Balanced SPH9500 conversion | Headphone Reviews and Discussion - Head-Fi.org

amimemeami · Jan 20, 2017 at 1:01 AM

After reading may reviews, I decided to purchase the SPH9500 as a stepping stone into this crazy audiophile world. Originally I was simply looking for a good sound stage for positional audio/ immersion in games. Then I started down the rabbit hole. I am a bit of an information sponge, and I really had no idea how much information was out there about how headphones sound

A week later... and I am considering converting my brand new SHP's into balance headphones. (Which have not even shown up yet Delayed due to weather.)

Here is my plan.
Replace 1/8 TRS female jack on headphone with 1/8 TRRS jack and split the grounds internally
I will wire inner ring and sleeve as the two grounds, so the stock cable will connect the two grounds making it electrically the same as stock for unbalanced outputs.
I will create a 1/8 TRRS male two 2 -1/4 TRS cable.
I am looking at the Focusrite Scarlett 2i2 to act as a balanced output dac/amp. If you think there is a better low cost balanced amp let me know.

I want to do this for as little money as possible seeing that I do not have much in the way of extra right now. As it is I will have to save up for a bit to get the DAC/AMP and cables/connectors.
Has anyone tried using a shielded network cable as a headphone cable? The solid core cables are not as flexible, but it has twisted pairs. I was not able to find an inexpensive 4-pin XLR cable.

Am I crazy or could this be a good idea?

Dulalala · Jan 20, 2017 at 2:48 AM

I really don't think that's a good idea for multiple reasons. Firstly, to my knowledge, the SPH9500 has no user serviceable parts, so I'm not sure how you would install a new cable onto it without destroying the headphone itself. Secondly, the XLR 3 pin on the USB interface you have chosen doesn't even function as a headphone out. They only function as a line out at best (used as inputs also) and have 94 ohms of impedance, which is 3 times the impedance of your headphone. Thirdly, even if you wanted this USB interface for it's single ended output, it's still 10 ohms which is way above 3.2 ohm (from the general 1/8 rule).

amimemeami · Jan 20, 2017 at 10:35 AM

dulalala said:
I really don't think that's a good idea for multiple reasons. Firstly, to my knowledge, the SPH9500 has no user serviceable parts, so I'm not sure how you would install a new cable onto it without destroying the headphone itself. Secondly, the XLR 3 pin on the USB interface you have chosen doesn't even function as a headphone out. They only function as a line out at best (used as inputs also) and have 94 ohms of impedance, which is 3 times the impedance of your headphone. Thirdly, even if you wanted this USB interface for it's single ended output, it's still 10 ohms which is way above 3.2 ohm (from the general 1/8 rule).

Do you know for certain that they are held together by glue, hence you can not take them apart without destroying them, or are you assuming they are because they do not have servicable parts. I have fixed many things that do not have user servicable parts. I would agree that if they are glued together this project is a complete no go. Once my headphones arrive I can confirm for certain.

Thanks for looking at impedance I had not thought to do that. I had read this http://www.head-fi.org/products/focusrite-scarlett-2i2-2-in-2-out-usb-recording-audio-interface/reviews/12299 and Another forum article I can not find anymore where the Focusrite was recomended as a low cost balanced DAC option, and just assumed that the impedance was more reasonable... My mistake...

So, my next challenge is finding a better low cost headphone balanced DAC or DAC/AMP. Is there anything under $200? Are there DIY projects for balanced headphone AMPS in that price range? I have an electronics background, albiet slightly rust from disuse.

Dulalala · Jan 20, 2017 at 11:46 AM

amimemeami said:
Do you know for certain that they are held together by glue, hence you can not take them apart without destroying them, or are you assuming they are because they do not have servicable parts. I have fixed many things that do not have user servicable parts. I would agree that if they are glued together this project is a complete no go. Once my headphones arrive I can confirm for certain.

Thanks for looking at impedance I had not thought to do that. I had read this http://www.head-fi.org/products/focusrite-scarlett-2i2-2-in-2-out-usb-recording-audio-interface/reviews/12299 and Another forum article I can not find anymore where the Focusrite was recomended as a low cost balanced DAC option, and just assumed that the impedance was more reasonable... My mistake...

So, my next challenge is finding a better low cost headphone balanced DAC or DAC/AMP. Is there anything under $200? Are there DIY projects for balanced headphone AMPS in that price range? I have an electronics background, albiet slightly rust from disuse.

Yeah I'm pretty sure I saw somewhere, someone saying that he was looking to mod these, but couldn't because he couldn't remove any parts to get to the internals without destroying the shell. You can use it as just a DAC via it's line output to connect it to another balanced amp. I don't know any balanced headphone amps in that price range unfortunately and also, you have to be careful when selecting a balanced amp. Just because it has XLR doesn't necessarily mean it's truly balanced. The internals could be single ended then converted to balanced at the end.

amimemeami · Jan 20, 2017 at 12:18 PM

Correct me if I am wrong, but the 1:8 impedance rule only applies to unbalanced, and it is used to reduce RF noise. Therefore it is not as critical with balanced, because it uses other methods to remove RF noise.
I still have to rule out the 2i2 because it does not have balanced outputs. I was under the impression the front channels where able to toggle between input, and output. However, that is completely wrong.
2i4’s do have ¼ balanced outputs. So that is a $165 option for the older model. $199 for the newer.

ProtegeManiac · Jan 20, 2017 at 2:11 PM

dulalala said:
I really don't think that's a good idea for multiple reasons. Firstly, to my knowledge, the SPH9500 has no user serviceable parts, so I'm not sure how you would install a new cable onto it without destroying the headphone itself.

From this vid it looks like the drivers are accessible from that side. I saw a vid before where the reviewer said the earpads are not removable, but I guess that's only if you want to put them back on. HM5 earpads are known to fit.

https://www.youtube.com/watch?v=VW2txDV5UNQ

Past that though what I'd be concerned about is where to run the cable, assuming the glue doesn't come off with a hair dryer as with Grados.

amimemeami said:
Correct me if I am wrong, but the 1:8 impedance rule only applies to unbalanced, and it is used to reduce RF noise. Therefore it is not as critical with balanced, because it uses other methods to remove RF noise.

First off, the output impedance needing to be low enough vs the nominal impedance isn't primarily about noise. Yes, it can happen that it can add noise, but in many cases it has as much to do with a noisy amp and a very efficient head/earphone. A too high relative output impedance has one more common effect: lower damping factor. It can either boost or reduce the bass but either way it goes with the volume output you can end up with inarticulate bass for example.

Second, you just ignored one other bit that he pointed out: the 6i6 only has balanced preamp outputs on the back, Balanced TRS on the front are for microphone input. The headphone output AFAIK is single ended. The balanced outputs are preamplifier control outputs on the rear that will connect to studio monitors.

amimemeami · Jan 20, 2017 at 3:19 PM

Past that though what I'd be concerned about is where to run the cable, assuming the glue doesn't come off with a hair dryer as with Grados

Click to expand...

Here is my plan.
Replace 1/8 TRS female jack on headphone with 1/8 TRRS jack and split the grounds internally

The headphones should look the same, or very close to the same when I am done with them, as when I started, Which means detachable cable. Also, by swapping cables I can change from balanced to unbalnaced.

First off, the output impedance needing to be low enough vs the nominal impedance isn't primarily about noise. Yes, it can happen that it can add noise, but in many cases it has as much to do with a noisy amp and a very efficient head/earphone. A too high relative output impedance has one more common effect: lower damping factor. It can either boost or reduce the bass but either way it goes with the volume output you can end up with inarticulate bass for example.

Click to expand...

Good to know. Looks like I need to read up on damping factor. I looked at a few balanced DAC/amp combo's and they listed accepted load impedance, but not Source impedence.

Second, you just ignored one other bit that he pointed out: the 6i6 only has balanced
preamp
outputs on the back, Balanced TRS on the front are for microphone input. The headphone output AFAIK is single ended. The balanced outputs are preamplifier control outputs on the rear that will connect to studio monitors.

Click to expand...

The 2i2 that I was originally looking at did not have any balanced outputs. I am now looking at 2i4 which has balanced 1/4 TRS outputs on rear. Yes they are 94 ohm for studio monitors, but I was hoping they would work for headphones... At least before you pointed out that it could create a damping problem.

amimemeami · Jan 20, 2017 at 5:08 PM

Ok, so after a lot of searching.... My dream is dead... At least untill I change jobs. The cost of a USB DAC that has a balanced headphone output way out of my current budgetary constraints. Even the DIY ones are more than what I am willing to pay right now.

It was a fun mental excersize at least, and I learned a few things.

My next thought is what should I get for my first USB DAC/headphone amp. Under $150. I am thinking something small and portable that I can also use at work with IEM's. But there are already lots of threads related to that topic, so I won't go any further down that thought train here.

Dulalala and ProtegeManiac,
Thanks for the input it was very helpfull.

amimemeami · Jan 26, 2017 at 10:55 AM

For anyone who wanted to know. You can take apart the SPH9500's! After you pop off the ear pad on the Left ear, there are 4 small philips screws that you can remove. These screws hold the outer grill with the L on it in place. Under the grill ther is a inner cover that has SPH9500 on it. Push on the side of it to rotate it counter clockwise it will pop out and reveal the wires underneath. The wires themselves look like they have been coated with a black silicone or something of that nature that was blobbed on after the speaker was soldered. That is as far as I went,because the next part is would be more work than I was will to do for just looking.

From what I could see the wire that connects the left to the right through the head band is glued in place with black silicone. It runs from headphone connector counter clockwise to where the earcups pivot on the horizontal axis (This is the hassel that I did not want to deal with at this time). Once that is freed you push the inner portion of the ear cup toward that pivot point and it will pop and free the other side (I did try that part). With the slack in the cable you gained by freeing it from the Silicon you can the remove the cups from the pivot. The part you just freed sepeartes into to halves the inner driver slides through the outer portion that the earpads connect to. That is as far as I could get without actually freeing the right ear wire from the silicon.

Hope this helps. I could not find this information posted anywhere.