Orthodynamic Roundup

[nick n]

Congratulations.
Anyhow there are others more suited to answer that than myself in here.
 

 

[DeathDomokun]

 

not really wanting to try and make a silk purse out of a sows ear

 
I can recommend you buy a modded T50RP from an experienced modder and tell me the T50RP drivers are sows ears.
Also the bass texture on stock T50RP's is pretty **** imo

 

[khbaur330162]

 
wualta: Couple questions. Keeping the acoustic resistance the same, but increasing the volume or time in which it takes for that resistance to be realized by the backwave... what's that do to the sound/diaphragm resonance? You mentioned varying PPI (pores per inch) in different foam layers. My initial reaction was thinking about foam donuts and wave guides, but in a less dumb sense, conceptually cut an oversized disc of felt, place over some open-cell foam seated directly on the back of the driver, glue the circumference of the felt down to the magnet, place larger block of open-cell foam behind felt, then A/B that with a simple disc of felt glued directly to the driver. What's that Technics-esque cavity do?

People have been experimenting with special foams for years (remember AudioCats and his HP ink-cartridge foam?). 

Yup. Wasn't it soft when wet, and rock hard when dry? That sounds close to what you're looking for, imo, assuming its resistive properties are close to what we want. I'll admit, though, I don't understand where this foam is coming from. How could you get a large enough piece to cover a driver from an inkjet cartridge?
 
Last question. Wouldn't a low density, insanely thin, high strength, slightly elastic polymer material (as equally unobtainable as TotalFoamHeadphoneCup and more expensive) for a diaphragm be key? What if we could get away w/o any damping like Stax? Polymethylpentene seems pretty PMP'in, although, I think it's tough to manufacture below 35-40um without pinholes. Its density is like whoa, though. 
 
 
 
Quote:

I bought my first orthos, a pair of $79 Fostex T50RP's.   Always been a Grado person,  but there is a quality to the midrange that the fostex does very well.  At their price I assume they are the bottom of the barrel as far as orthos go.  I helped them by lining the inside of the cup with craft foam.
 
But not really wanting to try and make a silk purse out of a sows ear could someone recommend an ortho that has the midrange brilliance and bass texture of these fostex with less of the closed in distortion ?  I've been reading about the HE-500 and HE-5LE,  but really confused as to what is a step up in the ortho game for a Grado lover.

So, when you say T50RP's have a nice quality to the midrange, what do you exactly mean? Ortho's are detailed virtually by nature. T50RP's aren't special in this regard, imo. If you mean FR I've heard Hifiman's can be bright which seems to be synonymous with Grado. Of the Grado's I've auditioned personally (RS-1, RS-2, PS-1000) they all sound flat, imo, and I wouldn't spend money for any of them. With that in mind, I might not be the best person for this question either, but I semi-agree with DeathDomo. I'd advise you to stick with your T50RP's for a while and try some other mods. This hobby, like any I'm sure, is a slippery slope. I'd hate for you to lay down a stack of cash on some new headphones and there be a level of regret. The T50RP's are really really good. For $80 they are stupid good, imo, considering another $25-$35 and 30 minutes of your time can score you a fully modded pair.

 

[rhythmdevils]

The T50rp doesn't suffer from distortion, especially coming from John Grados.  I think what you probably want is in fact more distortion.  There's no ortho that will give you that howling at the moon bleeding ear feeling of Grados, although you could tune them to be really forward in the upper mids in a simlar (though still more accurate) way.  The whole point IMO is in fact to give you a fast, detailed sound without that howl. 
 
But a Hifiman is probably your best bet.  Maybe the original wooden HE5.  People often described it as a planar RS1
 
Also, a closed wooden cup isn't going to fix anything in your T50rp.  it's all in the damping

 

[wualta]

 
Quote:

 
1a ) Keeping the acoustic resistance the same, but increasing the volume or time in which it takes for that resistance to be realized by the backwave... what's that do to the sound/diaphragm resonance?  [thought experiment as an example:] ...conceptually cut an oversized disc of felt, place over some open-cell foam seated directly on the back of the driver, glue the circumference of the felt down to the magnet, place larger block of open-cell foam behind felt, then A/B that with a simple disc of felt glued directly to the driver. 
 
1b ) What's that Technics-esque cavity do?
 
2 ) ... I'll admit, though, I don't understand where this [HP-ink] foam is coming from. How could you get a large enough piece to cover a driver from an inkjet cartridge?
 
3 ). Wouldn't a low density, insanely thin, high strength, slightly elastic polymer material (as equally unobtainable as TotalFoamHeadphoneCup and more expensive) for a diaphragm be key? What if we could get away w/o any damping like Stax? Polymethylpentene seems pretty PMP'in, although, I think it's tough to manufacture below 35-40um without pinholes. Its density is like whoa, though. 

 
1a ) Since air is compressible, I always wanted to get the damping layer right next to the driver. Inside the driver would've been ideal. I wanted the driver to "feel" the max pushback from the acoustic shock absorber (the felt). If the air pumped out by the driver was allowed to compress (which the damping layer is making it do), by the time it got to the damping layer it would no longer be an analog of the original pressure wave. Compare with a car's muffler. Still, this felt-covered foam-dome would be interesting to try. I imagine the result depends on what the foam is doing to the pressure wave, if anything.
 
1b ) Near as I kin figger, it's an antiresonance (at multiple frequencies? dunno) intended to shape the frequency response. Compare and contrast with the AKG Sextett's tuned passive diaphragms. A Technics owner could expeiment by filling those cavities with blue-tak or stretching some felt across them.
 
2 ) AC was kind enough to send me one of the HP foams and my first thought was the same as yours. SFIs and YHDs only unless you were a clever gluer. Again, it was a cost 'n' availability issue.
 
3 ) I've liked the idea of a foam diaphragm ever since we thought we'd found an ortho with a foam diaphragm (Denon?). Standing waves would be easier to deal with, certainly. It would be self-supporting and self-damping, if the right material were chosen. Maybe heavier, possibly lighter. Would solve, partially, the need to control "doming" in a narrow driver.

 
 

 

[khbaur330162]

 
Very interesting. 
 
Those Denon's seem to sell, or at least ask, for obscene amounts. I was looking into them just for kicks. I wonder what they actually are. :/
 
Foam in the 10um range, though? The foam damping patent I linked to earlier, which you seemed to touch on, seems easier, imo.
 

[0008] Preferably the diaphragm is clamped at its periphery and stressed to a bowed shape by contact with the resilient buffer and support member against at least the central portion on the concave face thereof. This is made from a specially selected grade of polyurethane foam. Alternatively, however, it could be made of soft down or mineral wool. ... and this element acts not merely to prevent the diaphragm from hitting the magnets, but also to tension the diaphragm and to control its resonance frequency.

 
And if we're cool with adding mass to increase structural stability of the diaphragm why not just have a non-driven honeycomb pattern on the reverse side ala T50RP? A foam diaphragm sounds like more work than it's worth to me, but maybe this is just my ignorance.
 

 

[Nevod]

Quote:

And if we're cool with adding mass to increase structural stability of the diaphragm why not just have a non-driven honeycomb pattern on the reverse side ala T50RP? A foam diaphragm sounds like more work than it's worth to me, but maybe this is just my ignorance.
 

I also have doubts in foam diaphragm or an all-driver-filling foam. IMO, diaphragm frontsides shouldn't make physical contact with anything except air. Foam is too stiff and all the motive force would be spent compressing it with minimum air movement. Foam could also deretoriate over time.
 
Hitting the magnets isn't such a problem in orthos, they have relatively big gaps and even if diaphragm hits the magnet, it would just clip, no risk of diaphragm destruction due to current rush like in electrostats.
Stax SR-507 (and other Lambdas probably too) uses multiple small domes distributed across stator plates, with height about half of the stator-membrane gap. They are believed to be used to increase dynamic range a bit by fighting diaphragm doming by essentially dissecting diaphragm into multiple many small sub-diaphragms at high deflections. This is still however not a pistonic movement.
 
For pistonic diaphragm movement, there are also patents, and they are relatively obvious - a relatively stiff diaphragm with thin and flexible suspension - say, a diaphragm that's thin and pleated on the very edge and reinforced and stiff elsewhere, over the most of it's surface - just like the dynamic driver. I suspect pistonic movement may be the reason why dynamic bass is said to be punchy compared to orthodynamic/electrostatic. And may be the reason why Yamaha's ortho's bass is said to be punchier than that of other orthos - their pleated diaphragms are more pistonic than stretched-film diaphragm of others. These also supposed to have very low resonant frequency, which is also positive, as resonance may be even completely out of audio band.
 
 

 

[Nevod]

Quote:

Last question. Wouldn't a low density, insanely thin, high strength, slightly elastic polymer material (as equally unobtainable as TotalFoamHeadphoneCup and more expensive) for a diaphragm be key? What if we could get away w/o any damping like Stax? Polymethylpentene seems pretty PMP'in, although, I think it's tough to manufacture below 35-40um without pinholes. Its density is like whoa, though. 

Mylar/Kapton are already good for that. But the voice coil weight is still significant anyway, and if you reduce it, you lose sensitivity. IIRC, some damping would always be required if you want to kill diaphragm resonant modes. IMO, diaphragm is better made rigid, albeit heavy, and then use damping.
 

 

[khbaur330162]

Nevod: Yup, pretty much. :/
 

 

[Indread]

So what amps are considered the best for a modded Fostex T50RP, for under ~$100? Or for any Ortho for that matter.
 
Thanks!

 

[DeathDomokun]

You can't get the best amp under $100, that'd be silly. As for the best amp >$100 I don't know
My only amp is an O2 and it sounds great with my T50RP's.
 
Does anyone know anything about the Sansui SS-10? I know there's plenty of info on the SS-100, but I can't seem to find much about the SS-10

 

[Indread]

I looked it up. Only found figures on pricing for prebuilt versions. How much would it cost to build one?
 
And any other recommendations for the best under or around $100?

 

[DeathDomokun]

You could try messaging http://www.head-fi.org/u/159248/jschristian44 pertaining the O2

 

[maverickronin]

Quote:

You can't get the best amp under $100, that'd be silly. As for the best amp >$100 I don't know
My only amp is an O2 and it sounds great with my T50RP's.

If all you want is clean power it's hard to go wrong with the Objective2.  Its great with my orthos.
 
Quote:

I looked it up. Only found figures on pricing for prebuilt versions. How much would it cost to build one?
 
And any other recommendations for the best under or around $100?

I think you can get all the parts for a about $60-75, IIRC.  You'll have to get the BOM from the designer's site (which I can't link to unfortunately...) and load it in to Mouser to get the exact cost.

 

[wualta]

Quote:

So what amps are considered the best for a modded Fostex T50RP, for under ~$100? Or for any Ortho for that matter.

That's easy. Realistic STA-2200. Heh heh.

 
Quote:

Originally Posted by DeathDomokun /img/forum/go_quote.gif
 
Does anyone know anything about the Sansui SS-10? I know there's plenty of info on the SS-100, but I can't seem to find much about the SS-10

Plenty of info on the web, including that it's not an orthodynamic.