[DJDuck]

Hey hey hey

Went thrifting today and found a pair of Solo HDs, no fakes, the real deal. Only headphones, tho, no cables or anything. Made a new cable for them and tried them out. Oh boy, $150 new, what a crock of sh!t. Don't like the sound at all. Maybe would be okay if they were like $50 new, maybe I'd consider. But that's not the biggest problem. Left driver keeps cutting in and out. Tried resoldering all the solder joints, didn't help. I don't want to throw them out, they look cool, are built well and have good isolation and comfort.
Now I'm looking for drivers to put in. Anyone got any recommendations what to look for in a driver that would work well in a small, sealed enclosure?
The original drivers look like Chinese poop. Titanium diaphragms, but looking at the back you can see their generic-ness. They are 2-way headphones and have a tweeter and a crossover in there in front of the driver, which is a cool designs, I'll give them that.
If you guys have any ideas whag to do with them, let me know. Meanwhile, I'll be looking for replacement drivers to do the swap.

 

[Music818]

Like the new Solo HD, without the small driver may improve the sound a lot.

 

[DJDuck]

  Like the new Solo HD, without the small driver may improve the sound a lot.

That's what I thought, too!
There is a 1st order crossover in there. Which means that some highs are overlapping since they're not cut out. The tweeter alone seems to play quite high, but when the woofer is connected as well, a lot of the highs disappear, which is my main problem with these. 
But I'll still have to replace the drivers, since one of them keeps cutting in and out and I think it's one of the voice coil wires, because when you blow onto the driver to make it move in and out, it comes back sometimes. I tried heating the solder pads on the drivers and adding new solder, hoping for them to re solder the voice coil wires, didn't help much, still quite... unstable. 
 
Now I'm thinking of two more things:
1st, what about using the AKG K404 drivers? They have about the same inner cup size, therefore similar tuning. They're also exactly the same size. And I like the sound of the K404 and the fact that they fold nicely. But they look kinda tacky and feel cheap, plus I'm worried about the hinges breaking at some point because the plastic is a bit, well, ****. Also the cable is starting to act up.
2nd, how do I get the glued drivers out? Easiest way to get the Beats' drivers out is to just pull them out with pliers, who cares if it ruins them. But the AKG drivers have to come out and go back in in one piece.
 
By the way, I've heard the new Solo 2 and I really liked them, definitely a huge upgrade over the originals and a very good deal for $200

 

[Music818]

Usually I'll use a cutter to "scratch" the glue, then use a flat screwdriver and a hammer to separate the driver and the driver plate........

 

[DJDuck]

I used a small flat head and got the Beats driver out in one piece. Then destroyed it afterwars because it was dead anyway. I kept the small driver, might use it for another project.
Now to find some donor headphones.

The plastic piece of crap is tge Beats driver (or whats left of it) and the other is the magnet and back of a Sony MDR-XD100 driver, a pair of $25 headphones.

 

[DJDuck]

Making progress: the first K404 driver is now out Took a while but it survived.

 

[DJDuck]

And they're done! The K404 drivers are in and so is a bit of damping material. Still need to put some glue on the drivers to seal them in nice and tight and maybe play arou d with the damping but overall, the surgery was a success and I'm quite happy with the results so far. They sound pretty good. Quite bass heavy, whic both the K404 and Beats were, but its quite a nice extension, punches good and fairly accurate. Mids are smooth. Highs a bit rolled off but detailed and very easy to listen to. Overall smooth and non fatiguing sound, sounds like the new Solo 2 with slightly less treble. These are my new portables now since the K404 are now, well, gone
But who cares, the K404 were kinda ugly and felt cheaper so they probably wouldn't have lasted too long anyways.
You can also see the blue shielded OFC cable I rigged up for these since mine didn't come with the original cable.

If anyone has recommendations on how to reduce the bass slightly and lift up the treble, I'd really appreciate that. Not that they sound bad, but I just really like lighter or neutral bass and a bit of sparkle. Nothing wrong with the cans, just my preference

New drivers in the baffles, old driver for comparison.

Front view of new driver

All done, new cable attached

 

[Music818]

Good job!

To reduce the bass..........see there're 2 small vented holes on top of magnet. You can use a tape to cover one of them and hear the difference.

 

[DJDuck]

  Good job!

To reduce the bass..........see there're 2 small vented holes on top of magnet. You can use a tape to cover one of them and hear the difference.
 

Thanks!
 
These holes were originally sealed on the AKGs. I opened them up and it seemed to make the sound more dynamic and made the bass tighter as well. I'll try covering them and we'll see what happens. 
 
EDIT: Tried it, helped a little, but still kind of bass heavy. I guess it's just the way the Beats were designed? They don't sound bad, as I said, but they could be a little brighter. But still way better than originally. They're my new portables now, really comfortable. And you've gotta admit, they are some of the sexiest cans out there 

 

[Music818]

Great!

 

[DJDuck]

Alright, tried another damping method. Removed the tape to give the driver a little more breathing room and then filled the cavity inside the cup with open cell foam. So far, this is the closest I've got to flat. Brought the mids and highs out a little more, but bass is a tiny bit loose. What about opening up one venting hole behind the driver? Or opening one hole and covering the center? I don't want to just open it up without someone smarter telling me what the effect might be, because it's hard to reverse that. 
So far I have this configuration:
All holes covered on the back of the K404 driver
Center hole open
Open cell foam inside the rear cup
 
What about opening the baffle up? There is room around the driver to drill holes into the plastic and vent it into the pad. You know, like some bigger headphones where the rear chamber opens into the the front, around the driver.

 

[Rocko1]

Are the Solo HD's the only Solos' with dual drivers?

 

[barbadread]

  Alright, tried another damping method. Removed the tape to give the driver a little more breathing room and then filled the cavity inside the cup with open cell foam. So far, this is the closest I've got to flat. Brought the mids and highs out a little more, but bass is a tiny bit loose. What about opening up one venting hole behind the driver? Or opening one hole and covering the center? I don't want to just open it up without someone smarter telling me what the effect might be, because it's hard to reverse that. 
So far I have this configuration:
All holes covered on the back of the K404 driver
Center hole open
Open cell foam inside the rear cup
 
What about opening the baffle up? There is room around the driver to drill holes into the plastic and vent it into the pad. You know, like some bigger headphones where the rear chamber opens into the the front, around the driver.

The things you are considering doing, opening up the holes behind the driver, opening a vent from the housing and opening the baffle size, will increase the bass end of the headphones. I've been experimenting quite a bit with this on closed designs. Both the bass vent between driver and baffle as well as between baffle and atmosphere has to do with the freedom of the diaphragm. The size of the baffle has to do with resonance. A large enough baffle will yield the same effect as a bass vent though as the resistance of air pressure will become negible with a very large baffle.
 
When the diaphragm moves and produces sound, it moves air on both sides. If the air flow behind the diaphragm is hindered in some way, by a layer of tape with one, single hole in it for instance, it will put a work load on the membrane. The lower frequencies, that require a larger movement of the diaphragm to reproduce, will become less pronounced as large movement is supressed due to the elastic resistance, and flow resistance, of the air behind the diaphragm. Opening up either the hole in the tape on the back of the driver will allow the diaphragm to move more freely and the bass will increase and become bloated even.
 
Same goes for adding venting to the housing. That's the method I've been using to tune the bass on my builds. I use a very small baffle connected to the atmosphere by a bass vent. I tune the vent using reamers. Half a mm makes a big difference!
 
Might be worth mentioning that different materials for lessening the baffle might have different effects on the sound. A very loosely packed material might even increase the baffle size in the eyes of the driver. (Not sure about the physics behind this). A very dense foam rubber that leaves almost no air behind the driver will leave you with the least bass. Loose wool (or no filling at all), removed tape on the back of the driver and bass vents between housing and atmosphere will leave you with the most bass.
 
Hope this makes sense!
 
Karl

 

[DJDuck]

Thanks for the info, barbadread!
 
I have experimented with these a bit and found them to sound good enough for a portable as they are. I do, however, have on problem. When taking them on or off, you can hear the driver flexing in there, since your ears will be putting air pressure on the diaphragm. Is there any way to avoid this and does it damage the drivers?
 
I think these are the only dual driver Beats, not sure tho. Despite having a titanium driver and additional tweeter with a dedicated crossover, they managed to be absolutely void of any highs whatsoever. 

 

[barbadread]

 
I have experimented with these a bit and found them to sound good enough for a portable as they are. I do, however, have on problem. When taking them on or off, you can hear the driver flexing in there, since your ears will be putting air pressure on the diaphragm. Is there any way to avoid this and does it damage the drivers?
 
 

 
Heh... This is actually pretty funny. I asked the exact same question in the sound science forum only a couple days ago.
 
http://www.head-fi.org/t/775207/acoustics-resonance-and-filters-how-to-deal-with-standing-waves#post_11776989
 
Check Don Hills' excellent answer. It comes down to that you need to provide a port that allows air to escape when the cushion is compacted but still doesn't create an acoustic short circuit of importance or any resonance.