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NBPK402

Our new Home Theater build...Negatron 2

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I think that your problems have been computer related. I assume that you're going to place the ICEpower amplifier on the compression driver channels(?).  In my experience, the gain of the ICEpower 50ASX2 modules has been the same as the Crown D75As, so the task of finding the correct bass bin amplifier gain control setting will be very straightforward.  Remember that your issues currently are that your settings aren't predictable from REW measurements.  This is something that is caused by computer issues, not amplifier issues. When that part is under control, the dialing in process is very easy when changing out amplifiers having different gain.  You still need to take initial measurement(s) to get approximate balance of the channels initially, but the secondary balance using REW measurements to set the Xilica channel gains is usually a one measurement task, i.e., very easy.  This is the way that it should be--relative independence of EQ from swapping out amplifiers (except amplifiers having high output impedance--like SETs).  Have patience, and faith.  It will work out.  Mark is right about his comments in this area.  Just take it one at a time.   It took me a while to figure out how to dial in loudspeakers, starting from zero.  My purpose is to help others avoid having to go through a long discovery and learning process in order to get good sound.  You're almost there.

 

Chris

 

 

You have been very patient, and have the knowledge to tune these 1000% better than I ever could. I have 3 of each Icepower 50asx2 BTLs, and 125asx (running in bridged balanced mode). So no way to adjust gain. default_sad.png Sent from my SM-T830 using Tapatalk

 

 

 

 

 

 

 

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The 50ASX2 has a voltage gain of 27 dB (bridged mode), while the125ASX2 has a voltage gain of 30.7 dB (bridged mode).  I assume that you'll use the 125ASX2's on the bass bin channels and the 50ASX2's on the compression driver channels. 

 

The K-402-MEH woofers in my unit are considerably less sensitive than the compression driver channels, so the voltage gain differential of the two amplifier types will actually work in favor of balancing the gains using the Xilica.

 

Chris

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Yes, you are correct... I will use the big amp modules for the bass only.

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On 4/4/2020 at 3:56 PM, Chris A said:

BTW: the tradeoffs that are made for MEHs are far less of a compromise than using separate horns like on "conventional" loudspeakers...in terms of the resulting sound quality and issues with lobing at the crossover frequency bands--among other issues such as time misalignments.

 

Chris

I second the motion. Correct does as correct is.

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I got 50 Hockey Pucks that I am starting to install for my MEHs, and my AV Rack...has anyone tried these here? I have seen others in other fourms swearing by them. I am now waiting for my felt pads to attach to the bottom of the Hockey Pucks to make them slide better on the floor. My rack must weigh at least 300lbs with all the equipment loaded. I am putting 10 or 12 of them on the bottom of the rack. I have heard of people putting 1 for ever 1000 lbs.

I drilled a hole for the wood screw to go through, and then counter sunk it. I got them close to center, but not perfect...not that perfectly center will mean much once they store being used under my rack or my speakers. I think it spaces up just enough to protect from moisture, and prevents damage to the speakers from moving.

 

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69aa5f14782edde8bf12dcdd055d4a83.jpg

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I changed the rear cage, and the way the horn is supported...this is the center channel, and will also be the test for a cabinet. All of the front 3 will have the same framework...even if I decide to keep them as OB.

 

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48bc825f451ccb9acc346ce146d84f92.jpg5b63bb131450b64fcf64355754dce898.jpg

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Ron how did you mount those larger “#3” panels to the horn?  Permanently with glue I think you said but what glue and what about the curve in the horn there?

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Ron how did you mount those larger “#3” panels to the horn?  Permanently with glue I think you said but what glue and what about the curve in the horn there?
I sanded down the ribs, and then we used construction adheasive. For the woofer pads I used silicone, and I have to tell you the silicone is very strong...I have to pound a putty knife in between the seams to remove the woofer mounts. The construction adheasive works great, but you have to be careful with shear strength as if it gets a sideways movement it can fail. With the silicone adheasive it seems to hold up in every direction. I would be very tempted to just use silicone adheasive as I think it might be stronger in this situation. If you try it and do not like it...it is not hard to remove from the surfaces with a putty knife. I run the silicone for the pads overlapping the #3 panel ends, and it works great. I am in the process of removing the woofer pads to round them all (instead of square), and also when my router bit arrives I will route the ports with a 45 degree chamfer bit.

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Thanks Ron.  Yes, I see looking more closely at your pics that you sanded down the stiffening/strengthening ribs, 2 on each wider side and 1 on each woofer mounting side completely.  Not concerned about loss of strength there?

Also I measured one of my horns and an Eminence woofer.  The curve in the horn begins on both wider and narrower sides 12" from the input flange - before 12: they are straight flat sides.  Clearly your stiffening #3 boards made out of mdf and your woofer mounts are flat yet extend into the curved area of the horn for the 15" woofer.    So again I ask, what about the curve in the horn?  A flat board cannot lay flat on that curve.  Are you trying to account for that or???  

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I figured the MDF would increase the stiffening. As far as the curve in the horn I believe the construction adhesive was but on thick enough to fill the gap in the curve.

I mainly did the #3 pieces to avoid drilling into the horn, as I did not want to screw up.

 In addition I had originally thought of running 4 woofers, which would have required mdf on all 4 sides. When I started to look T how I wood have to arrange the panels, I decided 2 was enough.

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2 minutes ago, Negatron said:

I figured the MDF would increase the stiffening. As far as the curve in the horn I believe the construction adhesive was but on thick enough to fill the gap in the curve.

I mainly did the #3 pieces to avoid drilling into the horn, as I did not want to screw up.

 

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I see what you did there! HaHa😄

 

so you must have to lay on the silicone pretty thick too on the woofer mounts just to mate the port holes cuts in the mdf to the cuts in the horn wall not too mention not wanting to create a resonating cavity between mount and horn wall.

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I had thought of using Green Glue, but I did not have anymore left from my last theater... Inam not sure if it would have worked properly either. I do know irpt worked great on wood to sheetrock though.

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I see what you did there! HaHa
 
so you must have to lay on the silicone pretty thick too on the woofer mounts just to mate the port holes cuts in the mdf to the cuts in the horn wall not too mention not wanting to create a resonating cavity between mount and horn wall.
When it comes to the port holes it is pretty tight....just a slim line where they join together. Not noticeable to me at all, especially when you paint the MDF in the ports.

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Sometime this next month I am going to be making a new rear cage... it will be made with 1/8" x 3" aluminum. The problem with the cage I have now is duplicating it with precision is very difficult for me to do with a circular saw, and a compound miter saw. This time Inwill have real wood for the uprights attached to the front board, and also in the rear. The design will look something like this except I will have a large gap in the rear for accessing the drivers in case I go with a cabinet. My machinist friend will be doing all the bending, and I will be doing the easy part...cutting wood to 4' long, and then cutting 3" wide grooves 1/8" deep. If Inend up with a cabinet the sides will be attached with nurled screws from the inside going through the aluminum then into the plywood or mdf sides.

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8 hours ago, Negatron said:

When it comes to the port holes it is pretty tight....just a slim line where they join together. Not noticeable to me at all, especially when you paint the MDF in the ports.

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Of course it's not important whether it's "noticeable" or not visually but whether the mount surface and the horn surface have a gap between them that resonates / vibrates at certain frequencies.

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I also found out that the different vintages of the k402 are different thicknesses. I have 2 of the fiberglass ones, and 2 ABS ones . It was interesting that the between the ABS ones they were way different in thickness.

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I would think the best way to fill the cavity would be to build it up, and sand flat...then add the #3s, but I think what we did is sufficient.

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I got tired of not being able to get my mic positioned exactly the same everytime....so I cobbled together this from my leftover pieces of 8020.6d18499a53f5e9f03126205ee2ac5dae.jpg

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New amp is almost together now...keeping fingers crossed that my first assembly try works.d71635c6ce58b1cf2b1d4d6d9d732660.jpg8b29ddf9ab889b7f08f3aed491824f03.jpg3db724e881ddd6a5a9952dae67125966.jpg

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On 9/22/2020 at 8:05 PM, NBPK402 said:

New amp is almost together now...

 

Six channel power amp looks good. Appears to be wired for dedicated bi-amping of the L-C-R speakers. What will be connected to the 2 extra blue Neutrik power cord receptacles?

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