Impedence switch boards

[Noskipallwd]

Hey Doc, is the TRS jack that is supplied with the sex2.1 still the switched type?

Cheers,
Shawn

[Doc B.]

Nope, can't get those anymore.

[fullheadofnothing]

The jack is different now, but it does cut the signal to the speakers when you plug in phones, if that is what you're asking. This works with or without the impedance boards.

[Noskipallwd]

Joshua, yes I was wondering if the jack cut off the speakers when the plug is inserted, thank you. Sorry Doc, should have been more specific.

Cheers,
Shawn

[Todd R]

@Todd, yes, getting the grounds separated will allow balanced use.

So if I have both XLR & TRS jacks installed, can I run the 4 wires to the XLR, then connect them from the XLR to the TRS jack with both grounds connected at the TRS together? I think that's how it was set up in the Smack as I recall.

[Paul Joppa]

The jack that switched the speakers off in the SEX amp was only in production kits for a short while. We can't get a suitable jack at this time. The current jack still cuts the speakers, but no longer has the 120 ohm resistance to equalize the level across different impedance headphones.

The impedance switch board has three outputs - Pos, Neg, and Ground. The tip-ring-shield jack goes to Pos and Ground, the balanced outs get their signal from Pos and Neg.

Yes it took me some time to figure all that out!

[Jim R.]

Ok sorry, I'm confused here -- do the currently shipping headphone jacks on the 2.1 cut the speakers when the phones are plugged in?  It appears this is what Josh is saying, but it appears that PJ is saying the opposite.

A clarification would be great, and then perhaps an update to the product page?

-- Jim

[fullheadofnothing]

I hate to disagree with you Paul, but the current jack (marked "new" in the pic) does cut the signal to the speakers when a TRS is plugged in. I'm actually listening to my cans right now though such a jack and the speakers aren't making a peep.

My understanding of the choice for the "old" jack was to utilize the 120Ω resistors and still have the shorting feature. Since those resistors ended up being eliminated, the new jack could be used for the S.E.X. 2.1.

Todd, how many outputs are you planning on having? As far as I know, these boards have only been used as the TRS/XLR in Smack and TRS/Speaker-binding-posts in the S.E.X. TRS/XLR hasn't been attempted in a S.E.X. (but I don't see why it wouldn't work) but TRS/XLR/Speaker-binding-posts might be more complicated than I can wrap my feeble mind around. I think wiring as Paul suggests will make the BAL/UNBAL switch a selector between your TRS and XLR and my guess is you may have to choose which configuration you want your speakers in when you wire the binding posts (if you are indeed wiring the binding posts).

Please take my wiring comments with the very large grain of salt that I don't necessarily know everything that's going on here and my electrical knowledge falls pretty squarely in the average (or a bit below) of most Bottleheads.

[Paul Joppa]

Josh, you're right, and I have edited my post. I remember the disappearance of the good switching jack, but mis-remembered the choice that was made of what to do about it.

[Todd R]

Todd, how many outputs are you planning on having? As far as I know, these boards have only been used as the TRS/XLR in Smack and TRS/Speaker-binding-posts in the S.E.X. TRS/XLR hasn't been attempted in a S.E.X. (but I don't see why it wouldn't work) but TRS/XLR/Speaker-binding-posts might be more complicated than I can wrap my feeble mind around. I think wiring as Paul suggests will make the BAL/UNBAL switch a selector between your TRS and XLR and my guess is you may have to choose which configuration you want your speakers in when you wire the binding posts (if you are indeed wiring the binding posts)

I'm not using the speaker terminals so it will just be the TRS & XLR (provided there is enough room to make a new hole)

[Doc B.]

I'd just like to say that I really enjoy having so many smart guys working with Bottlehead now. With so many kits and projects going at any one time I just can't keep up with all of the questions anymore, and PJ, PB, Shawn and Josh have been amazing when it comes to stepping in to answer everyone's questions. Thanks guys!

[Jim R.]

Thanks Josh and PJ for the clarification.

-- Jim

[Todd R]

$14.83 shipping on the impedance boards??
That can't be right.
Can you check your shopping cart settings before I order Doc?
Thanks

[Jim R.]

Todd,

There is a note about this in the stickeys at the top of the general discussion forum.  Basically, they know this is a problem and will credit your card/paypal after the purchase.

-- Jim

[Jim R.]

Paul, is this a good time to remind you about the wiring description for these boards?  I won't be building the smack right now but will be building a s.e.x. dedicated to headphone use and want to do the same thing with a set of 3 exposed switches on the top plate -- or maybe even just two.

Thanks,

Jim