Loving your setup Brian! And it’s also nice to put a face to the name that has helped me so much with Proffie stuff over the last few years.
I’m amazed that guitar TX is coping so well with such high levels!
So am I right in saying you haven’t done anything in terms of wiring to reduce the level out of the speaker tails - you’ve just done it all on the software volume setting? If so that’s amazing - especially as it still sounds clean at 2000, which I would say is driving things pretty hard.
Either way I’m defo going to get a guitar system myself. From what I’ve seen they’re pretty inexpensive and it will be really useful if the presenter I work with ever wants to use a lightsaber on the show again. He’s done it once or twice in the past, but sound has always been disappointing because obviously he’s wearing a lavalier mic which doesn’t pick up much of the saber when it’s in his hand. Taking clean audio from the hilt will make it sound amazing, and will allow me to control the mix of hilt versus voice. Then I would just send the saber audio back to him over the studio foldback so he can hear what he’s doing.
Thanks again to you and Fredrik for all the tips on this. Definite progress made!
Correct, raw Proffieboard speaker output pads to the transmitter via 1/4 mono jack.
I just adjusted the input level at the interface if the gain was a little too hot, but it’s not distorting at the transmitter it seems.
If you do get a guitar transmitter, be aware that it does stick out a bit as “a thing” hanging off the bottom.
This one actually has a decent amount of weight to it, enough so that maybe I’d be concerned of it flying out (although the axial inertia at the bottom of the hilt isn’t much I suppose).
There are even cheaper models than this line6 one that I’ve read good reviews about, like this (USA amazon link) https://a.co/d/087oZBQ8
However while lighter, it’s larger, so a trade off?
While it might sound crazy, you could probably get away with a lav gaffed to the pommel, wire up the sleeve to insde jacket pocket and go
Yeh, I thought about that, but that means he’s shackled to the saber for that part of the show (the show is all live) so a wireless option would work better.
And yeh, I thought about the dangling side of it too, but the jack socket is a pretty snug fit (pretty hefty Switchcraft job: https://uk.rs-online.com/web/p/jack-plugs-sockets/6287023) so I’m hoping would be pretty secure. I notice lots of these guitar TXs are kind of hinged, but I was going to avoid one like that so that it isn’t flapping around. If all else fails, a little extra gaffer tape will hopefully do the job. Gaffer tape to my industry is like the Force to Yoda - it literally binds the entire industry together! LOL!
Interesting… I’m far from an EE (so I have no clue what I was really doing) but that looks suspiciously similar to a circuit I made while messing around to try and reduce noise out of an amp I put together.
This is amazing!
Thanks so much Prof. I’m gonna do a little reading up and tracking down of the components and then give it a shot if I can.
Will report back.
Thanks again.
Amazing work as always Prof.
Unfortunately I’ve dropped the ball on all of this lately as I’ve been up to my eyes in some refurb work on my house for the last couple of months. But I’m close to the end of that now, so I’m back in Saberland!
So the big question - did it work as intended?
Well, that didn’t work.
It doesn’t seem to filter out the high frequency signals nearly as well as the simulation indicated it would. Not sure what went wrong. This is usually what happens when I attempt analog circuit design; it looks good on paper, but doesn’t work, and I don’t know why…
Following Brian’s suggestion above, I bought a very simple guitar Bluetooth setup to try with the audio output I trialled in the video above. Unfortunately there was still a level discrepancy and it was distorting pretty badly. I also found that using that adapter wired into a decent sound system like where I work, you could hear that it wasn’t quite right.
So after some more research, I found a very simple loudspeaker-to-line level wiring schematic online which just uses a couple of resistors. So I’ve had a play around with it, and I think I’ve come up with a pretty good setup for getting clean audio out of my hilt, which I’ve then connected to the little Bluetooth guitar system as per Brian’s suggestion above.
And this video gives a little demo of the results:
So I guess the next stage is to break open one of those guitar TXs, and if it’s possible, get rid of the jack plug and remove the pcb that must be in there and see if it can be stitched actually inside the hilt, so that you don’t need all that gubbins hanging out the back.
But for now, I think we can chalk today’s result up as a success.
This is a weird schematic.
The top makes sense.
The sleeve makes sense, but the ring (blue wire) should be connected to the same thing as the tip, not to +/- IMHO. What is that switch even for?
It’s to fudge the option to plug an unbalanced source into a balanced input, while keeping the option to use stereo headphones in the same socket.
Stereo headphones are unbalanced and so, for our purposes dealing with mono, we want the signal + to go to left (tip) and right (ring) ears (dual mono).
By contrast, you can fudge an unbalanced to balanced conversion by shorting the cold pin (pin 3 of a balanced XLR) to ground.
Since the Bluetooth TX is only 2-pole, it automatically shorts the sleeve to the ring when you insert it. If I’d hard wired the tip to the sleeve, inserting the Bluetooth TX would effectively short all three terminals together. By having that switch, I can have the best of everything - I can use a 2-pole Bluetooth module as in the video, or I can use the saber with regular stereo headphones, or I can even use a balanced XLR to 1/4" TRS jack microphone cable to connect it to a professional mixing console with balanced XLR inputs (with a male-to-male XLR sex changer of course).
It’s a poor man’s fully functional analogue audio standards converter! LOL! I guess the only danger is if I ever insert the Bluetooth with the switch set wrong, it will short both the speaker pads which could damage the Proffie (I assume?) so that’s one to be avoided.
The only feature I would have liked to build in but couldn’t was using the switchable contacts on the jack socket to automatically kill the audio to the speaker when you insert a jack. This was because all the stepdown resistor gubbins had to be in circuit to the jack socket, but out of circuit to the speaker. Hence the use of the dip switches.
And I realise of course that in an ideal world, I could have have just used a single dip switch across the speaker +, but I only had double dip switches in my workshop, so that’s what got used. LOL!
Yeh, I’m with you - and it’s quite possible that there will be a few pieces of audio kit out there that are a little sensitive and really don’t like it. But I’ve tested a couple of different setups now (domestic home amplifier and a simple portable film location sound mixer) and both have worked great. I plan to take the setup into work this week and test it on our broadcast systems there too.
But yes, the whole premise is Fudegeville Central! LOL! But as some clever fellow once said of his computer product line, “It just works”.
And it’s also nice to put a face to the name that has helped me so much with Proffie stuff over the last few years. 
I guess the only danger is if I ever insert the Bluetooth with the switch set wrong, it will short both the speaker pads which could damage the Proffie (I assume?) so that’s one to be avoided.