Genz Benz NX2 Driver Replacement

[MrRubbish]

I seem to have blown both my drivers on my Genz Benz NX2 cab. Which I love and always gets comments about how great it sounds…

 

I removed them and tried the 9v battery test and nothing. 

 

I was using my 900w shuttle head on the last gig and it got a bit of hand with the levels… 

 

what replacement drivers would you recommended I replace with? So I don’t have the same problem in the future?

 

Faital Pro 12PR320?

thanks

 

[Bill Fitzmaurice]

Those look like OEM versions of the 12PR300, so it's highly unlikely they were at fault. The PR320 isn't much better, if at all. You'd have to go FH520 for that. I'd have the old ones re-coned.

[ebenezer]

I'm amazed they both blew!...I had the same cab and ran at quite high volume levels and never had a problem. 

[MrRubbish]

Yeah I’m not proud of it..  the amp was running on full for most of the gig and then I kicked a fuzz and octave pedal in and the first 12 went.. then about 10mins later the 2nd went. A fool I am.. alas it sounded awesome until they went. 

[Bill Fitzmaurice]

An octave pedal is what you use if you really really want to blow drivers. 🤥

[Dan Dare]

3 hours ago, Bill Fitzmaurice said:

An octave pedal is what you use if you really really want to blow drivers. 🤥

 

Spot on. I should imagine not enough cabs or wattage (OP mentions he was running the amp flat out) to shift sufficient air didn't help, either.

[MrRubbish]

So I will order some Faital Pro 12PR300’s 

 

or should I go for the 12PR320’s? what’s better?

[Bill Fitzmaurice]

The 320 has lower Fs and longer Xmax, better for the low end output.

[Chienmortbb]

9 hours ago, MrRubbish said:

So I will order some Faital Pro 12PR300’s 

 

or should I go for the 12PR320’s? what’s better?

Funny you should say that as I was considering putting a PR320 up for sale. PM me. AS BFM says it has close to twice the XMax and goes lower so you would not need to push so much low end power from the amp.

[agedhorse]

It's very uncommon to see a failed driver in those cabinets.

 

The best replacement is the 12PR300, it's not exactly the same but the primary difference is in the mid voicing (the 12PR300 is a little more polite) and the original parts have a slightly longer VC winding height. The important part is that the 12PR300 will work with the same cabinet tuning as the GNX-12350 without any fuss. I do not recommend anything else.

[MrRubbish]

20 hours ago, agedhorse said:

It's very uncommon to see a failed driver in those cabinets.

 

The best replacement is the 12PR300, it's not exactly the same but the primary difference is in the mid voicing (the 12PR300 is a little more polite) and the original parts have a slightly longer VC winding height. The important part is that the 12PR300 will work with the same cabinet tuning as the GNX-12350 without any fuss. I do not recommend anything else.

Thanks. That’s very helpful.

 

I’ll order some of those.

 

The ones that died had done at least a 1000 gigs over the last 10yrs or so.. lasted well I thought

Edited November 15 by MrRubbish

[Bill Fitzmaurice]

On 14/11/2024 at 15:29, Chienmortbb said:

Funny you should say that as I was considering putting a PR320 up for sale. PM me. AS BFM says it has close to twice the XMax and goes lower so you would not need to push so much low end power from the amp.

+1. In the same box tuned to the same frequency the 12 PR 320 has the advantage in low frequency sensitivity (first chart) and maximum SPL (second chart).

[agedhorse]

On 15/11/2024 at 12:49, Bill Fitzmaurice said:

+1. In the same box tuned to the same frequency the 12 PR 320 has the advantage in low frequency sensitivity (first chart) and maximum SPL (second chart).

That's not the box and tuning of the NX2, and the mid voicing is much better (IMO) on the 12PR300 (as well as our custom variant). That's a way overdamped application which I have always stayed away from.

Edited November 21 by agedhorse

[choob.squeemer]

As it happens I have a 320 too which I was thinking about selling - so if you want two , seems we have them 

[Chienmortbb]

On 15/11/2024 at 20:49, Bill Fitzmaurice said:

+1. In the same box tuned to the same frequency the 12 PR 320 has the advantage in low frequency sensitivity (first chart) and maximum SPL (second chart).

When you see that dip, as with the 12PR300 on the graph, run like hell.

[Bill Fitzmaurice]

The dip on the maximum SPL chart is where xmax is reached. Since the 320 has considerably longer xmax it also has higher maximum SPL at those frequencies where xmax , rather than thermal power, is the limiting factor. You really don't want that dip in the 60-90 Hz range, as that's where the output demands of electric bass are the highest.

[agedhorse]

8 hours ago, Chienmortbb said:

When you see that dip, as with the 12PR300 on the graph, run like hell.

That’s with an overdamped tuning which is NOT representative of the NX2 nor the customized version of that driver. 

 

You are comparing apples and watermelon, the only similarity is that both are fruits. 

[Chienmortbb]

1 hour ago, agedhorse said:

That’s with an overdamped tuning which is NOT representative of the NX2 nor the customized version of that driver. 

 

You are comparing apples and watermelon, the only similarity is that both are fruits. 

I was not comparing any cabinet or driver. I was commenting on the graph of the 12PR300. The tuning of that cabinet suggests that in the area of that dip, the cone excursion would exceed XMax substantially at relatively low powers. 
 

 

 

 

 

 

 

 

 

 

 

 

 

[agedhorse]

1 hour ago, Chienmortbb said:

I was not comparing any cabinet or driver. I was commenting on the graph of the 12PR300. The tuning of that cabinet suggests that in the area of that dip, the cone excursion would exceed XMax substantially at relatively low powers. 
 

Because the tuning that produced that plot was a poor tuning choice and one of the impacts is poor mechanical power handling in exactly that region. It's no surprise, and no experienced designer that I know of would choose that either. They would quickly recognize that they were well beyond the optimized zone.

 

This is the plot for an equivalent 212 at 600 watts RMS with an appropriate tuning. Note that the driver I developed had 0.75mm greater winding height than the stock 12PR300 and a different mid voicing, but the majority of the improvement is a better tuning choice. The ideal HPF setting would be 4th order BW, ~50Hz.

 

The cabinet F3 is 57Hz, the F6 is 51Hz, and the F10 is 45Hz. 

 

Edited November 22 by agedhorse

[Chienmortbb]

11 hours ago, agedhorse said:

Because the tuning that produced that plot was a poor tuning choice and one of the impacts is poor mechanical power handling in exactly that region. It's no surprise, and no experienced designer that I know of would choose that either. They would quickly recognize that they were well beyond the optimized zone.

I think we agree but are just coming at it from a different angle.

[Bill Fitzmaurice]

If you want to get rid of that dip it's easy enough, reduce Pe to 200w. It has nothing to do with the cabinet design, it just shows that the driver mechanical limit is lower than its thermal limit. That's not the least bit unusual. For that matter prior to roughly 20 years ago it was the rule rather than the exception. Want to know why vintage drivers were so poor with respect to bass? This is the maximum SPL of the ubiquitous Jensen C12N, which were in my '65 Bassman. If all you looked at was Pe then the 50w rating would seem adequate. Leo Fender certainly thought so. But with 1mm xmax it was mechanically limited to 5w at 60 Hz. 😲

 

 

[agedhorse]

6 hours ago, Bill Fitzmaurice said:

If you want to get rid of that dip it's easy enough, reduce Pe to 200w. It has nothing to do with the cabinet design, it just shows that the driver mechanical limit is lower than its thermal limit. That's not the least bit unusual. For that matter prior to roughly 20 years ago it was the rule rather than the exception. Want to know why vintage drivers were so poor with respect to bass? This is the maximum SPL of the ubiquitous Jensen C12N, which were in my '65 Bassman. If all you looked at was Pe then the 50w rating would seem adequate. Leo Fender certainly thought so. But with 1mm xmax it was mechanically limited to 5w at 60 Hz. 😲

 

 

Or you can increase the Fb of the enclosure a little bit which will shift the ~43Hz peak upwards a bit while at the same time increasing the max SPL in the 50-70Hz range. If you want keep the LF extension the same (especially F10), then a slightly larger enclosure will offset this. 

 

It's very much a balancing act between variables, but IMO better choices could be made. Yes, this was much more common with vintage drivers, especially with extended low frequency tunings.