A good useful JFET for audio that's still available today is the Toshiba 2SK209GR. We build arrays of them with mathed pairs or triplets in order to get what we used to get from the old 2SJ10x audio-worthy JFETs
I was only half expecting it to work. And if it did, I was prepared for it to sound like trash. I hope this video can be a warning to others who find it.
Those old Unidyne microphones have 2 different Impedance outputs. You should try the other impedance to get a higher output. I remember doing this in the late 60's to get a better output. You may need to resolder the 4 pin connector on the output in the microphone. Also, the ones that I was using had a L-M-H switch to control the output level. I saw it on your mic, on the bottom in the back, it is Black and you need a screwdriver to change it.
I have tried every combination of wiring and switch setting over the 30 years that I've had the Shure mic. The weak signal that I'm getting **is** the highest level setting
That circuit looks like it should work. It's bargain basement but workable. I suspect that the transistor is open circuit. I heard some white noise in the test. That suggests that one of the junctions is not working. Maybe base to emitter OC. The SS9014 is a good choice for high gain low noise. Try swapping out for a good one.
The pre-amp would never work with a mic that requires phantom on it's input. it does not seen to provide the phantom power to it's own input to power any mic's attached to it.
I think they intended that pin 3 should conneect to the emitter Also, if the mic has any inbuilt electronics, they won't get power due to the capacitors
@@pileofstuffThe circuit as it is could be made to work but you’d need an audio-range balun transformer (which would not fit into that package) and a couple of resistors and caps, on the transistor output end. Maybe a proof of concept project for later?
as "simple" as that c**** circuit was you might be able to make one on a perfboard that might actually do something at least a complete circuit better then that interrupted one. I have the suspicion that some of the Chinese manufacturers do not scrap out the devices that fail testing and quality control but instead sell them of to some kind of sub market of dubious worth products resellars
@@unclefrogy743 Some of these unbranded products are out and out scams - Big Clive has covered a fair few of them. It seems this is likely one of them.
There is voltage across the emitter-collector of the transistor, but you're right, nothing is biasing the base side so it'll never turn on with a normal microphone level.
Would be mighty interesting if you build a descent one into this case. Thanks for the review !
A good useful JFET for audio that's still available today is the Toshiba 2SK209GR. We build arrays of them with mathed pairs or triplets in order to get what we used to get from the old 2SJ10x audio-worthy JFETs
Nice retro microphone! I Really like it. Would be nice to see it on your videos recording with it!
0:30 all the letters are there but with 2 added spaces... Still reads Pre-Amplifier
Nice unboxing and thanks for sharing!
No unbranded product from China has ever been honestly described 😂
Sorry, it turned out to be not what one would expect. EBay can be a jungle of good and trash stuff.
I was only half expecting it to work. And if it did, I was prepared for it to sound like trash.
I hope this video can be a warning to others who find it.
I like beer-flavored beer.
Those old Unidyne microphones have 2 different Impedance outputs. You should try the other impedance to get a higher output. I remember doing this in the late 60's to get a better output. You may need to resolder the 4 pin connector on the output in the microphone. Also, the ones that I was using had a L-M-H switch to control the output level. I saw it on your mic, on the bottom in the back, it is Black and you need a screwdriver to change it.
I have tried every combination of wiring and switch setting over the 30 years that I've had the Shure mic.
The weak signal that I'm getting **is** the highest level setting
That circuit looks like it should work. It's bargain basement but workable. I suspect that the transistor is open circuit. I heard some white noise in the test. That suggests that one of the junctions is not working. Maybe base to emitter OC. The SS9014 is a good choice for high gain low noise. Try swapping out for a good one.
The pre-amp would never work with a mic that requires phantom on it's input. it does not seen to provide the phantom power to it's own input to power any mic's attached to it.
@@TheEmbeddedHobbyist Of course. The dynamic mike that Pileofstuff uses does not require phantom power.
I think they intended that pin 3 should conneect to the emitter
Also, if the mic has any inbuilt electronics, they won't get power due to the capacitors
To be fair, the sale page does say that this is only for use with mics that don't otherwise need phantom.
I thinks that is not for a dynamic microphone. Maybe is working with condenser microphone
This type of pre-amplifier always says that it's only for dynamic mics and other mics that don't need their own phantom power.
That sucks, at least it didn't damage anything other than the wallet
One word for that device, JUNQUE
Why not rebuild it?
That's definitely a possibility. Especially given that the proper schematic is available.
I'll need to order some parts first, though.
Make a video doing it
@@pileofstuff
@@pileofstuffThe circuit as it is could be made to work but you’d need an audio-range balun transformer (which would not fit into that package) and a couple of resistors and caps, on the transistor output end. Maybe a proof of concept project for later?
We need to know the sex to noise ratio.
My sex to noise ratio is very high. I'm not sure if that would make me a good a m plifier or not.
as "simple" as that c**** circuit was you might be able to make one on a perfboard that might actually do something at least a complete circuit better then that interrupted one.
I have the suspicion that some of the Chinese manufacturers do not scrap out the devices that fail testing and quality control but instead sell them of to some kind of sub market of dubious worth products resellars
@@unclefrogy743 Some of these unbranded products are out and out scams - Big Clive has covered a fair few of them. It seems this is likely one of them.
Even the pre amp did not pass on the phantom power the its own input connector. So you mike was never going to work 😊
There is voltage across the emitter-collector of the transistor, but you're right, nothing is biasing the base side so it'll never turn on with a normal microphone level.
It is more like trying to rip off a FetHead. But the principle is the same on all the devices... And wait... what video?
Here is a comment to please the algorythm 😊
OMG that was just white noise. Build your own, you have a case to put it in. Ha ha
So, in short, for this unit it is all noise and no sex?
beer has lactose = BLEH thats one i cant do sorry lots of junk on ebay
The same junk is also on Amazon and other places as well.
Buyer beware.
Knock off sE Electronics DM1 "dynamite"
What utter garbage! Even $20 is too much. There are $2 worth of components in it, at most. 9014s are very common and a couple of ¢ents each.
I hope this video can be a warning.
I also hope youtube pays me enough to offset what I paid...
TH 10-20k range is good, BUT, the 0.5% makes it crap fro anything other than a speaker.