[bagwell359]

Here you go.

 

[Philimon]

Here you go.

https://systematicsound.wordpress.c...e-6-early-4-screw-vs-late-4-screw-vs-6-screw/

 

[johnjen]

Please explain what you mean by ‘symmetry’? I dont know, I am curious. This newb is guessing you mean matching front vs rear acoustic impedance.

Im using stock screens because Im too lazy to purchase customs then install my own dust covers. I prefer dust covers and grills for safety. Ive not experimented with damping rear-side. I have experimented with front-side via earpads and I prefer more porous pads, Dekoni T50RP velour being my favorite. This setup may have drawbacks like @bagwell359 described where there is less precise bass but I prefer the tonal response and reduced bass bloom characteristics of the porous velour pads. However, I try not to comment too much as my HE500 may not be very representative of others as mine’s been modified by removing the pad ring adapter mounts. The pad rings + mounts I worry could become a source of air leak so my HE500 might not be comparable since it foregoes Hifiman pad mounting system for adhesive pads instead for good seal and convenience (i dislike pad swapping with the HFM rings because they are difficult to install).

Yes giving the driver the same 'load' or resistance to movement in both directions so that the created acoustic pressure wave is matched as it is created by the driver.
So no matter if the created wavefrom has a 'positive' or 'negative' pressure, the waveform shape is identical, only phase reversed.

And it doesn't seem to matter whether creating positive air pressure or negative, since the driver is 'seeing' an unequal acoustic load on each side of it's diaphragm.

As in, one side of the driver is facing your head with a designed, damped and 'controlled' acoustic resistance while the other side is facing 'free air', albeit with a screen in the way, or not, in some cases.

So yes I can see where there can be a noticeable sonic change by modifying or removing the screen, and for some, these sorts of changes may be 'better' while for others, perhaps not.

This asymmetric response is usually not a desirable trait in any transducer, for the obvious reasons.
But in one case in particular, it was designed in as a 'solution' to other design criteria which are endemic to planar's and electrostatic drivers, that being a 'structure' needs to be placed between the driver and our ears.
That 'structure' gets 'in the way' of the created acoustic waveform as it travels to our ears.

There are several 'design solutions' to 'help' with this situation and one of them is to modify the 'obstruction's' acoustic nature that sits between our ears and that side of the driver by changing the acoustic impedance on one side vs the other. in other words making the holes/slots bigger on the ear facing side.
Another is to channel the acoustic wave into those holes or slots to 'aid' in their travel thru that 'obstruction'.

Why don't they just match the holes/slots on both sides?
Because making holes/slots bigger also reduces the amount of magnetic field strength, or electrostatic force, which in turn means less efficiency which is already a 'problem' for these designs.
IOW trying to solve one problem, the obstructions detrimental effects, creates additional consequences, and in one particular case it resulted in an asymmetrical driver design which is independent of any acoustic impedance mismatch between inside facing vs outside facing of the driver itself.

This is why I'm investigating changing the shape of the screen, as a priority, instead of changing it's impedance.
And it's not that I won't play with hole size and overall porosity, because I will, but I also pay even closer attention to resonances of the structures themselves and the stock screen, once it becomes dish shaped, becomes much less resonant which is reflected in what I'm hearing.

My experiments and research continue as I look for other screen material to test (I have some titanium screen material inbound) and McMaster Carr has a variety of choices to choose from as well.
And a couple of them look 'promising'.

JJ

 

[johnjen]

This is very interesting. Please keep at it.

Not yet, but perhaps later. What about going with some other substance - that is less resonant. Then when you add blue tack/dynamat/sorbothane it would make a difference. I used to have sorbothane on where the cans go into the strap, but it didn't do much since I had the dynamat in place already.

I prefer to not generate resonances to dampening them after they have already been created. Mostly because not creating a problem completely negates requiring a solution to begin with. I utilized this approach with my mods for my hd800's, with gratifying results.

Have you measured this? I don't think it is the same as a piston speaker handling bass in a closed box vs a port vs baffles. Those are all distinct and need to be designed to work. What this issue to me seems is like putting a loosely rolled hand towel into a speaker port. It changes the dampibg a bit - pick your preference. It's not a huge change.

No I haven't measured it and for sure this isn't the same as a speaker driver and for the obvious reasons. And to my mind the most obvious one is the shear amount of travel/air movement ability between HP's and speakers. The amount of resonant 'artifacts' while WAY less with HP's also relates to what does get created, which has a greater net effect on the acoustic wave presented to our ears. This can be observed by dishing the screen.

I like the open sound and from what I see out of HFM is that Mr. H.E. was a genius on designing the driver but everything else seems like they barely got a thought. I do believe F.B. said it was fine to take the damping material out of the back of the HE-6 (4 screw time frame I believe).

Is the blind design of the long cup cans just for sound, or a cool looking way to protect these large drivers? They are not magnetic.
The stock screen is magnetic does that change the load?

I don't know from 1st hand experience quite yet, if the magnetic properties of the stock screens contribute to resonant effects or not, when my titanium sheet arrives and I form it into screens, perhaps then I'll have a better idea.

I can see it as a tuning issue. For sure there is less bass in all my HFM's with the screens off. I liken that to the effect of closed cans with more bass than open backs. Its almost always less damped and louder but hardly better. Not for me is +5 db at 150 Hz.

With my current EQ bass boost settings I have NO lack of solid, articulate, impressive and compelling bass, like at all.
In fact it is the most musical bass with impact and dynamics and intonation I've yet heard.
It isn't impressive just to be so, indeed unless the music itself is meant to 'get your attention', (like when they smack one of those 6' drums and the whole room lights up) the bass line is just there and is not obscured in the background.

FLASH: see post 19.996 for URL. That has a chart late in the piece under "grill mod" that goes into impedance and FR changes on the late version of the 4 screw. The 500 is almost a twin with the same driver with aluminum traces vs gold and some retuning of the mids.

Yeah that link doesn't work for me either.

Lastly, I did hold my dished screen betwixt thumb and forefinger and excite it with a metal rod, like I did when it was flat.
The resonance was significantly reduced in amplitude and it didn't 'buzz', and it also seemed to have much greater self dampening properties as well.

Just like I like.

JJ

 

[bagwell359]

JJ - I was talking about closed back headphones when I said "+5 db at 150 Hz".

In its stock form the bass of the 500 to me:

Excellent timbre - serious and potent in a way the Ananda just isn't.

Strong down to 30-35 Hz.

Does not posses the slam of its brother the HE-6 6 screw. What does?

However I do find the mid/upper bass to be under damped. Like a speaker designed to add more bass from 60 to 250 Hz to disguise it's lack of bass 20-50 Hz. Examples are the Sundara, 400 (and all variants), and speakers with passive radiators and ports that lack low bass and try and disguise.

On the 500 Steve Wilson remastered stuff by Yes and King Crimson or fusion jazz from "Bitches Brew", Stanley Clark, Weather Report, and "Romantic Warrior" by RTF. All of these have lots of bass and more to the point multiple bass instruments. On the stock 500 there is too much overhang and actual bleeding of these bass instruments at times. Perhaps bass heads and others don't notice or like it. Not me. The HE-6 SE for instance has less of this. HD-600, HEX v2 also no.

Dynamat and EQ takes care of it enough to keep me from worrying about it.

No screen means no worries about resonances and the chart I pointed at shows less of a change due to that than yiu'll find in most pad changes. But outside of that the Q in the mid/upper bass is simply higher than your "New England" sound which is at/near best/most accurate Q at. 707.

 

[SilverEars]

I heard @bagwell359 's modded HE500 and it's an improvement over the warm and fuzzy stock sound. Better clarity, in which it needs.

I keep holding onto my HE-6 because it's the not warm and fuzzy HE500.

 

[bagwell359]

I heard @bagwell359 's modded HE500 and it's an improvement over the warm and fuzzy stock sound. Better clarity, in which it needs.

I keep holding onto my HE-6 because it's the not warm and fuzzy HE500.

I'd take your 6 screw no problem. Eye shutting bass impact not heard even on the Phi.

With EQ and some refinement of my 500 it's even a bit more clear and tonally correct. But that's about it. It does have a relaxed warmth in the mids that's notable. But technically it can't match lots of cans, and that's fine if you accept that.

I'm tired of the choosing specific cans for specific music. Trip to hear the new Raal in the cards. If it's what I hope lots of stuff headed out the door... But upgrades to support it might be required.

 

[Philimon]

@johnjen Thanks so much for the explanation. May I ask, how do you know so much? Did you go to school?

I have a driver transplanted HD800 if you care to borrow johnjen. You too bagwell.

@bagwell359 I dont doubt your observations. Like you said, some like me are less sensitive with silverears and bassy preferences.

@SilverEars Cool to see you here. I thought you were a Sennheiser guy.

 

[Philimon]

@johnjen
Speaking of symmetry… In the HD800 mod photo above I felt it sounded better to seal the driver vents when using hybrid pads. But with velour pads, I preffered the vents open.

 

[johnjen]

JJ - I was talking about closed back headphones when I said "+5 db at 150 Hz".

Ah, that helps explain it. Thanks

In its stock form the bass of the 500 to me:

Excellent timbre - serious and potent in a way the Ananda just isn't.

Strong down to 30-35 Hz.

Does not posses the slam of its brother the HE-6 6 screw. What does?

I aim for sub 20 Hz myself. To me the extreme bottom end is the very foundation of the whole spectrum and while it is unrealistic to expect such a range from speakers (unless you want to spend $$$$$$+) HP's can, when properly setup with equipment that can deal with such extremes, provide a visceral foundation to the music, well, when it is present in the recording that is.
As for slam or the immediacy of a 'fast' low frequency transient (think lighting strike or gun shot etc), speakers will ALWAYS have more difficulty with such 'events' simply due to their greater mass, which HP's can deftly avoid. This is why I aim for such low frequency capability from HP's, because I can feel my chest get thumped and my head get compressed which nearly always evokes a big grin. Just like I like.

However I do find the mid/upper bass to be under damped. Like a speaker designed to add more bass from 60 to 250 Hz to disguise it's lack of bass 20-50 Hz. Examples are the Sundara, 400 (and all variants), and speakers with passive radiators and ports that lack low bass and try and disguise.

On the 500 Steve Wilson remastered stuff by Yes and King Crimson or fusion jazz from "Bitches Brew", Stanley Clark, Weather Report, and "Romantic Warrior" by RTF. All of these have lots of bass and more to the point multiple bass instruments. On the stock 500 there is too much overhang and actual bleeding of these bass instruments at times. Perhaps bass heads and others don't notice or like it. Not me. The HE-6 SE for instance has less of this. HD-600, HEX v2 also no.

I ascribe "overhang" and the smearing of the mids, (and everywhere else) to overshoot, which I will address when I get all my ducks in order.

Dynamat and EQ takes care of it enough to keep me from worrying about it.

No screen means no worries about resonances and the chart I pointed at shows less of a change due to that than yiu'll find in most pad changes. But outside of that the Q in the mid/upper bass is simply higher than your "New England" sound which is at/near best/most accurate Q at. 707.

Do you mean 0.707?
At what frequency (range) does this apply?

And I do understand about no screen, no problem.
On the HD800's removing the screen over the magnet assembly was a no brainer, but then the earcups of the 800's are not sealed to begin with so the net effect of the change of impedance, that the driver sees, is minimal.

JJ

 

[bagwell359]

Ah, that helps explain it. Thanks

I aim for sub 20 Hz myself.

Sure. I am saying the 500 runs out of steam in the 30-35 Hz bracket. It obviously has output at 20 Hz. and even add EQ as I do but its run out of impact - basically the same thing as a speaker with a bass resonance of 40 Hz. You can play 20 Hz thru it but when you compare to a speaker with a 15 Hz resonance the difference is crystal clear.

My HEX v2 has output at 15 Hz. But it lacks impact/life. Thats what I observe. It's probably an artifact of my father's Quad ESL 57's and frequent trips to the BSO AND my experience with building sub woofers, woofers, and all my experience with room tuning for speakers. All I care about personally is 30 Hz and up. Shaking buildings or skulls isn't produced in the music I listen too. Also top safe speed of my car is 140 on a public highway as I learned. It would probably get to 155 on a closed track. Big deal. If I can't drive a car on a highway offramp 3x the posted limit I won't buy it. We all have our things.

As for slam or the immediacy of a 'fast' low frequency transient (think lighting strike or gun shot etc), speakers will ALWAYS have more difficulty with such 'events' simply due to their greater mass, which HP's can deftly avoid.

Not an issue with the best speakers I owned, and my best rooms which impressed folks enough to contract me to do rebuilds and new builds of dedicated listening rooms for them.

This is why I aim for such low frequency capability from HP's, because I can feel my chest get thumped and my head get compressed which nearly always evokes a big grin. Just like I like.

but, not my aim

I ascribe "overhang" and the smearing of the mids, (and everywhere else) to overshoot, which I will address when I get all my ducks in order.

OK. In bass I refer to Q and damping. Planars ring a tremendous amount which isn't bothersome to many because of the coherence of the initial pulse generally from bass resonance to 2k. After that and above that is a lot of chaos. Stopping is not the strong point of planars. Go look at a waterfall plot of say a HE-400i vs a HD-300. Oopsie.

Do you mean 0.707?
At what frequency (range) does this apply?

Bass in speakers. The Q of .707 is widely considered the ideal in order to convey both impact and heft - among other things. Too high is blob City. Too low is a dry desert. .65-.85 is close enough for me.

And I do understand about no screen, no problem.
On the HD800's removing the screen over the magnet assembly was a no brainer, but then the earcups of the 800's are not sealed to begin with so the net effect of the change of impedance, that the driver sees, is minimal.

JJ

 

[johnjen]

@johnjen Thanks so much for the explanation. May I ask, how do you know so much? Did you go to school?

I've been at the audio 'hobby' for many decades and have always enjoyed learning the details of what is and isn't significant.
No, when I was in school, audio was not on most schools curriculum, so it was my own research and study that 'paved the way' so to speak.

I have a driver transplanted HD800 if you care to borrow johnjen. You too bagwell.

My HD800's are on the 6th (and final) generation of tweaks and modifications.
After I dialed in the overshoot 'problem' the resulting SQ took a mutha may I step up and I 'finished' that project.

JJ

 

[bagwell359]

More on bass resonance. Let's talk sealed box speaker. Speakers with ports have complex and multiple resonances.

Once you get below a resonance point the driver just flops around. And the more power (EQ just accelerates it) not only does it flop around more (and not reproducing music anymore but tossing distortion into the brew), other frequencies get affected too and not in a favorable way.

If you have a planar lacking bass under 60 Hz such as HFM: HE-400, Sundara, HE-5 LE, etc. Go ahead and do a +6 from 60 down to 10 Hz on a parametric and listen loud, listen past the obvious bass - then try a bass with a lower resonance such as any HE-6. You can play around w/ EQ and it won't blow up the higher frequencies. This is more obvious on the HD-600. Pump 6 db @ 20 Hz into it. Not good or convincing - at all.

 

[Tacanacy]

Has anyone used Harmony pads and Pali pads (2020) on HE500 who can compare them? I'm using Pali pads, and I'm considering getting Harmony pads, but that price, though...

 

[ozz007]

OK, I changed the pads to the Sundara leather ones, angle. I also did the Grill mod, from grills from eBay; I think they are made of steel cause the magnets like them, lol

Also, tweak the EQ, and I can tell they sound a bit clear, and the bass has more punch.

And got a Hybrid cable since the original broke.