A-2X problem

[mayloc]

Hi Chris, I was curious because in the photo they show the panels without the grilles and I thought they could be removed without touching the panels. However, I have to dismantle everything because the frames are slightly damaged and the panel is not fixed well to the base, I have to change the canvases. In your Soundlab experience can the A-2x with a 25w OTL amplifier with two 6C33Cs work? Not for the volume, certainly low, the low impedance of the panel at 20khz scares me. Thanks Daniele

[ChrisSoundLab]

Hi Daniele, Honestly, I’m not so qualified to answer that with any confidence – especially because I cannot give you any specs or experience because I have not owned these before. the low impedance at high frequencies is not tough to drive (relative to low impedance at low frequency) – turning down the brilliance does increase the impedance however … the impedance curve for new Sound Labs is attached for your reference – note the difference with brilliance low and high.

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[mayloc]

Thanks Chris, what a gift you gave me.. A-2X like mine with the inventor and you who repaired mine, all in one photo, perfect timing. But to remove the grida covers, don’t you need to remove the panel? Daniele

[ChrisSoundLab]

Thank you for the feedback!
You do not need to remove the panels on new models…I would think not necessary on yours either.
Normally you remove the outer wood frame (easily) and the covers are most likely stapled into the panels. Not so difficult to remove if you strip or cut off, but not so easy to put back without a little skill to make them taut – pulled tight across with no wrinkles (takes practice).
Shall I check the detail for you?
Cheers
Chris

[Massimo Stefanizzi]

Congratulations Chris! You are doing a great job, I really appreciate the videos and the interview with Roger.

[ChrisSoundLab]

Most appreciated, I will do what I can!

[ChrisSoundLab]

Hi Daniele,
I was just at Sound Lab … really rare and interesting timing, but he has a pair of same speakers in from a customer to give them a ‘face-lift and fix up’ – but they sound great just as they are …. not sure if you have seen them without the grill cover …and to note the high frequency … you may want to have them position so highs are on the outside to give wide sound stage (opposite as this photo shows… up to you to experiment. Hope all goes well!
(I’m not so important, but you might like to see Roger who is the inventor, designer, brains behind all of Sound Lab.)

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[mayloc]

Hi Chris I can’t see your contact, can you resend it to me? Thanks Daniele

[ChrisSoundLab]

That’s interesting, I suppose I am not able to add a web address in the forum … please see photo or try googling
Sound Lab Electrostats Japan

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[mayloc]

Hi Chris, today I tried to adjust the bias and the settings were both completely counterclockwise. With your suggestion I turned clockwise until I heard light crackling and turned up the music volume. Now the music can be heard, not loud but I had to raise the bias until almost the end of the ride. Are there any problems with the panel if the bias is set that high? Thanks Daniele

[ChrisSoundLab]

Let me know if there is anything else I can help you with.
If you are new to this site and Sound Lab, you may wish to see my new website and contact me thru that contact:

Please note that I can offer service to you anywhere in the world.
All the best,
Chris

[ChrisSoundLab]

Hi Daniele, there is no problem with bias being set at any position, the bias is intended to be best at higher levels and better performance more to the right clockwise as long as there is no crackling sound which interferes with the music.

[mayloc]

Hi Chris, yes I checked the fuses first but I didn’t know how to adjust the bias. Let’s hope it’s just the bias that needs adjusting. I’ll try tomorrow. Thanks Chris, your advice is invaluable. Daniele

[mayloc]

Hi Chris I tried to disconnect the 220v voltage from a panel but I can’t hear anything so I don’t know if I have 10000v but there is something. for the power supply voltage I think it is right on the back it has the typical European VDE connector. Do you know anyone who may have a wiring diagram? Thanks Daniele

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[ChrisSoundLab]

Sorry to ask simple question – but you have confirmed fuse is OK?

And have you used the bias adjust control?

Counterclockwise bias is very weak and volume would be low, turning clockwise will increase bias and sensitivity to membrane and should be a crackling sound – proper position is to be just before crackling sound begins. (no damage to membrane with crackle)

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[mayloc]

Thanks Chris for the information, let’s see if I can quickly build a 1:100 probe for my fluke meter. Another test is to disconnect the 220v from a panel to see the difference. both panels sound very low but the same… it is difficult for there to be the same defect in two panels. What do you think ? thanks Daniele

[ChrisSoundLab]

I’d say its rare to have exactly same defect in both panels which is why I suspected no power to charging the panel – if that’s true then yes, disconnecting the power to the backplate and if nothing changes (same very low output) will likely confirm that. Assuming of course that the panels were originally built for 220v?

[mayloc]

here’s a photo of the back

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[mayloc]

Hi cris thanks for the quick reply
and for your interest, they are not the ones in the photo, mine have light fabric, of the A-2x I only know that they have the upper part the same as the dynastats and the bass part as a panel, do you think the polarization voltage is missing?
How many volts should the bias be? Thanks Daniele

[ChrisSoundLab]

Hi Daniele,
It would seem so, yes … but I cannot really speculate.
I was checking a little on google, I found this model to be from around 1985. The backplates were much different back then – really everything was different and still in development stages. The regulated bias voltage in back plates now are variable and I have been told many times and I continuously forget. But the old models the voltage potential was much lower because materials and insulation could not survive higher voltages. I know the panels now at peak music power will generate up to 30,000 volts. The older maximum was more like 10,000 I think. Keep in mind the backplates now only draw 2 watts to charge the panel… but I am not at all qualified to comment more and I am afraid I am not sure how I might help you, but someone else on this forum might help.

[ChrisSoundLab]

I was trying to find the A-2X – my goodness, this goes back a very very long time … I would have to ask Roger (if you are new to the site you should note Roger is the founder and owner of Sound Lab) – but I guess these go way back to the 1980’s…. someone else out there might now more than me on this. (I will see Roger next week though)
I found the photos of A-2X on line…. I don’t suppose these are the actual speakers you are referring to?

Chris

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[ChrisSoundLab]

First comment I can quickly make is that if the sound is very weak, it is quite possible that there is no power going into the panels.
If amps are powered up and connected to the speakers, there will be still some very low volume sound even if the speakers have not been plugged in.

Chris

[mayloc]

Hi everyone, I’m new to the forum and I’m asking for advice on the A-2X I bought recently to overhaul the structure and change the canvas. Finally I was able to connect them to a 200w amplifier but the sound can be heard on both but very weak. Can anyone give me some advice? sorry for the English, I’m using the translator. Hi Daniele

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