Sennheiser 800: Time to go balanced. Options.

[Grahame]

You plug one of these (or similar) into the 4 pin socket

4 pin gives you 4 connectors (2 independent wires per ear, which can be connected as required) . you can also wire this to a 3 pin trs (shared ground/return) - but you can't do this the other way round. which was the whole point in re-terminating the stock cable, which is already 4 conductor for its whole length up to the stock end.

Terminate with a 4 pin xlr + then you can add which ever end termination / adaption you want, rather than have to get a new single function terminated cable for each configuration. Make sense?

[digger945]

LOL

Here's what I might do for fun, like some others suggested: I'll buy some cheap crap that I can scuttle and experiment with to hell and back and get my DIY skills up from practically zero to something halfway viable.

Whatever I do, I do NOT want to mess with the 800s stock cable.

I was gonna suggest the same. Once "doing it" a couple of times you will lose the reterm anxiety syndrome. Isn't the 800 supposed to have a pretty jam up cable on it anyway?

But this is the whole reason why people have suggested that you get the stock cable re-terminated with a balanced 4-pin connector. Whoever does it for you can cut off a few inches at the end and turn the current 1/4" plug into an adapter. If it will get you over the top, I will send you mine and you can compare.

this. I've done it twice using the old trs to make an adapter. I won't lie you and say it's a piece of cake the first time, but since you're mulling over the idea of butchering modding a cheapo pair then there's plenty of opportunity to ask questions and get some good pointers before the real deal.

If the GS was active ground capable you could hear benefits even when using an unbalanced source. Maybe that will be available in that new amp Justin is working on. edit: maybe the GS-x is active ground, as it has an RCA / XLR switch on the faceplate.

Edited September 12, 2010 by digger945

[Eric5676]

I was gonna suggest the same. Once "doing it" a couple of times you will lose the reterm anxiety syndrome. Isn't the 800 supposed to have a pretty jam up cable on it anyway?

You can pull it out. First time isn't terribly easy. Not as easy as the older Sennheisers but essentially about the same.

this. I've done it twice using the old trs to make an adapter. I won't lie you and say it's a piece of cake the first time, but since you're mulling over the idea of butchering modding a cheapo pair then there's plenty of opportunity to ask questions and get some good pointers before the real deal.

No, you got it right the first time with that butchered descriptive most likely.

If the GS was active ground capable you could hear benefits even when using an unbalanced source. Maybe that will be available in that new amp Justin is working on.

Might be.

You plug one of these (or similar) into the 4 pin socket

http://www.wyvernaudio.com/images/HeadphoneCable/K1000/K1000_2.JPG

4 pin gives you 4 connectors (2 independent wires per ear, which can be connected as required) . you can also wire this to a 3 pin trs (shared ground/return) - but you can't do this the other way round. which was the whole point in re-terminating the stock cable, which is already 4 conductor for its whole length up to the stock end.

Terminate with a 4 pin xlr + then you can add which ever end termination / adaption you want, rather than have to get a new single function terminated cable for each configuration. Make sense?

It does now. Pictures help.

[Voltron]

I wasn't sure of the connector on the GS-X, and you can have it re-terminated into 2 x 3-pin XLRs if you want the most straight-forward option. But I still like the convenience of the 4-pin XLR as the termination, and then use adapters as needed for whatever amp you have at the time. I have pretty much any kind of connector covered with various adapters, some going in each direction (M to F and F to M, etc). It is still too bad that Headroom went with the 2 x 3-pin as standard for their early balanced amps, when they could easily have chosen 4-pin and made all of our lives easier.

[Eric5676]

I wasn't sure of the connector on the GS-X, and you can have it re-terminated into 2 x 3-pin XLRs if you want the most straight-forward option. But I still like the convenience of the 4-pin XLR as the termination, and then use adapters as needed for whatever amp you have at the time. I have pretty much any kind of connector covered with various adapters, some going in each direction (M to F and F to M, etc). It is still too bad that Headroom went with the 2 x 3-pin as standard for their early balanced amps, when they could easily have chosen 4-pin and made all of our lives easier.

That's one of many things that have been educational for me in this thread. That 4-pin concept is neat.

[purk]

Just read this thread and I'm doing the exact same thing with the Senn HD-800. I will convert the SE Apuresound V3 cable into 4-Pin balanced XLR connection. I'm getting Fitz to turn my Gilmore Reference SE into Balanced so I could utilize a full benefit from my Exemplar Denon 5910 with the Senn HD800 and my Qualia.

[bada bing]

What are you using for the PCB for the additional channels ?

The balanced bridged configuration of the Dynamic/Dynalo amp has some advantages over full balanced end-to-end. You don't get to use all 4 wires of a balanced source, but it runs off a two channel pot and avoids the added complexity and potential for component mismatchs by having a 2 channel verses 4 channel front end. I messed around with a couple versions of fully balanced Dynalo before I went with the balanced bridged configuration. The trade offs work better for me and it makes an almost perfect amp for a "balanced" HD800. Eventually I'm going to do the same retrofit to a Dynamite.

I've never seen the innards of a Reference, but it must be as easy, and somewhat cheaper, to balance bridge as opposed to clone two entire channels.

[luvdunhill]

Fitz can handle this one on his own. He, unlike you, has seen the insides and it's not hard to figure out how to proceed once you have that info.

[bada bing]

Fitz can handle this one on his own. He, unlike you, has seen the insides and it's not hard to figure out how to proceed once you have that info.

I don't think there is any doubt Fitz can handle this one, I'm not reading where I wrote anything even slightly contrary to that. Maybe there's a translation error from Alaskan and Texan. Happens to me all the time at work as well.

Not seeing the insides of one version of the many Gilmore Dynamic variants doesn't seem to invalidate my post in any way. Anyone spending the money to mod a Gilmore Dynamic variant to balanced ought to consider the balanced bridged option. I think maybe it gets less consideration than is due because SE input to Balanced output seems funky. It's cheaper, easier, less complex and aurguably a cleaner implimentation than full four channels in a Dynalo because of the unique servo arrangement and the differential signal created at the inputs. Maybe in this case it's been considered and rejected or there's some other tweak going on. That would be interesting to see discussed, at least to me. I'd love to learn something about the dynalo/Gilmore dynamic or be given a new tweak or tangent to try. I've spent quite a bit of time on dynahi/dynalo projects, partly because they make good HD800 amps to my ears.

[cetoole]

I don't think there is any doubt Fitz can handle this one, I'm not reading where I wrote anything even slightly contrary to that. Maybe there's a translation error from Alaskan and Texan. Happens to me all the time at work as well.

Not seeing the insides of one version of the many Gilmore Dynamic variants doesn't seem to invalidate my post in any way. Anyone spending the money to mod a Gilmore Dynamic variant to balanced ought to consider the balanced bridged option. I think maybe it gets less consideration than is due because SE input to Balanced output seems funky. It's cheaper, easier, less complex and aurguably a cleaner implimentation than full four channels in a Dynalo because of the unique servo arrangement and the differential signal created at the inputs. Maybe in this case it's been considered and rejected or there's some other tweak going on. That would be interesting to see discussed, at least to me. I'd love to learn something about the dynalo/Gilmore dynamic or be given a new tweak or tangent to try. I've spent quite a bit of time on dynahi/dynalo projects, partly because they make good HD800 amps to my ears.

Do you have NFB around the - output phase?

[bada bing]

Do you have NFB around the - output phase?

Just the standard NFB loop from "+" output to "-" input as documented in the project files. No NFB on the "-" side.

I have my dynamid gain set at 3 (10k & 5K resistors I believe). Servos set-up as in the project files for balanced bridged.

I haven't had this bridged version on a scope yet but no audible signs of bad behavior. Sounds better I think than the same

boards did configured as 4 full channels.

Are there tweaks to try for feedback loop(s) ? Is there an improvement by adding a second feedback loop ?

Any hints or a link ? I've done some due diligence with search engines and reading, but I've never found

much on adding the second (-) feedback loop beyond the observation it would require major mods to the circuit.

I'd be very interested to read of practical methods to address the potential non-linearities on the "-" side of the amp.

It does seem to be the biggest theoritical downside to a pretty elegant circuit.

[purk]

The boards in all Gilmore Ref units contain both balanced PSU & Circuit boards. Half of the circuit board is populated in SE amp, so all it takes is to populate the remaining parts, add balanced output & input jacks, replace existing 2-Channel DAC-T with a 4-Channel one, and you get a balanced amp.

Purk

What are you using for the PCB for the additional channels ?

The balanced bridged configuration of the Dynamic/Dynalo amp has some advantages over full balanced end-to-end. You don't get to use all 4 wires of a balanced source, but it runs off a two channel pot and avoids the added complexity and potential for component mismatchs by having a 2 channel verses 4 channel front end. I messed around with a couple versions of fully balanced Dynalo before I went with the balanced bridged configuration. The trade offs work better for me and it makes an almost perfect amp for a "balanced" HD800. Eventually I'm going to do the same retrofit to a Dynamite.

I've never seen the innards of a Reference, but it must be as easy, and somewhat cheaper, to balance bridge as opposed to clone two entire channels.

[digger945]

Any hints or a link ? I've done some due diligence with search engines and reading, but I've never found

much on adding the second (-) feedback loop beyond the observation it would require major mods to the circuit.

I'd be very interested to read of practical methods to address the potential non-linearities on the "-" side of the amp.

It does seem to be the biggest theoritical downside to a pretty elegant circuit.

Don't know if you have read it or not.

http://www.passlabs.com/pdfs/articles/susy.pdf