Yes, that is what I did (I think), but when I use a value of 7.2, I can find no way to balance the watts between a 4 ohm and an 8 ohm speaker.
Perhaps I do not know what a "ballast resistor" is as opposed to a "resistor" and hence the confusion.
Here's what I did... ("Speaker B" is a resistor):
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ballast in this sense means "dead weight" serving to balance the load - just "resistor" should suffice
the rest is cerebral flatulence - I definitely need more coffee (or less) - of course the voice coils nominal DCR aren't an even 4 & 8, and 20R should be a readily available - but this should put a fairly benign impedance load on the amp - more so than a lot of complex multi-way XOs.
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If it matters
The average DCR of my 4 partially broken in EL70s is 3.7n. The average DCR of my 2 partially broken in CHR70.3s is 7.3n.
The average DCR of my 4 partially broken in EL70s is 3.7n. The average DCR of my 2 partially broken in CHR70.3s is 7.3n.
Thanks for this info. Just out of curiosity today I plugged the rated DCR values of the EL70 and CHR-70 (3.6 and 7.2, respectively) into the same spreadsheet application (referred to by Chris) and the numbers still work fine with a 20 ohm resistor. I can only assume that the numbers work fine in that spreadsheet across a pretty good margin of impedance, which should accommodate any driver-to-driver variances.
I think this is my way forward. A 10 watt 20ohm resistor should be plenty, considering that even if I push my amp to its full 50 watts the resistor will only be getting 8.4 watts of the load. I typically push between .3 and 1.3 watts, so I doubt the resistor will even get warm.
However, I have just been informed "if you want that Marlin 336 for Christmas, then don't be buying any more G-D speakers" (spoken in the nicest possible way, of course 🙂 ) Since I hope to add a SxS 12GA to that Marlin, I think she might be right (this time).
So, I will have to wait till the new year before I try this out. Plenty of things to keep me busy over the next few weeks anyway... 🙂
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does the person speaking the above have a shoe collection, or Lulu-lemon yoga outfit?
LOL. No, not too bad with the shoes, and I have managed to convince her that Lululemon is for douchebags. 😀
But you should see the effing purses/hand-bags !!! She's the Imelda Marcos of *******' purses...
We have something else in common (besides a higher power to answer to). I also have a 336 in 30-30. A very enjoyable shoot. 
So the higher impedance driver receives more power when in series 😉 I knew something was off about the discussion and what was being drawn from that quote. That makes a lot more sense because it's a higher load, so it burns up more power. If in parallel, my analogy applies, because the current floods the lower load.
I still feel the resistor is not required. I'd take the time to try with and with out. The top firing woofer is more a BSC device than anything. Having said that, I'm not the designer and I haven't heard this speaker, so it may be more than that.
I still feel the resistor is not required. I'd take the time to try with and with out. The top firing woofer is more a BSC device than anything. Having said that, I'm not the designer and I haven't heard this speaker, so it may be more than that.
y'all can drop by Gordon Head some time to hear a pair with EL70s in a more normal (or at least tidier) venue than the mountain
We have something else in common (besides a higher power to answer to). I also have a 336 in 30-30. A very enjoyable shoot.
I've been lusting after one for quite some time, and just recently I got an e-mail from my brother-in-law that he has a 1975 version (in 30-30) that was his dad's and he doesn't use it; wondering if I wanted him to bring it when they come to visit over Christmas (along with a Winchester Model 88 in .308, a Remington 870 Wingmaster 12GA, and a Spanish SxS 12GA). If the prices are right, the Marly and the SxS will be mine 🙂 The range is 10 minutes from my house. Looks like it is going to be a fun Christmas weekend 😀
Sorry for the OT, guys.
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I think the top driver is much more than BSC. Vertical dispersion is huge with this configuration, and sound stage is as deep as it is wide. The sweet spot is very large, even when standing up in the room and I can often still hear stereo separation in the adjacent room. Chris' comments early in this thread http://www.diyaudio.com/forums/full-range/148901-microtower-bipolar-ml-tl-chr-70-el70.html (something to the effect of "man, can these mTs fill a room!") is bang on. I would take Chris up on the offer to go have a listen, if I were you. 🙂
BTW, I did some more playing with my EQ last night, based on a reference to Fletcher-Munson curves in another thread.
Up until this point, my EQ efforts have been directed at compensating for the roll-off on both the low and high end of the EL70 frequency response, with some additional tweakage of the low end. This achieved an approximately flat response, but after looking at the work done by Fletcher and Munson, I realized that rather than merely compensating for the EL70s curve, I should be doing other tweaking.
Taking my base "EL70-flat" EQ preset as a starting point, I referenced the 60dB F-M curve and proceeded to layer those adjustments on top of my "EL70-flat" settings. The result looks quite aggressive, but the sound is very "natural" (as described in another recent thread on spherical enclosures). The bass is of course that much richer, but I really notice a big difference in the highs. Not just "more air" in the highest highs, but smoother and subtler low-highs, due to a significant reduction in the 2k to 5k range.
This once again has me thinking; "do I really need to mess with CHR-70s?"
The answer is still yes, because it'll be fun and interesting to do so, but I feel like I have come that much closer to getting the most out of the EL70s...
Up until this point, my EQ efforts have been directed at compensating for the roll-off on both the low and high end of the EL70 frequency response, with some additional tweakage of the low end. This achieved an approximately flat response, but after looking at the work done by Fletcher and Munson, I realized that rather than merely compensating for the EL70s curve, I should be doing other tweaking.
Taking my base "EL70-flat" EQ preset as a starting point, I referenced the 60dB F-M curve and proceeded to layer those adjustments on top of my "EL70-flat" settings. The result looks quite aggressive, but the sound is very "natural" (as described in another recent thread on spherical enclosures). The bass is of course that much richer, but I really notice a big difference in the highs. Not just "more air" in the highest highs, but smoother and subtler low-highs, due to a significant reduction in the 2k to 5k range.
This once again has me thinking; "do I really need to mess with CHR-70s?"
The answer is still yes, because it'll be fun and interesting to do so, but I feel like I have come that much closer to getting the most out of the EL70s...
time to stir the pot - try them with 10-15 W tube amp (from my muckin' aboot, P/P seems to work best)
Sadly, my available copilot refuses to drive at the pace I am comfortable with. I suppose I could just paypal a "beer proxy" and a photo.
Actually, BC is high on my list of places to visit. A plane ride and a call to say "hello" are within the realm of possibility for 2012.
Actually, BC is high on my list of places to visit. A plane ride and a call to say "hello" are within the realm of possibility for 2012.
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Been quiet since i didn't want to come out and say that the idea was closer to the former than the latter. But now 50-60 posts in that is becoming evident (i just skimmed, busy getting flat-paks out).
If Cogi can get some CHR70.2 it might work, with CHR70.3 that unit will -- on average -- be 3dB down from the EL70 (actually more like 5 dB given that EL70 is a couple dB more efficient than CHR).
Given how easy it is to try, i would, you might make one of those serendipitous discoveries. And if that 2w i saw somewher is a Decware E84, wire them in parallel.
Now using 2 CHR.3 + and EL70 is a more interesting proposition, but then it would be time for a new box.
The idea of trying to fudge things with a resistor is anathema to me.
dave
I'll gladly come out and pick up at the ferry or airport given sufficient lead time.
dave
Finally someone else said it! 😱 😱
I was starting to feel like I was crazy and missing something.
Like I said... yuck 😛
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