Ricci's Skram Subwoofer & Files

[peniku8]

@Droogne I don't know how you're getting to these numbers, but 3-4db difference between the SAN214.50 and the 21SW152 sounds like you're comparing them using the same voltages while using the 4Ohm version of the SW.

Here is a model of one of my designs at 1Watt into Znom, black line is LaVoce, grey the B&C:

 

Here is the max output graph (at their rated AES power, basically an excursion limited efficiency graph), LaVoce in green, SW in blue and 21IPAL in pink.

 

Also, 650€ for the 21IPAL is a very good price, could you paste a link to that supplier? That's like the regular street price for the 18IPAL here

 

Edit: all models used Josh's complex inductance parameters

[Droogne]

58 minutes ago, peniku8 said:

@Droogne I don't know how you're getting to these numbers, but 3-4db difference between the SAN214.50 and the 21SW152 sounds like you're comparing them using the same voltages while using the 4Ohm version of the SW.

+1. This is why I keep posting my models here. I'm bound to make mistakes. Here is the SW152 in a 2 port config, with 2000W 4ohm (instead of the 2000W 8 ohm I used earlier..). On the other hand, the model I care the most about is the Xmax limited, which stays the same (SW152 already hits it Xmax at 60 volts, which is still lower than the 89V at 2000W 4ohm).

That said.. is 'Xmax limited' something that is a logical way to approach this? I made the same mistake on the ohm/voltage front, so for the IPAL you cannot input 53V (as 2500W 1ohm is 50V), but it doesnt make any real difference dB wise. This means the IPAL can be used to its full power in the Skram, while the SW152 and Lavoce clearly dont as they need to restrict their input by ~30-40V to stay below Xmax. This is clearly reflected in the output, which favors the IPAL even more. 6-8dB in favor of the IPAL (I see you modelling shows a slighter difference which is probably due to not being Xmax limited?) . Normally I'd say, 6-8dB makes an IPAL Skram x4-6 times more worth it, so the extra few euros (in my case the IPAL isnt even twice as expensive as the cheapest LaVoce I can find) would be saving me money by needing less subs (and space!), but sadly the 1 ohm load of the IPAL is the dealbraker. No way I can afford one of those ultra expensive amps that can take on a 1ohm/channel or 2om bridged load. Otherwise I would have placed my IPAL order this evening. 

 

Quote

Here is the max output graph (at their rated AES power, basically an excursion limited efficiency graph), LaVoce in green, SW in blue and 21IPAL in pink.

So.. Xmax limited you mean? Or just full 1700, 2000 and 2500W without looking at Xmax?

Quote

Also, 650€ for the 21IPAL is a very good price, could you paste a link to that supplier? That's like the regular street price for the 18IPAL here

It's up on Bluearan in the UK. Always the best price as far as I can see. Next one where I normally look is TLHP in France (but IPAL over there is still at the regular 900 euro).

Quote

 

Edit: all models used Josh's complex inductance parameters

I urgently need to use his parameters too, instead of manufacturer listed ones.. dont know why I didnt do that from the get go.

[klipsch]

11 hours ago, menace said:

Not that I can see. At least not any more. If it's true I trust you only reported after purchasing....

Naturally . There were 9 in stock. I bought 2. 

I use camelcamelcamel.com for price alerts. 

Perhaps there are similar sites for those not in the States. 

[peniku8]

@droogne that's a lot to reply to, I hope I manage to catch everything posting from my phone.

The 2nd graph I posted shows the maximum output of the cab/driver combination which is either Xmax limited or power limited (depending on frequencies).

I killed the colours for the B&C drivers, but the LaVoce graph line is two colours: green for power limited and red for excursion limited. You'll see that the graph is red from 0 to 29Hz and green from 29 to 38Hz. That correlates to the excursion minimum at the tuning frequency, so the driver hits its power limit before it hits Xmax at this frequency band in that cab.

If your system hits Xmax with 50% power at a certain frequency that's okay. Unless you're running heavy limiting, program material will not contain 0dbFS sine waves. When you're far away from excursion limits using the rated AES power, it is likely that your cab is too small.

As you can see in my comparison, the IPAL is about 3db ahead both in the power limited as in the excursion limited bands. I don't know how you're getting your 6db difference, but it doesn't seem correct to me, no matter the cab. How are you determining the headroom?

[Droogne]

10 hours ago, peniku8 said:

@droogne that's a lot to reply to, I hope I manage to catch everything posting from my phone.

The 2nd graph I posted shows the maximum output of the cab/driver combination which is either Xmax limited or power limited (depending on frequencies).

How do you get these kind of graphs?

10 hours ago, peniku8 said:

I killed the colours for the B&C drivers, but the LaVoce graph line is two colours: green for power limited and red for excursion limited. You'll see that the graph is red from 0 to 29Hz and green from 29 to 38Hz. That correlates to the excursion minimum at the tuning frequency, so the driver hits its power limit before it hits Xmax at this frequency band in that cab.

If your system hits Xmax with 50% power at a certain frequency that's okay. Unless you're running heavy limiting, program material will not contain 0dbFS sine waves. When you're far away from excursion limits using the rated AES power, it is likely that your cab is too small.

As you can see in my comparison, the IPAL is about 3db ahead both in the power limited as in the excursion limited bands. I don't know how you're getting your 6db difference, but it doesn't seem correct to me, no matter the cab. How are you determining the headroom?

I see youre graph shows a 3dB, not 6 tot 8dB difference. I havent figured out how to compare several graphs like you. I modelled it based on the displacement graph in the wiazrd function:

 

This graph shows the displacement of the SW152 in the 2 port configuration at full 2000W 4ohm (89V, GRAY). Xmax is listed at 15mm, so you can see it maxes out at ~42Hz. When I reduce the volts to 62 you can see it stays below the 15mm Xmax. 

This results in the following output, which shows a 3-4dB loss due to reduced input.

When I do this for the IPAL 21 I get the following graphs, showing an Xmax that alway stays below the listed 22mm. 

 

Comparing those:

                                             IPAL 21                                                                                                                    SW152

=> I dont know if I made a mistake earlier, as the difference isnt that big anymore, but still. At 20hz there is a major advantage for the IPAL (at least in a 2 port config).

20hz: 125dB vs 118db aka 7dB

30hz: 125dB vs 123dB aka 2dB

40hz: 128dB vs  124dB aka 4dB

 

 

 

DISCLAIMER: i'm new to modelling, so dont take these results for what they are. 

[peniku8]

4 minutes ago, Droogne said:

How do you get these kind of graphs?

In the acoustical power window hit ctrl+M and enter values there.

[Ricci]

I'll reply a bit more later but let me say that when modeling for maximum output, otherwise known as  "Bench Racing", there are a number of limitations about simulations that should be kept in mind. 

1.) Sims are usually greatly simplified and usually lack a variety of effects that occur in the real world like non linearity in the drivers BL, suspension, thermal effects in the voice coil, port and other air flow related losses, etc. All of these cause compression of the output.  

2.) Sims are only as good as the data input.

3.) Amplifiers are not constant power devices, they are constant voltage. Speaker impedance varies with frequency.

4.) System output is usually limited by a number of different factors. Driver excursion, amplifier voltage, amplifier current and the resulting amplifier power are the main limitations. Which limitation kicks in first depends on the frequency range. There are also other factors such as vent compression, PR excursion limitations and thermal compression or power handling of the driver to consider. Horn Response allows a good approximation of max output based on entry of a number of these parameters. This is what Peniku was showing in his simulations. Limiting by wattage isn't really the best way to go about it. 

5.) Power handling and xmax ratings are not all created equal. 

6.) Eq can modify the driver excursion profile and which frequencies run the amplifier or driver into the limits first.  

[Droogne]

 

6 hours ago, peniku8 said:

In the acoustical power window hit ctrl+M and enter values there.

Thanks! Awesome tool! I cant pick 'Lossy Le' when doing this, might explain some different values between us. What would be the most accurate modelling, lossy Le ON or OFF? In any case, this is what I get with the 2-port configuration (the one I'm most interested in for modelling) using their respective max voltage inputs and Xmax: 

SW152

La Voce

IPAL 21

Looks like 2-3dB might be closer. Considering the LaVoce is about half of the price of the IPAL, is readily available and is much more amplifier friendly I will probably go with that one. I was briefly considering using a 5000W 2 ohm car amplifier with an AC/DC transformator, but that seems somewhat complex to work out. 

 

PS: how do I put all these graphs over each other?

 

 

[SME]

There's also the new Eminence driver --- probably a better option for those in the USA.

[klipsch]

3 hours ago, SME said:

There's also the new Eminence driver --- probably a better option for those in the USA.

The Eminence NSW6021-6?

[peniku8]

@droogne when you double click the Le input, a small window appears where you can enter the complex inductance parameters. When you turn those on, 'Le' will turn green to indicate that you're simulating with CI. I have set up my driver files to automatically load these for maximum convenience; I can attach the files here if needed.

I overlayed the graphs with Photoshop.

The street price on the Eminence looks to be still almost twice the price of the LaVoce, plus it's very heavy. It gets within .5db of the IPAL thou, so basically equal to the 2Ohm IPAL I guess.

[SME]

6 hours ago, klipsch said:

The Eminence NSW6021-6?

Yes.

2 minutes ago, peniku8 said:

The street price on the Eminence looks to be still almost twice the price of the LaVoce, plus it's very heavy. It gets within .5db of the IPAL thou, so basically equal to the 2Ohm IPAL I guess.

I must have missed something.  Is there a 2 ohm IPAL?  Anyway, the NSW6021 should be easier to drive with common amps.

[peniku8]

26 minutes ago, SME said:

Yes.

I must have missed something.  Is there a 2 ohm IPAL?  Anyway, the NSW6021 should be easier to drive with common amps.

Yes there is, it's just not public. The stats are a little worse compared to the 1 Ohm thou. You can only get the 2 Ohm IPAL as commercial customer I guess

[chrapladm]

I think Bennet stated you could get the 2 ohm IPAL if there was a 50MOQ. BUT that being said this new Eminence 21 does look pretty awesome available and hits the low end better than most if not all Pro drivers. 

[klipsch]

3 hours ago, chrapladm said:

I think Bennet stated you could get the 2 ohm IPAL if there was a 50MOQ. BUT that being said this new Eminence 21 does look pretty awesome available and hits the low end better than most if not all Pro drivers. 

So many driver choices. Great news! 

Sure would be nice to have a comparison of each in one set of graphs

[peniku8]

6 minutes ago, klipsch said:

So many driver choices. Great news! 

Sure would be nice to have a comparison of each in one set of graphs

Since Ricci didn't measure the SKRam cab yet, the data isn't as perfect as the SKHorn's. I can could these graphs for the latter thou. At least with the most popular half a dozen. I won't include all the RCF and 18sound ones, that would just be TMI for an overlay

[klipsch]

1 hour ago, peniku8 said:

Since Ricci didn't measure the SKRam cab yet, the data isn't as perfect as the SKHorn's. I can could these graphs for the latter thou. At least with the most popular half a dozen. I won't include all the RCF and 18sound ones, that would just be TMI for an overlay

Thanks! I feel that would be appreciated by many

[Droogne]

Me being in the EU makes the Eminence harder to get than the IPAL, sadly  I think I got the modelling right (checked vs the models listed above here), but still not sure to model with or without lossy Le. Thanks for running me through the process!

 

At this moment I have a pair of Sundown Audio ZV4 18D2 drivers, so I modelled them for reference. Keeping aside pragmatic problems (it being an 18" driver with a huge rubber hangup) I quite like this. A 5-10dB gain to the sealed I have right now, and only 2dB loss vs the 'cheaper' 21"ers mentioned above.

All ports open (for reference)

Compared to the sealed config I have them in now:

Sealed, 140L

[peniku8]

6 hours ago, Droogne said:

still not sure to model with or without lossy Le. 

You should model with the input of the 6(?) complex inductance parameters, which are usually not to be found in the T/S parameters the manufacturer lists.

[peniku8]

Btw I posted the Skhorn driver comparison to the Skhorn thread. Skram should be similar (in terms of differences between drivers). Noteworthy is that the cheaper drivers all offer the same headroom, the Eminence more bottom end headroom and the IPAL more overall headroom. IPAL is above the Eminence at all frequencies, the difference ranged from a fraction of a db to like 3db around 80Hz iirc. 

I also just ordered two more 21DS115, but I won't be building Skrams, or I could post some measurements. I'm currently more interested in my own design, which models just to my liking (Skram is too big).

[klipsch]

4 hours ago, peniku8 said:

Btw I posted the Skhorn driver comparison to the Skhorn thread. Skram should be similar (in terms of differences between drivers). Noteworthy is that the cheaper drivers all offer the same headroom, the Eminence more bottom end headroom and the IPAL more overall headroom. IPAL is above the Eminence at all frequencies, the difference ranged from a fraction of a db to like 3db around 80Hz iirc. 

I also just ordered two more 21DS115, but I won't be building Skrams, or I could post some measurements. I'm currently more interested in my own design, which models just to my liking (Skram is too big).

Thanks! 

The Eminence really models closely to the IPAL and should be much easier to drive. Price VS modeled performance is an interesting decision

[Ricci]

15 hours ago, peniku8 said:

You should model with the input of the 6(?) complex inductance parameters, which are usually not to be found in the T/S parameters the manufacturer lists.

It's 5

Listed as "Measured Complex Inductance Parameters" under the individual "Drivers" page.

[Ricci]

11 hours ago, peniku8 said:

IPAL is above the Eminence at all frequencies, the difference ranged from a fraction of a db to like 3db around 80Hz iirc. 

They have the same amount of total displacement effectively. The 21Ipal is a little more efficient. 

[peniku8]

I've recieved the two 4 Ohm 21DS115's today and I can't help but feel that they have a bigger magnet than their 8 Ohm siblings. I'm too lazy too move the SKHorn and open it up to have a look at the 8 Ohm drivers in there; does anybody else own both versions of the driver and noticed a difference?

The only obvious difference was that one came with the fast-on/solder terminal and the other with spring loaded binding posts.

[menace]

What do people think about speaker grills for these? It would seem they would alter the tuning some? Any thoughts?