CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS

Lobby => Headphone Measurements => Topic started by: Marvey on September 12, 2012, 03:28:27 AM

Title: StratoGrado Measurements
Post by: Marvey on September 12, 2012, 03:28:27 AM
I got these StratoGrados in last week but hadn't had a chance to get to them until now.

A quick listen tells me that these sound like Grados, but with more bass extension (yes!) and slightly less "Grado". Some nice deep deep bass extension. They still have those annoying (or charming) Grado characteristics. On well balanced recordings, it's not annoying at all. The problems come when I throw the marginal tracks. The midrange shoutyness and upper midrange edge are aren't as exaggerated. However the minor mid-treble peak found on most Grados is sounds more evident with the StratoGrado. I wouldn't call it minor anymore. Again, it's track dependent. The classic Grado articulation and detail are certainly there.

Compared to the HF2s, the StratoGrados sound warmer, but with the exception of the aforementioned treble spike which really sticks out. I'm guessing 9kHz.

I'll take measurements and see what happens.
Title: Re: StratoGrado Measurements
Post by: Marvey on September 12, 2012, 03:52:57 AM
StratoGrado  Frequency Response and CSD Waterfall Plots

Great bass extension.

The RS1 has peaks at 2k, 5k, and 9k with 5k being the sharpest, and 2k being the broadest. In contrast, the Stratogrado seems to shift the midrange peaks down to 1k and 3.5k. The 9k ridge really sticks out, at least for me when I'm listening. The 3.5k peak does not bother me.
Title: Re: StratoGrado Measurements
Post by: Questhate on September 12, 2012, 03:57:29 AM
That bass extension is lovely. Do you know what the mods are on these?
Title: Re: StratoGrado Measurements
Post by: Marvey on September 12, 2012, 04:01:55 AM
Grado drivers put into semi-closed cups. There's a small hole (not pictured - cut off) in the center of the outside surface of the cup. I think the cups may be stuffed with something inside. The Strato pads must be used to obtain the correct results.

Too bad the bass can't from the these can't be combined with the Koss driver.
Title: Re: StratoGrado Measurements
Post by: Marvey on September 12, 2012, 04:30:23 AM
StratoGrado Harmonic Distortion
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 12, 2012, 02:22:22 PM
Thanks for measuring these, Purrin.

As I contacted Purrin via PM about measuring these I informed him about my objectives with this project, which were as follows:

1) Answering the question if a closed Grado could work (even more so  because it seemed common knowledge it was not possible)
2) Improving the bass extension.
3) Reducing or eliminating the Grado shout.

I ended up with a setup that sounded acceptable to my ears and I thought measurements would certainly tell me if I was on the right track or not. Listining to the headphones I thought I was, but you never know before you actually see the graph.

As for the 9k peak, I did not find it that annoying, maybe because I focussed too much on the bass and midrange.

FYI:

Used drivers: Grado SR80i
Cups: Wood cups RS1 style
Bass vent: 8mm bass vent at the bottom of the cup (damped internally)
Damping:  felt, medium density foam and sheep's wool
Driver damping: Now this is the tricky part. Compared to the Koss driver the Grado driver is a bitch to get working in such a setup. Whereas you just put a Koss driver into the cup and you have a working headphone, you can't just do that with a Grado driver. You literally have to choke it to get it working.

Now if I were Grado, I would use some shiny exotic wood cups, some drivers that have a better response in the higher frequencies, copy the StratoKOSSter pads and apply the StratoGrado damping scheme. Then I would call it the "Grado Revolution" and sell it for USD 1K. And make some dough.

@purrin: If you happen to have time, I would be very thankful if you could try the following and hear/see for yourself if the results changed for the better or worse:

a) putting some foam (like the Koss earpad foam disk) between driver and ear
b) lifting the drivers a bit from inside the cup to increase cup volume
c) changing the damping on the driver back (different variations of felt/paper)





 
Title: Re: StratoGrado Measurements
Post by: jerg on September 12, 2012, 08:54:50 PM
So is this evidence that lower-tier Grado drivers are plain inferior to Koss KSC75/35 drivers?
Title: Re: StratoGrado Measurements
Post by: Marvey on September 13, 2012, 12:09:22 AM
Not necessarily. The Grados have more capability for bass extension.


Also, I will follow up on Strat's ideas to tone down the treble with the StratoGrados.
Title: Re: StratoGrado Measurements
Post by: jerg on September 13, 2012, 03:54:09 AM
Not necessarily. The Grados have more capability for bass extension.


Also, I will follow up on Strat's ideas to tone down the treble with the StratoGrados.

That is indeed true; the one major weakness with Koss KSC drivers are that they aren't built for strong bass reproduction. They tend to wobble and distort with any major bass in music on relatively loud volumes, and the texture is suboptimal.
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 13, 2012, 10:14:29 AM
The StratoKOSSter bass is not bad, although the StratoGrados sound fuller and extend even better. Distortion looks better too, also compared to the distortion graphs of other Grados on Innerfidelity.

As for the rest, the Koss drivers are simply more well-behaved and unproblematic. You can simply put a KSC-75 or KSC-35 driver into a foam-damped cup, mount the StratoKOSSter pads, and  you will end up with a nice and decent headphone. If you do that with a Grado driver, you will end up with sonic desaster. You have to gag the driver and teach it a lesson.

When developing the StratoGrados I decided on using SR80i drivers I had lying around, just to see if it could work. I did not want to ruin a more expensive Grado driver (the PS500 drivers with their lack of hf energy could be an option) and burn my wallet.  Let's see if Purrin can measure a positive effect of changes to the setup. Then I might sacrifice Magnum drivers to create a really decent headphone.

Then again, even if the StratoGrados V80i are still imperfect, it is definitely nice to listen to a "Grado" with real bass extension, comfortable leather pads and decent isolation.
Title: Re: StratoGrado Measurements
Post by: jerg on September 13, 2012, 01:04:55 PM
The StratoKOSSter bass is not bad, although the StratoGrados sound fuller and extend even better. Distortion looks better too, also compared to the distortion graphs of other Grados on Innerfidelity.

As for the rest, the Koss drivers are simply more well-behaved and unproblematic. You can simply put a KSC-75 or KSC-35 driver into a foam-damped cup, mount the StratoKOSSter pads, and  you will end up with a nice and decent headphone. If you do that with a Grado driver, you will end up with sonic desaster. You have to gag the driver and teach it a lesson.

When developing the StratoGrados I decided on using SR80i drivers I had lying around, just to see if it could work. I did not want to ruin a more expensive Grado driver (the PS500 drivers with their lack of hf energy could be an option) and burn my wallet.  Let's see if Purrin can measure a positive effect of changes to the setup. Then I might sacrifice Magnum drivers to create a really decent headphone.

Then again, even if the StratoGrados V80i are not still imperfect, it is definitely nice to listen to a "Grado" with real bass extension, comfortable leather pads and decent isolation.

I see! Thanks.

Is the prototype looking similar to stratokossers?
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 13, 2012, 03:59:19 PM
Quote (selected)
Is the prototype looking similar to stratokossers?
Yes, I was using the same cups, with the only difference that I left the bass vent open with the StratoGrados, whereas the StratoKOSSters are completely closed. If there is too much bass (yes, too much bass with a "Grado", haha!), you can partly close the bass vent or reduce air flow with foam.
Title: Re: StratoGrado Measurements
Post by: gurubhai on September 13, 2012, 04:17:50 PM
Maybe you guys should try porting the stratokossters as well.They do seem to need some lower end boost .
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 13, 2012, 04:22:20 PM
porting the stratokossters does not help, there is simply not more bass energy to be achieved. porting results in bloated lower frequencies, whereas the closed stratokossters have a nice and tight bass and a good balance
Title: Re: StratoGrado Measurements
Post by: gurubhai on September 13, 2012, 04:30:22 PM
^Are you using any kind of damping in the cups ?
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 13, 2012, 04:36:46 PM
stratokosster damping is documented in the stratokosster thread, stratogrado damping in a post above
Title: Re: StratoGrado Measurements
Post by: gurubhai on September 13, 2012, 04:50:45 PM
Sorry, I missed the post above. IIRC, you were only using some foam in the Kosters. May be a scheme similar to grados would have helped a ported version of kosters.Perhaps, you already tried that as well though .
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 13, 2012, 05:16:21 PM
Cup damping is almost the same with both Stratos.

And, yes, I tried the StratoGRADO driver damping scheme with the Koss drivers and that simply did not work! Personally I also do not really worry about the StratoKOSSter bass, it is nice and decent. To my ears the StratoKOSSters are a fairly good setup, quite neutral and balanced. Plus they are easy to produce. The StratoGrados are a different story, though ...
Title: Re: StratoGrado Measurements
Post by: Marvey on September 19, 2012, 04:39:36 AM
I put two pieces of felt in front of each driver in an attempt to reduce the mid-treble peak. Success! At least subjectively. Treble is still sharp at times, but definitely tolerable.

Here are the measurement results.

Not a huge difference in the CSDs, but the FR is smoother from 1kHz to 12khz.
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 19, 2012, 07:56:15 AM
Yeah, that is definitely a step in the right direction.

Now, what would be really interesting is the question if something can be done about the dip around 500Hz. Any chance you might change something about the driver dampening, i.e. try the felt and/or the damping paper alone as damping and check if this has a measurable effect. If the FR can be flattened out in that region that would be quite a nice Grado FR, in fact quite unlike other Grado frequency responses, don't you think?
Title: Re: StratoGrado Measurements
Post by: Marvey on September 29, 2012, 09:00:50 PM
@strat:

On attempts to remove the upper bass dip:

Took measurements with different materials in the cup and also moving the drivers out. No change (hence no measurements posted.) I suspect the dip is the result of the port. (I know that speaker bass porting does have a similar effect, a resonance peak at the port F coupled with a dip somewhere higher up. Maybe this effect is more pronounced in headphones?) I will cover the port or maybe partially stuff it with felt or foam.

Sorry for taking so long. Been too hot, been sick, busy with work, and have about 10 other headphones in the queue.
Title: Re: StratoGrado Measurements
Post by: stratocaster on September 30, 2012, 07:18:31 AM
Thanks Marv, take all the time you need. I, and I am sure all the others here, are very grateful for the work you are doing and conscious of the huge amount of time you are investing.

As for the port, blocking it will have a big impact on the bass, thinning it out. I had acceptable results though, when I used a very small piece of open-cell foam to partly block the port and thus limiting the air flow.

The port was necessary when I used the felt + damping paper behind the driver. This resulted in the best bass response.
I have a second set, which has only the damping paper aka coffee filter glued to the back of the driver. Then you do not need the port.  This set has a shallow profile though, yours has more inner cup volume. So, I am not sure if using just the damping paper in your set will have the same results as in mine.

At the moment I have this paper glued to the back of the driver, cup interior damping with high-density open-cell foam. I also use discs of stock SR80 pads  between driver and ear (held in place by the leather pads) to tame the highs. I am VERY PLEASED with this set. It certainly bests the StratoKOSSters.



Title: Re: StratoGrado Measurements
Post by: stratocaster on October 03, 2012, 04:20:42 AM
The dip around 500Hz is, tests seem to underline this, a result of the port. If you find the time to measure these with the ports closed, I am expecting a change in the lower mids and bass. The dip should be alleviated, but bass extension might suffer.  Changes in the mids and highs are not likely to happen. Sound signature will surely change.
Title: Re: StratoGrado Measurements
Post by: purk on October 03, 2012, 06:55:51 AM
Purrin,

Have you ever measured b/w the RS-1 and RS-1i? If so, what is the better one of the two.   I have a vintage RS-1 with a broken driver and wonder if I should repair or upgrade to RS1i.  Thanks.
Title: Re: StratoGrado Measurements
Post by: stratocaster on October 03, 2012, 05:48:48 PM
And I almost forgot: It is absolutely essential that the distance between driver and ear is as small as possible. This will result in the best low-mid and bass performance. I am using very thin and soft leather at the moment (whereas your Stratopads have thin but less soft leather) and I make sure that the headband is bent in a way that ensures a very tight fit, pushing the driver against the ear  with just a disc of soft foam in between. That way the lower mids move up a few db and the bass becomes even fuller.

At present I am working on some StratoMagnums. These sound VERY promising.
Title: Re: StratoGrado Measurements
Post by: Marvey on October 03, 2012, 07:02:36 PM
Purrin,

Have you ever measured b/w the RS-1 and RS-1i? If so, what is the better one of the two.   I have a vintage RS-1 with a broken driver and wonder if I should repair or upgrade to RS1i.  Thanks.

The two RS-1 measurements I have (I think only one is indicated on this site) were semi-vintage from circa year 2000. They measured consistently (hence why I only posted one measurement). I don't have RS1i measurements.

I know I had a pair of "very" vintage RS-1s in the late 90s which were a bit bassy and not trebly at all. They do not sound like the current or semi-vintage RS-1s. The ones I had may have possibly had the pink drivers.

I'm not sure if you can even repair vintage or semi-vintage RS1s. If you sent them back to Grado, they would probably just give you the new RS1i drivers.
Title: Re: StratoGrado Measurements
Post by: purk on October 04, 2012, 05:48:48 AM
Purrin,

Have you ever measured b/w the RS-1 and RS-1i? If so, what is the better one of the two.   I have a vintage RS-1 with a broken driver and wonder if I should repair or upgrade to RS1i.  Thanks.

The two RS-1 measurements I have (I think only one is indicated on this site) were semi-vintage from circa year 2000. They measured consistently (hence why I only posted one measurement). I don't have RS1i measurements.

I know I had a pair of "very" vintage RS-1s in the late 90s which were a bit bassy and not trebly at all. They do not sound like the current or semi-vintage RS-1s. The ones I had may have possibly had the pink drivers.

I'm not sure if you can even repair vintage or semi-vintage RS1s. If you sent them back to Grado, they would probably just give you the new RS1i drivers.

The one that I have contains a pink driver.  Grado informed that the cost to upgrading to RS1i is only $100 and it will involve installing new drivers as well as upgrading to the RS1i's cable.
Title: Re: StratoGrado Measurements
Post by: Marvey on October 06, 2012, 06:35:15 PM
The pink driver is a good one. The RS1i do sound different.



Back to StratoGrados:

Blocking the port with various materials does push down the bass so the region between 20Hz to 300Hz becomes flat. However relative to this region, the broad 1kHz bump is still there. This is a bit of conundrum. If we can fix the 1kHz bump by experimenting with internal absorption materials, the treble would be slightly elevated in relation to the lowered bass/mids.

Below is the FR for the port lightly stuffed with TP and the drivers moved closed to the ear (flush with the cup).

I should be sending these back to you, unless you want more tests.
Title: Re: StratoGrado Measurements
Post by: stratocaster on October 07, 2012, 06:59:20 AM
Thanks for trying and measuring the tweak, Marv!

The graph visualizes why I preferred the sound of the vented StratoGrados. The bass is better, the mids and highs less edgy, thus resulting in a more balanced signature. The problem that I see is the dip around 500Hz, clearly a result of the port. When closing the port, you can address this issue, but then the bass is gone.  When listening to the vented set, this dip around 500Hz does not seem to bother me sonically, though.

Will try to experiment on this dip and come up with a more even response.

Marv, there is no need to send the StratoGrados and StratoSenns back. I have additional sets to experiment with. If I come up with a more promising tweak, I would be more than happy to be able to ask you to try that out on them.

You have already helped me tremendously by measuring the Stratos. That way you have helped me learn that I can trust my ears. And that is what I do.
Title: Re: StratoGrado Measurements
Post by: Marvey on October 09, 2012, 05:16:52 PM
Thanks and much appreciated. My wife is using the StratoGrado on her Mac. I need to buy some pads from  you for the two other pairs.
Title: Re: StratoGrado Measurements
Post by: thefoundMIDrange on November 23, 2012, 12:35:18 AM
ime, the koss drivers do indeed behave poorly when the volume is anything more than moderate and like others have noted, the bass will not hold together. And also as noted, the bass has very little punch to begin with. For me that is a + since bass slam in my cochlea is one of the biggest turnoffs but seemingly super popular among the 'general population'. Seems like alot of full size and iems have overdone and artificially punchy bass......In any case, I actually like the koss drivers low end and find it's extension and articulation enough for me to hear and enjoy all my favorite bass lines. i agree with the other post that mentioned its texture or tone-nuance not being outstanding though and it is a bit too prominent.
Title: Re: StratoGrado Measurements
Post by: stratocaster on July 24, 2014, 12:41:51 PM
I have finally set up my own measurement rig (big thanks to Keith aka Bluemonkeyflyer over at HF!) and have been about it for some time now. I am using measurements to make modding easier by getting  'objective' feedback. Doing so I have done some work on the battered set of SR125i drivers with inner wood sleeves and outer SR325 goldies you see below. I will call this set StratoGrado v2 aka Stuffed Turkey, since there is an awful lot of damping used, both channels requiring largely different damping approaches.

(http://cdn.head-fi.org/5/5d/900x900px-LL-5dfb9509_gold_125.jpeg)

Now, these are the measurements:


(http://www.ginrim.at/content/wp-content/uploads/2014/07/overlay.jpg)

(http://www.ginrim.at/content/wp-content/uploads/2014/07/left.jpg)

(http://www.ginrim.at/content/wp-content/uploads/2014/07/right.jpg)

(http://www.ginrim.at/content/wp-content/uploads/2014/07/left_wf.jpg)

(http://www.ginrim.at/content/wp-content/uploads/2014/07/right_wf.jpg)
Title: Re: StratoGrado Measurements
Post by: Moosecraft on July 24, 2014, 01:39:49 PM
Looks very nice  :)p1 :)p1
Title: Re: StratoGrado Measurements
Post by: spoony on July 24, 2014, 03:34:44 PM
Nice! Say, do you enjoy these over the stratokosster? I have a pair of SR80 that I want to modify and have to decide whether to use their drivers or switch to the KSC75 instead.
Title: Re: StratoGrado Measurements
Post by: stratocaster on July 24, 2014, 08:31:00 PM
These are open, though damped fairly densely. They definitely do have a fuller bass than the one provided by the KOSS driver.  If you plan to put drivers into closed cups and strive for neutrality the KSC75s are the way to go. But you have to consider that you would need leather L-cushions for the KOSSters.
Title: Re: StratoGrado Measurements
Post by: spoony on July 24, 2014, 09:16:38 PM
Oh, I see... Are you willing to share your damping scheme on this pair?, you've done a great job taming the Grado nasties.
Title: Re: StratoGrado Measurements
Post by: stratocaster on July 24, 2014, 09:44:57 PM
In this measurement you see the differences between the two Stratos, the purple line representing the left StratoKOSSter driver, the green line being the StratoGRADO left driver. The StratoGRADOs look slicker.

(http://www.ginrim.at/content/wp-content/uploads/2014/07/stratos.jpg)

As for the damping scheme, it varies from driver to driver, at least with the two SR125i drivers I have got. Basically I use felt, damping paper aka coffee filter and cotton, in varying layers,  thickness and amount of material needed depends on the driver.
Title: Re: StratoGrado Measurements
Post by: spoony on July 24, 2014, 09:59:42 PM
Thanks, and that's very nice performance. What happens when you pair your 'leathered' pads with a grado driver?
Title: Re: StratoGrado Measurements
Post by: stratocaster on July 24, 2014, 10:11:26 PM
too much midbass ...