Realisitic 2 Electrostat Crossover Help

[SFinSF]

Disclaimer- I'm pretty green at working with caps, etc. This is a "learning" project.

Hoping someone could help me identify a part on the crossover for Realistic Electrostats. There are approx 3 versions of this crossover and most of what I can find deals with a later version.

Mine has power issues to the electrostats which seems to be common. The solution is to replace the diodes. However, I'm not exactly sure what to replace them with as they don't seem standard. The board is marked Se/1MΩ, the actual part is marked "SM". See link below for pics:

Realistic Electrostat 2 Crossover - Album on Imgur

I'm hoping some of you could help identify what type of diode this is and go even further by explaining why the design looks so different.

Thanks!

 

[bentoronto]

Are those electrostatic panels?

If true, you should try posting in the planar and ESL forum where your questions will be answered right away.

Ben

 

[SFinSF]

They are, thanks for the advice.

 

[ticknpop]

Any hv diode rated 5 kv or higher should be fine.

Those gray capacitors should be replacecd with similar values of film cap , preferably polypropylene and even better film and foil polypropylene.

Date code looks like 6612 on the resistors 1966 12 week or month?
I'd replace those with some HV rated ones just given thier age

 

[SFinSF]

Thank you!

I was definitley planning on replacing the caps. .05uf @ 600v seems in short supply. Would a .047 or .048 be okay?

 

[bolserst]

Although it is probably a good idea to replace all the caps and diodes considering the age, they may be working fine.
In another thread we traced the problem on a model 2a to loss of contact between the diaphragm coating and the frame.

Here is post with schematic and notes for testing to see if the bias supply is working.
Bias supply only runs about 300Vdc so you can measure with most any DVM.
HELP! Low tweeter output, hybrid esl...post#13

If bias supply is working, check for continuity between the aluminum coating on the outside of the diaphragm and the metal frame as in pic4 here:
HELP! Low tweeter output, hybrid esl...post#27

Let us know what you find out.

 

[SFinSF]

Nice! Thank you so much. Will report back.

 

[ticknpop]

Yes .047 is fine, i would change them, the originals are 50 year old electrolytics, not film caps and not high values so easy to update to film caps for reliability reasons , let alone improved sound

 

[concertgrand]

Realistic Electrostat 2a woofer data

Tested two woofers that came out of a pair of Realistic Electrostat 2a speakers.
They are fully functional.
Ran DATS on them and they both passed the buzz test.

 

[concertgrand]

The DATS test was run on these

Since there may be a variety of woofers used, here are pics of what they look like.

 

[concertgrand]

A better woofer for the Realistic Electrostat 2a ?

I replaced the existing woofers with the following.

W 200 - 8 Ohm | Visaton

They don't fix the bass problem but they sound better to my ears.
No drilling of new mounting holes is necessary but I did have to buy new M4 type bolts that are of the same length but are threaded all the way to the end.


If anyone knows of a better plug-n-play woofer for the 2a please let me know.

 

[concertgrand]

Realistic Electrostat response with new woofer

Used OmniMic software. Mic 1m from speaker and directed at lower tweeter element. Tweeter control on back of speaker set to MAX. Used Realistic Electrostat 2 speaker terminals on back of speaker.

 

[concertgrand]

Realistic Electrostat 4a schematics

View attachment Realistic_Electrostat_4a.bmp

 

[concertgrand]

Realistic Electrostat 4a woofer parameters

6 screws on each woofer

Hole cut-out on speaker box = 243 mm
Screw diameter center to center = 262 mm
Recessed cut-out to mount speaker = 284mm
plus/minus 2mm


Using DATS:

 

[bolserst]

@concertgrand,
Thanks so much for taking the time to post your measurements and schematic for the model 4a.

Used OmniMic software. Mic 1m from speaker and directed at lower tweeter element. Tweeter control on back of speaker set to MAX. Used Realistic Electrostat 2 speaker terminals on back of speaker.

Was this measurement taken using the original woofer? Or with the Visaton replacement.

…They don't fix the bass problem but they sound better to my ears.

What is the bass problem you experienced?

 

[concertgrand]

Reply to questions about the Realistic Electrostat 2a

Q: Was this measurement taken using the original woofer? Or with the Visaton replacement.

The measurement was taken using the Visaton.

Q: What is the bass problem you experienced?

The word "problem" is incorrect. I meant that I wished the bass go deeper.
From the frequency plot of the speaker it takes a nose dive at 70Hz.

I thought this speaker is an acoustic suspension speaker but then shouldn't the bass drop by 12db per octave? Or can the room alter the bass response?

 

[bolserst]

The room can definitely alter the low frequency response. Try taking a measurement with the mike about an inch from from the woofer to confirm what the low frequency response of the woofer is.

 

[concertgrand]

Visaton woofer nearfield

Mic placed next to speaker grille cloth.

 

[planet10]

Since there may be a variety of woofers used, here are pics of what they look like.

The numbers (the format) suggest a woofer OEMed by Coral. Not surprising, many RS speaker si have disassembled have nice Coral woofers, usually in too small a box.

dave

 

[concertgrand]

Identification of Realistic Electrostat 4a mid-range

Can you identify if either of the following mid-range speakers I pulled out of two Realistic Electrostat 4a speakers are Coral drivers and if either is original?





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