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Posts posted by peniku8

  1. On 7/20/2024 at 10:54 AM, chrapladm said:

    Which amps did you start with and go to?

    We had a Sanway DP10Q before (which I added balanced post-dsp outputs to, so we could add our FP-13000 while on the same processing for more subs).
    The amps are well-built and do output good power, but as we know, they have no protection circuitry and the dsp is just.. "basic". You get 8 points of PEQ, adjustable Xovers and an unpredictable limiter that doesn't work well.
    It's just one peak limiter, so you have no way of protecting your speakers against thermal overload.
    On top of that, the amp's inputs clipping point is 12dBu, so I had to build 12dB pad XLR cables to avoid overloading the inputs with the mixing console. Then the channels have a maximum gain that's way too low. As soon as you use substractive EQ points, you won't be able to hit maximum output levels anymore, so I had to sacrifice one PEQ point per channel to make it a 20Hz High Shelf as makeshift gain control. Atrocious, really.

    Now my company bought a sample of a Powersoft OEM-only amp which I'll be using as development platform for my own speaker designs, so I can bundle system amps with the speakers, like the big manufacturers do. It's coming with us for field-testing and after setting up dsp profiles this week, the first show with it will be next week.
    It's basically an X4 with less 2R power. 4x3KW into 4R. 2U, touchscreen. We also bought M-Force and the M-Drive is a great amplifier too, of course.

  2. 9 hours ago, klipsch said:

    The wood will fail before the PL premium. 

    Just as it will with regular wood glue. PL is great when your cuts are rough and you need the glue to fill gaps to prevent possible air leaks. If you have nice clean cuts and dados, then wood glue >>> PL, since it's easier to work with. PL being very viscous means it doesn't spread nearly as well and you need high and consistently distributed clamping force (clamps directly on the material will not work!). Just make sure you have the water resistant wood glue and you're good. I paid 50 bucks for my 10kg (22lbs) bucket, which is probably enough for several dozen speakers.

  3. On 6/21/2024 at 8:54 PM, rolo95 said:

    I think its pretty well known that the chinese amps deliver when it comes to power, but you don't buy Powersoft just for the power, you buy it for the great dsp that lets you run your subs way harder while knowing you won't burn the VCs. Running subs without the true power limiter (or something similar from another manufacturer) is just leaving headroom on the table. I run my subs very conservatively right now and I'm sure that they'll gain a few dBs just from being able to replace the (unfit) RMS limiter with a 150ms attack time that's currently holding them back with the true power limiter, aside from the upgrade in output power.

  4. Eminence was acquired by B&C so it makes sense they'd like to expand the selection for the IPAL system, however, the motor force looks to be closer to the "normal" good 21's out there (320 for this driver) than to the IPAL models. LaVoce did release a driver very similar to the 21IPAL tho, but at about the same price point iirc.

  5. 8 hours ago, btwhite92 said:

    Hi all,
    After 2 years of having a SKRAM build on my radar, I'm finally nearing the end of the construction phase of my first (of hopefully 6 someday). This is my first cabinet build with an access hatch, and my plan for attaching the hatch to the rear panel was to use threaded inserts. The engineering part of my brain wants to love threaded inserts, but after many failed attempts with them - including just now on this build - I've learned that without either a CNC, or a drill press and a laser interferometer, they're basically impossible to line up straight enough by hand to be useable. Is it common to just run plain old deck/wood screws to attach an access hatch? I'm not expecting to be inside the cabinet often (hopefully never) but a bit nervous about threads blowing out after a couple times taking hatch on/off. 


    The two most important things here are the type of threaded inserts you use and the accuracy/size of the hole you make. For hatches I use M6 bolts and the hole for the threaded insert is a 7.5mm. The holes are drilled on my cnc with cnc drills, producing an exact 7.5mm bore, which will guide the insert perfectly so it's 'pull' itself straight simply because it doesn't have room to sit at an angle. If you drill holes by hand, a lot of factors have an impact on the actual bore size you end up with, so I'd recommend testing different drill sizes on some scrap material and measuring the actual bore, so you get that right. You might find out you need a 6.5mm drill to make a 7.5mm hole (holes turn out 1mm larger, if the drill tip if offset by 0.5mm for example).

    I've tried out just about all types of threaded inserts I could find and these are imo by far the best ones:


    They grip the wood much better than anything else I've tested.

    I use this Makita to install the inserts:



    For the through-holes on the other panel I drill holes 1mm oversized.


  6. 9 hours ago, Father Francis said:

    Question for anyone running four plus skrams, last weekend we were running 4 cabs standing strapped together with 2*215 , and a pair of F1 res3 sh , 

    anyway after the gig the two cabs in the middle were pretty hot, the cabinets plywood like very warm , cabs are loaded with B&C Sw 152 8ohm running all four off a K20 

    Are they painted black and some strong lights were pointed at them? :P

  7. I watched the movie two days ago and was very confused and disappointed about the bass I was getting, even tho it seemed to go deep by the graphs and didn't even need BEQ. Turns out MadVR doesn't downmix the LFE channel into stereo! I'll have to see how I can fix this, since my mains go to like 16Hz. (this was the first movie I watched on the stereo setup)

    Edit: I solved this problem with the LAV Audio Decoder. It baffles me that the default MPC-BE option (ffmpeg?) only downmixes center+surrounds into stereo and leaves out the LFE. There is no slider for LFE mix, which you luckily get with LAV. But in LAV, the mix sliders don't give you values in dB, but in numbers and the default is 0.707. What the hell!

  8. 13 minutes ago, klipsch said:

    With all of the vents open, maybe start off with a 24db BW at 30hz and 110hz respectively? 

    A sharper slope could be used on the low end if really pushing the cab/driver. On the higher end, it really depends on your mains. 

    I typically like to grab the HR sim and use the filter wizard so that the maximum excursion below tuning doesn't exceed the maximum excursion above it. With a 4th order Butterworth that typically lands a few Hz below the tuning point, which is around the same point as you suggest, for this cab's native tuning of 30Hz.

  9. Draw a 1:1 sketch onto the wood (optional but helpful). Then make a 6° jig for the table saw and cut it where it needs to be cut

    15 hours ago, lawbadman said:

    Question for the more proficient woodworkers here.

    Referring to baffle brace J in the construction plans.

    I don't have a CNC machine, I only have a table saw, circular saw and jig saw. My tools are usually only good for square or rectangle cuts.

    Can anyone advise me on the best method/trick of accurately making the 6 degree angle cut (on the right side) with the tools that I have? Its a tricky cut with the tools I have...



    skram J.png


  10. 1 hour ago, Lex breijs said:

    Upon completion i would like to submit measurements. I think i have everything (software, calib. mic., mic, stand etc) Could anyone point me in the right directions on a step by step measurement process?

    I know theres a big chance this thread is dead, no one will be reading this but im trying anyway and like to thank Josh again for the nice drawings.

    Here is a small guide of what you need to obtain accurate measurements of a subwoofer:


    • Microphone with a known frequency response (ideally an omnidirectional mic, something like a UMIK for example, but technically for this purpose any microphone with a calibration file for on-axis (free-field) sound will work)
    • Audio interface
    • Amplifier
    • DUT (Subwoofer)
    • A computer with REW, ideally something portable

    Measurement process:

    • Calibrate your electrical chain (I'd personally not recommend this step to beginners as it's possible that you'll be making things worse. So if you don't know how to do this you can omit this step, since it's likely not gonna make a huge differency anyways if you have decent gear)
    • SPL calibrate your mic (not needed if you just care about frequency response)
    • Find a suitable open space to obtain your half-space measurements in. This means outside on a flat surface with no objects within a certain distance to your DUT (say ~10m or 30ft; parking lot for example or your backyard if it's large enough
    • Place the subwoofer in the intended configuration with the radiating source (aka reference axis) towards the microphone
    • Place the microphone one the ground and at least 4 times the widest dimension of the baffle/frontal area (typically diagonal) away from the cab, which would be about 4m in your case
    • Take a measurement sweep in REW. Start with a low level to avoid mishaps and define a sensible sweep range (for example starting two octaves below the expected tuning point and ending two octaves above the intended maximum usable frequency, which would be something like 10Hz-500Hz in this case)

    Interpreting sweeps is an entirely different topic, but I hope I didn't forget anything here so you can obtain some high quality data!

    • Like 1
  11. 17 hours ago, Bionico said:

    Hi Robin,

    I already noticed last week that you are selling yours and I also knew this customized copy from your making of documentations in the AVS forum. It’s a really nice piece of work and the customized look fits to your other components.

    I first considered your enclosure as an option, but finally realized there are just too many mismatching points for me:

    -          I really like the look of the integrated handles on the sides, the top and the bottom. I fully understand they were omitted when not using CNC

    -          The vinyl painting wouldn’t fit for me and I have no experience in removing it for a repainting

    -          My Eminence NSW-6021-6 have a smaller Bolt Circle Diameter and a smaller Baffle Cutout Diameter than your previously owned B&C 21DS115

    Beside transportation costs from Saarland to Hamburg at least the latest point on the previous list is a knock out criteria.

    I mean, these are all problems that can be solved. If you pay me a bit extra I'll modify the cab to your liking and then you can compare my price to the CNC quote you get ;) Shipping would be around 100€, looking at a quick google search. I would just prefer to not have to paint it (the vinyl wrap can just be ripped off). But you'll have to get yours painted too, so either way you'll have to figure that out.

    • Like 1
  12. 3 minutes ago, Bionico said:

    After reading so many convincing posts and measurements about Ricci’s Skhorn, it was only a question of time until I desperately want to have one of these.

    I already have two Eminence NSW6021-6, each one running in a self-made 200L ported enclosure and each one driven by a bridged FP14000 clone. The enclosures work, but I am convinced that the drivers are running far below their potential and I’m also not really satisfied with the sound characteristics.

    Meanwhile I was lucky to find a nearby CNC shop in Germany willing to build one for me. They asked for metric version measurements and I found a pdf with metric drawings in the original post. After a closer look it turned out that these drawings provided by Robin Mahler (peniku8) were created for building without CNC and contain various design changes.

    I really like the design change to build the braces in one piece and with holes as done by dsl1 for his CNC version.

    @dsl1: from all versions I have seen so far, yours is the one I like best. May I kindly ask you to share your files, knowing that my local CNC shop might still have to do some adjustments to consider material and cnc setup.

    Or is there anyone who already built a Skhorn with CNC and metric sizes?

    Wait, you're in Germany? I'm selling my Skhorn, without the drivers. I'm in Germany too, hit me up if you want it

  13. As the title says, I'm selling my Skhorn. I took the drivers out and built single driver subs with handles for PA use, because I don't have space for a subwoofer anymore after moving. As such, I'm just selling the cabinet without the drivers. The port blocks are still installed.

    Plenty of pics here:

    Asking for 1000€, that's about its plywood cost atm (18mm BB). Fixed price, for anything less I'll rather keep it.

    I live in Germany near Luxembourg. No shipping, unless you handle everything. I have an epal pallet which I could put it onto. Would charge 50€ extra for that.
    I can not transport it either, so it must be a local pickup. Has 4 wheels installed on its back currently to move it around easily.

  14. Heya, I wanted to update this thread with my recent findings comparing straight ports with shaped ones from two 21" subs.

    I build two cabs of identical size and tuning loaded with 21DS115-8 drivers, where one cab has a straight port and the other one has a port with continuously changing area. The shaped port has a moderate ratio of 2.5 (largest to smallest area).

    I put both cabs up for compression sweeps at 2m half space and the results are quite interesting.

    Port compression is visible at around 20V for both cabs, but I don't care much for fractions of a dB of compression. It starts getting interesting at 64V, where the shaped port went 0.5dB into compression and the straight port was at 1.5. The difference remains 1dB at 90V, but now we see power compression starting to kick in as well, centered at around 75Hz.

    Here are both cabs at 128Vrms input:


    The difference is still around 1dB at tuning, but now we see a stark difference of around 2dB near 70Hz. The cab with the shaped port behaves much better overall producing a smooth curve, which would still sound excellent at those levels, while the straight ported one starts being kinda all over the place.

    The difference at tuning is easily explained: the aerodynamic port reduces 'air resistance' so the cab is more efficient there. The expansion at 45Hz I can explain too, or at least speculate: This is where impedance and particle velocity is high, which means no power compresison in this region and vortices forming along the surface, reducing friction with the cabinet walls. The dramatic difference at 70Hz I have no clue. The port does nothing at that frequency...

    Interestingly, the sweeps at 181V look similar, because both drivers are heavily into power compression at that point, but the shaped port wins out by 1dB on average.

    Distortion looks pretty similar across all levels, except for the 128V sweep, where the cab with less compression also has quite a bit less distortion (around that 70Hz).

    So, conculusions.. It looks like overall a shaped port can extract 1-2dB more out of a subwoofer of a given volume, depending on which frequencies you need for your application. The cab with the straight port performed almost identically from 40-60Hz, but for other frequencies, it might be the difference of bringing 6 to bringing 8 cabs to a show.

    On another note: hornresp predicted this subwoofer's max output at 44Hz to be 124dB (1m full space), limited by Xmax. But I measured 129dB (2m half space) with just 7% THD... 5dB is a pretty big difference, especially since hornresp doesn't factor in any sort of compression...

    • Like 3
  15. Randomly came across this old topic and I thought I'd elaborate on what (probably) happened here, in case someone comes across this in the future:

    Some amps have their 2nd channel running double reversed. Their input phase is flipped and then the output wiring is also reversed, flipping the phase back. This seems to make it easier on the power supply, since one channel generates a positive voltage swing, while the other goes negative, creating an overall balanced load on the PSU. It's kinda like running bridged.
    Since the output wiring is flipped on channel two, 2+ will be neutral. And since both channels are running on the same PSU, ch1 and ch2 have a shared neutral, which means you're running 1+ and neutral, essentially the same as 1+ and 1-. If you hook up 1+ and 2- while feeding both channels the same input, you're running bridged (differential) automatically.

  16. 20 hours ago, jay michael said:

    These amps conveniently have power factor correction, so they will take what ever voltage you throw at them reliably

    I was under the impression that the variable input voltage thing was a doing of the SMPS itself, not PFC. Are you sure these amps have PFC?

    12 hours ago, chrapladm said:

    Where can I find out more info on this said device?

    I got an email from them announcing the D-3004 with 4x8600W@2Ohm but in the follow up mail their rep said that the amp isn't really 2Ohm stable lol. But if it really performs up to spec, you could run 3 Skrams per channel for a total of 12 cabs off of a 1U amp, which would be pretty sick. But of course pushing the amp pretty hard.

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