Ricci

On ‎12‎/‎16‎/‎2018 at 7:45 AM, dsl1 said:

I'm glad it's not any bigger...

Yeah me either.

How are those tops blending with the Skhorns? Got your processing all figured out?

16 hours ago, chrapladm said:

Had been looking at building a slightly bigger single version myself but just trying to increase the low end a bit. I am not chasing numbers and would most likely be happy with the normal single driver version the way it is. But figured might as well see what can be had with a little more space. Unfortunately I have been away for months now with no time to simulate. But hopefully will get a break soon.

You know it's odd I spend all this time trying to keep this thing as compact as possible for being a double 21 and everyone seems to say I wish it were bigger! Never would have expected that. 

It does improve the low end some with more size. Hoffmans law of course...It also gives more room to fit things like casters or handles. I haven't got a plan for a larger version but this is close to what Paul did with his.

24x32x54= 24cu ft or 680L external

27x36x60= 33.75cu ft or 956L external. That's more than a 40% increase in size. You may be underestimating just how big and heavy this larger cab would be.

I'm glad that you found it easy. I was hoping it would turn out not so hard. The hatches are likely the most difficult parts. I wanted to make it even simpler but didn't want to compromise in other areas too much.

17 hours ago, radulescu_paul_mircea said:

I just bought a pair of B&C 21SW152-8, a pair of RCF 21N551 and a pair of 18Sound 21NTLW5000-4 and I'll load all of them in my XL version to see how close the sims get to the real deal and why. 

You are the 1st person that I know of who has the 21NTLW5000's. They haven't shown up in the states yet. This is one driver I've been keeping my eye on. The back story on them and other potential drivers in development using what is essentially DD topology is interesting and may be getting more interesting in the future. At least that's what I've heard...

I'll be looking forward to your impressions of the 551 vs the 451 also. I don't know of anyone with the 551's either.

Next year I'll finally test the 21DS115's in the Skhorn and that will be followed by the 21NLW9601 and the 21ID's. I'll probably have a look at the Lavoce 21 too. Sadly all my audio related time lately is porting data over to the new DB site. Haven't had time for any new designs or investigations.

Jesal,

I do not know what would happen running the 2 different drivers. I expect that there would be some degradation of the response shape and perhaps a lessening of the output capabilities. Even though the 2 drivers model very similarly this will be a much greater difference than production tolerances or series wiring of 2 of the "same" driver. It would probably "work" at moderate or lower volume levels. If you wanted to get deep into the rabbit hole with it this could be simulated in Akabak. If you have the drivers and measurement capability it would probably be quicker to try it carefully. Long term I definitely wouldn't recommend it.

I would go with another 21SW115-4 out of those 3 options. Displacement is ultimately king.

The 21SW115-8 might be ok...It doesn't look so good once the generic LE is added to the sim. The response gets a bit "humpy". 40Hz and 110Hz with a dip in between. I don't have the complex LE components measured for that driver so it is hard to say how it would turn out exactly. It's an approximation otherwise. This is why I hesitated to recommend it. I just don't know for sure. 

7 hours ago, Father Francis said:

I have ordered 4 drivers 21SW152 8ohm to have a go at these , reasons it’s easier to run 8ohm drivers , and if I don’t like them easier resale, on the second hand market, Any disadvantages with using them drivers , same drivers we wil use for our Othorn , just added a setup we did last weekend with 8 of my ported BR boxes

link to Sp https://forum.speakerplans.com/pd2150-2151-in-br-bins_topic97769.html

 

The 21SW152's should be good. There's at least one guy already using those.

How do you like the PD drivers? Those are rare over here in the states.

I believe their TH412 and many other of their multi driver fullrange speakers are also. It is not uncommon.

BC 21-IPAL 2ohm 21_004K-2.pdf

On 11/10/2018 at 5:08 PM, radulescu_paul_mircea said:

I don't have 2 ohms 21Ipal drivers. They do not exist for now.

The power of the IPal module is exactly what a 21Ipal driver is able to handle in a well ventilated enclosure. I'm not that impressed either.

But I don't have access to SpeakerPower amplifiers in Europe, especially with the taxes we have around here . It wouldn't really be a good competition for the price I can get the modules or other amps.

 

Hey Paul I understand sourcing the SP amps would be expensive but more so than the IPAL mods? Those are very expensive here. More than double the price without a heatsink or the dsp interface. 

There is a 2 ohm 21ipal. Its not on their website. Bennett has told me they will sell it if someone asks at least here in the states. I have the pdf. I only mention it because it would be easier on the amps than the 1ohm. I don't know of an amp that will be happy with the 1ohm drivers in parallel. I don't like running half bridge amps for bass either. 2 modules per cab seems very $$$$!!!

This is why I am also skeptical that this is an issue worth worrying about. Its not like running drivers in series in a cabinet is new. This is very common practice going way back. Any drivers and cabs will exhibit differences and drivers never behave exactly the same in any scenario. That is known.

What is interesting here is whether series wiring amplifies the differences vs parallel wiring. It really shouldn't.

Paul B&C does have a 2ohm variant of the 21ipal. It has less motor force but would be easier to run 2 off 1 amplifier.

I'm not really that impressed with the power of the Ipal module. Have you thought about the Speakerpower 6000? 

40 minutes ago, radulescu_paul_mircea said:

I am referring to electrical series not acoustical. I confirmed my theory by Akabak first and then I measured the voltage at the drivers connectors and they differ by up to 6 V when driven with 80 V. So one driver gets 37 V and another 43 V at the same time measured at 38 Hz where driver excursion is maximum. 

I'm going to test them as you said Sunday. Outdoors with drivers in series and parallel impedance and magnitude.

 

Ok.

What were the driver specs used? Different for each driver I assume? That is a large difference in voltage. This would likely be caused by differences in the drivers performance rather than the wiring type unless there is a big difference in the amount or type of wire used between each driver. It makes me wonder how well matched the drivers are. If it isn't too much trouble flip the polarity or wiring on the drivers when you do this and see if it stays with a driver.

Perhaps I'll investigate on mine next time I have a chance.

Paul,

I've been busy.

Why do you think the series connection is causing some sort of performance impact? Is it because of the info I posted about the Skhorn/ MAUL design process and uneven driver loading and excursion profile with the MAUL? In that case the word "series" had nothing to do with electrical wiring. The word "series" is in regards to the acoustic loading of the drivers. The drivers were physically in series acoustically inside of the horn/slot. This causes uneven cone loading not the electrical wiring. The Skhorn is symmetric so this does not apply.

Series connection vs parallel connection of the woofers should not amount to anything significant unless the 2 drivers are way off spec from each other, in which case you will still see this with parallel wiring.

Any objective quantification of it would have to be very strictly controlled as well. Same cab, same drivers, measurement equipment, same environment, same day, etc. If you have some of this I'd like to see it. Impedance curve taken back to back with the wiring resistance compensated would be ideal.

1 hour ago, bear123 said:

I'd love to have these, would you consider an HST18-d2 plus some cash?  I would drive to meet.  I'd also trade a PA-460....would be very cool to see measurements on this popular budget driver.

I appreciate the offer but no thanks. I need to sell drivers not acquire more!

1 hour ago, radulescu_paul_mircea said:

I did the measurements again to directly compare the 21ID Vs 21IPal

I can say that the drivers in series are a problem, a big one IMO. Very different excursion at 35 Hz between them, that's why the output is lower there 
 

How do you know this? Do you have cameras in the cab or some sort of viewing window?  I don't see how you would confirm this? I'm doubtful.

Mine do not exhibit issues with this. The drivers have separated vented chambers partly because of this reason and these control the majority of the driver excursion in this design until above 65Hz where there isn't much excursion. The horn section only loads down to about 65Hz. I know it seems like the pressures in the throat would be insane and amplify any small difference in driver behavior but it simply isn't a big factor compared to the motor force of these drivers on the voice coil and the individual vented chambers. This wouldn't be too much different than a pair of individual vented subs both operated facing into a corner or in a vehicle hatch which people do all the time.

35Hz is getting close to maximum driver excursion in band. Output is about what would be expected...40Hz is higher frequency, 31.5Hz is loading on the vent. 135dB at 35Hz in this setting is going to be well past xmax.

Thanks for details on the equipment and testing areas. I'd suggest bridging the K20 or any bridgeable amplifier for high power bass testing. It definitely performs better for longer term signals. It may not make much difference for burst testing though.

Sorry to hear about the RCF. I've slammed my fair share of drivers but the B&C and 18Sound stuff seems exceptionally resilient to mechanical bottoming. Perhaps RCF is slightly less so. Was this the 451 or 551 driver?

Paul if you keep this up you might as well start adding to the Data-Bass. I can get you a login and password you know...You seem to have better access to the high end pro speakers than I do. I feel like this stuff is going to get lost in here and is getting a bit off topic. I can move it out to another thread...

Why the switch of amps for the RCF test? I assume this is outdoor GP testing? Are you using the bursts inside of REW?

I have to run but Paul and myself are discussing 2 different things. One of which is punch, which I had thought he said that the Skhorn lacked in that department, which made me think he was crazy town...He meant the RCF 21 reflex sub. The other subject was the shape of the response knee at vent tuning, something I started about the RCF 21 reflex by making an observation about the response shape. 

Bolserst is a long time contributing member over at DIYAudio forums. He has developed this spreadsheet that will take an impedance measurement and calculate the complex inductance of a driver. David McBean the author of HornResponse has added the capability to simulate using this data into HR. This is a much more accurate way to simulate and design speakers and subs.

In short if you are designing bass systems using modern, high power, long throw drivers and you are not accounting for complex inductance in your modeling; The models are probably not representative of what you would be building. Previously you would need to purchase costly software in order to derive and simulate using these parameters, or figure out a way to roll your own way.

The spreadsheet imports a text file of an impedance measurement and calculates the complex inductance specs. Additionally if you have an added mass or Vas (Known air volume) impedance measurement you can also import it and the spreadsheet will calculate all driver parameters needed for modeling. A driver file can then be exported for use in HR.

Semi-Le_Calc_V3.xlsm

Ah...That makes more sense. I was baffled thinking that your XL lacked punch!

I also worded my response badly when talking about the RCF driver reflex. I agree with damping and motor strength as the main contributing factors. I've found that reflex systems with a flattened knee at the vent tuning (undefined or less defined rolloff or tuning point. RCF measurement) seem to perform worse overall than reflex designs with a very defined sharp knee (rolloff below vent tuning, 21Ipal measurement).

THD is one component, but there are also non harmonic mechanical and operational noises that seem to give a signature to the sound of direct radiator cabs. Especially when the speaker is being pushed hard. I believe that this second factor is an important component of why people like the sound of horns and some BP subs and say that they sound different. This was a big consideration for me when I designed the Skhorn. It allows horns and BP's to be pushed further before these driver noises to start coloring the sound.

How do you like the MC2 amplifier? They are rare over here in the US.

On ‎10‎/‎20‎/‎2018 at 9:47 AM, radulescu_paul_mircea said:

635 Liters net reflex enclosure, 1680 sq  cm port, 40 cm length measured in the same place, same mic, same calibration, same windowing. I am very surprised that the Bandpass SKHorn XL loads the driver that low. The enclosure is very big and I don't like how it sounds on music, it lacks the real kick. But the deep end is very powerful and clean.

Lacks kick? That's odd to me. Not the way I'd describe mine at all. What was the processing used while listening? In room or outdoor? Compared to what?

Which RCF driver is in the measurement? Is it measured in the same cab as the 21Ipal reflex? I've noticed something over the years in vented cabs with that type of response shape. In general it looks good but will tend to exhibit greater losses and compression near tuning and less low bass output with higher distortion. Indicative that the airspace is undersized and the vent is not loaded sharply if that makes sense.

21 hours ago, radulescu_paul_mircea said:

The results I got with one and 2 F221 this summer were not ok, something was absorbing a lot of power under 60 Hz. I got +6 dB now from them today in comparison at 25 and 30 Hz. But still no match for a single SKHorn XL. It seems that it is very close to 4 TH18 at 30 Hz and 3 of them under 100 Hz. 

Thanks for posting the extra measurements. I'm always glad to see data.

What do you think the cause was with the lower values on the previous tests? Perhaps a limiter setting left on? Same amp used?

For sale a Stereo Integrity HST-18D2 version 2. This is not the current version 3 for sale. In good condition.

$450 shipped.

On 10/25/2016 at 11:28 AM, Ricci said:

Updated for sale list...

I'm in the Louisville  KY metro area. No international shipping.  All equipment is used and may have cosmetic marks but otherwise functions correctly unless stated otherwise.

 

BMS 18n862 18's.

1 pair. Low distortion with excellent all around performance. Little bit of oxidation on the motors. 

BMS 18's back up for sale. $750 takes both.

Samps it's really no different than a vented cab. Look at the group delay measurements for the cab or the spectrogram. Consider these during design in your simulation software. In general the deeper the frequency the less group delay or ringing is of a concern IMHO. Below 25Hz it is much more difficult to hear than at 100Hz. 100Hz is less of a concern than 300Hz, etc. Pay more attention to the upper / XO range of the design you are working on. You don't want sudden spikes in delayed energy or ringing in narrow frequency bands either. As long as GD is smooth over the operational bandwidth and remains below 1 cycle of delay I don't worry about it. For an example of a bad sub issue that was audible look at the DTS10 at 55Hz. Also even if the cab imparts significant overall time of flight delay such as with a large FLH the mains can be delayed relative to the subs to match more closely over the XO region. A small room such as most HT's will greatly affect this far more than a few ms delay inherent in the design.

I do not think that would help. Just make sure to brace the hatch. Or just sit the cabs vertically with the hatch on the ground.