Audio splitter troubles

[moody07747]

ok
last wiring sheet for this project...i hope

the inputs will be tied so i wont have to make any splitting cables.

the output of both mixer circuits will be joined to combine into one plug which will go into an amp


input will be any audio device and the mixer will allow me to controll the balance allong with volume

 

[audioguru]

the inputs will be tied so i wont have to make any splitting cables.

Tied? Don't short inputs together or you will be shorting the outputs together of whatever connects to them.

the output of both mixer circuits will be joined to combine into one plug which will go into an amp

Don't short together the outputs of the mixer.

I nearly forgot. High speed opamps oscillate at a high frequency when they directly drive the capacitance of an output cable. Therefore add a 100 ohm resitor in series with each output like this:

 

[moody07747]

ok ok no shorting :lol:

then this means i have to feed the left output circuit to one amp/speaker and the right output circuit to a seperate amp/speaker

that should be good, correct?

 

[moody07747]

...but then???

my drumset and guitar have a 1/4" jack on them for headphones or whatever

how do i connect a 1/4" plug into the input of this to get both...

wait, i may have just answered my own question

on a sterio phone jack there are 3 connectors
one connects to the threads, the other two connect to the plug that you push into the jack

my pic shows a blown up version of a phone plug

the pin at the left picks up the the signal for the Right audio output
and the pin at the right picks up the signal for the left audio output

i would ground the threads(i think), attach all the LEFT pickups to the LEFT circuit and then attach all the ight pickups to the RIGHT output circuit

i guess that would work
ill have to draw it all out again

 

[moody07747]

ok i think i finally got it

look at my 3rd wiring sheet

if its not correct someone might want to spend some time redrawing it for me bacuse i am more of a visual learner meaning if i see something (like in a pic) i learn it better/faster.

here we go (see pic)

 

[Nigel Goodwin]

You appear to be confused regarding the jack plug connections?.

Firstly, almost ALL 1/4" jack plugs are mono, not stereo - only a very small percentage are stereo, and are mostly used for stereo headphones (also used occasionally for balanced inputs as well).

The 'threaded' connection on the jack soket is ground, and the tip is the signal - IF it's a balanced input, the ring is the inverted signal.

Guitars are almost always a mono jack, and microphones are normally a mono jack as well - if they are balanced they usually use an XLR connector.

The mixer you're proposing is line level only, and you couldn't use a microphone with it, unless you add an extra preamp stage (like the original design did).

 

[eblc1388]

You have to use a suitable jack though.

Here is the corrected schmatic.

 

[moody07747]

thanks for that wiring sheet redo and the info on phone jacks

its all clear to me now :lol:

the jacks i plan on useing are sterio with 3 solder tabs, not the type enclosed in plastic

 

[eblc1388]

You can use 5 (two-ganged) variable resistors instead of ten separate ones because most of the times you control left/right channel together.

Look at the schematics and you will see they are VR1A/VR1B,....etc.. When you adjust VR1A, VR1B will be adjusted also because they are mounted on the same shaft.

 

[audioguru]

Shouldn't a gEEtar also have a preamp? I think its output level is too low for this line-input mixer.
Then the preamp can be turned up way too high for fuzzzzz, or the preamp can have its own fuzz, sustain and wha-wha circuits.

 

[Nigel Goodwin]

Shouldn't a gEEtar also have a preamp? I think its output level is too low for this line-input mixer.
Then the preamp can be turned up way too high for fuzzzzz, or the preamp can have its own fuzz, sustain and wha-wha circuits.

It all depends on how the mixer is going to be set up, and what it's feeding. A guitar has far more output than a microphone, but less than line level, so by keeping the guitar input turned up high, and the line levels turned down low, you could balance them. Obviously this depends on the output levels required from the mixer.

You could always alter the input resistors and feedback resistor to give more gain on some inputs as well. A further complication is the input impedance, passive guitars require a high input impedance (about 250K minimum), not the low impedance of the design so far. An active guitar (quite common now) would be fine, higher output level and a lower impedance.

However, there was no original reguest for guitar inputs!.

 

[audioguru]

my drumset and guitar have a 1/4" jack on them for headphones or whatever

I think Moody wanted to short the output of his drumset to the output of his guitar before he learned about mixers. So he needs a boosted mixer input for his guitar.
If they were shorted together like that, wouldn't the guitar play by itself when a drum was hit? He, he. :lol:

 

[moody07747]

You can use 5 (two-ganged) variable resistors instead of ten separate ones because most of the times you control left/right channel together.

Look at the schematics and you will see they are VR1A/VR1B,....etc.. When you adjust VR1A, VR1B will be adjusted also because they are mounted on the same shaft.

i was going to do that but decided to get 10 VRs so i could controll the balance too.


heres what i want to feed into the mixer
up to 2 electric guitars, one tabletop electric drumset (Yamaha DD55), and two keyboards (Yamahas)

now i know how to put the mixer togeather but i think this pre amp stuff is gunna drag me down again :lol:

 

[moody07747]

as for an amp

i was thinking of building this 22watt unit
https://www.aaroncake.net/circuits/amp20w.htm

this is where i get some of my audio ideas
https://www.aaroncake.net/circuits/index.asp#sound

i would build the 50 watt amp but it looks...complicated
https://www.aaroncake.net/circuits/amp50w.htm

 

[Nigel Goodwin]

heres what i want to feed into the mixer
up to 2 electric guitars, one tabletop electric drumset (Yamaha DD55), and two keyboards (Yamahas)

Have you considered buying a mixer?, you can buy some excellent spec ones for very little money these days - try looking for Behringer models like this one . These will be more versatile than the simple one you're looking at building, and they are of good quality and performance.

I've recently bought a lot of Behringer gear, and I'm VERY pleased with it :lol: including a PHM880S mixer/amplifier - which is a great piece of kit and 400W RMS per channel!.

Got our first gig next Sunday using it, and we practiced last Sunday - it all worked well, the gig is at a local football club, and we're next to the local radio station, so might get some publicity out of it?.

BTW - I only do the PA, it's a teen girl rock band, which includes my daughter Melissa - have a look at **broken link removed**.

 

[moody07747]

i have thought of buying one but if i can save money by building one, why not

plus, i could use the practice in the electronics category :lol:


theres just something about building and completing a project that gives you a giid feeling. every time someone looks at my mixer and amp and ask where did you get that from i can always tell them that i built it myself.


im a real DIY, (do it yourself) type persion and will attempt to build/do something before calling someone to do it for me

 

[moody07747]

another one of my DIY items

this is what the case will look like when its done...well the shape will look like this

i plan on welding some 18 gauge sheet steel into the final enclosure.

 

[Nigel Goodwin]

i have thought of buying one but if i can save money by building one, why not

plus, i could use the practice in the electronics category :lol:


theres just something about building and completing a project that gives you a giid feeling. every time someone looks at my mixer and amp and ask where did you get that from i can always tell them that i built it myself.

I built a full scale mixer for a band back in the 70's that I did the PA for, it had 10 or 12 channels, bass, middle, treble, pan, input gain, and a slider on each channel, plus switchable PFL and VU meters.

Back then mixers were really expensive, and we saved a LOT by doing it, but at current prices I didn't consider it! - just buying the controls and knobs would cost more than a Behringer mixer :lol:

BTW, again back in the 70's, I found myself with a disco to do - and one of the band members had the mixer!. I designed and built a two channel mixer, from bits I had, in about 20-30 minutes!. This included building it in a small diecast metal box as well, and powering it from a 9V PP3 battery - my younger brother watched me do it, and couldn't believe it worked :lol: Perhaps my resistor calculations put him off?, "I'll have one of those, it's a pretty colour", and "I've got lots of those, throw me some of them" - it's really VERY easy to design a simple mixer - opamps make it childs play.

 

[audioguru]

as for an amp

i was thinking of building this 22watt unit
https://www.aaroncake.net/circuits/amp20w.htm

With a 12V supply and using its 4 amps bridged for a stereo amp:
It delivers only 4.4W per channel into an 8 ohm speaker, or 8.5W into a 4 ohm speaker.

i would build the 50 watt amp but it looks...complicated
https://www.aaroncake.net/circuits/amp50w.htm

Its main IC has been obsolete for some time, and the transformer in the parts list has a voltage and current far too high.

 

[moody07747]

maby ill just buy the amp then