Jump to content


  • Posts

  • Joined

  • Last visited

  • Days Won


Posts posted by peniku8

  1. 3 hours ago, chrapladm said:

    Looked at making a template out of some scrap I have. I was hoping to recess the interior panels but wanted to know the depth others are recessing the panels? 1/4"/ 6mm? More?

    If you're talking about the dado joints, I always make them 3mm. That way I can cut them with max feed rates on my machine without worrying about inaccuracies too much. I never felt the need to make them bigger, they're mostly for easier positioning anyways, so 3mm is just fine for that. imo it doesn't matter stability wise, unless you expect to throw the cabs off a balcony often.

  2. And the loadbank causes another casualty.. this time it's a Yamaha CR-600. Fuses are done for, but I hope everything else is still good. Measurements of my Hypex FA123 coming soon. Also ordered dedicated measurement equipment, since I already had trouble measuring the true performance of the Hypex amps... Fireface not clean enough. Getting the Cosmos ADC to use with a Topping D10b. Probably also going to get the Cosmos APU once it releases, which includes a 1khz notch and a preamp capable to delivering phantom power with lots of gain.

  3. 1 hour ago, m_ms said:

    What's entailed in "people really appreciating the change" from double 18's to the Skram's? What's their feedback in more detail about any change in presentation here - is it simply about (more?) capacity, or does it come down to a perceived difference in presentation between the two box and driver types? 

    @Ricci and others: Earlier this evening I was at local cinema watching 'Ghostbusters: Afterlife' (an amusing and largely successful follow-up to the '84 original), and was quite impressed by the bass impact and overall quality in the some 400 seat auditorium (with Atmos sound). Turns out their speakers are from QSC, and the subs they use are these:


    I take it the 21" driver used here is the B&C 21SW152, and I believe I've read only two of them subs are used in this auditorium, though I find it hard to believe given how much the bass shook the whole locale. 

    My question here is: how would the QSC sub compare to a Skram, say, with the same driver? Does the Skram make more outright use of both its front and back wave of the cone by comparison, or are they comparable to one another in overall SPL and presentation?

    The QSC sub is larger and probably has more vent area compared to the Skram (when you block Skram ports to reach the same ~25Hz(?) tuning), meaning the QSC will be louder in the sub bass. Skram is front loaded, which means it's more efficient (louder) in the mid/upper-bass region. Skram is basically a band pass, which means it also masks some distortion.
    That would be the 3 main differences I guess. Skram has a rising native voltage sensitivity, while the QSC is probably pretty flat, going by my gut feeling here.

    • Thanks 1
  4. 38 minutes ago, Fink_Newton said:

    I have them loaded with B&C 21ds115-4's.   The soundsystem will be primarily used for small to medium sized outdoor parties where we might not always have adequate generator power so i figured the extra sensitivity of the 21ds115's might come in handy in certain cases.  Although from what I understand the 21sw152 will go aprox 2-3db louder before power compression sets in? We also considered the new Eminence drivers however they seemed like they would be even harder to power properly in order to get the most out of them.   The 44m20 amp has been absolutely incredible to use. I reckon it could power 8 Skrams in a pinch. We were using a Morin k30 before and although it had plenty of power it was extremely hard on our generators.  The Linea seems to be much more efficient and also there was a noticeable improvement in the tightness of the bass produced. The linea amp also limits it current draw to match the power source which has been super handy as well as integrating seamlessly with our Linea ASC48 in System Engineer.  Also wanted to say thanks for all your hard work and time you put in to sharing your knowledge and designs with us!  This whole project has been extremely fun and rewarding and wouldn't be possible without resources such as these.

    The ds and sw are very similar in maximum output at their respective program powers. Bennett from B&C said you should only really use the sw if you need the higher power handling, otherwise it doesn't really matter which you pick so you should go for the cheaper one. Here is a hornresp of different drivers I've compared in the SKhorn


    • Like 2
  5. And I just moved and only have headphones at the moment 😖

    I'm just gonna say that I believe that most, if not all difference in tonality between different drivers or these subs vs 'normal' subs in a home setting is due to a lack of EQ/calibration. I've been using the SKHorn in my HT for over a year and calibrated to the same response I could hardly hear any difference to the 12" Klipsch sub I had at lower volumes. The SKHorn integrated into my HT just like any other sub. Electrically. Not physically...
    These type of cabs often have a significant bump somewhere between 100 and 200Hz, which means your acoustic crossover will be higher than expected (unless they're on a dsp), which probably is what you're describing as 'Brute-ish' or 'dark'.

    Thanks to rona I have 4 unused 21ds115's in my basement right now. It makes me sad not letting them loose from time to time. Maybe I can fit a DO 15TBX100 sub into my new room, but maybe I won't even need it with 4x8" woofers from the mains I will be setting up soon. Okay, who am I kidding, of course I will need more woofage.

    @jay michaelI had to mount 4 braked wheels to my cabs. If I don't engage the brakes after they're set up, the wheels will rattle, but it's a downfiring design. How are yours behaving?

  6. 20 hours ago, jay michael said:

    I haven't man, sorry.  Hopefully someday the Skram will get the full testing treatment, I would think the Skhorn results should be a pretty good representation of what to expect obviously with lower output. The Skram also has larger vents so overall we would expect 2 skrams to outperform a single skhorn. At the end of the day it comes down to cabinet size. The Skrams 36x34x24 dimensions makes it a real compact 21" cabinet, I doubt any diy plan packs as much punch and deep extension in those dimensions. I can move these around on my own but they are at the very edge of what I would call manageable if its just you. If you have a dedicated crew that will help you move them into storage at 5am then perhaps look into larger cabinets

    Do you have casters on the back of the cabs? My DIY 21" cabs have slots, which serve as handles inside the horn mouth and wheels on the back (on the hatch, which is almost as big as the entire rear of the cab), which makes them really easy to move around. I imagine the horn mouth of the SKRams would also server as a good handle to throw them onto their backs. I'm sure stacking 3 ain't fun. My back hurts from looking at that stack, the SKRam looks like it's at least 150lbs!

  7. 11 minutes ago, kipman725 said:

    The level seems quite low.  I would expect the noise to be constant with level so SNR should improve if a larger signal is used.  The Fireface UC is spec: THD+N AD: < -98 dB (< 0.0012 %), THD+N DA: -96 dB (0.0015 %) so you're getting pretty close.

    What do you mean by low level? The last measurement was taken at 0dbFS, which produced 6,6V at the Fireface's output.

    Here is a direct measurement of the FF without the pmillett in the loop (max output 6,6V as before):


    Best THD is achieved at 0.5V output, best noise floor at maximum.

    Here is the THD/Noise vs output plot:


    • Like 1
  8. Pmillett Sound Card Interface loopback measurements:

    Measurement chain is Fireface UC → SCI (Generator input) → Internal loopback → Fireface UC
    The SCI converts the balanced signal of the Fireface internally and outputs either balanaced or unbalanced, which can be switched. It doubles the output voltage, so if I input 2V balanced, it outputs 4V balanced or 4V unbalanced. Voltages seen are after conversion (means the Fireface outputs half the voltage displayed).

    Measurements are sorted by voltage ascending.








    The 1V measurement looks similar to the Fireface loopback, so I guess the pmillett isn't adding too much distortion.
    The pmillett started distorting at about 8.6V output (unbalanced). When I switched it to balanced, the distortion increased a bit, but there was more headroom (presumably twice the voltage).
    Here is a measurement of the Fireface at 0dbFS, which produced 13,25V at the Pmillett's generator output, which is about 24,6dbU:


  9. I figured out the mains hum, which was a rack power strip mounted above my patchbay in my outboard rack.
    The following measurement was taken with the power strip switched off:


    THD looks good, but THD+N still pretty bad, I'm not sure why that is, as I can't really see anything that dirty in the rta there...

  10. 9 hours ago, kipman725 said:

    I did some loopback tests of a presonus firebox, they are ~7dB worse than your results for noise and distortion.  However your distortion is much lower.


    should be more than adequate for PA amplifier characterization.

    The Fireface had been RMA'd once and ever since it seems to reset the connection to the PC occasionally when a ceiling light (LED or Tungsten) is switched on or off, which is very annoying. I suppose there might be something wrong still, which might also cause the mains hum (50hz here in Germany) plus its 3rd harmonic, which is the reason the THD+N gets tanked. I think I should contact RME customer support to confirm whether these results are expected or not. I ran this through my patch bay in the outboard rack, which meant 50ft of cable, but it was balanced so it should not matter much?

  11. I took some new distortion measurements of the interface and the Pmillet Sound Card Interface I'm using.
    I decided to use REW's RTA to take these, as it gave it more flexibility with window sizes and averaging etc. 0dbV is not correct, but I had to 'calibrate' it to zero, since I couldn't find a way to take the fundamental as reference.




  12. Been doing some tests with my Hypex amps and just out of curiosity I ran them without water in the tank, because I wanted to see how warm the elements got when testing lower power levels.

    I put the bank on 8R (two elements in parallel) and gave it 50W for a minute. I could still touch the elements after the test was over. They were probably around 50°C (110°F?) at that point. Good news for me, as that means I can test everything below a few hundred watts without having to fill up the tank. I will give it a bit more power tomorrow to see how much the resistance changes, but it shouldn't be much. It's 8.2-8.3R cold and 8R under full load (3KW per element, which would mean an amp with 6KW into 8R would be required to saturate one channel).

  13. 19 hours ago, Ricci said:

    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.

    I agree on the 3 seconds part. Amps either drop off from burst power to sustained power within a fraction of a second or they're burst power=sustained power type of amps. Looking at my Sanway test reveals that nothing much changes after the cap banks are drained (after just shy of a second). After 2 seconds it ended up on its sustained power level, which would happen even faster when driving two channels.


    I think I'll go with 3 seconds at 1k, 100, 60, 30, 15 and 8Hz. It cuts down on my testing time, is less hard on the amps and my breakers are unlikely to trip like this. Looking back at my initial test, the 90 seconds test was pretty stupid. 90 seconds 100% duty cycle into 2R of a fan modded amp...

    I will fool around with REW and stepped sine wave tests as well, maybe that reveals some interesting results (It can step level now and not just frequency)


  14. 3 hours ago, atltx said:

    Some things happen for a reason I guess.  Lean-business.co.uk has sold out of the handmade horn.  Definitely need to relax my mind with a challenge and make the best use of my dollar.

    I'm about to ask for a lot of help.  Can somebody please post a list of recommended equipment needed to make horns.  Example: What type of table saw works best?  What other tools would be a best purchase?  

    I'm pretty good with fixing stuff and will figure this out.  Not afraid to try.

    Thank you

    Tbh I'd personally buy a large enough 3D printer. I have all kinds of equipment, which includes a CNC router, but even then, making horns is something I'd find cumbersome to do. Doing it on the CNC would require doing it in something like 1" slices. Doing it by hand with something like a large Dremel... inaccurate and really tideous work...

  15. 4 hours ago, Ricci said:

    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. 

    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.

  16. 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.

  17. On 9/25/2021 at 9:11 PM, M88@FL450 said:

    Hi Gang. After considering this monster I’m debating a driver. 

    The IPals unless I can get a vendor to slash the price is a non starter for me. 

    Would you all agree the next best is the Eminence NSW21? 


    Beyond that the DS and Lavoce are third in terms of performance by my analysis here. 

    In terms of most economical of output per dollar, would the Lavoce be the pick or the Eminence? My intended bandwidth is 35-100 with emphasis on kick drum (66-90hz)



    I'd say you have a pretty good overview already. I have 4 21ds115, but if you want some 1-2db more headroom, go for the Eminence. Your call if you wanna spend the extra on that. For me (in Germany), the Eminence is twice the price than the 21ds115. It's actually almost the same price than the 21IPAL here. In the states it's more like 500 vs 700$ between LaVoce and Eminence I think. I'd personally go for the latter there.

    • Like 1
  18. On 9/6/2021 at 12:39 AM, jay michael said:

    Yeah man, just a pair of 3002’s on the 6 Skrams on 15 amp plugs, the venue has shit for power. Still zero complaints, they work hard, stay cool and sound great. Think the k10 is getting lonely staying at home all the time, I’ve actually put it up for sale 

    You mentioned running limiters. Do the CVR amps have true power limiters? I'm looking for an affordable amp with a proper limiter and plenty of power. I own two Sanway amps (an FP13k and a D10Q, which is a dsp amp), but both have pretty useless peak limiters...

  19. On 9/2/2021 at 5:26 PM, jay michael said:

    I was running about 20% down from where the start of the limiters would engage during the headliner slot, so yeah lots of headroom remaining. I feel like I’ve had some breakthroughs this summer with tuning, I can get things sounding real full and impactful without it ever feeling tiring or abrasive, it’s a real pleasure to listen to. Open invite dude, I’m a big fan of alien technology, let’s set up a play date :)

    another clip recorded from the mezzanine upstairs, notice the bass warping the video recording…. Some serious pressure going down


    That looks dope! Were you running them off the CVRs?

  20. On 8/13/2021 at 9:46 PM, Ricci said:

    Live streams just aren't the same. 

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

    Nah, that wouldn't impact the direct sound at a close range like that. It sounded like there was an 8khz high shelf on the bottom 2-3array elements which boosted that region by some 6db, in addition to being way too loud (it was an easy 10db louder there than everything past some 20ft from the stage. I didn't dare to go there again..!

  21. 1 hour ago, Ricci said:

    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. 

    Yup, had everything cancelled for the last 15+ months, bar a single wedding.
    First show in a long while was 2 weeks ago. Audience of 200 (seated) in a location for 2000... was an interesting show.
    They had l.acoustics there with 10-12 Kiva line array elements per side. They were all running the same settings, which sounded to me like a distance compensation for ~30m (100ft) or longer, which meant the 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

  22. 8 hours ago, Chris said:

    Hi all I am looking at a DIY FOH build. For the top boxes looking at the Peter Morris PM90 and was wondering if this sub in two per side would be a good match. I plan to bite the bullet and spend once so the Eminence NSW6021-6 will be the driver. On that what would be ideal power amps to run the show



    Almost the same setup, I think @dsl1 was very happy with it  ;)

  23. Thanks for the paper, I've been looking for some more info the topic!

    If you had access to a flow sim software, you could probably get some decent info out of that, even if it works with (non compressible) liquids.


  • Create New...