciseverything]

Excellent advice. Thanks again. TG

[boulos]

Hi,

I have a pair of WE 111c isolation transformers.  Can I use them as output transformers for headphone use for the Quickie? (they're too big so they would have to be mounted to a separate box).

Please find attached their spec sheet.

Thanks!
Boulos

[Paul Birkeland]

Hi,

I have a pair of WE 111c isolation transformers.  Can I use them as output transformers for headphone use for the Quickie? (they're too big so they would have to be mounted to a separate box).

They don't quite have the ratio that you'd want for this purpose.

-PB

[boulos]

Is this the case even when the transformers are wired as 600 -> 150 ?

Thanks!

[Paul Birkeland]

Is this the case even when the transformers are wired as 600 -> 150 ?

Yes.

-PB

[boulos]

Alright, thanks!   I'll find a different use for them.

[Paul Birkeland]

Alright, thanks!   I'll find a different use for them.

You could hang them off the output of your BeePre.

[boulos]

You could hang them off the output of your BeePre.

ooh, nice.  I don't have one but I built the one GerryE has.  I can ask if he'd like them.  Would it be 600 -> 600?

[Paul Birkeland]

600:600 or 600:150.  On the downside, they will load the output of the BeePre if they are installed, even if nothing is hooked up to them.

-PB

[cpaul]

I've finally decided to convert my Quickie 1 to a headphone amp.  I'm using nothing special for cans and they are low impedance.  Edcor no longer makes the EM0735 (I suppose one could custom order it and pay the setup fee) so I bought a pair of the Specos to wire for 32ohm (they are the new ones and weigh in at 4.75oz).  They were quite cheap so I'll give them a try, but they are VERY small so I have my doubts.  Then I took a quick look this morning and found this:  http://www.mcmelectronics.com/product/555-7120.  It sounds virtually identical to the old Specos, weighs just about 10oz (according to the specs) and costs $4.99.  Any thoughts?  I'll probably order a pair to try out.

In both cases I'll post back if/when I have success. 

[Paul Joppa]

Seems unlikely - those dual-voltage (70 and 25v compatible) line transformers usually don't have enough inductance for decent bass. But until someone tries it, we'll never know for sure!

[cpaul]

Thanks, Paul.  Transformers are a big black box to me, and I certainly didn't know that about dual voltage (I don't really understand how a dual voltage would be wound in the first place...).  And frankly, I hadn't even noticed that it was dual voltage.  It came up as 70v and I went straight to the specs.  Now I see that.

[cpaul]

Tonight I hooked up the tiny Speco transformers per the wiring diagram on post 65 by mcandmar (thanks!) and had a listen.  Quickie performs reasonably with these transformers.  I don't notice substantial loss of bass, midrange is full and clear, and the high end is certainly good if not quite good.  At the same time nothing is outstanding.  Now, this is with Grado SR60s (old version) and Fostex T50RP, both of which are on the low side of impedance (32ohm and about 60ohm respectively).

I got the best performance using the 0.25W tap as the input (attached to the RCAs) and the brown tap (10W) connected to the headphones.  I tried the recommended 32 ohm wiring per the diagram in post #65, but there seems like there's something wrong with that.  When I inadvertently left out the jack ground, I got a small amount of very hollow sounding audio.  When I put it back in, I got nothing.  Checked and re-checked but found no problems.

As I read the diagram (see image), the ground is pulled off of the transformer BEFORE the headphone output.  Wiring is input to 0.25W tap, common on the multi-tap side tied to the ground on the 8ohm side and that connected to Quickie ground, followed by the output attached to the 8ohm tap  That would seem to be a recipe for no sound output even ignoring what the core is doing to the 8ohm "secondary."

Am I misunderstanding something here?  Anyway, I tried a number of variations on the 32ohm wiring to no avail.  I got little or no sound out each time.  But since I was getting reasonable performance with the brown/50-200ohm wiring, I just went with that.  I may experiment more, but reasonably satisfied with the way it is.  I did try the red and orange taps (5w and 2.5w) and they weren't bad, but not as good as the brown/10W tap.

These Specos cost me less than $6 each plus small amount of shipping.  At that cost, it's well worth experimenting.  And I have a reasonable headphone amp to boot.  I'm new to headphone amps, so not sure I have a good baseline to compare, but it's better than the output of my CD player (and OLD Pioneer PO-M6) which is no doubt op-amp based.

[mcandmar]

I found the blue/brown combo worked the best for me too.    The 32ohm wiring is for the old style Specos (large), for the new style (tiny) just ignore the secondary windings.

[cpaul]

Thanks, mcandmar.  I'm curious, though, about the diagram even if it's for the "old" version.  The first drawing (where it says "New")  shows wiring for 32ohm cans.  As I read it, it ties together the two black "common" taps, connects that point to ground, and pulls the signal off of the red 8ohm tap (on the secondary).  So it seems the signal would come in via the blue 0.25w tap, go out the common on that side and get tied to ground.  In that configuration, I suppose it could be using the Speco as a true transformer instead of an autoformer?  If that were true, I'd expect to at least hear some output, but I got nothing.  Maybe I'll try that again.

Can anyone confirm that the diagram is correct for 32ohm for the New Speco?  And is it right, then, that it's using the Speco as a transformer?  I have some other configurations I may try out for learning purposes, but I'm happy enough as it is.