Review: CharterOak Acoustics SP-1 (GMP 450 Pro) - Page 21

I'd like to report I'm still very happy with a double padded GMP 450 pro. Been using it at work for the past 6 ish months for classical, hip-hop and metal (power, prog, mdm, sym, heavy). Tried it with the Objective2 (o2) amp from Epiphany audio for the last week and it sound great. Perceived tighter and deeper bass response vs MD11,and slightly better highs resolution.

 

 

Yeah, the velour earpads are quite hard to replace... my way to install and remove the velour earpads is to slip my fingers underneath them and pull the outer vinyl edge out in order to pull off or fit around the plastic frame of the headphone.

Those pads will gain some elasticity with time and use, first and second time is always terrorizing but then it's peace of cake. :)

 

Stock earpads never gave me much trouble really, I've noticed that they're a bit more elastic than the other earpads.

 

I assume that you received the non-perforated velour pads?

 

I can't be sure of how those earpads and the stock foam filter would work, but if your leather ones are really screwed up....

I can't recomend it, because that will change the sound and I don't know if you already like the velour sound as is or not...

That will depend on your preference.

 

In my experience, I've found that the sonic benefits of the foam filter of the stock earpads is that it smooths out and flattens the FR, midrange - up, and it filters some of the reverberations emanating from the enclosures and the protective grids in front of the drivers.

It will give the sound a darker tonal balance, and a warmer and softer character... this is good if the fundamental sound of the headphone is bright like the GMP 450 Pro.

 

The downside of this is that some upper treble extension and fine detail will be lost.

 

However, if there is a distance between my hears and the filter, in doublepadded configuration, it's degrading effects on the upper treble are much less obvious... at least I can discern fine detail much better this way.

 

I presume that using the filter with the velour earpads would darken and smooth out the FR but I haven't tried this...

 

The dust protectors that should have come with the velour earpads are acustically transparent, they don't affect the sound. It's a thin web of some fiber.

 

Sorry for insisting with this again, lol, but the GMP 450 Pro sounds so good doublepdaded that I wouldn't feel OK with myself if I hadn't tried to, one more time, persuase you to buy the 41-6050 earpads instead of a new set of leather ones (if you are actually going to do it and if your stock ones are still functional), even taking the risk of making you waste money. ;)

 

Looking forward to your impressions!

 

 

Would I be asking to much by requesting a brief side by side between the O2 and your, 95% chance, already forgotten D100 on the GMP 450 Pro? :)

O2 = neutral D100 = brighter? this? more or less or what?

I'm actually waiting for the desktop version of the O2 amp and maybe even getting the ODAC if it's worth and sell the Yulong.

Seems to be the way to go for a transparent setup.

 

Edited by kkl10 - 1/17/12 at 12:59pm

An update on my quest for a transparent GMP configuration:

 

Open version GMP 400;

mass loaded;

modified dampening scheme on the drivers;

Beyer DT880/990 earpads with felt ring underneath (bass lens?);

 

This is the status now. Next and step will be modifying the protective grid in front of the drivers.

I'll receive some more spare parts (new set of drivers included) next friday to continue with experiments.

 

Once I resolve this step and depending on the results I might send my GMP for measurement.

 

I would like to play with some recabling to but I'm not experienced with that...

d100 sounded borderline horrible and bright to my taste. with o2 you also get the effects of your dac upstream and md11 is rolled off in the highs (slightly) on the rmaa, so it's not nearly as bright/harsh/attacky. (not bright to my taste, about right instead (similar sound to what I get on um mage).
(plus it's double padded vs single stock pads. or maybe I tried double on d100 too, idr tbh.

how much of it is to do with the dac is questionable, but I had a similar experience with connecting stax amps and hp to dac1, d100 and md11/30 (lol and whether I'm imagining it all and would pick the differences out in a blind test)

The earpads are the non perforated black velvet 41-6085 pads.

 

I've been able to do some fast swaps with the pads by just placing the pad between the cup and my ear and relying on the pressure to keep them in place (feels no different than if the pads were attached).  This is the only way I can still use the stock leather pads.

 

Unfortunately I still think the stock pads are the best ones.  The velvet pads do improve the soundstage ever so slightly, but details are lost and so is a lot of the energy this headphone has (for my personal tastes).  The velvet pads do indeed tame the treble a bit, as the sound does sound a bit brighter with the stock leather pads.

 

I love these headphones for their dexterity and detail.  I'd prefer to not give up those sorts of things just for a very minor improvement in soundstage.  It is time for me to investigate how to get a pair of the stock pads replaced without paying a lot of money.

 

For kicks I even threw the 41-6015 pads in the mix from the 805, and honestly I think I might even prefer those to the velvet pads.  It was kind of a middle ground, not taking away as much of the treble presence as the velvets and also not improving the soundstaging as much as the velvets.

 

Honestly, the velvet pads reminded me more of the QP400, only a bit worse in the bass department and even thinner in the treble 

 

That's the other thing... the bass response is so much better on the stock pads IMO.  It has some punch but loses zero layering/texture as compared to the velvet pads.  Bass impact decreased with the velvets, but for the most part the tonal response was sustained.

 

I'm going to go ahead and say the engineers knew what they were doing when they selected the pads for these headphones.  CharterOak's decision to implement the 41-6085 pads on remaining stock of the SP-1 is resulting in an inferior sound.  Although, he did mention to me that the leather pads were rotting in humid environments and that is essentially what caused them to make the switch.  Rotting pads are no good, so maybe in the grand scheme of things the right decision was made.

 

I've been meaning to ask if the production of the SP-1 is still on-going or not, because that would be interesting seeing as MB Quart is no longer making headphones and newer SP-1 would indeed be GMP450 and not QP450 Pro variants.  I suppose the headphone could be the same if he does his own dampening or whatever, unless GM decided to make FR tweaks to the driver used in the QP450PRO (rather than other changes they may have made, as kkl10 as stated he remembers the QP =/= GMP).  I should ask him which serial number they are on, if they are still being produced (Mine is #42)

 

Back on topic...

 

The sound is just so thin with the velvet pads it becomes insanely boring and on top of that I lose some energy and detail.  I'm already hearing things in a new album I haven't spent much time with on the stock pads that I wasn't hearing with the velvets.  Details that just jump out that I didn't notice on my first couple run throughs of the album.  I know people say "night and day" way too often around here, but I feel like because of things like this, the difference is substantial.

 

I will say I may be hearing some of those reverberations with the stock pad you were describing long ago, as the sound is certainly more closed in on the stock pads.  Regardless, I enjoy being right on top of the sound.  I like the detail and energy provided by the stock pads enough to overlook the less massive imperfections.

 

If I really demand adept soundstaging I will just use my loudspeakers, which inherently do imaging/soundstaging better than headphones (at least any headphones that I have heard).

 

Maybe I will try the velvet pads with the 805, since that 'phone has a more than healthy bass presence as it is.  Could be a winner combo!  I don't have the time now, but soon.

I've got a GMP450 Pro recently and its sound rather disappoints me. Compared with AKG K702 and K601, It's too bright and thin to my liking. It's paired with Nuforce icon HDP and has about 20 hours burn-in. Is it just the sound signature I don't like or synergy problem?

single padded GMP450 on a bright source is pretty bad.

alternatively I've lost the rest of my HF hearing from listening to the double padded version on a slightly dark sounding amp.

I see. It really explains something as I discovered that Grado SR80i also sounded terrible on HDP. "double padding" seems quite complicated to an non-DIY guy like me, so I'm selling the GMP 450 Pro. 

 

Thx!  

 

Edited by matrim - 2/26/12 at 12:43am

I've also found they're really tough to drive and extremely unforgiving to the recording and source... but when you pair everything right you really do get a lot of detail and energy.  I agree the high maintenance aspect can be a turn off.  Few people want a headphone they have to try several amps/dacs/sources with before they get it right... most people (understandably so) just write it off before they try out multiple of the aforementioned.

I‘m very satisfied with the performance of K702 and 601 on HDP, so I've no plan to get a new DAC/amp in the near future. GMP450 Pro resembles K702 when the latter first arrived - metallic highs and thin mids, which changed dramatically after some 150 hours burn-in. I wonder if the same could happen again. Maybe I'll give it another try for a few days... 

You'll have to let us know your impressions.

 

I don't know much about the HDP, but metallic highs and thin mids almost sounds like it might be underpowered?  Do you find it nimble and detail rich, like other users have reported?

 

The more info out there the better... it can give us a better idea of what pairs well.  Also, it may be that the SP-1 is pretty different from the GMP450 PRO so that makes me even more interested in your impressions.

According to HDP's spec, it has 152mW rms @ 300 Ohm. As GMP 450 Pro are the only high impedance cans I own, I've no idea whether 152mW is power enough to drive them. But I found when using AKG k702, to get the same volume level as GMP 450 Pro, I have to turn up the volume knob. Is it the proof that k702 is more power-hungry than GMP 450 Pro? 

 

After 2 days the highs get tamed a bit, but still aggressive to my taste. and I can hear deep, speedy bass, plus a lot of details, though the mids are still somewhat thin, so the overall impression doesn't change much - an overly bright sound sig. I'll tell you my thoughts after 10 days. Let's wait and see... 

k702 is known to be power hungry as well.  152 mW should be plenty... a quick look for a continuous ideal power rating on the GMP450 PRO came up empty but I did read somewhere for the QP805 (also 300 ohm, different drivers though) needed at least 100mW continuous.

 

The volume difference could also be a result of the open v. semi open design (lets be honest, German Maestro calling the GMP450 PRO closed is worth laughing at) and just the fact the the driver sits so close to your ears with the stock GMP450 PRO pads.

 

Using the velvet pads and moving the driver further from the ear tames the sound quite a bit actually, but it kind of took away some of the bass texture, speed, and liveliness.

 

Also found this:

 

However, as kkl10 discovered earlier in this thread, the drivers in the GMP450 PRO might be 410 ohm as suggested by a marking he found internally on one of the driver enclosures.

 

^ Let me correct that information there.

 

On my previous post I didn't mean necessarily that the GMP 450 Pro drivers might be 410 Ohms (oversimplification here), I suggested (supporting my propositon with some measurements taken in a russian review of the MB Quart QP 450 Pro) that the GMP 450 Pro drivers might not have a flat impedance value across the frequency spectrum.

 

But I have, since then, found some pictures of the back of the GMP 450 drivers on a forum from Singapore (or Malysia?) where it shows the same sticky but with a very high number so that's probably not an indication of impedance... maybe serial nº... don't know.

 

Found it. It's here. A lot of drooling to, lol..

 

R-Audiohead, looking forward to your impressions of the Sony Z1000.

 

I've received new spare parts for the GMPs including new drivers.

 

It's now clear to me that the old defective drivers weren't working quite right, the new drivers are much better sounding.

And my issue with ressonances and reverberations was being caused in part by the defective drivers!

Had to rework my mods with these new drivers. There's a very apprecciable improvement in depht of soundstage and imaging, treble is much cleaner to.

I explicitly requested well matched drivers when ordering from German Maestro.

I've only heard these new drivers on the GMP 400 configuration, still haven't tried them on the GMP 450 Pro...

 

The connectors on the new drivers have slightly different dimensions and coloration, when I swap the 6,3 mm adaptors on the same pair of drivers there seems to be a slight change in sound... but the diffrence is very, very subtle, might be placebo...

 

 

 

If you're into modding:
Add a ~2-3 mm felt donut inside the earpads (between the padding and the foam filter)

This wil damp some reflection on the back of the earpads and take out some of the resulting brightness and add more weight to the bass and lower midrange.

This will require a lot of trial and error with materials and shapes to get the right balance though... I haven't dived into great depht with this mod yet... but very easy to end up with a very enclosed/claustrofobic sound signature.

 

You could start with something like this:

 

 

Just a suggestion.

 

EDIT: Otherwise a GMP 400 would probably be more to your liking.

Edited by kkl10 - 3/4/12 at 2:59pm