Reinvent older sealed sub box, help?

[KenM10759]

I recently picked up a Miller & Kreisel V-90 subwoofer from a US Audiomart seller. I bought it primarily because the 15.25" wide x 15.5" deep x 17.5" tall oak-veneered cabinet is a near-perfect visual match for the Hafler 300 floorstanding speaker it's going to be mated with.

Initial tests have shown that this 90 watt 12" subwoofer of unknown age is barely able to beat the bass output of the Hafler speakers. I would like to plan an upgrade of the amp and driver. I figure the internal volume of the cabinet is around 2900 cubic inches, or just under 1.7 cubic feet. Budget is as=yet undetermined, though I'd like to keep it under $500 total. The sub is front-firing, the internal amp is on the back.

Yeah, I know I can get a number of good new subs with warranty for that, but I'm anxious to have this good-looking set work. I've been looking at various drivers and amps on Parts Express, but I really don't know enough about matching the 3 major components (cabinet, driver, and amp) to be reasonably sure it'll sound right.

Any advice...other than leave it as it is and buy something good?

 

[William Lemmerhirt]

I think in this case I might go diy via the help of PE or tlsguy. PE has a variety of veneers, and if they don’t have what you like, try a local cabinet maker. They might have access to material and tools as well as advice for finishing. I like where your going here, as I am not a lover of bedliner coated subwoofers although it’s very easy to get a decent finish that way. You might end up over budget, but probably not a super lot, and in the long run, I think you could have a really nice pair of subs that match the haflers, and you won’t miss the MK at all.

 

[KenM10759]

Thanks, but no, I don't want to start from scratch.

If no one wants to help with what I really want to do, I'll take my chances. This sub is in a 2nd floor bedroom, above our kitchen. I do not need not want double subs capable of 20hz or below. I want something just a little more powerful than what the M&K is now, and maybe hits down to 24hz or so.

 

[William Lemmerhirt]

Ok. I would think someone(maybe PE) could model a couple drivers to see if the internal space would work, then put a bash 300 in a box hidden somewhere and call it good!

 

[lovinthehd]

I'd suspect the amp has issues rather than the driver but hard to know from your description. The amp is more about the dimensions of the plate, whether it will fit the current box or not. You could leave the current amp in place and supplement it with an external amp if you can't find a plate that fits. I'd think it wouldn't be too hard to find a driver that will work in 1.7 CFt sealed....the idea of asking P-E for help is a good one.

 

[KenM10759]

It's both the driver and the amp that suck. A 90watt amp isn't going to move a large voice coil and long- xmax driver, and the driver is neither of those things.

If SVS can get a driver and 500 watt amp to work in a 1.7 cu ft box (actually a little smaller) of the SB2000, and Rythmik can do similar with the L12, I should be able to come up with something. The amp plate size is not going to be a problem because the M&K amp's plate is pretty big. I have "manufacturing capacity" and can easily make an adapter plate.

 

[lovinthehd]

It could have used a relatively sensitive driver; I can think of some subs that have a 85dB sensitive driver vs some with 93dB....makes a big difference as to how much amp power you'd need. More power could well be better but is the driver damaged? Or you just want to junk the driver no matter what? M&K chose poorly?

 

[KenM10759]

They didn't choose poorly. They made a subwoofer for the times that put out perhaps 35hz but not even a close to what THX reference levels are today. I have the gain at 75% and can just then see the driver moving. And it's not very loud. A 300w amp like I have in my KEF Kube 10b would seemingly do much better. A driver with a roll surround rather than pleated paper could move more freely. All assumptions on my part, but I keep going back to modern sealed subs of similar size that it should be able to mimic if I choose correctly.

I'm not even going to junk the driver nor amp. If I sell the sub I want to be able to include the original parts.

 

[lovinthehd]

What about full gain? Does that improve things? You sure you have sufficient pre-out level? (how did you calibrate sub level to the mains?)

I don't look at my drivers to determine their functionality...takes a lot to make them visibly move. More power might help, the driver's surround I don't think has a lot to do with it.

Seems like it would be easier to just put together a better diy sub and veneer it the way you like....

 

[KenM10759]

I've used my Denon's Audyssey to try getting the most out of this sub as it is. As with any lower-level Audyssey setting, I can and often do go back in to see where it's set various parameters and make adjustments to suit my ears. No matter what combination of pre-out level and amp gain I tried, it all sounds muddy. When I compare what this sub sounds like to my two modern subs, it's weak and muddy sounding. Never approaches the lows nor the force of either.

Of course it makes more sense to create what I want from a kit. Can't you see that I simply don't want to do that and really want to use this box? It's a heavy, apparently well-built cabinet to be this solid after at least 15 or 20 years.

I did some reading up on the subject on the Parts Express website, and will take this driver out tonight to see how the driver and cabinet are each built. I'll take more measurements and decide if the cabinet needs any internal bracing. With that info in hand, I'll call Parts Express and seek their assessment, though I've now got a better idea of what I can do after reading quite a bit.

Thanks for the help.

 

[lovinthehd]

Just fleshing out what you have now. Many have said such nice things about the M&K subs....

Yes, I get it you want to use the pretty box Shouldn't be all that hard to use another 12" driver (as long as it fits) and change amp....good luck!

 

[KenM10759]

I bought it specifically because so many good things have been said about M&K subs, it looked good, and it made some noise. The seller demo'd it for me with his Verity Rienzi speakers, speaker on and off. It sounded the same there, but I bought it anyhow because I see potential. I can't know if a V-90 was ever a good sub because info on it searching with Google was really thin.

 

[MrBoat]

I bought it specifically because so many good things have been said about M&K subs, it looked good, and it made some noise. The seller demo'd it for me with his Verity Rienzi speakers, speaker on and off. It sounded the same there, but I bought it anyhow because I see potential. I can't know if a V-90 was ever a good sub because info on it searching with Google was really thin.

Either way, you're at the point where you have to either find a driver (same O.D. too) that works in that size cabinet, or altering it. You could remove the plate amp from being flush mount, to building in an extension off the back to mount the amp there to gain some volume that way. I know there is a design for the RSS315HF-4 that calls for a 2 cu. ft sealed enclosure, which is what I use with that driver and it sounds very nice.

Here's a RSS315HO-44 12" (12.36" O.D.) that will work in a 1.36 cu. ft. box, vented, (you could port those cabinets) that claims 27hz. You could shrink the volume of that box with additional bracing, perhaps, which would help with the more powerful driver.

 

[KenM10759]

Thank you! Both of those I was looking at. I measured the opening and the existing driver. The conterbore is 12.25", so they won't quite fit. I've been looking at a couple others similar to that one, but I also might be able to alter the cutout to fit it.

I am considering using the spacer they offer to mount whatever amp I choose outside as you mention. I like the features of their Dayton digital amp with DSP. Having the DSP gives me some control I don't get with the receiver's low level Audyssey. And it's not overly powerful. It should be just about right for what I need.

https://www.parts-express.com/dayton-audio-spa250dsp-250w-subwoofer-plate-amplifier-with-dsp--300-8010

 

[lovinthehd]

Which Audyssey version does your avr have?

 

[KenM10759]

MultEQ. Not XT, not XT32.

 

[lovinthehd]

MultEQ. Not XT, not XT32.

At least it's not 2EQ...just checking

 

[KenM10759]

I took the driver out (temporarily),measured the inside dimensions and put it back together. Pretty solid build, though I've seen better. I sent the inside dimensions over to Parts Express along with all the other info I had. Anxious to see what they might come up with!

 

[everettT]

You can always add another piece of 1/2" to the baffle. No reason to search for the right cutout.

 

[KenM10759]

You can always add another piece of 1/2" to the baffle. No reason to search for the right cutout.

No, I couldn't. If I did it would look horrible because the oak veneer ends at that face and the grille meets it.

Thanks anyhow.