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Posts posted by peniku8

  1. I'm unsure if the drawing is accurately to scale, but 90cm of port length seems close enough if you add half of the port height.

    This is a very large port. I like to have at least 100cm² per litre of displacement. For the 21DS115 that is 5l and I ended up using ~550cm² in a design that prioritized space efficiency. Low port compression is nice and everything, but I'd try to see if more back chamber volume isn't more useful in this case. I also think a meter of port length is quite a lot. A port this long on a 6th order bandpass would have me keep a close eye on group delay for sure.

    The SKHorn essentially uses less than half as much port area with 50% more capable drivers and the compression results are very tolerable until output exceeds 130db from 30Hz and up.

    Cover the top part of the cab in Warnex inside out so you can use it as transport box for something else 😊

  2. Designing this thing on paper is pretty hard, I'm sure. Whenever I have a cab idea, I'm putting the whole thing together in Inventor and grab the measurements off the actual model, which I then input into HR. It's a lot of work for a concept which might be really bad, but it leaves very little room for error. This way you can create a very accurate feedback loop to get to the desired result.

    What's the actual frequency response of the cab? Did you find semi inductance parameters somewhere?

  3. If you don‘t mind the short drive through Luxembourg, I could get you the 21DS115 for around 450 a piece or cheaper depending on how many you need. Just in case you want to get more nice drivers some time in the future ;)

    S1 doesn‘t have a huge impact on the models. After all, S1 itself is not even in the path between the driver and the horn mouth.

  4. 48 minutes ago, Ricci said:

    That's one of the tradeoffs of this arrangement. Could always flip them once a year. 

    Do you really think it's an issue with the modern pro drivers? Most pro style cabs are simple vented direct radiators, which are stored on the wheels, so the driver ends up being in a horizontal position most of the time. I've never seen any manufacturer talk about that. If it's really an issue, I think we'd see the advice of storing them differently more often.

  5. 1 hour ago, klipsch said:

    However, when I heard the big bad towering and impressive looking JTRs, it was the first time I understood ear fatigue and "tinny-ness" I had read about on the forums for decades from people who did not like Klipsch speakers.

    I have some lower budget Klipsch speakers and I find em less fatiguing than my Sennheiser HD650 which are often praised to have a very flat FR. When I first tried the HD650 I was very disappointed. I didn't expect crazy deep bass from an open back design obviously, but the hump in the upper bass/lower mids were immediately apparent and muddied the sound a lot. Plus the boosts in the treble region, which made sibilant vocals really annoying and general listening experience pretty unpleasant over time.

    I've kept them after all after I accepted the fact that there are basically no heaphones which are perfect without EQ. When EQ'd flat the Senns sound great, especially in the mid range.

    I'm soon going to pull the trigger on ribbons for a DIY project. They can't quite keep up in dynamic range, but their definition seems to be stellar. And they're good to like 100khz so I can  annoy some dogs. Gonna be exciting.

    @SME I very much agree with your observations on sine waves vs bandpassed noise. I've recently had to mix a wierd bass guitar sound, which had some very high crackle, which I identified to be some sort of pick noise above 17khz. I still hear 18khz sine waves at fairly low volumes, but it's something entirely different if you have like an entire octave of noise above.

    That's also a good explanation on why I absolutely disagree with equal loudness contours. IMO it's exactly the opposite. I also disabled the DEQ feature in my Marantz amp. Studies have proven that people subjected to band-passed noise would come up with completely different "equal loudness contours" as those subjected to pure sine waves.

    It's the same with distortion. Yes I hear 0.2% THD of a 100Hz sine wave at 70db. Now listen to music and all the fancy analog studio gear already introduced 5% THD or more. Good luck trying to notice the 1% THD of your speaker.

  6. I think baffle gain will be more. Like I've suggested in my PM, my sims were much closer when I placed two cabs in Edge to replicate the half space environment. I simply made the cab twice as high and placed the mic in the center.

    I like how you treat the 21DS115 as 2 Ohm driver. That beast is so damn efficient!

  7. 31 minutes ago, Ricci said:

    Awesome! Already ahead of the game. 

    Is that your shop?  I'm jealous of the tools and space. I have nothing like that.  

    It's my dad's and my shop, yes. The biggest benefit is that my recording studio and my equipment storage area are in the same building. Plus everything is well isolated (acoustically) so that I can work way past midnight without anybody caring. The CNC was the latest addition to the shop last summer and it has easily been the most used machine in the room ever since 😊

    It may look spacious, but it really isn't. There are machines everywhere!



    • Like 3
  8. 2cm is nothing I‘d be comfortable with. The air speeds through the pole vents can get pretty high, so I‘d leave at least 5cm of clearance behind the driver.

    If height is not an issue, you could look at the Devastator design on AVS. I think it might fit into your dimensions, or be easily adjustable to do so

  9. DSP amps or system processors usually come with an IN EQ section and an OUT EQ section (unless it's a really bad one like the touchscreen dsp in the china amps). I like using the out section to EQ my channels flat and using the input EQ to do the signal shaping. If the signal shaping doesn't carry over to the mains , it quickly sounds unnatural imo.

    Here is some signal shaping that l-acoustics seems to like. Note that this is the response target without subs.


  10. 2 hours ago, Ricci said:

    Hmmm. Interesting. Frequency response spec looks not so great though. 

    Does that matter when you're applying a correction curve anyways? I calibrate the devices which are not part of the DUT section, so I tend to not care so much.

    Good pro audio gear is expensive, but it's still nothing compared to proper measurement 'lab' gear. I'm going to get 4 of those BSS DI boxes on Saturday, I can post a FR if you like.

  11. Interesting approach, I like how you ended up with almost exactly the same total system volume as I did. I just couldn‘t get below 320L, no matter how much I tried.
    Could you attach a FR graph? I‘m too lazy to copy the inputs over to HR ;)

    Will we see the typical bandpass FR with this type of front chamber? You can basically look at the driver from the sides, I wonder if you‘ll be able to see that in an upper bandwidth polar pattern.

    Anyways, now you‘ve got two projects without cabs. I‘d build you one if I lived in the states!

  12. I think in your case, a direct radiator approach would be more fitting. I don‘t really get what you‘re trying to achieve with the front chamber, so I can‘t really give any suggestions.

    Either way, firing the driver into the front panel might not be ideal. This way the panel distortion will maximize forward, probably the direction you‘re sitting in (if it‘s for a HT?). You could try throwing it around so you fire into the side or the floor to mitigate that issue a little.

    If it‘s for a HT, I don‘t think you‘ll need the mid bass sensitivity a front loading will provide. With a cab that size you can expect like 3-4db baffle gain from 100Hz and up.

    With a back chamber of this size, low bass sensitivity won‘t be anywhere near the mid bass sensitivity anyways. 

  13. 1 hour ago, Droogne said:

    Modelling it as a rear loaded horn does simulate exactly the same, as I exemplified here: 



    Interested in the results! 


    Yes, my models of the pure vented cab and the RLH were exactly the same (except that the tuning frequency of the RLH somehow ended up higher, even when using the same straight ports, so I changed the back chamber volume to match the original vented sim). Particle velocity at the mouth was reduced by 50%, which might give me a db or two more output at maximum output levels.

    Making those ports was probably 10x the work of simply doing a straight port, it better pays off. Look, it's a potty!


    • Like 1
  14. Btw @Ricci, the BSS AR-133 is my go-to DI box which also accepts signal inputs of up at ~218V when engaging the -40db pad. It's quite inexpensive and more feature-rich compared to the other -40db DI box posted earlier and much easier to get in the states, as it's sold by B&H for example. And of course you wouldn't have to source all the parts and build it yourself like the interface I have.

  15. 1 hour ago, SME said:

    Each SP2-12000 *channel* uses two amps in a bridged configuration, so they can't be bridged again.  The bridging capability of any amp depends on its design characteristics which should be specified by the manufacturer.  Some amps perform better or more reliably *with* bridging.  Others may be damaged if you try to do it.

    So the modules are already bridged, ok. One could still try to use them in parallel as mentioned above. That should work even with two bridged modules. Just don't mess up the wiring or bad things will happen... 😅

  16. 1 hour ago, dgage said:

    The modules in the SP1-4000 to SP2-12000 to my knowledge are not made by Hypex.  And since I use the SpeakerPower amps for my business, my only response due to potential liability is to get SpeakerPower’s recommendation before trying it.

    It's more about the general concept than the SpeakerPower amps itself. The Hypex is just an example. You could potentially damage one amp if they're not exactly level matched, which is maybe why it's not officially supported. It's a workaround if it actually works. I also don't know if both amp modules have to be fed by the same power supply for this to work at all.

    I have an old KMT LC1300 here which I can try this with. That amp is not officially bridgeable, but both output stages use the same power supply.

    All other amps I have can operate in bridge mode already.

     @Ricci might like the idea of a bridged SP2-12000 for output compression sweeps.

    Edit: A short look at the Wikipedia page confirms that this is indeed possible as long as both amp modules share a common ground. I'm not sure if the input ground or output ground is referenced, but it should be the same in theory.

    Another interesting thing is using multiple amps in parallel mode, which looks great for low impedance loads. Dunno if that's nothing new for you guys, but I haven't read into any of this before and just accepted that some amps can be bridged and some other cannot.


    For example, if two identical amplifiers (each rated for operation into 4 ohm) are paralleled into a 4 ohm load, each amplifier sees an equivalent of 8 ohm since the output current is now shared by both amplifiers — each amplifier supplies half the load current, and the dissipation per amplifier is halved. This configuration (ideally or theoretically) requires each amplifier to be exactly identical to the other(s), or they will appear as loads to each other.


  17. Has anybody actually tried bridging the Sp-12000 or are the 6000 modules already operating in bridge mode?

    You can bridge two separate amp modules as described here by Hypex and I think this should work with any two amp modules of the same type. 

    What Brian once described as ‚half-bridged‘ operation is (I think) flipping both input and output phase of one module when two amp modules are operating off the same power supply. This should be the case for amps which have output 1- and 2+ as neutral and thus bridge between 1+ and 2-. On this configuration, engaging bridge mode would probably feed channel B the same input as channel A and overwrite channel B‘s input and output sensitivity. 

    So unless the Sp-6000 modules are operating with a positive negative configuration and instead with a hot/ground output, you should be able to link them.

    I can eventually try this out with an amp that doesn‘t support bridge mode operation.

  18. 1 hour ago, Droogne said:


    Whoa, didnt think about that, thanks. So like this (modelling with the straight end horn)? I added 350cm to S2 and kept the rest the same. 



    Exactly. Btw, you don't have to fill out all 4 sections. You can input S45 data into S34 and leave S45 off (all values 0).
    What angle does your horn have? With your values it almost looks like the offset part is angled at some 20°, is that what you're trying to do? From the parameters it looks like you're doing something like firing into the back at quite an angle with a straight section running along a side wall/bottom to the front. Quite ambitious packing that much of a front chamber and a 96cm long port into a space this small. Are you sure the back chamber volume is correct? Looks like a bit too much for a cab of the dimensions mentioned earlier.

    I also noticed that the quarter space sim (plus baffle gain and -12db) matches my real measurement much better. I multiplied the Hornresp output with the calculated half space baffle gain in Edge and basically got the same voltage sensitivity (-12db) curve as I measured, which was really satisfying. The driver did get a healthy 4 hour break-in period and I've used Ricci's semi-inductance parameters.


    • Like 1
  19. I don't know much about particle velocity, except the basic fact that it causes compression at some point, and neither have I run compression sweeps of my cabs yet (waiting for better weather), but while looking at your hornresp parameters, I noticed that you haven't added the driver and front "chamber" volume anywhere. Normally you'd be using the driver's front air volume plus the small section with the thickness of the plywood you're using (was about 11000cc VTC with the IPALs iirc), but as to @Ricci's suggestion and my own comparisons with my finished cab, adding the driver's cross sectional area to S2 in horn resp results in a sim much closer to the real thing. For the 21" drivers you can add about 350cm² to S2 (driver+wood when back mounting).

    • Like 2
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