Shallow Heresy 1s and dampening

[Erik Mandaville]

Based on some really promising results of light stuffing of my Heresy I cabinets, I am wondering if any of you have used Deflex pads behind woofers in sealed enclosures. I think Deflex arrived on the market after I stopped building speakers (or maybe I just hadn't heard of them), but they are supposed to be very effective in terms of breaking up standing waves and deflection back onto the woofer.

Because these earlier cabinets are shallow and smaller than later editions, the preliminary trial of 1" poly fill sheets against the internal walls and approx. 12 oz of loose material inside has made a real improvement for the better. I have read positive reviews of Deflex pads, both linear and concentric versions, for awhile, but have no experience with the material myself.

Any thoughts on this subject are appreciated!

Erik

[Daddy Dee]

Erik,

Sounds interesting. I'm no help on the technical end of things.

I didn't know the early Heresy was smaller. About what are it's dimensions?

[chops]

Hi Erik,

Say, if those rear panels come off like they do on my Cornwalls, why not take the backs off and see what they sound like operating as Open Baffles?

Sorry, I have no usefull input for your question but I'm also on my OB kick right now as well. It's all I've been thinking about for the last month or so. [8-|]

[ben.]

Erik,

I bought some rectangular concentric pads about three years ago. I use them in my Ampeg B-15 tube combo bass amp. It uses a single 15" in a too-small box with a slot vent. When I got the amp it had the typical nasty fiberglass insulation stapled inside. I replaced that with the Deflex - it covers about half the surface area of the interior - and the sound is considerably more balanced and clear. I tried it with no materials on the inside and it was barky and harsh. I recommend them.

I think that the combination of these panels and some fiber filling would be best; I just haven't gotten around to trying it as I use an all-horn system now live, whereas the B-15 shines at low levels for recording.

Madisound had them significantly cheaper than anyone at the time, btw.

[Erik Mandaville]

Chops:

You're using the CWs at open baffles? Really? I have no experience at all with that, although I wanted to try my Lowthers on an open baffle on top of the LaScala cabs when I had those. The original reason I decided to 'go Klipsch Heritage' was mainly for the bass bins on a pair of LSs, where I was going to either use the Lowthers in the Oris Horns (when I had enough money for them) or on an open baffle. Interesting!!!

I have I know a guy in Germany who built a pair of Prometheus speakers, which I think use an open baffle.

Dick Olsher's BassZilla is another design I've been interested in, but this sounds like it would be interesting. I'm not sure that this pair of Heresies I have would do particularly well that way, but I'm willing to try anything.

Dee: Yes, the very early Heresy cabs are smaller than the pair of Heresy IIs we have -- one of the reasons Marie became all the more interested in them! She thought the IIs stuck out into the room too much and threw off our home decor equilibrium!

Ben: Okay, thanks for the information on the Deflex. I used fiberglass insulation (with paper backing removed) in the past, but just hate to mess around with that stuff. I think you are right about finding a good combination of deflex and batting.

Erik

edit: open baffle designs mentioned above: http://www.6moons.com/audioreviews/bastanis/prometheus_2.html

http://store.hifiauthority.com/olsherkits.html

[Erik Mandaville]

Dee:

The main difference between the two Heresies is in the depth. Front-to-back, the IIs are about 13 1/4" whereas the Is I have are just 11". That puts the highly reflective surface of the back panel within a pretty close proximity of the back side of the woofer, and that's the main area I wanted to address with this change. In addition to the side wall treatment, I also have a 1" layer of dense poly batting over the entire back panel; and this is where I was thinking a similarly sized Deflex pad may be even more effective (and maybe not). But I want to try it and see.

Erik

[chops]

Chops:

You're using the CWs at open baffles? Really?

No, no, no... Sorry, I didn't mean for it to sound that way.

No, I'm not running mine open baffle. I have 5 little curious kitties that roam around, and I wouldn't want them crawling into the Cornwalls, especially with that news paper-like padding that's in there. But don't think it hasn't crossed my mind a couple of times. []

I am planning on building a pair of bi-amped OB's though, using dual 15" drivers per channel and the Altec 511B on top. That's going to be interesting!

http://forums.klipsch.com/forums/thread/822497.aspx

[chops]

edit...

[Daddy Dee]

Interesting. Is the deflex made by the same folks that make the focalpods?

[djk]

More money, but another product to consider:

http://www.madisound.com/cgi-bin/index.cgi?cart_id=%Êrt_id%%&pid=311

[Daddy Dee]

Erik,

This makes sense that this solution would reduce standing wave issues in the shallower cab.

One thing I have wondered, and hopefully this is not a hijacking of your thread, is about the issue of filling cabs with stuffing type material. Since the days I first looked in an Advent cab and wondered, what is all that stuffing, it was my understanding that this makes the cab behave "acoustically" larger or some such thought.

This seems to be a kind of gospel among lots of speaker manufacturers. I have always kind of scratched my head that the Klipsch Heresy was not similarly stuffed. It would seem that a bass shy cab volume such as this could benefit. The cost is small for the benefit, no?

From time to time I read posts on the forum from members who have found pleasing results with this. I have been curious, but not enough to do it. I know there are pieces of some padded lining in CW's.

[Erik Mandaville]

Djk: Thanks for including that. It's nice they even include a screwdriver for installation.

Dee: Well, I agree a small amount of fiberglass would have been an inexpensive addition to the Heresy. My Heresy IIs do have a sheet of foam that loosely forms a circle around the back of the woofer, but the way it was installed makes it seem almost like an after-thought -- which it may have in fact been.

The Heresy 1s we have are also not truly sealed in the true sense of the word. I've made sealed design where every single joint and crevice was sealed with silicone glue; and that, per the instructions in one case I remember from another published design I made, even the drivers were glued to the baffle once testing was complete. Some have indicated that silicone can dissolve the glue on driver surrounds and suspensions, but I have never found that to be the case. I've seen other solvent based adhesives do that, and Liquid Nails contains an ingredient (Hexane, I think.......) that is caustic, but silicone fumes have never caused a problem -- at least for me.

It may be that the enclosure, as in the case of the back panel (which has no gasket of any kind) was designed to be slightly leaky, which is how an aperiodic enclosure works. It's really sort of a variation of a closed box design. An aperiodic box works by way of a stuffed, resistive vent, however it doesn't function the same way a vent does in a truly vented design. The effect is often described as being similar to the performance obtained with stuffing of a sealed design.

Anyway, that is one theory I had when thinking about your question -- that the rear panel was designed to be securely attached the rest of the enclosure, but intentionally left unsealed (and unfilled) in order to provide the above mentioned slightly leaky path ( as in the case of the aperiodic example) out of the box.

The the walls of the enclosure are also left untreated is kind of unique to me, since all my earlier experiences with this dealt with the reduction of box-induced colorations from vibration by way of dampening materials -- foam backed carpet glued to the sides, roofing felt, etc. -- that were glued to the wall with silicone, which itself has dampening properties once cured. About 10 years ago, when I put together our Lowther rear-loaded horns, I talked with the designer (JenaLabs) about filling the voids of the internal folded horn with sand, which she very highly recommended. It was a HUGE amount of work to pour all those bags of clean sand through a tiny little funnel into holes in the back of the cabinets. Once done, we sat down to listen to some music, and I was very disappointed with the resulting totally inert cabinet (in terms of vibration) which left the music sounding similarly lifeless. The crossoverless Lowthers still provide some of the best midrange I have ever heard. So, this is a case where cabinet treatment resulted, for me, in very poor performance, with all due respect to Ms. C., the Medallion II designer. It was really not my cup of tea, at all, and it took literally days with a modified vacuum cleaner to get all that sound out again.

Kind of a long answer to your question, Dee.

Erik

[Groomlakearea51]

Interestingly, the factory "stuffed" at least some Heresy-II's. It's a piece of sponge foam/ foam rubber, about 25" long by about 12" wide, by about 3/4" thick. I've found this in a number of the H-II's I've seen (and taken apart...). It is folded in a "curve" and looks like, if you can picture it, a dome that wraps around the top of the driver and horn extending down to the floor of the cabinet on both sides.

I've taken it out on some, put it back on others, and tried it on H-I's. Sometimes it works, sometimes not, but I think it's possibly related to where the speaker is placed. It seems to works best when the speaker is up on a bookshelf near the walls, or corners. The bass is perhaps not "bigger", but it sounds somewhat "cleaner". Heresy placement can be tricky.

The biggest bass improvement on the old, say pre-86', Heresy's I've found has been to check the inside panel seams and brace seams. Usually the wood, and the glue holding everything together has dried out and they can "leak". After re-beading all the seams with glue, and especially on the H-I's by putting a 1/2" wide thin foam weather strip around the access panel where it seals to the braces. It seals them again, and on a couple of ocassions, the difference has been very noticeable.

Hope that helps a bit.

[Erik Mandaville]

Groomlakeara:

Sure, some regluing sounds like it wouldn't be a bad idea, as well as bracing. I found the same as you re: the foam pad in the Heresy IIs. Wheather right or wrong about the lack of a seal on the back panel, I had some thoughts that addressed that above, too.

Thanks for contributing,

Erik

[Groomlakearea51]

Erik, sorry, the post "posting" thing gets posts all crossed up out there in the short wave ether of space and time....

You could be right about aperiodic issue. On the H-II's, I wonder?... Reason: The rear board is quite thick, routed to fit, and sealed, and because of the horns and woofer ring gaskets on the driver board it appears they wanted the cabinet to be sealed. But then again, the H-II is where the foam piece is found.

I'm also wondering if Klipsch did not simply go for the 50% rule on the H-II's where it helped at least half the time and simply put that foam in all of them.

The worst H-I "offenders" I have run across were ones with the braces that were not cut exactly to flush fit against the others, or in one case crooked where the rear panel fits! That left a gap in some of the corners, and on one pair, I simply ended up knocking out the old ones, re-cutting new ones, etc.

On "sealing", I've stayed away from silicone, etc. because of the vapors. Only exception is a dab of GE black silicone around the heads of the screws on the woofer rings. A little "detailed" maybe, but there can be a leak around the screw's shaft passing through the large hole in the gasket. It peels off easily though. I always just use a good quality woodworker's glue.

Old Heresy's seem to be an art more than a science!! I do wonder what does the H-III look like inside? Until they reach about 20 years, I'll likely never save up enough pennies to spring for a pair just to look!!!

[Daddy Dee]

Erik,

Thanks. That is a most interesting thought. I'd wondered about the back panel of Heresy's not being really sealed. Makes sense.

[Groomlakearea51]

Huhm.... Wonder why the E2 crossover is mounted on the side panel on the H-I's. Was it a some method of disrupting resonance? I've gone back through forum posts back to 2001 on bass issues with Heresy's, and the only common "thread", architecturally speaking, seems to be some type of fill, sealing vs not sealed, etc. One interesting thing that also comes out several times has to do with placement and the use of risers.

I'm also wondering about an actual reduction in cabinet volume (Shallow Heresy's....) and an experiment using some removable pieces of styrofoam board, or some expanded closed cell foam gasketing material, etc.. Off to the garage to see what I have and I'll see what I get from a pair of 1977 HWO's with fresh BEC caps, K-22's, K-55's and K-77's.

Anyone interested in some of the historical posts on this topic just type: Heresy + Bass.

[ben.]

Bear in mind the original design goal of the Model H. It was intended to be a center speaker for Klipschorns, hence the shallow depth and disregard for bass response. IIRC, PWK wasn't crazy about the resultant increase in overall apparent distortion and went on to develop smaller folded horn designs that could be placed along a wall and were more compact.

[Groomlakearea51]

Ben, that would certainly explain the original Heresy #8, or "the rarest Klipsch speaker" on display in Museum. The "H" next to it is the "smaller dimension". (photo)

I think that, in a way, we're trying to take PWK's eventual Heresy (as we know it), and obtain the bass we want or think it oght to have. After much "foolin around", I've finally kept the Heresy's away from the Klipschorns and LaScalas. They don't mix very well, except under certain applications (and even then well away from the "big boys" and not in any "array").

[Erik Mandaville]

Dee:

"That is a most interesting thought. I'd wondered about the back panel of Heresy's not being really sealed. Makes sense."

It's just speculation, and may be totally off the mark. Whether or not the panel is intentionally left unsealed, there may be some resulting aspects of performance that may mimic the performance of an aperiodic design.

I've been asked why I want to mess with PWK's design in the first place. My answer is that, while I have every respect for his work and approach, his ears and mine are not one (or in this case two!) and the same. Adding a small amount of fill and cabinet resonance treatment to sealed enclosures is more common than not, and I'm just experimenting to see if I can improve on things a little bit. PWK also didn't originally use plastic tubular capacitors in crossovers, but many people have reported a preference for the newer, non-oil poly caps (and others have been equally satisfied with the GEs formerly used by BEC).

Erik