JR Minis - Part 2
Here is the Crossover:
The following shows ON Axis response, impedance and impedance phase:
The increased output centered around 150Hz is primarily an artifact of mic proximity effect - so ignore.
While the negative phase is -50 degrees @ 3KHz, the impedance is still high at almost 10 Ohm. The impedance does not drop below 5 Ohm. The speaker is not hard to drive.
Let's take a look at the OFF Axis response:
It is actually smoother OFF Axis, but a bit more rolled off above 10KHz.
Now for a simulated 500Hz square wave:
Even though the tweeter is not connected in phase, the speaker remains phase coherrent up to a reasonably high frequency.
That's it!
Joe R.
Here is the Crossover:
The following shows ON Axis response, impedance and impedance phase:
The increased output centered around 150Hz is primarily an artifact of mic proximity effect - so ignore.
While the negative phase is -50 degrees @ 3KHz, the impedance is still high at almost 10 Ohm. The impedance does not drop below 5 Ohm. The speaker is not hard to drive.
Let's take a look at the OFF Axis response:
It is actually smoother OFF Axis, but a bit more rolled off above 10KHz.
Now for a simulated 500Hz square wave:
Even though the tweeter is not connected in phase, the speaker remains phase coherrent up to a reasonably high frequency.
That's it!
Joe R.
right on! thanks again Joe...i can't seem to thank you enough!
So just to confirm...this is acceptable as a center? You say to just mount the tweeter ontop of the mid/woofer? What if you turned it sideways...would that screw anything up?
next, you have no plans in the future to incorporate the peerless HDS tweeter, right?
So just to confirm...this is acceptable as a center? You say to just mount the tweeter ontop of the mid/woofer? What if you turned it sideways...would that screw anything up?
next, you have no plans in the future to incorporate the peerless HDS tweeter, right?
jpvt68 said:
Why not come and see me and hear the original Elsinores. You are in Sydney and I am where the M5 and M7 meet at Prestons near Liverpool. Bring some music as reference. No obligations whatsoever. I just love having visitors and it is easier for the Elsinores to do the talking rather than me.
Works every time! Joe R.
Great! I am sure you won't regret it. There are six in Sydney that I know off, and very happy. You will be number seven. There are three in Victoria, two in Qld and one in WA. They are the ones I know about - anybody can build them without my knowledge. Then there are a number in Europe and US & Canada and many in the planning stage. So it is starting to get real momentum.
Right now I am driving my pair with a 12 Watt Triode (and some amp it is) and the Elsinores are reaching outrageous volume levels. Talk about running on an oily rag (is that Oz?).
Phone me anytime for a chat, 96074650 & 0412-203382 - the numbers are on several websites, so no need to hide them here.
Joe R.
PS: Will be demoing them at Haberfield - ASoN audiophile meeting - on Sunday 25th between 3PM and 6PM. All are welcome @ 78 Dalhousie Street, same grey building as Haberfield Library.
Joe R.
jpvt68 said:
Do it (listen to them and build them), you won't regret it. I am one of the cain toads that has nearly finished a pair and couldn't be happier with them. They do everything I could want them to do (and plenty of things my neighbours don't want them to do) and without any of the disadvantages that some speakers force you to live with (eg, low sensitivity, low impedances, only suit one specific genre of music etc). The Elsinores let you have your cake AND eat it too.
And a big thumbs up to Joe, who managed to withstand my barrage of emails asking stupid questions without telling me to "sod off" even once
. Joe is an absolute pleasure to deal with.
rob323 said:
Hey Joe, I nearly have one of them finished, here's a sneak peek.
I hope I haven't broken too many rules by finishing them them way I did.
Hi Rob
Looks really good. As for rules, the rounding of the edges I think I can see, is of small radius and should not be a problem. Beveling or rounding of the edges reduces the actual area seen by the driver and has a diffractive effect. But you did not overdo it, so it's OK.
I know you have been listening to them, so you have obviously taken the 6.5" drivers to do the finishing. Wish mine looked like that.
Joe R.
m0tion said:
Thank you. Yep, all my own efforts, much blood sweat and beers. The cabinets themselves are very easy to make, the timber paneling wasn't that hard, just took a long time to glue it all up, shape it, sand it then lacquer it.
marchel said:
Again, thank you. For the timber work, I bought about 40 lineal metres of tongue and groove hardwood flooring, it was the only timber I could find of suitable quality (no knots and the grain structure I like).
I then ripped all the "tongues" and "grooves" off the lengths and glued and biscuit jointed them together. I made up a simple press to keep it all straight while the glue was drying.
Then, attacked it with a jigsaw to get the rough shape, then a planer and belt sander to the bevel on the edges.
The timber panels were then coated on both sides (to hopefully prevent bowing and warping) with clear 60% gloss lacquer.
Joe Rasmussen said:
Joe, there is a small (3mm x 3mm max) chamfer up the vertical edges of the mdf as I didn't want the leather to wrap around a sharp corner as it would damage easier if knocked. I also chamfered around the tweeter recess (about a 6mm chamfer) as the felt doesn't quote fill out the recess (partly because of the extra layer of 3mm mdf on the front that I put on there to recess the drivers) and that got rid of the sharp edge that would have been there. The chamfer actually lines up with the surface of the felt really well now. Once they are all cleaned up, I will take them outside for some close up shots of all those areas.
I know you have been listening to them, so you have obviously taken the 6.5" drivers to do the finishing. Wish mine looked like that.
Joe R.
Yeh, I pulled them all apart and taped up all the openings so they wouldn't fill with dust while I did the final routering/ sanding etc.
I had to remove the drivers to be able to glue the leather on.
Its been 5 days without being able to listen to them, luckily my medication is keeping me calm and subdued
PoorSound said:
If I have you right, you are going to use half the volume and just the top three drivers in MTM array. If so, then you will miss out on the diffraction loss that the two bottom drivers fill in below 1KHz.
You will need to do the following:
Change L2 from 1mH to 1.8mH or 2mH (main diffraction correction)
Change R3 from 3R to 6R to 8R (this changes Tweeter attenuation to -6dB)
For C14 use 2.7 to 3uF (the 8R2 larger value changes rollover point - this is the correction)
Leave the optional values in the Conjugate Filter as before.
The one value that needs to be tweaked by ear is R3. Try standard values 6R8 and 8R2 and some value in the middle of that.
The above should give quite good results, but as I have not actually built them (and measured them), I can only say that it ought to work well.
The centre channel will be lower sensitivity than Elsinores and I have not tried to entirely compensate for diffraction so as not to slug sensitivity too much, about 1-2dB short. But for centre channel this is no problem and a reasonable compromise.
If somebody down here would like to build Elsinore Centre Channel, then if they could build the box etc, then bring it to me for doing physical measurements confirming above results, then a Centre Channel could be published on the website. The Centre Channel could also be used as rear speakers in vertical mode. As a centre channel it is a little large, but alas.... use laterally of course.
The attached image shows the difference in the two, Blue is Elsinore and Red the new result - the difference in sensitivity is also revealed.
Re port, use 60mm (internal) and 120mm long. If the 60mm port is slightly less than 60mm, then that will be OK as well. But if it gets close to 55mm, then reduce length to 100mm.
ALSO: It is recommended that the bottom of the box have the same dimensions as the top, at least viewed from the front. For example, if we were to cut the box in two right in the centre of the tweeter, then the bottom should mirror the top. That way the lateral radiation from the box will be symmetrical when the box is on its side.
Joe R.
