I'm doing an open baffle and after reading posts here (was it twest820 or cuibono?) switched the choice of tweeter to BG’s Neo3.
When I quickly piggy backed (to combine & save shipping) as a friend ordered from PE, I think I goofed with the model, not realising there was a PDR model.
I thought when I bought Bohlender Graebener Neo3-PDRW Planar Tweeter w/Back Cup, the sensitivity of 90.5 dB indicated to me it was the open backed version. Now it’s arrived, I see I was wrong.
Without me possibly messing up a driver, can the rear chamber be removed?
Or, can someone confirm my new order . .
Personally, I’d sacrifice a little directivity up high for a little more sensitivity.
If i now have it right, the “normal” non PDR Neo3 is more sensitive, and produces consistent directivity up to about 8.5 kHz, which is good enough for me (my hearing starts to drop off at about 6 kHz).
To get the open back version from Parts Express (who have lower shipping costs to here – Australia) - which isn’t a separate item number, I assume you specify that somewhere in the order . .
Thanks
When I quickly piggy backed (to combine & save shipping) as a friend ordered from PE, I think I goofed with the model, not realising there was a PDR model.
I thought when I bought Bohlender Graebener Neo3-PDRW Planar Tweeter w/Back Cup, the sensitivity of 90.5 dB indicated to me it was the open backed version. Now it’s arrived, I see I was wrong.
Without me possibly messing up a driver, can the rear chamber be removed?
Or, can someone confirm my new order . .
Personally, I’d sacrifice a little directivity up high for a little more sensitivity.
If i now have it right, the “normal” non PDR Neo3 is more sensitive, and produces consistent directivity up to about 8.5 kHz, which is good enough for me (my hearing starts to drop off at about 6 kHz).
To get the open back version from Parts Express (who have lower shipping costs to here – Australia) - which isn’t a separate item number, I assume you specify that somewhere in the order . .
Thanks
Looking at the difference between the PDRW and the standard W versions, the difference is in the dispersion/sensitivity. They both have the removable rear cup. The descriptions indicate that the higher sensitivity of the standard non-PDR version is at the tradeoff of it being more directional with increasing frequency.
I'm pretty sure that John K uses the PDR version in the NOTE. This would be a benefit for a more extended dipole configuration, helping to maintain the figure-of-eight pattern slightly higher. This at the expense of lower sensitivity and possibly a requirement of a higher crossover Fc, if they are issues for the design.
Dave
I believe I suggested contacting Madisound about getting the backless Neo3s used in the Note driver kit some months back. I bought a pair of non-PDR Neo3Ws before the Note came out so that's what I use. I'm unsure of Cuibono and Saurav's current status on Neo3s---think it's mainly Saurav on the Neo3 PDRW.
And, yes, there's a reason my avatar is a picture of a Neo3 on a milling machine table surrounded by plastic shavings.
And, yes, there's a reason my avatar is a picture of a Neo3 on a milling machine table surrounded by plastic shavings.
You can use a knife blade to carefully pry off the back. I started with a corner. There is just a silicone like glue holding it on.
You can buy the Neo 3 without the back cup from Danny at GR Research, I did, Drivers. Just tell him what you want.
the right tool for the ob
Thanks bigdh,
Once I switched to a nice sharp 8 inch 200 mm bladed chef's knife, the backs were levered off in less than 30 secs 😀
(The mids were to be the 95 dB B&C 6MD38, but will now be the Neo10)
Thanks bigdh,
Once I switched to a nice sharp 8 inch 200 mm bladed chef's knife, the backs were levered off in less than 30 secs 😀
(The mids were to be the 95 dB B&C 6MD38, but will now be the Neo10)
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Now they are starting to sound like my speakers, what bass are you using? what about some pictures.
Hi DQ
First time I tried to posted a pic online: its too large - any suggestion on how to trim it?
I'm thinking over the mid tweeter baffle shapes & colours etc
Have you got a pic or 'elevation' drawing?
First time I tried to posted a pic online: its too large - any suggestion on how to trim it?
I'm thinking over the mid tweeter baffle shapes & colours etc
Have you got a pic or 'elevation' drawing?
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I started with the PDR, sold those and bought some non-PDR, and then bought some PDR again. Currently listening to the PDR. I don't get much stuff done in the winter, but it's starting to warm up again, and I'll probably start messing with my speakers again. For one thing, I discovered that my tweeter mounting scheme was creating one strong-ish diffraction null that I'd mistaken for a dipole effect. So that's the first thing to fix.
I bought all of them from Danny, and he took the backs off at no extra charge. He says it's easy to do, but I'd rather have it done by someone who's done it several times 🙂
I bought all of them from Danny, and he took the backs off at no extra charge. He says it's easy to do, but I'd rather have it done by someone who's done it several times 🙂
DQ,
I forgot to say: my bass drivers are 15" JBL 2135's.
Saurav,
I'm hoping to get to the workshop soon; could you elaborate on the tweeter mounting scheme - to be avoided - that creates the diffraction null?
Cheers
I forgot to say: my bass drivers are 15" JBL 2135's.
Saurav,
I'm hoping to get to the workshop soon; could you elaborate on the tweeter mounting scheme - to be avoided - that creates the diffraction null?
Cheers
I'm not sure how to trim the photo's but it is a bit hard to see. My speakers are still in the prototype stage. The are sounding very nice but I want to try the Saba mid in them before I finalise the design & build the final version, if I do go for the Saba mid it's going to cause plenty of aesthetic issue's, although I think most people already belive they have plenty of aesthetic issues now, no imagination I say 🙂
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Yes, flash glare from the window behind, sorry.
I did trim it to just show the speaker: there's an open "frame" above the bass units.
Rods about 40 mm thick are supporting a small shelf on the top. The mids & tweeter will be mounted within the open frame. To be decided: how
I did trim it to just show the speaker: there's an open "frame" above the bass units.
Rods about 40 mm thick are supporting a small shelf on the top. The mids & tweeter will be mounted within the open frame. To be decided: how
Note that I could still be wrong, but here's how I had my tweeter mounted:
I took some more measurements recently when I got my PDRs, and noticed a couple of things:
- If I leave the back cup on (held on by duct tape), the 7.5kHz null doesn't really change. This was the first surprise.
- If I mount the tweeter to the front of the panel, the null goes away. Of course, the off-axis response also changes, for the worse. So more experiments are needed here.
- The null frequency corresponds to a half-wavelength of about 1.2", which is about the distance from the middle of the tweeter to the rounded front edge of the panel. So that kinda adds up too, if I did my math right.
I have a couple of the BG faceplates, those will ensure a smoother transition to the baffle, but will of course require a much wider baffle. I'll probably get plywood panels, cut some holes, and play around with that faceplate at some point.
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I might be wrong, but I thought the narrower the baffle, the more extended the uniformity of directivity, ie narrower is better
eg Rudolf/ twest/ cuibono/ gainphile could confirm/ correct . .
Cheers
eg Rudolf/ twest/ cuibono/ gainphile could confirm/ correct . .
Cheers
is that a Lambda 15 . . . . that I spot as your bass driver?
They're suppsosed to be the ants pants, the bass the gods listen to 🙂
What range does or will it operate over?
Yep, I know, that's why I tried to come up with a baffle that's only a bit wider than the driver 🙂 It's not the baffle width that's the issue, it's the depth of that small 'roundover' on the front, I think. I think I'm getting a reflection off that edge. I've tried the driver nude, and that works fine, but of course looks kinda ugly.
Other options would be to make a flatter 'waveguide', or find some other way of mounting the tweeter flush with the front of the baffle. I might try counter-sinking it from the front, which will leave exposed screw heads, but I don't see a way around that.
I realize that if I go down the route of a wider baffle and the faceplate, I will be giving up off-axis consistency. There are different opinions on how much that matters up in the treble frequency range...
My friend with the CNC broke his wrist and is currently out of commission 🙁
It's the Acoustic Elegance Dipole 15, they are very good, but the postage to oz is a killer. I've got them going from 20 to 250hz, I'm pretty sure they will go below 20 but I'm not sure I can hear below 20, I will be doing more testing etc in the coming months.
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