JCW three way

[exojam]

I placed this information over here since I know it would not be allowed in the DIY section. Since this section does state “high end speakers”, I hope it is allowed to stay.

I wanted to take an opportunity to show some very nice speakers I had custom made. These speakers consist of a Lambda TD12H, PHL 1120 and NeoPro5i and are being called JCW’s. The name consists of the first initials of the folks involved in this project.

J=James, financier
C=Curt, crossover designer and sound tweaker
W=Wayne, cabinet builder and sound tweaker

I wanted to create this myself but my lack of knowledge in speaker building and due to physical limitations this was not possible. I had contacted a few folks about my concept but things did not work out. I got some advice from another forum member (Chuck) who stated I should see if Curt would be interested in this. After some initial discussions on what I was looking for the project took off.

I spoke with both Curt and Wayne many times during the build process on many different aspects of the build, where the speakers would be located, equipment being used, room size, veneer type, style, etc, etc.

The Lambda is being crossover to the PHL at 500 and the PHL to the NeoPro at 2000. The Lambda is in one cabinet and the PHL-Neo is in a separate one. Both are cherry veneer with solid cherry edges. Combined the two cabinets weigh about 122 pounds (for one side).

A couple of things I will not be discussing are the overall cost of these but will say the drivers themselves were around 1,500. Neither will I be showing schematics of the crossover that were created. Sorry but that is a choice I have made.

I have been using vinyl as my initial listening platform for these. My setup can be seen here:

http://www.avsforum.com/avs-vb/showthread.php?t=1052573

I hope someone enjoys the work of two guys that really enjoy (and know how to) make some kicking speakers in there spare time and I REALLY wanted to express publicly how enjoyable it was to work with them.

And by the way, these speakers rock. I am hearing things in music that I have not heard before. Allot of drum, cymbal and string sounds are “now” appearing. The voice section is also very nice, Alison Krauss has never sounded better (along with the Led Zepp and AC-DC). I am not really good at describing sound so I will leave it at that.

[exojam]

Pure wickedness:

[Chris D]

Wow, nice, dude! I don't hang out in the DIY area, so I'm not sure why you don't think it would go there, but thanks for sharing!

[Curt C]

Blacks Sabbath? I've got some titles on vintage vinyl you'd love to have:
Deep Purple and Mountain to name a couple off the top of my head...
Oh, and all the Tull albums... ;x(

Glad you are enjoying the speakers!

C

[exojam]

Chris,

Thanks for the compliment. I did not think it would be allowed since I am not discussing price or providing details on crossovers and such. Hopefully some of the DIY folks see these so they can see Curt and Wayne’s creation.

Curt,
We may have to talk about some of those LP’s.

[looneybomber]

Curt, and anyone else,

I am working on building a similar speaker (neo5i, undecided mid (maybe 2, 1120's), and TD15h). I'm trying to find more info on CTC spacing, but I keep finding conflicting data.

I was under the impression the XO point between the tweeter and mid, could be no more than the frequency of the wavelength equal to the distance between the center points of the two drivers. If that's the case, a XO point of 2000hz is ~6.75", but the distance between the 5i and 1120 is a fair bit more than 6.75"

Is there something I'm missing? Does this only pertain to an MTM design?

Thanks.

[Curt C]

Curt, and anyone else,

I am working on building a similar speaker (neo5i, undecided mid (maybe 2, 1120's), and TD15h). I'm trying to find more info on CTC spacing, but I keep finding conflicting data.

I was under the impression the XO point between the tweeter and mid, could be no more than the frequency of the wavelength equal to the distance between the center points of the two drivers. If that's the case, a XO point of 2000hz is ~6.75", but the distance between the 5i and 1120 is a fair bit more than 6.75"

Is there something I'm missing? Does this only pertain to an MTM design?

Thanks.

Nope, you are correct! :T
The same physics applies, but since ribbons radiate along their entire length, we get to bend that rule of thumb a bit.

If you use 2 1120's, I'd suggest a TMM, rather than an MTM, because we don't get to bend the rule there, and the CTC of the PHL's would be way too far apart when separated by the 5i.

-Better yet, save your money and only buy one PHL. Unless you are going to use this as a PA sysem, or your listening room is the size of an auditorium, the 113 dB SPL a single PHL can provide should be plenty loud.

C

[looneybomber]

Nope, you are correct! :T
The same physics applies, but since ribbons radiate along their entire length, we get to bend that rule of thumb a bit.

Ok thanks. I was finding so much conflicting info I was beginning to go crazy.

If you use 2 1120's, I'd suggest a TMM, rather than an MTM, because we don't get to bend the rule there, and the CTC of the PHL's would be way too far apart when separated by the 5i.

And just to confirm, CTC spacing of the mids in an MTM takes precidence over the CTC of the mids to tweeter? And for a TMM, it would then be the distance of the tweeter to the farthest mid right?

-Better yet, save your money and only buy one PHL. Unless you are going to use this as a PA sysem, or your listening room is the size of an auditorium, the 113 dB SPL a single PHL can provide should be plenty loud.

Well I was planning on making a passive XO between the 5i and mid(s). I contemplated using two mids to increase sensitivity so I wouldn't have to pad down the tweeter as much due to my BSC and an already low (in comparison to the 5i) 96db/1w sensitivity.

Plus I would rarely use these for my outdoor parties...later to be outdoor movie parties.

...Too keep from muddying up Exo's thread, you can PM me if you want.

[exojam]

Looney,

Don't worry about adding stuff in here.

[looneybomber]

Yeah but I don't want it to turn into "Help Looney and his build" thread. If anyone know's of some good reads on CTC spacing, I'm all ears because I don't want you guys to think I'm asking for sensitive XO info of Exo's build. Plus I don't want to copy the JCW's exactly. Mine will be slightly different.

I was just getting confused, that's all.

Exo: Are you a Metallica fan?
And I see that Ramones album, you don't have any Cure do you?

[exojam]

I like older Metallica (really nothing past "And Justice for All"). No, I do not have any Cure LP's, I never really got into them. I picked up the Ramones since I have never had any of their stuff.

[looneybomber]

Ah, Justice for all. That's the album with one of my "speaker audition" songs on it; One. I love to use the fast double bass around 4:30 to judge woofer performance/sound.

[Curt C]

Ok thanks. I was finding so much conflicting info I was beginning to go crazy.


And just to confirm, CTC spacing of the mids in an MTM takes precidence over the CTC of the mids to tweeter? And for a TMM, it would then be the distance of the tweeter to the farthest mid right?


Well I was planning on making a passive XO between the 5i and mid(s). I contemplated using two mids to increase sensitivity so I wouldn't have to pad down the tweeter as much due to my BSC and an already low (in comparison to the 5i) 96db/1w sensitivity.

Well, with a moniker like that, we can’t be having you go crazy now, can we? :B

The issue is two non-coincident drivers radiating in the same pass band. Assuming a symmetrical positioning around the design axis, the path length from all drivers is equal. Off axis, the path length can vary, and if the path length difference between two drivers equals ½ wavelength, the two signals combine destructively and create a null. For vertically aligned drivers this is only an issue in the vertical axis and vice versa for horizontally aligned drivers. There is nothing magic or sacred about the 1 wavelength rule, as the issue happens to a certain extent for all no coincident drivers. It just becomes a practical issue at about that distance.

2 salient points: (Actually the same one stated two different ways.)
The closer the drivers are mounted together, the further off axis you must be to obtain a null.
For a given point off axis, the closer the drivers are mounted together, the higher in frequency that first null appears.

For a mid and a tweeter, the issue only occurs at the crossover frequency, and in the stop bands of the mid and tweeter. Depending on the transfer function of the crossover this frequency band can be quite narrow.

For an MTM, the mids of course both radiate in their entire passband, and are further displaced physically by the tweeter flange diameter. So an MTM, given the same crossover frequency will always have poorer off axis response, albeit in the vertical axis for a vertically aligned MTM. TMM’s on the other hand can low pass, or at least shelve down, the higher frequency response of the mid furthest from the tweeter. This can potentially give us the best of both worlds: Higher sensitivity / excursion at the low end of the mid passband, but attenuated at frequencies which would cause the poor off axis performance.

I hope this ramble made some sense…

C

[looneybomber]

After visiting dictionary.com and wiki, I think I understand what you just said

So the long and short is aim for a TMM, keep the mids tight together, make the XO a quasi 2.5way instead of a 2way and use it for the BSC?

I hope that rambling made sense

[Curt C]

After visiting dictionary.com and wiki, I think I understand what you just said

So the long and short is aim for a TMM, keep the mids tight together, make the XO a quasi 2.5way instead of a 2way and use it for the BSC?

I hope that rambling made sense

That would be the way I would do it...

C

[looneybomber]

That would be the way I would do it...

C

Thanks! It gets me started, but the real work comes once I start testing/measuring and building test enclosures. Because of my schedule, maybe next summer you'll see a build thread from me :T

[exojam]

Pictures of the center channel to go with these speakers. I had to keep it as small as possible due to the fact it has to go on my TV. Again these were made Curt and Wayne, not myself.