ESTA 4u inside

[Pirx]

Hello

I had a chance to buy two pairs of Stax ESTA 4u speakers.

Both pairs look nice, but all four had imbalance issue and I decided to check what is inside and if I can repair them.

As you can see, drivers are easy to open. The disintegrated foam's particles got into drivers and stick to the diaphragm (foam was layered with some glue).

I had to clean it all from this and use Licron on diaphragms (I did that only with one pair atm).

Now the one pair works well, bas is not so strong, but it is enough to work with some active sub.

The stereo sweet spot is really thin, but when you seat in the right place the image is sharp and precise.

I'm thinking about rebuilding the second pair, but to use drivers to make custom speakers, rather tall, just to use it as computer speakers.

Naked driver.

[chinsettawong]

Thanks for sharing those nice pictures.  The driver looks so much like my JF clone drivers.    

Do you have its measurements?

 

[Pirx]

I don't have any measurements  except Stax data on picture.

What is the biggest surprise? This is 3 way project !

There are two diaphragms but 8 stators.

Looking from the back of the speaker:

the left driver is full playing bass and lower mids. The right driver is two way system. The very right part is playing bass and all mids. And the second part is driver with full signal from transformers.

 

 

Edited December 27, 2018 by Pirx

[chinsettawong]

I'm sorry, but what I meant to ask was did you have the driver's dimension?

 

 

[Pirx]

The open area (I mean the window where stators are open to outside) is 161x92 mm

The one stator is 104x171 mm (50x171 mm one part, mind the gap in the middle between stators in one driver).

Edited December 27, 2018 by Pirx

[spritzer]

So those are exactly the same as the kit Stax offered way back, one kit per speaker.  I need to dig that out but the plan was always to have an open baffle with a super quick woofer and a small enclosure in the bottom to house the electronics.  I need to do that at some point...   

[Pirx]

Open baffle for computer with small box at the bottom for electronics and maybe some little RIPOL (I have no idea if RIPOL can be made such small).

But this is what I'm thinking about. Those Stax speakers are to wide for my bench ?

[spritzer]

Yeah and I only have two electrostatic units so one per channel.  If you aren't worrying about the bass, then the baffle can be quite a bit smaller.

I might go look into some super stiff dynamic drivers now...

[Pirx]

Ah, you have one kit for one channel?  I see why you didn't do so much with it ...

And true, only simple baffle for one driver should be enough + some quick driver, did you consider Accuton? I have speakers with midbass and high from Accuton - for me the great drivers, and really quick for ESL.

[spritzer]

Those are great drivers but I'm far too cheap to use them for some project when I can spend 2K$ and get nice electrostatics.    I'm thinking something much cheaper...

[bwck2000]

Wow I haven't seen anyone owning two pairs of them before.Wiring them two speaker per channel makes them comparable with floor standing electrostatic panels. There was an offical accessory called JS-2 , a speaker stand for esta-4u. Although I couldn't find one for sale but I diyed one.

[Pirx]

Really nice looking stands.

At this moment I have Quads ESL63 and I have no more space for another pair of speakers ?

But I maybe I will give a try them stacked

 

Do you know that section with highs are on the opposite side when you flip speakers upside-down?

For sure the holographic can be better if speakers are in mirror.

I have rewired them and the effect is amazing !!!

[bwck2000]

On 10/24/2019 at 6:00 AM, Pirx said:

Really nice looking stands.

At this moment I have Quads ESL63 and I have no more space for another pair of speakers ?

But I maybe I will give a try them stacked

 

Do you know that section with highs are on the opposite side when you flip speakers upside-down?

For sure the holographic can be better if speakers are in mirror.

I have rewired them and the effect is amazing !!!

Actually there are two switches at the back for high/low frequency selection so it is not an issue.