Installed Imp Switch / Wrong Caps?

[feeench]

Hi everyone, I have a couple questions. I recently installed the Impedance Switch kit in my S.E.X. 2.1 with C4S which I've modified with a stepped attenuator as well as FT-3 interstage caps and Mundorf Supreme output caps... It's been singing beautifully. I have Blumenstein Mini Orcas and HD650's...

The volume isn't as loud now, however. I'm using balanced mode, which I understand only affects the speaker outputs. I do notice however that when I have the headphones plugged in and the switch to balanced, it's a bit quieter... Which I don't mind, I used to have to turn the pot down when using headphones but now I don't touch it when switching between headphones and speakers. I still have enough volume for my ears. So I've just been leaving it in balanced mode.

So am I missing out on anything by leaving the switch balanced? I've tried doing comparisons (not extensively though) but both seem to sound fine to my ears.

Also, I think I may have purchased the wrong output capacitors. The rating is listed as 410VAC, and 600VDC. I think I'm starting to hear a collapse in sound quality, but it might just be one of those days haha... Could this be why? Or am I missing something, or could I have done something wrong when installing the Impedance Switch Kit?

I did find that I like the 4ohm tap a bit better than the 8ohm tap I had hardwired in before.

My theory right now is that running balanced mode is quieter and so to get the same sound level I have to run the power output further into distortion... Is that right?

Upskirt shot:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fzf1lSlTl.jpg&hash=a4d354554d8f6310295afa0f0c0585a9d33364cb)
http://i.imgur.com/zf1lSlT.jpg<-- Larger pic

[Grainger49]

Congratulations on a fully stuffed SEX kit. 

Your caps need to be a 600V DC rating.  You have that covered. 

What you might be hearing is cap break in.  It takes 100 hours for the Mundorf caps to break in.  It might take 300 hours for the Teflon caps to break in.  So hang in there, things will get better.

[Paul Birkeland]

The volume isn't as loud now, however. I'm using balanced mode, which I understand only affects the speaker outputs. I do notice however that when I have the headphones plugged in and the switch to balanced, it's a bit quieter...

The stock headphone jack isn't balanced, when you use the balanced output setting with the headphone jack, you're abandoning half the copper on the secondary, and the output will be lower.

So am I missing out on anything by leaving the switch balanced? I've tried doing comparisons (not extensively though) but both seem to sound fine to my ears.

Yes.

Also, I think I may have purchased the wrong output capacitors. The rating is listed as 410VAC, and 600VDC. I think I'm starting to hear a collapse in sound quality, but it might just be one of those days haha... Could this be why? Or am I missing something, or could I have done something wrong when installing the Impedance Switch Kit?

You can always put the stock caps back in, but those values should work.

I did find that I like the 4ohm tap a bit better than the 8ohm tap I had hardwired in before.

The 4 Ohm tap is generally a great setting for headphones, and an OK place to be for speakers that don't need tons of power.

My theory right now is that running balanced mode is quieter and so to get the same sound level I have to run the power output further into distortion... Is that right?

Balanced and unbalanced modes should have the same noise level, except for the case of using your headphones with the switches set to balanced. You end up getting less signal out, so the noise level will also go down.  Additionally, going to the 4 Ohm tap from the 8 Ohm tap will lower the noise floor of the amp.

[Paul Joppa]

From the manual:

"S.E.X. users will need to note that the balanced/unbalanced switch will only function for speaker
output. The tip/ring/sleeve design of a headphone jack requires unbalanced output because of its
common ground. Switching to balanced mode will cause an impedance mismatch, essentially
utilizing only half of the output transformer's windings. This will not harm anything other than the
sound quality, but it is an issue to be aware of."

I went to some trouble to arrange the switching so that you would still get sound on headphones even if the switch is in balanced mode, but it does not make optimal use of the transformer, and on the lower two impedances it reduces the damping factor severely.

Of course it is possible to wire your headphones for balanced operation, and change to a kind of jack that allows balanced operation. We don't have parts or instructions for that.

[feeench]

Thank you all for the information, I missed the part about running the headphone jack in balanced mode getting only half the windings... :/ That makes perfect sense now though. I've done some critical listening and I can pinpoint a few differences now when listening through the HD650's while in balanced mode vs unbalanced.

I've always liked the idea of running the HD650's balanced. A lot of people swear by it it seems... I think I'm going to go this route. I have two cables for them so I may hack one up and try it on the binding posts to test. I think I could manage to install a balanced plug next to the trs plug and rig up some sort of switch to select which output I want. I see something similar is done in the mainline. Which switch do you guys use for that? By looking at the pictures on the product page it's got red base and it's probably the same switch that I got with my Quicksand, it has a red base. Also, where do you guys get that awesome Cat5/6 cable that's so lovely with the shielding and solid core copper? I'd love to pick up a bunch for a couple projects.

I think I am experiencing issues with the new caps, I've certainly not even hit the 100hr mark with them. There was a massive WOW factor with the Mundorf's when they first went in, it was jaw dropping! The KK's weren't near as impressive to me but certainly an upgrade, I have two pairs of them... After a few hundred hours I'm going to put the unused ones in so I can hear the differences. I'm very curious.

Oh, maybe this is silly but I don't understand it at all... Can someone please explain to me why the power cord needs to be disconnected when switching anything on the impedance switch kit? Does powering off with the power switch not suffice? What happens if I switch them while it's powered on? Cheers

[Doc B.]

Not to sound like a dick, but we're not really all that inclined to share the sources for our switches, wire, etc. You can usually find something equivalent from Mouser. Sometimes we get the part from them ourselves.

[Paul Birkeland]

I like the idea of the adapter cable.

If you don't unplug the amp, your fingers could touch the live voltage from the wall, which would make you drop the amp on the floor. 

If you live in a 220-240V country, you will fall to the floor with the amplifier.

-PB

[feeench]

Sorry I really don't mean to ask for your sources, I worded that poorly. I'm just trying to find the same pieces... I like things to match. It's like replacing car parts with non-oem pieces, it just seems wrong... At any rate, I did a bunch of digging and found the switches I need and some decent looking Cat5, so all is well.

[feeench]

I like the idea of the adapter cable.

If you don't unplug the amp, your fingers could touch the live voltage from the wall, which would make you drop the amp on the floor. 

If you live in a 220-240V country, you will fall to the floor with the amplifier.

-PB

I ask because I was thinking of making external switches for the board. I should be okay to do this and switch the amp while it being live, then?

[feeench]

Not sure why but I was pretty determined to get this done today. The local electronics store had everything I needed and here's the result!

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FaCM6wQtl.jpg&hash=eef2dda2af60a3834cb8f7920d7e25c0090d6024)

I thought I had the right screws to fasten the jack down but it turned out I didn't so it'll be to the hardware store tomorrow to finish that bit up, but it's working wonderfully!

I have a few questions:

1) The switch is an ON-OFF-ON 4PDT switching the positive and negative of each channel. Is there any harm leaving the position in the OFF position, disconnecting the output?

2) About the grounds... I took the ground from Terminal 23 which previously went to the TRS jack and connected it to the 4-pin XLR sleeve, then I ran a separate wire from each ground on the impedance switch boards to the XLR sleeve. I think I'm okay here but wasn't 100% sure...

3) If I want to get a 1/4" output again, I figured I'd make an adapter from the 4-pin XLR. If I do this, where is the ideal place to take the ground from? The sleeve, which is connected to T23 and the grounds on each imp. board, or should I attach both of the "negative" feeds from the impedance switch boards?

EDIT: Anyone with HD650's I'd recommend doing this. They're more transparent now. Very cool.

[JamieMcC]

Sweet looking set up, nice job on the Sex it looks great thanks for the tips.

[i luvmusic 2]

I installed my XLR in front of the Chassis and connect it to the Binding post so i don't need to do any rewiring.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fcdn.head-fi.org%2Ff%2Ff3%2F900x900px-LL-f31c79f9_DSC_3468.jpeg&hash=871736a8408aaf9b65deaf8f030138af129104f4)
(https://www.head-fi.org/image/id/6995005/width/900/height/900/flags/LL)

[feeench]

Ooh, that never occurred to me. I like that a lot, very simple. I really like your paint on the bell housing and choke covers.

Mine is connected up on my main desktop computer, and I like the ability to switch between the two outputs now without having to plug/unplug the headphone cable. I seem to do this quite a few times each day, when I'm using Skype for example.

I think I may wire in the TRS jack again for simplicities sake, right beside the XLR... I have another 4PDT switch that I might mount externally to switch the BAL/UNBAL switches... I only have the 1 pair of headphones for now though, so I've no need to do any of that yet.

[JamieMcC]

I installed my XLR in front of the Chassis and connect it to the Binding post so i don't need to do any rewiring.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fcdn.head-fi.org%2Ff%2Ff3%2F900x900px-LL-f31c79f9_DSC_3468.jpeg&hash=871736a8408aaf9b65deaf8f030138af129104f4)
(https://www.head-fi.org/image/id/6995005/width/900/height/900/flags/LL)

Nice idea I think I might try that one with my T1's later on

[i luvmusic 2]

The paint i used is a tire Rim paint.Thanks!

 Jamie I think your SEX have a choke installed near the front if you want to mount the XLR in front of the chassis like i did you need to make sure that the XLR will not interfere with those check the space carefully.i replaced the 22uf caps with SOLEN Poly those are large that is why i end up mounting the XLR lower than i would like to.