Ricci

On 10/5/2021 at 5:00 PM, peniku8 said:

It was 1khz, which meant maximum heat development in the amp, which was the cause for its failure.

It sustained over 7khz (single channel) into 2R for 260 milliseconds at 1khz. That's 260 cycles. Wouldn't that means it's able to do 2.6 cycles at 10Hz at 7khz or does it behave differently? I was planning on measuring at different frequencies as well, but I have so many things on my plate at the moment, I can't tell when that'll happen.
I was also pretty pissed when the amp went up in smoke, which is why I stopped testing. But I think it should be fine if I limit it to 10 second tests instead of 'seeing what will happen' (I left the amps running at max for 2 minutes). The amp threw my 16A 230V breaker after 16 seconds anyways, I should've left it at that instead of plugging it into a 32A circuit.

Yes things behave much differently towards the frequency extremes. 1kHz is the defacto standard test for amps a lot of the time. Where the power ratings are measured. Testing at 20Hz or 20kHz is a lot rougher on the amplifier many times. It depends though. Some amps behave differently than others. The best amplifier testing I recall was the Bink's tests from something like 15 years ago. 

10 seconds is more than plenty IMHO. Hell I think 3 seconds 100% duty cycle would be enough. Those types of signals simply aren't in 99.99% of music, broadcast or, movie soundtrack.

Skhorns in Norway...Nice. Thanks for the video link. 

I would use the Eminence or the 21DS115 as alternatives to the 21Ipal in this cab. 

On 9/29/2021 at 5:51 PM, peniku8 said:

My Sanway clone amp handled 2R (one channel) sustained without issues. I let it pump out 4KW (again, one channel; sine wave) into my loadbank for over a minute, but kinda forgot it was fan modded, so it overheated and blew up on me.

I'd be pretty confident with the newer and sturdier version (mainly power supply changes with an additional fan next to the parts which blew up) when it's not fan modded. It muted the output pretty quickly into 1R (matter of milliseconds; SC protection kicked in), so it might not like it if the impedance of the actual cab dips below 2R.

What frequency was it doing 4kw? 1kHz is easy peasy...30Hz not so much. The magic smoke strikes again! No doubt those amps make power. 

Load banks are purely resistive, speakers are not. Dual 21Ipal does drop below 2ohms. 1.6 ohms at certain frequencies or thereabout. Not too bad with dynamic music. Long sustained notes near the impedance min gets tough on the amp. 

SP6000 is great for 1 or 2 ohm loads. It doesn't have the peak voltage of the LG/PS amps but it can cook your drivers with sustained power. 

CJ,

Everything is in the first couple of posts. 

FYI. The Dayton has a large amount of inductance. It will modify the performance significantly if the effects weren't included in the model. 

You forgot to mention one of the most important pieces of information...Budget? 

The Eminence NSW and the Beyma drivers are a little better match for the SKRAM cab due to the extra air volume behind the driver. 

Impedance for the SKHORN with dual Ipal's is available in the measurements section for it. 

I do not have experience with the clone amps but I do not think it would like dual Ipal's in series on sustained bass notes near tuning. It's a 2ohm load with those drivers. That's why I use the SP6000

Graph above shows THD at various voltages.

Starting level = 2.83 volts

Ending level = 22.5 volts

I've not...I will say that the 2360A goes deeper than the K402 in practice. It legit seems to be able to provide loading / gain down to 170 or 180Hz. It needs an 8" mid shoehorned onto it really, but then the throat distortion is going to get boosted. 

The K-402 technically loads to a very low frequency too but it doesn't provide much useful gain at those deep freq's. 

The horn does play a big role. With that said. Even on the giant 2360A the Axi2050 still runs out of gas due to diaphragm displacement limitations near 300Hz. This isn't really seen until absurd output levels with more than 10 volts applied = REAL LOUD, so technically you could get away with a 300Hz Xo on that horn in most cases. Still it cleans up considerably just crossing at 400Hz on that horn and keeping the diaphragm excursion under control. Moral of the story is even after the best sims and thought put into it, test the combo and see what you've actually got. 

Note: The Axi2050 is quite durable. 🤪

I do wonder how good the Celestion horn for these are, but I'm not dropping that amount of money to find out. The B&C horn for the DCX462 / DCX50 also is interesting. 

I do like the 402 a lot. They aren't cheap if buying new. Mine were 2nd hand and have some wear and tear. Still expensive. Think it was about $1200 for the pair after shipping from Cali. Doesn't bother me because they are in an ugly warehouse room anyway. Sounds better to me than the 2360A's. The 2360A's do load the low end better / deeper.

Yes I've been running these on K-402's for a couple of years. I have a ton of measurements that I planned to post but never got around to. Eventually. 

Long story short...None of the CD's really want to be playing down that low. They may claim 500Hz but even on a very large horn that loads decently they get nasty with any real volume. The 2050's are better than any others I'm aware of. I settled on a 370Hz Xo with mine. The distortion rises precipitously below 350Hz. They may be fine down to 300Hz in a home with 0.25 volt drive levels, but for any real use with loud playback I'd recommend no lower than 370Hz with a 3rd order filter and that's on a BIG horn like a 402 or a 2360A. For work in a pro setting in a huge venue I'd consider 500Hz the minimum with 600Hz being better/safer.

None of the other CD's on the market (Except for some of the exotic dual diaphragm mid units) want anything to do with that low of a crossover in a pro use scenario, no matter what the spec sheet says. If your use is at home with flea powered amps and much more subdued playback levels you can get away with a much lower Xo. 

The Axi2050 provides roughly a half octave better low end extension and lower distortion when driven that low than most 4" vc 2" cd's. The top end is decent but they weren't able to totally defeat physics. Smaller, lighter diaphragm CD's will have better sensitivity, distortion and output >10kHz. The 2050 sounds fine up there but it does give up something. That's the tradeoff. I'm far more concerned with SQ in the 400-10Khz area than I am with >10kHz so it works for me. Sounds killer in the midrange. 

I put 22.5 volts through them during distortion testing. Wore ear plugs and shooting muffs. I am not in a hurry to do that again. It's weird when you can sense/feel the pressure from treble!

Great looking build. What's the outer dimensions of the cab?

Sed,

Winisd isn't very accurate. It doesn't include inductance effects for subwoofers. It also doesn't include baffle and directivity effects. 

Sealed cabs are very easy. There really is no tuning. Put it in a 23x23x23 cube and power with a big amp. It is very hard to damage this driver. Look at the testing done here on the systems page. Note the voltage used for the maximum level output sweep. Pick an amp that can provide this voltage or under. Done. 

Doubtful...The only things that break in on a driver are the soft parts (suspension compliance). 

I'm not a big fan of DATS... Have you measured other drivers with this setup that were close to mfg spec? I know some have had good repeatable results but others have not. 

The more ridged and stable the driver can be made, the more accurate the results will be. You definitely want the driver in a horizontal position as well. Use a decent amount of voltage. 1 volt + is better. 

Driver specs are expected to vary some 30% or so by major mfg's. Double the spec is way out of whack though. 

Jay how many of these do you have built now? 8?

Phase / time alignment is one of those things that still has a lot of voodoo surrounding it. Some would say it's overblown, others would say it's the final frontier. One thing is for sure it's a lot easier to dial it in outdoors! 

21 hours ago, peniku8 said:

First show in a long while was 2 weeks ago. Audience of 200 (seated) in a location for 2000... was an interesting show.

first few tables were being decapitated by extremely loud top-end... Guess we're all a bit rusty after such a long break or they just didn't care

Live streams just aren't the same. 

Possible that the extra 1500 to 1800 bodies in the room soak up that much HF? 

It's an isobaric. These are not known for huge output.

The output is still limited by the excursion capability of the front firing 21. The 18's rear side of the cones are connected to the BR chamber. The front side does not radiate to the outside. The 21's rear side doesn't radiate directly into the BR chamber. It's a way that can be used to extend low end response in a smaller cab but it will not offer the output gains of using the 3 drivers conventionally. The vent size will limit the output near tuning and the 21's excursion will set the limit on the output above the tuning. Using the 2 18's and the 21 in conventional cabs (much larger of course) would greatly increase output headroom.

I'm kind of surprised to see B&C use this arrangement. It's a very expensive and heavy cab due to the 3 drivers. 

23 hours ago, jay michael said:

Sorry to hear that. We were lucky enough to sneak a couple small outings like this during the summer…. But cases are getting bad here again so I wouldn’t be surprised if we get some restrictions again soon. Hope things get better for you soon 

Yeah it's heading back toward lockdown quickly here. I've already had a tour (performing not doing sound) canceled and a few spot dates with other bands that are likely to be canceled. Tour was billed right when things opened back up and reversed direction almost immediately. I've got a lot of friends who work as stage hands, or sound engineers and it's been devastating for them. It's a tough time to be a performing artist, bar or sound provider. Hell any type of person who makes a living from public gatherings. 

Hell yeah JM...That should make some NOISE and sound great doing it. 

You can use it as a vented cab without the front panel. It is designed to be used either way. If you read the initial (LONG) posts I made it goes into some detail about what the front panel "should" do. I never had a chance to fully GP test this cab design yet. 

Will separate...2445H CD's will ship for $200 plus shipping. 

Horns $500 no shipping. 

Hello Waipy.

8 vs 4 ohms depends on which driver. There is usually some small difference between 8ohm and 4 ohm models, but it is not enough that it would be very audible in most cases. Usually the 8ohm version will have slightly less motor force and higher Qes/Qts. I do not think you would be able to tell them apart in a blind listening test in most cases. 

Back panel brace T does not have an angle in the original plans. It is not divided in two.

Brace Q is removed if using a plate amplifier. 

These may have been modified in DSL's cnc files. Neither are critical to be exactly the same as the original plans. 

On 7/5/2021 at 4:31 PM, peniku8 said:

The magic of PFC... love it

Yep...Definitely helps get what you can from a junk AC supply