Protection of the high-frequency speaker when switching from passive crossovers to DSP separate amplification of the bands.

[Argentum 05]

My Yamaha NS 700X speakers, which I've decided to convert to DSP crossovers, use a JA 0580 tweeter (6 ohms).
I'm wondering how to protect the tweeters if a malfunction causes them to receive the full gain band. The factory crossover frequency is 4000 Hz. I intend to maintain the authenticity of the settings from the Japanese engineers.
For protection, I'm planning to install capacitors with a total capacitance of about 12 µF (2x5.6 + 0.68).
Would it make sense to additionally install a fast-blow fuse (250 V, 1 A) such as a Littelfuse 0216001.HXP or SIBA 179021.1?
Will soldering such a fuse negatively impact sound quality?
Also, is it even necessary to use this extra protection if the DSP is a Helix DSP 3?

Please excuse any stylistic errors - I use Google Translate.

 

[sergeauckland]

I had the same concerns as the tweeters on my B&W 801s are now pretty much impossible to replace.


I put a 68uF for the HF and 470uF for the MF to protect against the amplifiers going DC, and a 1Kohm resistor to ground to ensure a DC path as some amplifiers like to see a DC path on their output to get the lowest DC offset. These capacitors won't protect much against putting LF into the tweeters, so for that, I'm ultra-careful any time I have to disturb the connections. After double and triple checking, I play some music VERY quietly and make sure the right frequencies go to the right place. I use 4mm terminals, as they're convenient for making measurements as I can put a meter directly across any driver, but for safety, it would be better to use a multiway Speakon, as once that's right, it won't change. Only difficulty is getting thick enough cable into a multi-way Speakon.

S.

 

[Argentum 05]

I put a 68uF for the HF and 470uF for the MF to protect

So much?


I'll be using a Yamaha AX 892 amp for high-frequency boost. It'll be connected to the CD input. I'll probably have to turn the volume down each time, and then carefully turn it up when turning it on.

 

[wwenze]

Keep the original capacitor HPF and do your DSP as if you had a full-range driver.

 

[Devnull]

You want to be at least 2 octaves under your xover point for protection. So 25 uF at a minimum. Use a fuse holder if you must use a fuse.

I personally don't use any protection on my active 3 ways but I trust my DSP and use very robust drivers

 

[sergeauckland]

So much?


I'll be using a Yamaha AX 892 amp for high-frequency boost. It'll be connected to the CD input. I'll probably have to turn the volume down each time, and then carefully turn it up when turning it on.

Yes because I wanted the -3dB point to be at least an octave away from the crossover point. Anyway, they were meant for DC protection, not against incorrect connections, so I calculated (more estimated) the charging current that would not be sufficient to cause damage to the tweeter, and used that to work out the capacitor size.

S.

 

[Argentum 05]

You want to be at least 2 octaves under your xover point for protection. So 25 uF at a minimum.

I was planning to use a 12µF capacitor, based on the assumption that the true frequency (4kHz) requires 6.6µF for a first-order filter. If I lower it to 2200Hz, I'd need 12µF. This crossover frequency shouldn't interfere with the DSP.
Perhaps I'm mistaken?

Use a fuse holder if you must use a fuse.

That's the point, I don't know if it's needed)))

 

[Argentum 05]

Keep the original capacitor HPF and do your DSP as if you had a full-range driver.

Then the whole idea is lost. The mid-frequency filter will have to be retained or redesigned. Ultimately, little will change.

 

[Devnull]

Why go close to the xover point? You're guessing what the impedance is so you're better off going bigger than smaller. You don't want the protection having any impact on the frequency response.

 

[sergeauckland]

Why go close to the xover point? You're guessing what the impedance is so you're better off going bigger than smaller. You don't want the protection having any impact on the frequency response.

Indeed. In my case, with the crossover being 48dB/octave, I reckoned that as long as I was at least one octave away, it wouldn't have any audible effect on the frequency response. In any case, the whole system was equalised flat separately, so any anomalies were corrected anyway.

S.

 

[Argentum 05]

Why go close to the xover point? You're guessing what the impedance is so you're better off going bigger than smaller. You don't want the protection having any impact on the frequency response.

I assumed that at 12 µF, at the cutoff frequency (4 kHz), the rolloff would be about 0.1 dB. Error level.
I thought there shouldn't be any impact, and at the same time, a first-order filter would provide the maximum possible protection.
Do you think I should go lower?

 

[Argentum 05]

I'm curious, how likely is it that a DSP glitch could cause such problems?
I haven't heard of any such cases. My Wiim Pro Plus has never had any glitches related to volume changes.
Maybe I'm being overly cautious?
But as the saying goes, "Just because you're paranoid doesn't mean you're not being watched."

 

[dualazmak]

I am in the similar world of "PC-DSP-based multichannel multi-SP-driver multi-amplifier full-active audio setup" using SP drivers and cabinet of Yamaha NS-1000 (not NS-1000M).

I have been using protection capacitors all the way through my project for my treasure 8.8cm Beryllium dome midrange JA-0801 and for 3cm Beryllium dome tweeter JA-0513, as well as for additional metal horn super-tweeter Fostex T925A; 68µF, 10µF, 10µF respectively.

For the details of the latest total system setup, please visit my posts #931, #1,009 and #1,022 on my project thread.

I have repeatedly measured and confirmed the acoustic "transparancies" of the protection capacitors in their covering Fq zones as shared in my posts #402 and #1,009.

You can also find my DSP crossover configuration and the actual room sound Fq responses at my listening position in my post #1,009;

Some fonts in Fig.19 are very small and may be difficult to read. If you would like to see them clearly, therefore, you would please find and download the attached ZIP file (Fig19_post-1009.zip) containing high-resolution 2106 x 3077 pixcel .png image of above Fig.19.

 

[Gibsonian]

I actively triamp and use nothing in between amp and tweeter for protection. This with high buck beryllium dome tweets. I used to use capacitor for protection but no more. No need to be afraid

 

[Argentum 05]

I am on the similar world of "PC-DSP-based multichannel multi-SP-driver multi-amplifier full-active audio setup" using SP drivers and cabinet of Yamaha NS-1000 (not NS-1000M).

Oh, thank you! You've done a tremendous job. I'll definitely check out your topic.

 

[Argentum 05]

I actively triamp and use nothing in between amp and tweeter for protection. This with high buck beryllium dome tweets. I used to use capacitor for protection but no more. No need to be afraid

How long have you been using your configuration?
Perhaps I'm being overly cautious.

 

[JaMmy]

Indeed. In my case, with the crossover being 48dB/octave, I reckoned that as long as I was at least one octave away, it wouldn't have any audible effect on the frequency response. In any case, the whole system was equalised flat separately, so any anomalies were corrected anyway.

S.

Does the type of capacitor matter given that it’s in the signal path? And do you put that 1k resistor before or after the cap? I use a circuit that’s supposed to trip a relay if it senses DC ( Rod Elliott’s design) but I’m still faintly paranoid about my B&W 801 tweeters.

 

[dualazmak]

Does the type of capacitor matter given that it’s in the signal path? And do you put that 1k resistor before or after the cap? I use a circuit that’s supposed to trip a relay if it senses DC ( Rod Elliott’s design) but I’m still faintly paranoid about my B&W 801 tweeters.

Such relays, as well as fast-blow fuses, could be highly possibly "too late" to protect your treasure SP drivers from DC-like damage!
I remember @gene_stl nicely argued in this regard... @gene_stl, would you please come into this thread, if possible?

 

[Devnull]

I assumed that at 12 µF, at the cutoff frequency (4 kHz), the rolloff would be about 0.1 dB. Error level.
I thought there shouldn't be any impact, and at the same time, a first-order filter would provide the maximum possible protection.
Do you think I should go lower?

Again let me state - you are guessing what the impedance of the tweeter is. Until you actually measure the tweeter without the crossover you can't accurately predict what's going to happen at your chosen crossover point with the capacitor value that you have chosen. Therefore to provide some protection I would go at least 2 octaves down using your guess as to the tweeters impedance.

 

[Gibsonian]

How long have you been using your configuration?
Perhaps I'm being overly cautious.

Without any protection? About 2 years on tweeter. Always on mid and woofer. I’ve made some start up and shutdown booboos as well since then with some pops thru the tweets and no issues. I do no recommend that practice and I’ve since cleaned up my act!