Yamaha ns700x crossover high frequency section capacitor parameters

[Argentum 05]

Please help me find the nominal values of the capacitors in the HF section of the Yamaha ns700x crossovers.

I decided to check the capacitances in the crossovers of the acoustic systems, and there are aluminum cylinders on the HF, without any distinguishing marks. I can't find any technical information on them.

 

[Sokel]

Can't find 700's but 690's should be close:

 

[Argentum 05]

Can't find 700's but 690's should be close:

View attachment 472955

Thanks.
I was able to find the ns1000m and ns777 schematics. They have 2.7 and 3.3 capacitors. The ns690 has 2.5. They are all different.
I can't find anything for the 700x.

 

[Sokel]

Thanks.
I was able to find the ns1000m and ns777 schematics. They have 2.7 and 3.3 capacitors. The ns690 has 2.5. They are all different.
I can't find anything for the 700x.

You can calculate it by the x-over's frequency, for 700's it's 4kHz.

 

[Argentum 05]

You can calculate it by the x-over's frequency, for 700's it's 4kHz.

Yes, I did the calculation in the program. For a cutoff frequency of 4 kHz, it gives a result of a capacitor of 3.316 μF
Measurements of these two capacitors with a multimeter show 5.77 and 5.69 μF
A very strange result.
If this is capacitor degradation, is such synchronicity possible?

 

[thewas]

Loudspeaker drivers have almost never constant and nominal impedance and response, also effects like the baffle change the response so much that the real crossover functions and values differ a lot to the theoretical values, meaning they can be only measured and/or simulated but not computed with the standard electric circuit formulas.

 

[Cbdb2]

Why are you replacing them? I wonder why these caps are 1/10 the value of the woofer caps but the same size. Are we sure there electrolytics?

 

[Argentum 05]

Loudspeaker drivers have almost never constant and nominal impedance and response, also effects like the baffle change the response so much that the real crossover functions and values differ a lot to the theoretical values, meaning they can be only measured and/or simulated but not computed with the standard electric circuit formulas.

I mentioned above that three models, 1000m, 777, 690 used capacitors of 2.7 μF, 3.3 μF, 2.5 μF. Could the capacitor value (5.7 μF) for 700X be so different?

 

[Argentum 05]

Why are you replacing them? I wonder why these caps are 1/10 the value of the woofer caps but the same size. Are we sure there electrolytics?

There are no + - symbols anywhere.
I want to check the capacitors are correct to protect the tweeters.

 

[thewas]

I mentioned above that three models, 1000m, 777, 690 used capacitors of 2.7 μF, 3.3 μF, 2.5 μF. Could the capacitor value (5.7 μF) for 700X be so different?

It is not impossible. If someone has still an active account at Hifi Engine he can download its service manual below, unfortunately it seems my account was deleted due to inactivity.

https://www.hifiengine.com/manual_library/yamaha/ns-700x.shtml

 

[thewas]

There are no + - symbols anywhere.
I want to check the capacitors are correct to protect the tweeters.

In loudspeaker crossovers even if electrolytic caps are used these are bipolar as music signal is not DC.

 

[Argentum 05]

If someone has still an active account at Hifi Engine

I already asked in another chat. It seems that no one has access to that site.

 

[thewas]

I already asked in another chat. It seems that no one has access to that site.

In this case it doesn't cost anything to email your local Yamaha distributor or even Yamaha Japan, some companies even give a helpful reply.

 

[Argentum 05]

In this case it doesn't cost anything to email your local Yamaha distributor or even Yamaha Japan, some companies even give a helpful reply.

I guess I'll have to do that.
I didn't think it would be so hard to find information about these capacitors. I wonder why they are unmarked. In all the photos I found online, they look like clean aluminum cylinders.

 

[DVDdoug]

Measurements of these two capacitors with a multimeter show 5.77 and 5.69 μF
A very strange result.

Do you trust your meter? Capacitance measurements aren't necessarily that accurate. Maybe try a known good new capacitor, and the tighter the tolerance the better. There are tolerances so you can't expect them to measure exactly the same or exactly the value that should be marked.

If this is capacitor degradation, is such synchronicity possible?

Possibly. Plus there is tolerance. 20% tolerance is pretty common for electrolytics. Hopefully, they are using something better in a crossover but I don't even know if you can get 5%. Higher end crossovers use some kind of film capacitors. Film capacitors come in tighter tolerances and the are more stable (they don't normally age), and they are more expensive.

There are no + - symbols anywhere.

They are non-polarized. You can't use regular polarized electrolytics because audio is AC.

I want to check the capacitors are correct to protect the tweeters.

Usually as electrolytic capacitors age the capacitance goes down which makes the crossover/filter frequency to go up and that would give MORE protection, but of course it would make a gap between the midrange and tweeter. But it's not necessarily going to change at all or change enough to go out-of-spec.

It is possible for a capacitor to short-out and then the tweeter would be fried by the bass. That's very rare.

 

[Argentum 05]

Do you trust your meter?

I have pre-measured 4 new capacitors from different manufacturers. There were deviations from the nominal value, both positive and negative, but the largest deviation was no more than 3%. I use a cheap multimeter Aneng SZ08, but it measures capacitors adequately.

Usually as electrolytic capacitors age the capacitance goes down which makes the crossover/filter frequency to go up and that would give MORE protection

Yes, I know about it, but I heard somewhere that there are capacitors whose capacitance can increase with age.
Is this possible?

I apologize if I formulate the questions not quite correctly - I use Google translator to generate text in English.

 

[audio_tony]

I downloaded the service manual.

Here's the schematic. I have also attached the PDF.

 

[Argentum 05]

I downloaded the service manual.

Here's the schematic. I have also attached the PDF.

View attachment 473076

Thank you very much!