TO TWEAK OR NOT TO TWEAK THE STAX 007A? THAT IS THE QUESTION

[edstrelow]

I finally did the blutac mod on the 007A. It has been noted in the Stax Thread by Spritzer and possibly by others that the 007A differs from the earlier 007 because it has an open space in the driver just above where the cable is fastened (i.e. just above the black at the bottom of the picture.



He has noted that plugging the space brings the 007A more in line with the 007 by pushing the bass response lower. As well, flatenning the spring which holds the earpad in place so the pad does not protrude out as far, reduces the lower bass peak.

Having now tried these mods, I can say Spritzer is correct on both of these points. Actually while I did plug the ports, I didn't permanently bend the springs, I just pushed the pads firmly onto my head to flatten them. Plugging the ports definitely pushed the bass down more but made a smallish bass peak somewhat more pronounced. Flattening the pads, reduced that peak quite effectively.

However, the effect is not as euphonic as one might expect. My first impression upon doing these tweaks was to think that the 007A sounded more like the Stax 404, which has a deeper bass response and somewhat of a bass peak. Unfortunately it makes the 007A sound more like the 404 in also having less definition. While the frequency response of the 007A is clearly improved by these mods, this comes at the cost of some of the 007A's best features, namely its ability to articulate details. There is noticeably less air and ambience coming through, and dynamics and details are lost. The phones also seem to end up with a mid frequency emphasis.

So basically I took the phones apart again and pulled the tac out. On reassembling these and plugging them into the 717 amplifier, they sounded again like the phones that I liked so much when I first got them. A neutral sounding phone with 1) a remarkable soundstage, with very precise, stable localization of instruments and voices, 2) great dynamic detail and 3) details of timbre I had not heard on any other phones.

Some of those who prefer the 007 sound over the 007A seem enamoured of tube amps, especially the more expensive non-Stax models (not that the Stax amps are particularly cheap). It may very well be that the 007 with a better amp does sound better than the 007A with a cheaper Stax tube or transistor amp. But how much of that is the amp rather than the phones? At any rate my impression is that the 007A is well matched with the 717.

I may try these mods again, but for the moment I want my original sound back.

This section below is an edit to clarify the effect of earpad orientation on the sound of these phones. I should note at the beginning of this thread that the ear pads have a "D" shaped opening. Now Stax says nothing about correct orientation in its manual, just adjust to your preference.

However, as you will see if you get to the end of this thread, my take on the orientation of the earpads of these phones differs from many others. I position the curved part behind my ear, because my ear is curved. Others position the straight section behind the ear. Those who position the straight edge behind the ear note that the pad is thicker/deeper there and that it fits many heads better and give a better seal. I would agree with that except that the earpad presses on the back of my ears. As regards the head-fit issue (as opposed to the ear-fit issue) you can of course bend the metal bands to get correct fit and seal.

I have tried both earpad orientations, bending the headband to get the best seal each time, and markedly prefer having the curved section behind my ear. However I have not tried all permutations of pad orientation, blutack and spring mod. I am very happy where I am right now with these phones. Possibly someone else would like to try these variations.

Finally, given what I hear with the changes in ear pad orientation, that some of the complaints about these phones come from having the straight edge behind the ear. I did not start out this way and liked the phones from the begining , although the spring mod made them better.

[HeadphoneAddict]

I think I will hold off on the blu-tak mod a little longer - putting the pads back on is too hard.

I am not sure pushing the phones against your head will give the same results as the spring mod - i.e. stretching the diameter from 92mm to 100mm and flattening the spring attachment to snug down the pads.

This is the only mod I have done and the results were an improvement, where the mids didn't drill into my head as much. Burn-in made further improvement by 200-300 hours.

[edstrelow]

Originally Posted by HeadphoneAddict

I think I will hold off on the blu-tak mod a little longer - putting the pads back on is too hard.

I am not sure pushing the phones against your head will give the same results as the spring mod - i.e. stretching the diameter from 92mm to 100mm and flattening the spring attachment to snug down the pads.

This is the only mod I have done and the results were an improvement, where the mids didn't drill into my head as much. Burn-in made further improvement by 200-300 hours.

Hmmm. I did find a peak at about 8kHz in the unmodded 007A. I state that frequency based on how the 007A pulled up tape hiss. By fiddling with an equalizer I could tell the spectrum of most of the hiss. This peak is slightly annoying although I think this provides some of the timbre.

[spritzer]

Merely forcing the headphones closer to the head will not bring the same benefit as widening the springs unless you have some way of just pushing on the pins while not crushing the pads. Since you've plugged the port while doing this you are forcing the air inside the earcup and that also changes things. The sole reason behind altering the width and angle of the springs is to make the midrange fall back in line with the rest of the spectrum since it is far to prominent on the stock phones.

[edstrelow]

Originally Posted by spritzer

Merely forcing the headphones closer to the head will not bring the same benefit as widening the springs unless you have some way of just pushing on the pins while not crushing the pads. Since you've plugged the port while doing this you are forcing the air inside the earcup and that also changes things. The sole reason behind altering the width and angle of the springs is to make the midrange fall back in line with the rest of the spectrum since it is far to prominent on the stock phones.

I will agree that there is some upper frequency prominence with the 007A. I noticed that these phones made tape hiss more prominent and that this peak probably brought out some of the timbre of instruments. It never rose to the level of irritation that the 404 peak can sometimes bring but I could see some benefit to a minor reduction.

While I think I understand flattening the springs on the pad, they come at an angle which pushes the pads out somewhat. I am less clear on lengthening the springs. Do you just start the bend further back under the ear pads?

[HeadphoneAddict]

You bend it so the part leading from the lasso hoop to connect to the headphone grommet is now flat when you place it on a table. It needs to be 2-dimensional by the time you are done.

You also stretch the hoop out to be a larger diameter, it starts at 92 mm and should be 100-102 mm. I didn't want to lose my circularity, and stopped at 100 mm.

[edstrelow]

Originally Posted by HeadphoneAddict

You bend it so the part leading from the lasso hoop to connect to the headphone grommet is now flat when you place it on a table. It needs to be 2-dimensional by the time you are done.

You also stretch the hoop out to be a larger diameter, it starts at 92 mm and should be 100-102 mm. I didn't want to lose my circularity, and stopped at 100 mm.

I think I grasp your first paragraph. The second paragraph seems different from what I previously thought. Any photos?

[spritzer]

Originally Posted by edstrelow

While I think I understand flattening the springs on the pad, they come at an angle which pushes the pads out somewhat. I am less clear on lengthening the springs. Do you just start the bend further back under the ear pads?

To widen the springs I started off at the large bend to make the radius of the springs wider. Then I simply bent them a little bit at a time by hand to maintain the shape so that they looked like the Mk1 springs. I also rounded out the end so it wouldn't snag the leather but later I took a small length of similar wire and attached it to the spring with heatshrink so that it would reach full circle. It was mostly meant to allow the pads to be rotated freely and without the small chance of damaging the pads.

[edstrelow]

Thanks Headphoneaddict and Spritzer. Now we have all the information in one thread on Head-Fi.

I think I will try the spring mods now.

[edstrelow]

Ok I have done the spring mod and it certainly seems worthwhile leaving in place for longer than the Blutak plug in the port. Basically I expanded the diameter of the lassoo, which fits inside the leather ring, and flattened the center part of the spring.

Firstly I show the leather ring and screen which the spring fits into.



This limits the extent to which you can expand the diameter of the spring since this constrains the spring mechanism.

Neither the headphone pads nor the headphone cup no longer swivel freely although they can be moved. The earcup may also be a bit more airtight than before but certainly not like it as when the Blutac plug was in place

How does this make the 007A sound? It definitely reduces some of the treble/midrange peak. I noted a peak more in the region of 8kHz which I would call mid treble. Others think it is more midrange. Whatever. This peak seems attenuated now. As well the 007A seems a little more bassy. In fact it the tonal signature was somewhat more like the Sigma/404 except with deeper bass.

I am still not fully convinced that the basic tonal signature of the unmodded 007A needs changing. Certainly those who are used to the 007 seem to think so, but this may be more a matter of habit and familiarity. I am not sure that every listener will see this mod as a necessary or even desireable change. But certainly it is a useful option for tailoring sound which doesn't have the nasties that I seemed to hear with the port plug modification.

So thanks Spritzer for your research and Headphone Addict for clarifying these mods.

I will be interested to see what others think.

[HeadphoneAddict]

Without the spring mod, I was planning on selling the O2 Mk2 the first few days I had them. Vocals just blasted into my head with the too forward mids. The mod allowed me to keep them long enough to burn them in more, at which time the mids further mellowed out. I have had them now for 5 weeks and likely will keep them for much longer.

[spritzer]

Great impressions but... ehhh... the spring is in the wrong place. It is supposed to sit outside the fabric cover or rather to the back of it. There are two "levels" inside the pads, the smaller one holds the fabric piece and the springs in place.

I do agree though that the Sigma/404 sounds a lot like the Omegas which is why I ended up selling mine. It's quite enough to have just one headphone like that...

[edstrelow]

Originally Posted by spritzer

Great impressions but... ehhh... the spring is in the wrong place. It is supposed to sit outside the fabric cover or rather to the back of it. :

Are you saying the spring is not supposed to be inside the leather ring? This is how mine came from Japan. Or do you just put the widened spring on top of the ring?

[spritzer]

Originally Posted by edstrelow

Are you saying the spring is not supposed to be inside the leather ring? This is how mine came from Japan. Or do you just put the widened spring on top of the ring?

Either Stax has changed the way the earpads are mounted or somebody messed up your set since I've never seen the spring placed inside the leather ring. It will certainly not work well with the spring mod since the whole point is to make contact with the outer edge of the pads and fix them in place. The outer flange is this crappy pleather which has very low tensile strength compared to the leather in the Mk1 pads and this was the easiest way to force the pads to be closer to the drivers

[HeadphoneAddict]

I think Stax has changed the way the earpads are mounted then, because mine came with the metal ring under the stiff leather ring too. I suspect they do it that way now because the pleather rim is so soft and flimsy.

Are you saying the ring goes inside the outermost part, held on only by the pleather, while the pleather is still tucked in around the edges of the rim of the phone?

If so, then it seems the pads might always live on the edge of almost slipping off. I wonder if this why my burn-in has had more of an effect on taming the mids than my earpad spring mod?