peniku8

9 hours ago, lowerFE said:

That's some very interesting results. Did you find out whether maxing out one channel is enough to break in all channels? 

I'm the person that SME mentioned on Hypex amp experiences. It does some things very well, but some things are shockingly rough around the edges that I'm amazed they released a product with flaws like this. 

For example if the total gain on all filters exceed +24dB, the DSP crashes and sends full scale noise to the amp channels. Luckily, it spared the tweeter channel, and luckily the DSP recognizes the crash and doesn't go crazy after a restart. But this is still really bad. 

It is also possible to crash the DSP with a strong enough input signal. I suspect it is because I tripped the +24dB gain limitation because I had +20dB of boost due to Linkwitz transform, and I raised the master volume to +6. So when a -2dB or louder ULF signal hits the DSP, it gets boosted to +4, and since I had 20dB of ULF gain, I trip the +24dB gain and the DSP crashes and sends loud noise to the channels. 

This kind of bug should never happen on a commercial product.

I can also get my FA503 to power cycle when exceeding its power limits. I'm disappointed the soft limiter doesn't work. My previous ICEpower amp never power cycled no matter how hard it was driven. The soft limiter actually reduced amp power output with a stronger input signal. I'm sure that saved my speakers from blowing up during some extended loud parties.

@klipsch On the FA503's, Hypex actually did a pretty smart thing. It actually seems to turn the amp off when there is no signal to the DSP, and therefore the speakers are dead silent with no hiss. But there is actually a hiss, and if you feed it a silent/very quiet signal, the hiss is apparent.

While the Hypex are technically excellent amps, it really sucks on the usability aspect. I haven't even talked about the excessive heat combined with a low maximum temperature, or how the DSP/amp takes 5 seconds to wake from sleep, or there's a very loud click every time it wakes/sleeps that I can hear from another room. For my next speakers I will use Pascal L-Pro modules instead. I hope they have much better usability behavior than the Hypex. I wish I could get my hands on OEM DSP plate amps with Pascal amp modules. If not I'll build my own plate amp.

What firmware version did you experience these issues with? I'll try to replicate this today with my amps running 1.44 which I updated to yesterday. I didn't quite understand your remarks about the soft clip limiter; you say it doesn't work but then you say it reduced output power, isn't that exactly what it's supposed to do? It certainly worked when I tried it, but I haven't monitored the signal so I'm not sure if it was a gain reduction (soft limiting) or a peak reduction (hard limiting). I will run a signal to the amp and loop the output back into my interface to listen back to what it's doing. I'm just sad that you can't change the limiter's attack and release times, it's instantaneous, which doesn't make sense since loudspeakers are not linear devices.

The amps have a signal detection and automatic turn off functions, like most HT subwoofers do. My FA123 didn't mute the output signal while it was on and I could hear the noise from a distance of about a foot of the 94db/w/m tweeter. Not an issue there, but certainly audible on an unpadded compression driver (that was with an input signal connected thou and the input gain at around 0db, not sure if the noise came from the amp even).

The Pascal amps look higher power but also more expensive (their website was down so I checked a store which had like two modules listed?), to the point where I'd probably consider going Powersoft instead. The digiMod like is certainly on my list of amp candidates for active PA speakers. Not sure about their noise floor, maybe it's not good enough for a HT setup where you want inaudibility of the noise floor on unpadded compression drivers, if that's even achievable, but I don't need multi KW modules on tweeters.

1 hour ago, SME said:

Lastly, IIRC someone I know managed to get a Hypex amp (one with builtin DSP, I believe) to go unstable (i.e. noise at full blast) by feeding it high-level ultra-low frequency signals.

Mine power cycled when I tried to get it to output 20V into 4R at 10Hz (FA123).

1 hour ago, klipsch said:

I am interested in the newer self contained hypex modules to see/hear how they compare (e. g. Compare the original 500NC VS the 500mp or 502mp)

The FA123 I have consists of a NC122MP, NC100HF and MP-DSP Main plus MP-DSP Digin.

You can see better measurements than I could ever take of the NC252MP amp here:
https://www.audiosciencereview.com/forum/index.php?threads/buckeye-6-channel-amplifier-review.18579/

I think this one is very interesting and much cheaper than combining their other offerings:
https://www.hypex.nl/product/ncas500mp/174

This plus the dsp board is way less than the full FA253 (almost half the price). Dunno if it's available to non OEM customers thou.

I've noticed something very interesting I wouldn't have believed was true when experimenting with my Hypex amps yesterday. These amps needed to be "broken in" with a high level signal or they'll run at unusually high distortion.
Sounds like snake oil to me, but heres what I've seen from the data:

General info:
-Sweep of the audio interface max 0.005% THD 100Hz-24khz (sweep went to 48khz)
-THD somehow off rising to 1% at 20Hz (has been RMA'd once, guess it's still slightly damaged)
-THD numbers in the following paragraph are mostly constant through the frequency range, so I'm picking a 1khz reference
-Load is resistive; no water for cooling because heat dissipation is 100W max.

Step by step results:
-10V @ no load: 0.003% THD
-10V @ 8R: 0.048% THD
-10V @ 4R: 0.109% THD
-30s 200Hz signal @ 20V into 4R
-10V @ 8R: 0.004% THD
-10V @ 4R: 0.01% THD

Results were verified multiple times (like multiple sweeps @high THD and then multiple sweeps at low THD after 'break-in').
Results were the same for all 6 amps (with 3 channels each) I tested, but some didn't have high THD because I've had them in use before already.
Results were the same after I let the amps cool off (always low THD after being 'broken-in').
Results were the same the next day.

Whatever happened here, driving the amp modules to their maximum once lowered overall distortion by an order of magnitude (forever?).

Maybe someone can help tracing the issue. Whatever generates the current in the amp is affected by this, so it might be the transistors. Might be the solder heating up and changing its properties (but I don't think the amp is getting hot enough for that; at least I hope so because that would be approaching 200°C). Might be the power supply.
I'm not an expert in this subject, but I believed that electronics components don't change (excpet caps with age), as long as they're not hardcore overdriven and like literally melting.

RCA, yikes. Graph's looking good! I'd suggest placing a Butterworth 4th order high pass at ~30-35Hz for driver protection and maybe taming that hump down there as well. From the looks of it, you're probably running an acoustic crossover of 120HZ or higher because of that hump at the top. You can use REW to EQ the graph (PEQ like 98Hz -10db Q4 or so), which will clean that up if you add that point to your dsp.

Interesting product, haven't seen that yet. How low will it go? What kind of PEQ did you have on it?

I have low passed my TR system at 25Hz because I only want shake, not vibration (which I already get from my sub, and to me, shake from those devices feels unnatural and also unnerving), so anything that won't deliver in the sub 15Hz region is not of interested for me currently.

How have you mounted the device to the couch? Do you have the couch mechanically isolated from the ground to get enhanced tactile feedback?

12 hours ago, klipsch said:

Your good reviews sold me. 

I couldn't resist an opportunity to get 8 pa460s for $565.

Currently thinking of doing 2 dual opposed seales cabinets with 4 pa460 each.

Then wire both cabinets and all 8 drivers together for a single 4 ohm load. 

Build it

On 12/1/2020 at 1:55 AM, Gadgety said:

I'm wondering if it's an idea to put a resistor in series to up the resistance the amplifier will see.

The resulting damping factor will absolutely kill your sound quality. In addition to that, the resistor would probably have to be water cooled, due to the high power dissipation.

6 hours ago, kipman725 said:

Also does anyone know of a 35mm pole stand that could lift a large 30kg speaker high and stable? something more substantial than the usual tripod stands and with a crank for lifting.

I've worked with the Doughty T55510 and it's good, but expensive. Maybe the cheaper Adam Hall SWU 400 T would fit your needs as well. You'd have to make a mounting plate with a 25mm Spigot where the speaker can rest on, but there are also VESA mounting plates with the same spigot, which might work in your case.

10 hours ago, SME said:

Ahh, very interesting.  If that's true, then perhaps measuring distortion might be a decent proxy to assess how well the speaker construction is controlling these mechanical resonances.

I mean, theoretically the entire cab acts as passive radiator, which means it amplifies frequencies. It does that well once those frequencies excite a panel resonance, which will then likely result mostly in harmonic distortion. I 'd guess that this kind of distortion has its own complexities, since, for example, a 3rd order resonance at 333Hz will excite 1khz, which will have a complex directionality emanating from a speaker side wall the size of a few square feet, so it might actually be challenging capturing this behavior reliably with a single microphone, especially if the mic is on-axis, which will probably not pick up many resonances coming from the side panels. Mounting multiple Piezos to the cab might yield good results. Piezos are pretty cheap and I happen to have a dozen (drum triggers). I might do some testing in that regard when I have absolutely nothing better to do at some point in the future 😅

12 hours ago, lowerFE said:

Oh yeah I want that Klippel near field scanner so bad! Especially for this speaker because it's asymmetrical in both X, Y axis and Z to an extent.

That's some interesting note on the distortion from panel vibration. Do you have a link to the AVS thread with the software simulation?

No chance I could find that again, it was buried in the middle of a random thread iirc. What the guy was posting looked quite thorough and well thought out, but I'm not sure how well his simulations would translate to the real world. His conclusion was that his top priority was minimizing panel flex after his research. Maybe those top of the line speakers with strengthening rods and plates inside or filling up the walls with sand has much more of a merit that we might anticipate. Another method I've seen was multi-layer walls EpoxyPaint-Ply-Aluminum-Ply-Resin, which of course makes the production much more complex and the speaker super heavy. Genelec studio monitors are made from cast aluminum entirely and cast metals have decent damping traits due to their porous structure (I think that's the technical explanation at least, might also be due to the crystalline structure). I've opened mine up, which you can see on here.

Pretty cool thread I haven't come across yet. It's filled with knowledge and information; I'll read through the entire thing at some point.

If you don't want to do all the measurements manually, you can just buy this, you know:

And it's only around 100 grand including some peripherals you'll also need, sounds like a no-brainer to me (sarcasm off: I want it so bad!).

Sturdy construction is important for sure. I recently built a few speakers lining the inside with Dynamat-like mats, to minimize panel vibration and I think if you do that, it's better to actually have thin panels, because the wood resonates in itself at some point. Knocking on 3/4" BB ply lined with Dynamat made much more noise than knocking on a 1/4" MDF panel lined with the stuff. That pretty much eliminates higher cabinet vibrations, but panel flex (due to the thin construction) will now cause issues at lower frequencies, which is why you'll need elaborate bracing. Combine that and the cabinet should be pretty dead.
In my case, I used 3/4" plywood for the entire cab and used non-symmetric bracing cnc machined to maximize strength (bunch of triangles in the corners). Every (floorstanding) speaker was lined with about 10lbs of the damping mats. I think it would've been better using 1/2" plywood with more bracing instead (I now have a brace about every 8-10").

I've seen a discussion about panel vibration on AVS some time ago and remember someone using a software to simulate/calculate distortion introduced by cab flex and he came to the conclusion that you reach the point fairly quickly where panel vibration makes up the largest part of your distortion when you're using at least half-decent components.

I saw this on IG earlier, but I scrolled so fast I didn't realize it was a whole new design, I thought it was a slight redesign of the existing model.

Stats are insane as "usual". Re of 0.26Ohm thou? Recommended to run two series drivers off a single X4L channel (which is running in bridged configuration)?

BL²/Re is 1700, but the data sheet says 1600 and that T/S params are not fully accurate for the M-drive type transducers, if I understood that correctly, but holy cow. Has as much surface area as two 21" drivers. Does 5KW. I'm just not fully understanding the sensitivity ratings. Either way, 94db at 0.5V is pretty impressive for a 2.5kg moving mass.

Do I want one? No, I want 10.

9 hours ago, Dionysus88 said:

i have jl audio f113v2 x 2, the room stopped responding at around 18hz. With the 32 i can go down to 8hz

Did you really just compare two overpriced 13" subs to a 32" sub?

1 hour ago, kipman725 said:

They seem to be sealed boxes won't they work fine into the 100Hz+ range?

I have seen infra subs that are very narrow band using tuned pipe enclosures arranged in an array of varying pipe length to cover a frequency range not possible using a single pipe.

I thought about doing this a while back, but I decided to not go that route, as I could imagine that the resulting phase issues would be severe, thereby working against myself (lowering system sensitivity and efficiency). Probably takes a lot of testing/aligning to get right, just like using multiple subs with different tunings (although FIR filters could help you out in the latter scenario).

21 hours ago, klipsch said:

Nice texture on that finish! 

Thank you, that was actually the fist time I've worked with Warnex (European equivalent of Duratex), but it worked very well.

I used two 1KW stage lights to speed up the drying process, which shortened drying time to 15 minutes, which was a massive help. Gonna get some curing lamps for future projects.

I've been using Hex nuts for a while now and they never let me down. They're awesome.

10 hours ago, klipsch said:

The cab can double as a tunnel for a toddler or cat. 

Bonus points when you let it rip at the same time

ot, but it always makes me chuckle when I read the word "subsonic" in this context

3 hours ago, kipman725 said:

Placement looks fine, the main thing is to have more subs and place them in a diverse set of locations around the room, they don't care which direction they point.  Real rooms differ from the research (in your case you have a large lossy door on one wall) so its not necessarily true the best locations would have been mid wall anyway.

Box volume isn't very important (as long as your using EQ) as what produces the sound is the cone moving in and out a larger box is just requiring less power to reach a given SPL when operated below Fc.  

I think he is planning to run a double bass array, which works best if everything is perfectly symmetric. I'm not sure how well this particular arrangement would work, but I guess it wouldn't hurt to try.

6 hours ago, Bobby said:

Don’t know if I can afford to buy B&C,but I find the Lavoce saf184.03 for 200€ and can buy 8 of them( can accommodate another two sealed cabs behind the screen)Presume the 8 can give me the kickbass that I’m looking for and makes a drum solo sound more real life like and think that output is not a problem, but do they reach 20Hz and a little bit under in the ULF? or are there alternatives to the Lavoce until 300 per driver?

 

200€ for the 184.03 is very good, it's about 240 where I usually order. 8 sealed 18" drivers with some 15mm of one way excursion will probably be enough to dig below 20Hz. Maybe not below 10Hz, but that's better handled by dedicated TR devices anyways.

On 9/27/2020 at 12:21 AM, stoneeh said:

I tried measuring with the CEA 2010 standard [...] I'm pretty sure I measured correctly

CEA2010 seems straightforward in theory, but is a real PITA in practice. So much so, that people are saying that you can't compare measurements made with different setups/by different people. The results can vary as much as several db, even when everybody thinks their setup is perfect. There is an interesting read on ASR on how temperature influenced bass response and the differences are quite big. I'm certain that would also show up in large signal distortion measurements.

I've read somewhere that Don Keele compared his measurements with a loudspeaker manufacturer and somebody from an audio magazine and their results were up to 3db apart at some frequencies. It might've been in the paper I attached, but it also might've been elsewhere.

So it's generally advisable to approach and compare those measurements with care.

CEA2010 Average.xls CEA-2010.pdf

On 9/21/2020 at 8:48 AM, SME said:

When designing a sealed system, it's always a good idea to look at excursion vs. the max power (based on amp choice) vs. frequency, which can be viewed in most design programs.

That's what I tell people as well. Make the sealed sub as big as you can, until you can reach Xmax at Pmax. Usually the cab will be smaller than what it takes to do so, so it doesn't make sense bothering with a HPF, unless you wanna reduce the load on the sub, like when you HPF it at 15Hz because your sealed 12" sub won't have meaningful output below that anyways.

14 hours ago, Kyle said:

I don't add one on my sealed HT sub, then again, I made a mistake once with the amp maxed out and now I have a voice coil ring dent on my metal dish cone

Still works fine tho!

  Was it a 5400?

When doing roomEQ I try to avoid positive EQ points of a Q of higher than 2 or 3, because it starts sounding bad quickly. In my studio I have a point at 31Hz which goes to -35db (almost round room), adjustments of this magnitude are normal.

Where are you crossing the sub to the mains? The way the graph looks, you might have the sub on wrong polarity crossing at 60Hz, but it might also be a room issue as well. Try to flip the phase of the sub and see what the new measurement looks like.

Burning subwoofer cabinets; been there, done that. Feels bad man.

Pretty sure you'll be fine with just the Othorns and the PM90s. @dsl1 uses them with two SKHorns and is pretty happy with them, so I've heard.

Also, I'd say 100Hz is more upper-bass than mid-bass. If crossing the Othorn at 80Hz or higher, remember to take care of the spike at 108Hz, but other than that, the combo should perform nicely over the crossover region.

The 18N862 is 670€ while the 21DS115 can be had for 450 (430 each if you buy two), but I think both of those would be overkill for a music setup.

I recently bought a 15TBX100 for a friend, which is just 200 bucks. It will perform nicely in the available space.

I could probably do it, but I'm booked out at least until the end of October. Had a glance at your assembly and it's quite a big project with all the bracing going on and stuff. Also, I'm not exactly sure how I'd ship that flatpack from Germany to the UK and if that would be a reasonable thing for you to do. Shoot me a PM and we can talk about the details.