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Old 14th February 2013, 10:58 PM   #41
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Quote:
Originally Posted by zeonrider View Post
I forgot, 303 or 404.

Sound was quiet and high raised THD.

Regards zeoN_Rider
That sounds like the problems I had with just one transformer. Was it also driven by a step up transformer? Did you put the volume to maximum just to hear something?
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Old 14th February 2013, 11:11 PM   #42
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Original set up Stax energizer + headphones worked OK.

Something did not add up, Stax energizer+Koss headphones.

Regards zeoN_Rider
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Old 14th February 2013, 11:13 PM   #43
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Dear all,

Thank you for your advice has been very practical and so incredibly useful.

In terms of measurements most I want to take are to find how "ideal" the transformer is for the power range I am using. I think

It will be a while before I get to into full system measuring, as the Spanish say, baby steps baby steps First I will be measuring accurately the peak voltages in every part of the system.

I want to define volume and peak values for signals both current and voltage. I will want some form of limiting preferably with a considerable level above listenable to prevent arcing if some one decides the Staxs are so nice they want to hear them as speakers. At the moment the limiting is provided I suspect by the non linearity of the transformers and the Quad 306 shutting down. This has been how I have been able to experiment without fear of damaging the headphones.

Quote:
Originally Posted by Bazukaz View Post
Anyway take measurements with a big grain of salt.
Knowing what your measuring is so often a problem I have seen this in my work. Its my suspicion that an ear makes all sorts of distortion to the sound its self but our brain expects it and without it all would sound odd to the listener.

I'm surprised how measurement free this project has been so far, and also how I saw the measurements measuring the wrong thing. I should hurry up, follow Bazukaz advice since the begging and just rig up 4 transformers per channel and see what I think.

Thanks again

Owen
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Old 14th February 2013, 11:49 PM   #44
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Quote:
Originally Posted by zeonrider View Post
Original set up Stax energizer + headphones worked OK.

Something did not add up, Stax energizer+Koss headphones.

Regards zeoN_Rider
From what you wrote, I strongly suspect you need to drive the Koss headphones with a higher voltage in Bias and from the transformers than the Stax.

For the Stax Lambda Pro with 580 Volt Bias and low distortion for +-300V peak to peak signal that I am currently targeting but will also try and not require a power house like the Quad 306.

The current needed is totally unknown, so I don't know it this is practical, but I should like a stylish 15 W per channel into 16 Ohms capacitor coupled amplifier I have to power the headphones. but we will see if we nee as much as 4 W per channel.

The good news is that you can up the Bias to increase sensitivity or reduce sensitivity within limits, Keeping Bias + Drive voltage going up slowly I continue to hope I avoid flash over by listening, if the volume is getting audible, then up the voltages slowly is my feeling, so I guess down with the bias and up with the step up ratio, and see how it sounds is my next plan.

Regards

Owen
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Old 15th February 2013, 08:43 AM   #45
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Hello zeoN_Rider,

koss-esp6-refurbished-vintage-electrostatics

I am not sure your model is similar in construction to this review.

Regards

Owen
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Old 15th February 2013, 08:58 AM   #46
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The SRD-5 and SR-3 that I got at a good price from ebay arrived today and I am pleasantly surprised how well they work in their original state. From what I have learnt already I can without doubt improve the SRD-5, and it should immediately have its capacitors replaced as although they don't do much work, and will have little effect on the sound, but they are older than me and could blow at any time.

Interestingly my SRD5 is multi voltage supporting 110 V and 240 V AC, most of the links I have seen on the web show only 110 V operation.
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Old 15th February 2013, 01:45 PM   #47
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Default impedance Stax transformer

I found another old measurement back

Impedance is very important for a esl(headhone) transformer. It makes the difference between good sound or not good sound and also easy to drive or difficult to drive.
Click the image to open in full size.
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Old 15th February 2013, 02:26 PM   #48
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Quote:
Originally Posted by esltransformer View Post
I found another old measurement back
Impedance is very important for a esl(headhone) transformer. It makes the difference between good sound or not good sound and also easy to drive or difficult to drive.
Thankyou very much esltransformer, that does like like an easier load than I would have expected. I feared an impedance curve similar to the Quad ESL 57 with nasty low impedance dips.

Regards

Owen
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Old 15th February 2013, 04:56 PM   #49
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Originally Posted by owenhamburg View Post
Thankyou very much esltransformer, that does like like an easier load than I would have expected. I feared an impedance curve similar to the Quad ESL 57 with nasty low impedance dips.

Regards

Owen
The Stax measure pretty good, only frequency and fase (+ & -) response from my own is better.
Maybe i will develop a new transformer for the Stax soon. I have new HiB (M0) material and my brother has bought a Stax too so if people here are interested i maybe can reduce the research cost.
See here a picture of my transformer:
Click the image to open in full size.
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Old 16th February 2013, 01:20 AM   #50
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Originally Posted by zeonrider View Post
I have a Koss ESP 9, does the driver for Stax responsible for the Koss?

Regards zeoN_Rider
SR-3 and Koss ESP 9 review.

So it looks like you have some nice devices their as these SR3's are very nice, though mine do need some maintenance.

Mine looks like all the pictures of a srd-5 except my plugs and leads and extension lead have what look like higher quality plugs on them, that are definitely not compatible with Stax 5 pin plugs as the it looks to me like a shielded 5 pin din as attached. I expect this is old work, probably before 1980, as I have only seen such solid construction of plugs and sockets on very old equipment. This "upgrade" is exceptionally well done work around for the lack of Stax Sockets, though today I would use a very different design of plugs, and I definitely doubt Shielded DIN plugs are not rated at 230 V RMS. When 5 Pin XLR plugs are rated 125V RMS, or maybe these are an older standard. It might have serial number 9059.

Regards

Owen
Attached Images
File Type: png 455px-DIN-5c_Diagram.svg.png (34.3 KB, 59 views)
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