[BoilermakerFan]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif Bah, I'm not very good at tuning those older orthos. If I was, mine would all sound better. That's one of the reasons I'm pretty much sticking to the T50

Well, Don and I have your back.

I did get my cable and O2 pads out to you via FC mail so you should have them Monday or Tuesday. Man, I can't freakin' wait! TPs, RP18s, and SR- Lambdas sound like a pretty sweet Trifecta to me.


I found another set of T10/T20 sized Oz felt discs, so I can get ourfpshero's T20v1s and your T10s tuned properly.

I'll have to wait until Ludoo can get me more Oz felt to redampen mine and I may need it for MPI's T40s.

 

[BoilermakerFan]

Quote:

Originally Posted by wualta /img/forum/go_quote.gif So roughly a quarter-inch circular dot. Okay, Tony, try that, then if that doesn't do it, try the anti-dot (aka donut) of felt, but try offsetting the opening as well as centering it. [Pst, Don-- how about ventral/dorsal instead of anterior/posterior? just a thought..]

Let's make it more feminine, mammary / posterior FTW!

 

[antonyfirst]

I have been listening to the cans the whole day (again!). It's a drug and the bass is of exceptional quality: it took me a bit to get used to it but I prefer its presentation to that of the Omega 2 (where the bass is kind of liquid in comparison). The "peak" only bothers me with a minimal selection of electronic music, and basically no vocals after I did the digital interconnect swap.

 

[mypasswordis]

Does anyone know the frequency ranges reflex dots boost, and how these ranges change based on size (or shape)? I'm wondering if I can just boost the very highest of the treble, 16kHz+, without affecting anything else.

 

[dBel84]

Quote:

Originally Posted by wualta /img/forum/go_quote.gif [Pst, Don-- how about ventral/dorsal instead of anterior/posterior? just a thought..]

heh, this flashed through my mind when I responded but realized medial lateral would be the best anatomic descriptive

and BMF, this is just sad Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Let's make it more feminine, mammary / posterior FTW!

On the frequency response front - this is the principal I work on, no idea how accurate it is but most of the damping responses work

I consider essentially 2 types of drivers ( I know this is a gross oversimplification but their reaction to damping can be split this way )
1. center pinned
2. not

The center pinned drivers - most of the yamahas, the PMBs all behave like a ring radiator ( but again not quite) Because the center is pinned the diaphragm in this region moves less that the diaphragm at the periphery . My simple interpretation is that most high frequencies come from the center and the bass comes from the edge. I thus damp these drivers differentially, emphasizing the heavier damping centrally to control the mids and push up the highs while leaving the edge some freedom to move air.

The other drivers ( not all ) are attached at the edges and although the force exerted is evenly distributed, I treat these as the converse of the center pinned drives - ie bass comes from the center while the edges produce the highs/mids and thus differentially damp them to keep the ceneter less heavily damped . This is where the donut concept comes in.

..dB

 

[Kabeer]

Quote:

Originally Posted by mypasswordis /img/forum/go_quote.gif Does anyone know the frequency ranges reflex dots boost, and how these ranges change based on size (or shape)? I'm wondering if I can just boost the very highest of the treble, 16kHz+, without affecting anything else.

It is strange, since a reflex dot is very close to the diaphragm, say, 0.2cm or less. Hence the wavelegnth it should effect should technically be way above the 30khz range.....

And yup Don, thats pretty much how I view it, except, I view it in the donuts case, the treble exists at the centre pin, and the outer clamp. Because thats the least extrusion. So the bass would be at the center point of the donut width.
At least in the Fostex case you agree with my 'Differential Donut' damping theory (see ludoo's search engine if ya wants to search).

 

[smeggy]

I have used the donut and front dot to great effect. The t50rp is a little different in it's construction so it doesn't work in the exact same way as the 'standard' ortho. The dot just becomes regional due to the driver assembly. the magnets are bar and are held by a perforated cage, held by a gridded front housing so the sound already comes out more diffusely and less funneled like on the perforated magnet style. So in effect the dot hovers in front of the driver and doesn't 'block' like the other orthos. the same effet would be to place a dot a few mm away from a regular old ortho. The effect of the dot is less profound and more subtle in its effect which is good. It's easy to do and undo. The other thing is to try a small wad of dense felt instead of dot. jut tacked on so as to provide an absorbent area rather that a barrier. Again, easy to do/undo.

 

[wualta]

A reflex dot is meant to be what its name implies: a reflector. The smaller the dot, the less low-frequency stuff is reflected-- the longer wavelengths simply diffract around it. So if one wished to boost the highest highs, one should use a small dot, say, about 10mm or less. In fact one could use several small dots on a large diaphragm driver, as long as one is careful not to seal too many holes, which would change important things like resonance frequency and thus bass output. The reason we place a reflex dot on the magnet is to keep the interference effects (looks like a comb, thus the term comb filter) that result from any straight-on reflection from coming down into the audible frequencies. As Kabeer points out, the short travel time to and from the dot-on-the-magnet keeps the peaks and troughs up above audibility.

Just to be clear, what we were originally talking about with Tony and the T-Pants (a great name for a band, by the way) was using a dot on the ear (ie, proximal-axial) side of the driver to try to break up a narrowband resonant peak. Its function is more akin to that of a phase plug in a compression (horn) driver, to prevent sounds originating from different points on a largish diaphragm from mutually interfering with one another (because of slightly different arrival times at the entrance aperture, in this case your ear hole) and roughing up the frequency response curve.
.

 

[smeggy]

what Walt said

 

[mypasswordis]

wualta, have I ever told you that reading your posts is akin to having a breath of fresh air in a stagnant room? Thanks for the explanation, I do remember you mentioning this before, now that it has been mentioned again.

 

[wualta]

And what Smeggy said. The mk ii Fostex have a unique magnet structure with perforated pole pieces (not unlike the Monsoon planar computa speakers). Plus, the holes are tiny, as if they were intended to homogenize milk. Weird but effective.

The point is, ya gotta experiment, do a lot of cut-and-try to gain experience, then check back here to see if others are getting the same results.

MPI, thanks for the kind words. I'm always trying to improve the clarity of my writing, and I'm never satisfied with it.

 

[iQEM]

aaahhh, miss great ortho again...

NAD RP 18 Elekret High-End-Kopfhörer, Rarität, bei eBay.de: (endet 23.02.10 11:08:42 MEZ)
so, whose the lucky guy that have it ?

 

[sachu]

Quote:

Originally Posted by iQEM /img/forum/go_quote.gif aaahhh, miss great ortho again... NAD RP 18 Elekret High-End-Kopfhörer, Rarität, bei eBay.de: (endet 23.02.10 11:08:42 MEZ) so, whose the lucky guy that have it ?

wow that is a really nice deal ..hope someone here got it

 

[iQEM]

x2 on that...

 

[gurubhai]

^^ I agree.

All this talk about treble peaks got me curious & I did a frequency sweep with sinegen.
I found my T20 to be smooth from 1k to 10k apart from a dip between 7.5-8k & the sound alternately pans to one ear in that range.
Can some one explain this?