Hello to everyone! Newbie here! Hope you're doing great!
Decided to finally pull out from the shed my old analog mixing desk , it's an italian FBT 18SR from the 70's , 18 channels , I'm planning to use it for my drum kit , but before that, I want to test all channels real quick.
Being a very old mixer , it only has TRS jacks (mono) ,to test it, I was thinking to hook up an SM57 to channel 1's input , insert a mono TRS cable into one of the outputs (Either Mon 1/2 or L/R outputs and connect it to a guitar amp (in this case a VOX AV60 , or a couple of speakers (w/preamp) that use RCA jacks. Not getting any results , (because I have no idea what I'm doing) , so I ask you kind experts: what are the different ways to hook up this mixer to test it? Just to get a sound.. , I'm sure I'm making ridicolous mistakes!
Apart from trashing this old lady , I'm willing to hear your opinions!
RR/RS
Decided to finally pull out from the shed my old analog mixing desk , it's an italian FBT 18SR from the 70's , 18 channels , I'm planning to use it for my drum kit , but before that, I want to test all channels real quick.
Being a very old mixer , it only has TRS jacks (mono) ,to test it, I was thinking to hook up an SM57 to channel 1's input , insert a mono TRS cable into one of the outputs (Either Mon 1/2 or L/R outputs and connect it to a guitar amp (in this case a VOX AV60 , or a couple of speakers (w/preamp) that use RCA jacks. Not getting any results , (because I have no idea what I'm doing) , so I ask you kind experts: what are the different ways to hook up this mixer to test it? Just to get a sound.. , I'm sure I'm making ridicolous mistakes!
Apart from trashing this old lady , I'm willing to hear your opinions!
RR/RS
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You might try contacting FBT to see if they can provide a manual, since it doesn't seem to be freely available on the web.
short of knowing more about the console and it's pinning standard i would try a different channel, insuring that standard things like gain and other appropriate things like the faders both channel and master are at nominal levels that should allow signal through...
this poor thing looks like it's lost many of it's knobs and fader caps!
TRS jacks can be used for "stereo"(but that's a whole different application) but in the case of a mic mixer they would be "balanced" just like an XLR with "tip" being" positive", "ring" being "negative" and sleeve GND, so depending on the pinning of the cable you have you may not actually be driving the "differential" input of the mic pre's. and that could also apply to the outputs...
i must confess i'm stumped as to the function of the switches on the channels designated "F" and "E" i've no idea as to whether or not they are a pad or gain type selector (try switching those?)
this poor thing looks like it's lost many of it's knobs and fader caps!
TRS jacks can be used for "stereo"(but that's a whole different application) but in the case of a mic mixer they would be "balanced" just like an XLR with "tip" being" positive", "ring" being "negative" and sleeve GND, so depending on the pinning of the cable you have you may not actually be driving the "differential" input of the mic pre's. and that could also apply to the outputs...
i must confess i'm stumped as to the function of the switches on the channels designated "F" and "E" i've no idea as to whether or not they are a pad or gain type selector (try switching those?)
Thanks turk182!
Don't worry I have the rest of the original knobs! (not the faders though , sadly) , that "F -E" stands for "Flat" and "Equalized" , I saw this switch in many 60s/70s Italian mixers , "E" cuts low-mid frequencies off the channel , nothing special
I see what you mean, all about the right cables.. what about in a stereo application? How could I quickly set this up for testing?
Are you sure the inputs are meant to be microphone inputs? If they are line level, you will have to shout very hard.
I don't wanna be spitting lies , but I believe so! I just had a long phone call with the phone-lady at FBT , she put me in contact with this old tech and I managed to get my hands on a basic "manual" of the 18SR, check out the wiring:
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What is a mono TRS ? Do You mean XLR to TRS balanced cable ?
Use a XLR to TS cable not TRS unless ring and sleeve are shorted.
Do the VUs move when speaking to the mike ?
If they move, Your problem is in the output section /cables /power amp.
Try a line level source like a CD player or even Your phone.
Back when I was a kid we had mixers without XLR connectors. We just called them phone plugs which is what your inputs appear to be.
Have you tried adjusting the gain knob at the top of the row for MIC use?
I would set the channel slider at the bottom about halfway and also mess with the output knobs along with the master sliders
Have you tried adjusting the gain knob at the top of the row for MIC use?
I would set the channel slider at the bottom about halfway and also mess with the output knobs along with the master sliders
My Bad! I meant TS! The VUs are not moving , most probably cause I gotta sort out my cables first and connect things decently
Yep , I screwed around with the gain knob and sliders on channel 1 , still no use , I'm gonna try again
Nice find. Good collection of jacks, pots, case. Could be useful in a home studio but not for field recording. At least it is stereo.
When I buy a $35 used mixer, I test inputs for phantom power tip to 2nd or tip to shaft. Usually tip to 2nd ring. No phantom power, I test with a portable FM radio as input, and my cheapest power amp as output. Connect earphone jack to 1/4 phone plug, left & common to tip & shaft. Set earphone volume to 1/3 or less, radios can put out 7 vac on earphone jack. Tip ring of phono plug output to center ring of RCA jack of amp. May require adapter. Check output for DC before connecting to amp.
I check the power supply, usually on 4 & 8 of the op amps. No op amps, look at collectors & emitters of the transistors.
Then check for sound. None, fiddle with knobs. Usually the master volume knob is ittermittant. If that doesn't work, off comes the cover. I check for sound inside with a 20 vac scale of an analog voltmeter, protected by a ,.047 series cap on the ground lead to prevent AC reading on DC signals.
I used an Ampeg transistor mono mixer for a couple of years for performance. I sat on its side with the keyboard on an organ bench. Keyboard output was too soft to drive amp to full volume. Ampeg boosted it nicely.
When I buy a $35 used mixer, I test inputs for phantom power tip to 2nd or tip to shaft. Usually tip to 2nd ring. No phantom power, I test with a portable FM radio as input, and my cheapest power amp as output. Connect earphone jack to 1/4 phone plug, left & common to tip & shaft. Set earphone volume to 1/3 or less, radios can put out 7 vac on earphone jack. Tip ring of phono plug output to center ring of RCA jack of amp. May require adapter. Check output for DC before connecting to amp.
I check the power supply, usually on 4 & 8 of the op amps. No op amps, look at collectors & emitters of the transistors.
Then check for sound. None, fiddle with knobs. Usually the master volume knob is ittermittant. If that doesn't work, off comes the cover. I check for sound inside with a 20 vac scale of an analog voltmeter, protected by a ,.047 series cap on the ground lead to prevent AC reading on DC signals.
I used an Ampeg transistor mono mixer for a couple of years for performance. I sat on its side with the keyboard on an organ bench. Keyboard output was too soft to drive amp to full volume. Ampeg boosted it nicely.
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0) I am "an old Tech from way back then" so pretty familiar with this kind of mixers, including FBT, LEEM, and all other Italian mixers (including the mythical Semprini).
And TRS 6.35mm jacks were the most used ones
Same era American mixers (think Peavey or Acoustic or Kustom) even used plain TS jacks, go figure.
Proud Germans (think Dynacord or Echolette) stood by their own very impractical DIN connectors.
1) make an adapter cable.
2 versions, one or the other should work with your mixer
* Plain TS plug (unbalanced similar to Guitar type):
XLR TS
1 Ground/Sleeve
2 Tip
3 Ground/Sleeve
try this one straight into your VOX guitar amp, it should work.
Maybe not too loud, since output is weaker than a guitar pickup but you must hear sound through speaker anyway.
If not, either microphone is damaged or wiring was improperly made.
TS plug cable should work in FBT input, since it also accepts Guitars with obviously that kind of plug.
IF it works, then rewire to TRS simply to have better hum rejection.
* TRS plug (balanced)
XLR TS
1 Ground/Sleeve
2 Tip
3 Ring
Once Mixer "works" (VU meters show some kind of activity) then connect Mixer out to Guitar amp using TS to TS cable (plain guitar cable).
And TRS 6.35mm jacks were the most used ones
Same era American mixers (think Peavey or Acoustic or Kustom) even used plain TS jacks, go figure.
Proud Germans (think Dynacord or Echolette) stood by their own very impractical DIN connectors.
1) make an adapter cable.
2 versions, one or the other should work with your mixer
* Plain TS plug (unbalanced similar to Guitar type):
XLR TS
1 Ground/Sleeve
2 Tip
3 Ground/Sleeve
try this one straight into your VOX guitar amp, it should work.
Maybe not too loud, since output is weaker than a guitar pickup but you must hear sound through speaker anyway.
If not, either microphone is damaged or wiring was improperly made.
TS plug cable should work in FBT input, since it also accepts Guitars with obviously that kind of plug.
IF it works, then rewire to TRS simply to have better hum rejection.
* TRS plug (balanced)
XLR TS
1 Ground/Sleeve
2 Tip
3 Ring
Once Mixer "works" (VU meters show some kind of activity) then connect Mixer out to Guitar amp using TS to TS cable (plain guitar cable).
Ok JMFahey, before making the adapter cables here's what I did:
I plugged my guitar into the FBT's channel1 input (with a basic TS cable) , then I extended another TS cable from the FBT's Left Output1 into the VOX's main input (maybe I was meant to plug it into the VOX's "External Speaker Output" or "Phones" or "Aux In" jack , dunno) , no sound at all , THOUGH when I fiddle around with the TS cable that goes into the FBT's output it starts humming and suddenly it becomes ground "ground sensitive" (pass my stupid term) , when I touch the guitar strings OR the FBT's chassis the humming gets much louder .. no guitar output though.. VU meters never moved
Thanks so much for your help! I took a peak within the chassis and I noticed that many ceramic caps have big cracks on them (not that circuit issues can be detected with a naked eye), I have spotted different ICs , tomorrow I'll test them