Reversible Ported Mod for the heresy

[DrWho]

Well I finally got started on my RPM for the heresy and wow it's a lot of hard work. I spent over 6 hours today just measuring and remeasuring a billion times and then cutting the wood. In fact, I'm not even done cutting all of the pieces yet! My woodworking skills are very lacking, but I was able to piece it together and I'm within a 1/16" all around (not bad for using just a circular saw and a jig saw...in fact, I bought the jig saw today, yay for new tools).

Anyways, I figured I'd start a thread and start sharing the finalized plans and dimensions and all that.

So first up is a 1/10 scale drawing (.1" = 1") that shows all the pieces that need to be cut and their dimensions. It's a bit confusing so I'll post some real pics of all the pieces and write in the dimensions tomorrow (provided all goes well).

Not included in the drawing is configuring the rear panel to be able to house the original heresy panel. This way you won't need to do any wiring modifications when switching back and forth between ported and sealed (except maybe increase the length of the lead between the input panel and the crossover). The other advantage to this is it makes it a lot easier to attach the RPM as well (gotta get inside and screw it into the normal holes that the original panel screws into). Though I won't do it on this speaker right now, I think it would be beneficial to use T-Nuts instead of just straight up wood screws so as to avoid thread wear.

And lastly here are the predicted results calculated using WinISD:

Lite Blue = K-22E Ported

___Yellow = K-22E Sealed

Dark Blue = K-24K Ported

___Orange = K-24K Sealed

The net end result is a 3.9 cubic foot enclosure tuned to 33Hz. I went with these parameters because it works for both the heresy and heresy II. Power handling decreases rapidly below 30Hz so a 2nd order Butterworth high pass filter at 30Hz might be considered to control excursion with low frequencies at high SPL.

I have no clue how to integrate this into the circuit path so it would be real cool if one of you smart crossover gurus could provide the specs.

Would it be a 56.3 mH inductor wired in series with a 439 uf capacitor wired in parallel? Where would one go about finding these parts? Would a different type of filter be better?

Well that's all for now, but there should be more pics coming up very soon. When I finally get this finished I'll be sure to take some measurements and comment on the sound. If anyone is interested, I would be more than willing to ship the RPM around for anyone that wants to try it out. I only have a single heresy doing center channel duty so there's only the one available. If I like how it sounds, then I might find myself in the market for another pair of heresies...if you compare the specs against the chorus/cornwall this mod should go just as deep (but less max SPL). And as a fellow board member pointed out, a ported heresy is essentially the Tangent 400: http://www.klipsch.com/product/product.aspx?cid=156&s=specs, so we can expect similar results.

[Al Klappenberger]

Dr.

What your doing is similar to my "Heresy on steroids" den speaker. Mie si 4.3 cubic feet tuned to 34 Hz. It uses the K24 of Heresy II.

Note the round braces inside to kee the sides satable. You should do this too. The performance was sold down to 30 Hz. I'll post the plot next.

That "breathing filter" you need to protect the extreme low end is usually built in to amps. Thats why the roll them off below 20 Hz with R-C networks.

Al K.

[Al Klappenberger]

Dr,

Here's the response with the mike stuck right into the woofer cone and right into the port. You add the output of the two. At the extreme low end everything comes out the port.

Al K.

[Al Klappenberger]

Dr,

Here's some plots take with the mike back in the room. The rest of the speaker is a K55V driver on a K500 horn (From a Belle) and a Beyma CP09 tweeter. As you can see, it's solid down to 30 Hz and goes to beyond 20 KHz.

I think you should get similar performance if you can make that box solid enough. With it built in segments like that it will REQUIRE lots of stifining inside.

Al K.

[DrWho]

outta curiosity, when do you know that the cabinet is braced well enough? Other than when you don't hear the cabinets vibrating of course

In fact, one of my biggest issues with the heresy speaker is that the back panel is only 3/8" and when you tap on it, you get a nice resonating sound. Once I heard that resonation, it always sticks out whenever I'm pushing the volume and I'm surprised more people don't comment on it or even performed mods with thicker rear panels. Is it originally thicker on the Heresy II? I would think fixing this would have a larger effect than damping the horns (It's in the same frequency range too).

Anyways, the largest cabinet faces are still with the original heresy cabinet so I'm going to put off on bracing for this original build...not like it couldn't be added later.

Btw, nice job impementing those steroids I did a quick comparison between the 3.9 versus 4.3 cabinet volumes and the larger cabinet moves the F3 down 2 Hz, so I'm looking forward to getting similar results...I should probably get back to building

[Al Klappenberger]

Dr,

As I understand it, you can feal the sides vibrating with your finger tips. I am quite sure that you WILL NEED bracing. All sides of my big Heresys where of 3/4 particle board and I will put bracing in it from the beginning. It is nothing more than 1 inch diameter wood dowell held in on each side by a long wood screw.

Al K.

[DrWho]

Well I finally finished and got the chance to do some listening outside and run some test tones. I didn't even bother screwing the back chamber into the heresy because the pressure fit was more than tight enough. No air leaks anywhere and I couldn't feel any panels vibrating (though I didn't really push it all the way cuz of the neighbors).

The -3dB point actually turned out to be lower than 36Hz (31.5 perhaps?), which is lower than the calculated 40Hz. I'll be sure to take more precise measurements of both the heresy and the mod to provide a better comparison.

I was kinda hoping though that the extended bass would help tame the squaker, but that was however not the case. I remember reading somewhere that different taps could be used to reduce the squaker output so I'll be reading up on that. I'm thinking the tweeter output might need to be reduced too but I'm not sure. I think part of what I'm hearing is the ringing of the squaker. Seems I'll be damping that sucker in the near future.

Pics will probably be up by wednesday (when my bro can do his camera thing)

[Al Klappenberger]

Dr,

Nope.. Extending the bass won't change the squawker level at all. You need to dittle with the netwrok to do that. Another way to test for cabinet vibration. since you are outside, is to put a thin layer of sand on a flat surface. You will see it dance of it's vibrating. It will also show exactly where to put the braces!

Al K.

[DrWho]

Ya, I was kinda hoping a little bit of extra low end would make the squaker seem to be not as loud, but that doesn't seem to be the case...I guess that's a good thing because it means I didn't really alter anything but the LF extension.

I tried a few searches, but the search function here really sucks because the text body search doesn't work and titles are always misleading. I was under the impression that you could simply use different taps on the transformer. I suppose another alternative would be to install L-Pads which gives me the option to adjust the volume. Can an L-Pad just be dropped in without affecting everything else?

Btw, I like your sand trick idea...I'll have to bring the speaker out to back and really let it blast away. I have a feeling the pressure fit won't be sufficient so I'll actually have to screw the sucker in.

[colterphoto1]

Mike, try to reach Bob Crites or DeanG regarding the Tap points on the autoformer. You should be able to get a -3 db reduction somewhere.

btw, where did you come up with Heresies, poor college boy!

Theres a pair of Cornwalls in Chicago with my name on em na na na na.

M

[DrWho]

lol

when I picked up your heresies for you, I tried one of them as a center channel and then decided I wanted to buy one for myself. I managed to find a single heresy for sale which arrived just after our meeting down in urbana. This poor college boy is only able to afford one at time

So you picking these cornwalls up yourself that are in chicago? If so, you should totally swing by for dinner or something and I can show you all my toys (and then you can show me how to rope caulk as well). At the very least we should meet up somewhere since you'll be in the area. Ironically, I can't even use this mod because it's too big for where I would like to put my center channel. I set all my mains to small anyway so it's pointless to put too much effort into making it work. If you want, you could take it back with you and try it out on your heresies (which are going on the back patio?) How many speakers do you have nowadays anyway? lol.

I'll post a new thread about the autoformer and see if Mr. Dean or Bob bite

[colterphoto1]

Good Job on the purchase Mike!

I recently had my KLF-C7 down to put PopBumbers Kstack xover in it and used a Heresy on it's side for center for a couple days. It does really well, even lying on it's side!

Michael