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Did a Jubilee, now it's time for a Jamboree


jwc
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Dana would be the authority to answer that for you.

The build is worth it at this point. I'm doing the best I can to be patient and try several options before I pull the trigger on building another. It is tempting to build a pair for listening/finishing and keep this one for forever toying with.

The options are endless with this design...the tinker may never end.

jc

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JC, if it were me, and I was going to build a pair, I'd go with the 218 version which is probably going to be a good bet being that it can more easily accept 18" drivers.

The horn is very much the same, except the 218 would have a slightly smaller horn mouth. Still within specs, of course, and still inside the same footprint.

As another "mod" to the current Jamboree test bed:

I also thought of another "mod" to the motor board (current)... It consists of a 6 x 6.5" slot, the 6 being the horizontal width, and the 6.5" being the vertical dimension. The reasoning behind this is that the horn throat channel expands vertically, and our previous motor board slot is 13 x 3", that is, the narrow portion allows for diffraction to the sides of the channels, which don't expand. Both slots afford the same cross-section of 39 sq. in., of course.

Therefore, I wonder what effect the diffraction to the expanding top and bottom of the channels would have? Might be a good thing...

Dana

post-13458-1381932587792_thumb.jpg

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I follow you. And this is another "mod" for the front loaded horn ...right? That makes sense. I would have never thought of that. I have an extra pair of uncut motorboards.

My next move is the Rear load. With your motorboard suggestions. Get to it soon. I have 2 extra front panels cut already for mods.

I ordered parts for the correct network for two ...parallel....600Hz XO. Just waiting for Solen shipping. Then I will listen.

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JC, yes - another front-loaded mod, sorry I didn't think of it before. Up to you whether you want to check it out or not. I don't know whether it is worth doing or not.

Anyway, before you move away completely from the front-loaded configuration, could you please get me the impedance for the Crites drivers (front-loaded) wired in series on the small slot and I'll have Al K. make me a crossover for them, too. Looks like a pretty good setup at a reasonable price to me.

Thanks,

Dana

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OK. Been a little while. need to update this thread with a

DISCLAMER

For those here who don't know me well and aren't familiar with my skill level, take "technical data" from speaker testing with a grain of salt. AS....I am no expert.

curve coming

jc

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Here is the Jamboree raw curve. 2 Bob Crites woofers-stamped wired SERIES! Curve is "smoothed". Front loaded. 3 x 13" slot. 5 sheets insulation....which has been considered in the last few pages of the thread to be "max Vb". I may consider down the road to add one more sheet of insulation with the Crites drivers. Explanation...logic of that another day.

The series configuration lost a minor amount of dB in the low frequencies <50Hz. However....the plus is the gain in the 80Hz to 100Hz. Yes!

The rest of the curve is a little smoother.

jc

post-16499-13819325951412_thumb.jpg

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OK. Been a little while. need to update this thread with a

[:D]

DISCLAMER

For those here who don't know me well and aren't familiar with my skill level, take "technical data" from speaker testing with a grain of salt. AS....I am no expert.

curve coming

jc

No, Oh, No.........Its a little late for that............[:D]

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I didn't expect THAT! Hmmmmmm...

JC, are you up for the SERIES configuration using the 13x6" wide slot motor boards? (I'm cringing as I ask this)...

I'll do an overlay when I get home tonight.

Thanks, JC!

P.S. wired in series we are 8 Ohms instead of 2 (parallel) - did you change the output impedance to compensate?

Dana

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Sure. I can do that. Good idea.

Will delay the rear load a little.

So what do you think? Why do you think that area 80-100hz looks better in series. I repeated the test more than once and it was consistent.

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Dana.

I didn't change the taps. Left it at 4 ohms like all of my tests.

Spoke with McIntosh about the taps. From my impression...with the autoformers.....it will only make a slight difference in distortion. So I haven't been messing with it.

The watts won't change.

That is what I understood.

jc

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Overall impedance has changed - series is at least 8 Ohms. Change the output taps on the amp to 8 Ohms and we should see a drastic change (drop) in efficiency, too.

The current flow is higher in 4 Ohms than 8 Ohms, which is why wattage ratings always are higher at lower impedances than higher (voltage is the same for both settings).

The benefit of series wiring is that the overall power handling doubles in the case of the Crites drivers from 150 to 300 Watts. The drawback is that it is only as loud as a single driver.

I figure that's OK, because it puts the Heritage series components back into the game.

Dana

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JC wait - before changing out the motor boards, try the 8 Ohm taps first on the narrow slots and take a curve of that - it will be informative, that's for sure.

Should clear things up once and for all, anyway. My guess is that it will "flatten out" the curve as it looses some efficiency.

Dana

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