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Author Topic: The Official Guide to Converting your Quickie for Headphone Use  (Read 61574 times)

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Offline cpaul

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #15 on: August 23, 2010, 05:40:23 PM »
OK, so the Speco won't work with low impedance phones like my Grado SR60s (35 ohm "normal" impedance)?  So is there something I could do if I choose to purchase a Quickie (ummm, my wife isn't listening is she???)?  I mostly want it as a line amp, but was interested in potentially adding a headphone output.  I'd probably use some switch mechanism to remove the headphone iron when not in use unless there's some reason not to do that.

Thanks all.

Offline Paul Joppa

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #16 on: August 23, 2010, 07:37:11 PM »
What you want is an 8K:35 ohm transformer. I'm not aware of any. Here are some ideas:

1) Look for a small 4K:16 or 5K:16 - the turns ratio is right at least, and you might find something acceptable, maybe one of the smaller Hammond 125x series.

2) Somebody like Edcor might make one custom, they seem pretty flexible these days.

3) The new Stereomour output is not currently available separately, but if Doc decides to sell it you can wire it for 8K:32 - I always planned to use it in a revised SEX eventually.

The power level is very low compared to even transistor-radio standards, so a very small transformer will be plenty big enough. The only risk is, many tiny transformers are designed for small portable gear and may have inadequate inductance for good bass.
Paul Joppa

Offline vanofmonks

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #17 on: August 24, 2010, 02:38:59 PM »
Actually Edcor EM0735 is an 8kct to 250 ohm transformer with a 32 ohm tap.  I had them make it, so the design fee is paid for.  You can check the price for them.  I haven't used them yet mainly because I have been too lazy to figure out how to hook them up.  Is there a way to use these as an autoformer like the speco?  Or should I just connect them like a regular transformer.  I would be willing to donate a pair to someone who has the equipment and ability to optimize their use.

Offline Paul Joppa

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #18 on: August 24, 2010, 07:46:48 PM »
The Speco has many taps on the high-impedance primary winding, including one at 500 ohms, so an autoformer is the only way to drive high impedance phones with it. The Edcor you describe has no such limitation, and can easily be used as an ordinary transformer. That's how I would do it.
Paul Joppa

Offline cpaul

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #19 on: August 25, 2010, 04:36:32 AM »
Thanks for the replies.  I have contacted Edcor about the custom iron, and will research this more.  May just build it without to start, and modify later.

Offline Dr. Toobz

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #20 on: August 25, 2010, 11:38:50 AM »
Edcors should work well - I've experimented with their mid-range irons (8k to 8 ohm) with the Quickie circuit, both in series and parallel feed. (For the latter, I used 150H plate chokes and 3.0uF coupling caps). While there is definitely less power at 8 ohms, the Quickie seems to work great with Edcor transformers. An 8k to 250/32 ohms would be quite ideal.
A Bottlehead since 2009: S.E.X. 2.0, Stereomour (2A3), Eros & Seduction Phono, Crack, Quickie 1.0 (sold), Klipsch Heresy III speakers, Grado SR-325e headphones

Offline cpaul

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #21 on: October 24, 2010, 03:31:21 PM »
Edcor got back to me about the EM0735.  As of September they were $10.23 each, plus shipping.  I did order the Quickie - still waiting for it to arrive - but haven't decided what to do about the output for headphones.

Offline Doc B.

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #22 on: October 24, 2010, 04:16:41 PM »
Quickies have been back ordered due to a snafu in production of the last batch of chassis plates. The replacement plates were completed this weekend and there should be a big stack of Quickies shipping in the coming week.
Dan "Doc B." Schmalle
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Offline cpaul

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #23 on: October 24, 2010, 04:34:39 PM »
Thanks for the update, Doc.  I was wondering what the timing would be.

Offline SPaulMac

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #24 on: March 26, 2011, 10:47:39 AM »
I recently completed my Quickie with the headphone conversion and would like to share my experience. Everything went swimmingly until I pulled the Speco transformers from their boxes to find they were almost exactly nothing like those described in the post. Although the boxes were labeled as T7010 transformers, mine were physically smaller, only had two wires on the secondary side, had seven wires on the primary side none of which were .625W and a completely different color code. Worse yet, two wires exited from the last notch in the bobbin leaving me with no idea which should be connected to the signal. While I can follow directions well enough to assemble a kit the finer details of electronics are beyond me and not having found any specifications for this newer version of the T7010 online I was (after a trouble night) left with the brainstorm of measuring the relative resistances between the 10W brown wire and the other wires. Having done this I settled upon the Violet wire as being that labeled as .5W which was the closest value available to the .625W suggested in the original post. If anyone can suggest a better selection than the 10W/0.5W that I settled upon, I'd greatly appreciate your input. In fact, I would enjoy hearing any suggestions on my implementation that might improve the sound of this lovely little amp.

Correct or otherwise, the Quickie has turned into a quite enjoyable little headphone amplifier. While the output is not substantial enough to drive my inefficient AKG K501 to anything above barely acceptable levels, it has proved a wonderful match for the Beyer DT880 (250 Ohm).

If it should be of any help, as best I can determine, this is the color code for the version of the T7010 I received:

Primary

Common: Black, 10W: Brown, 5W: Red, 2.5W: Orange, 1W: Yellow, 0.5W: Violet, 0.25W: Blue

Secondary

Common: Black, 8 Ohm: Red

(http://i893.photobucket.com/albums/ac140/spaulmac/Bottlehead/IMG_0244.jpg)
Stephen Morris

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Offline Paul Joppa

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #25 on: March 28, 2011, 09:18:46 AM »
That news is quite distressing. When we chose the Speco from a field of more than a half dozen candidates, we did so because the transformer we had been using changed without notice, and the new version was quite inferior. If the Speco has changed substantially, we may have to go through that exercise again. Stay tuned ...
Paul Joppa

Offline sbelyo

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #26 on: May 02, 2011, 07:17:44 AM »
Actually Edcor EM0735 is an 8kct to 250 ohm transformer with a 32 ohm tap.  I had them make it, so the design fee is paid for.  You can check the price for them.  I haven't used them yet mainly because I have been too lazy to figure out how to hook them up.  Is there a way to use these as an autoformer like the speco?  Or should I just connect them like a regular transformer.  I would be willing to donate a pair to someone who has the equipment and ability to optimize their use.
I just ordered a pair of these.  Now I just have to get a quickie

Offline Wanderer

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #27 on: May 02, 2011, 10:25:30 AM »
That news is quite distressing. When we chose the Speco from a field of more than a half dozen candidates, we did so because the transformer we had been using changed without notice, and the new version was quite inferior. If the Speco has changed substantially, we may have to go through that exercise again. Stay tuned ...

Inquiring minds want to know....

Looking at the S.E.X. page seems the Specos are currently NOT useable. My ones are the "old" style so lucky me!

Are youse guys gonna sell the Stereomour outputs separately for headphone conversion? Would these be a big up from the Specos? Better bass? I would assume they would cost more then the cheapsy old Specos.     
Kevin R-M

Offline InfernoSTi

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #28 on: May 02, 2011, 04:04:07 PM »
Where did you order those from?  Do they look like these? http://www.amazon.com/Speco-10W-70V-Line-Transformer/dp/B001MJFB8E/ref=sr_1_1?ie=UTF8&m=A3AFCSA6JU2B0W&s=merchant-items&qid=1304387790&sr=1-1  I think the specs listed are the same as the old specs but the model number isn't listed. 

John

I recently completed my Quickie with the headphone conversion and would like to share my experience. Everything went swimmingly until I pulled the Speco transformers from their boxes to find they were almost exactly nothing like those described in the post. Although the boxes were labeled as T7010 transformers, mine were physically smaller, only had two wires on the secondary side, had seven wires on the primary side none of which were .625W and a completely different color code. Worse yet, two wires exited from the last notch in the bobbin leaving me with no idea which should be connected to the signal. While I can follow directions well enough to assemble a kit the finer details of electronics are beyond me and not having found any specifications for this newer version of the T7010 online I was (after a trouble night) left with the brainstorm of measuring the relative resistances between the 10W brown wire and the other wires. Having done this I settled upon the Violet wire as being that labeled as .5W which was the closest value available to the .625W suggested in the original post. If anyone can suggest a better selection than the 10W/0.5W that I settled upon, I'd greatly appreciate your input. In fact, I would enjoy hearing any suggestions on my implementation that might improve the sound of this lovely little amp.

Correct or otherwise, the Quickie has turned into a quite enjoyable little headphone amplifier. While the output is not substantial enough to drive my inefficient AKG K501 to anything above barely acceptable levels, it has proved a wonderful match for the Beyer DT880 (250 Ohm).

If it should be of any help, as best I can determine, this is the color code for the version of the T7010 I received:

Primary

Common: Black, 10W: Brown, 5W: Red, 2.5W: Orange, 1W: Yellow, 0.5W: Violet, 0.25W: Blue

Secondary

Common: Black, 8 Ohm: Red

(http://i893.photobucket.com/albums/ac140/spaulmac/Bottlehead/IMG_0244.jpg)

John Kessel
Hawthorne Audio AMT K2 Reference Speakers
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CAPS V3 w/SOtM Linear Power Supply & PPA USB

Offline SPaulMac

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Re: The Official Guide to Converting your Quickie for Headphone Use
« Reply #29 on: May 02, 2011, 04:42:20 PM »
Hello John,

I purchased mine from Wallco Industrial Electronics. They don't look anything like those in the Amazon photo; are rather generic in construction with a simple electrical tape type wrapping on the winding and in fact have no Speco nor T7010 markings whatsoever. The boxes did have Speco's branding and were sized correctly for the smaller transformers I received, but I'm getting the sinking feeling I may have received cheap substitutes. My fault for discovering Bottlehead so late in the game. :)

Stephen
Stephen Morris

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Adcom GFP-565
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