500 series Level-Loc project

[c1184701]

I hear you guys, and I've used the real level loc as well as the soundtoys but they do not have that loud noise. It's not just hiss... It's clearly a pitch noise if you have had a chance to listen to the file I attached.

Noise floor on this would not be a problem, I use guitar pedals in mix all the time and they sound this way too but now I am hearing more of a power supply noise or something.

But I guess everyone is having that same noise ?

I've built a few of these, and although they are all quite noisy none of them have that particular pitched high frequency in your audio file. More just a dark hiss. My 500 units would buzz anytime I touched the metal toggle switches for release etc, so I put those little rubber sleeves on them.

 

[Bobby Baird]

I may have to rework a pcb for these. Pretty busy though with other projects.

 

[JMan]

Oh, I had missed your sound file. I am in the same boat as MonoCutter, my unit has the hiss but not the tonal whistle.

 

[c1184701]

I may have to rework a pcb for these. Pretty busy though with other projects.

I had a partly-gutted Shure M67 mic mixer sitting on my shelf, so last year I decided to try making a level loc pcb as a way of learning EasyEDA software. I used the mic transformers from the M67, and housed it in the chassis. My pcbs were single-channel with the power filter mod (mentioned earlier in the thread) built in. I soon realised I could fit two in the chassis by stacking them, so I ended up with a stereo level loc! Was very surprised that my first pcb attempt actually worked.

 

[Bobby Baird]

I had a partly-gutted Shure M67 mic mixer sitting on my shelf, so last year I decided to try making a level loc pcb as a way of learning EasyEDA software. I used the mic transformers from the M67, and housed it in the chassis. My pcbs were single-channel with the power filter mod (mentioned earlier in the thread) built in. I soon realised I could fit two in the chassis by stacking them, so I ended up with a stereo level loc! Was very surprised that my first pcb attempt actually worked.


Are they quieter with the filter mod?

 

[c1184701]

I didn't try them without to be honest. I think the mod potentially reduces hum, not the hiss. I also have a pair of the irfrench 500 versions from the start of this thread, the noise floor is the same on those as my standalone version.

 

[manulaudic]

Great build, ok so maybe something something isn't right then. It must be my mistake.
I'll trouble shoot it when i receive my extended slot card

Thanks guys for the help

 

[BGroen]

Hey guys,
I'm building this one, but with the mic-mod. So I adjusted the pad and used the Lundahl input transformer.
But I don't get any signal passing the transformer, and I feel I'm missing some link or connection.

Has anyone tried it as a mic level unit with the input transformer? Maybe you can help me out a little...

 

[Bobby Baird]

Don’t forget to jumper (jumper or wire)
UB-send to UB-send1
UB-in to UB-in2
UB-ret to UB-ret2
UB-out to UB-out2
These are points for switching/testing purposes. If you look at the schematics you’ll see that you could take the blend option out of the schematics.
Be sure to check ‘errata’.
The names R11 and R2 did not get placed correctly, so they appear to be in each others footprint.
The names R42 and R43 did get placed correctly but got be switched around.
The level loc was built for the LL1528 transformer!! omit all parts underneath the footprint and you'll be good!

 

[Bobby Baird]

Transformer datasheet.

 

[BGroen]

Hi Bobby thanks for your response.
I did not forget the jumpers and I saw the errata's. Those are fine.
Any other idea that could be the case? Has anyone used this specific board with the LL1528?

 

[Bobby Baird]

Maybe your transformer has been damaged. I would measure the coils with a ohm meter to make sure it still has a connection. Those have very fine wires going to pins. Could be grounded out. You traced the drop of signal up to the input transformer? Should be pretty easy to determine if it has a bad pin connection are open coil. Probe it with multi-meter.

 

[BGroen]

Hey, little update,

So the transformer is OK. But I figured it out.
To check if the transformer was grounded I removed one to observe the traces and know what to measure. Unfortunately killed one pin. But I am building 4 so could continue testing on the other 3.

I eventually saw that the transformer was not grounded properly. The traces on the board are not sufficient, I made the connections as in the image and now I get signal Of course I need to do it more nicely as below but that's up next.

So if someone is building the Mic-mod. Don't forget these connections!

Next step is now to test everything else.

I also uploaded how the end result is going to look like, pretty nice

 

[BGroen]

Hi all,
My unit seems to work fine. Only that the WET signal is gained. After checking with the original schematic it makes sense because this design includes the 'aux output' from Shure. Which according to the original user manual should be around + 60 dB.

Now of course the Mix-function of the unit does not make sense as the WET signal is +60 dB. I cannot see from which point to get my signal for being mic level from the schematic. Does anyone know? See attached the original schematic.

 

[c1184701]

Hi all,
My unit seems to work fine. Only that the WET signal is gained. After checking with the original schematic it makes sense because this design includes the 'aux output' from Shure. Which according to the original user manual should be around + 60 dB.

Now of course the Mix-function of the unit does not make sense as the WET signal is +60 dB. I cannot see from which point to get my signal for being mic level from the schematic. Does anyone know? See attached the original schematic.

Hi there,

Yes the point you have highlighted on the original schematic is an unbalanced line output. I think it is somewhere between -10 and +4 standards... definitely much hotter than mic level anyway.

The original Level Loc takes the mic-level output from a different point on the circuit. Take a look at the attached schematic, I have added some highlights. The mic-level output is taken from the E point near the 'distance selector'. This E point is wired across to the bypass switch, and when the unit is engaged it is routed to the output transformer. The output of this transformer is at microphone level, so you would then plug the output of the level-loc into a mic preamp.

 

[ip_dalie]

Hi,

To be honest I'm not sure if Marek is still offering these. The PCB traces are available here if you can etch your own:

http://irfrench.tumblr.com/downloads

I've not spoken to Marek for quite some time - I hope he is well!

Ian.

Hi Guys, does anyone still have the documents for this project for self etching?
I tried to download it on Ian site, but the access is denied for all the files.

Thank you
Ipin

 

[c1184701]

Hi Guys, does anyone still have the documents for this project for self etching?
I tried to download it on Ian site, but the access is denied for all the files.

Thank you
Ipin

Hi Ipin, here are the files I have

-Ross

 

[ip_dalie]

Hi Ipin, here are the files I have

-Ross

Hi Ross.

Thank you very much!! I really appreciate it. Can't wait to start the project.

Ipin

 

[JAY X]

Hi!

Does anyone know what is the current draw of this circuit?

Jay x

 

[Whoops]

Hi!

Does anyone know what is the current draw of this circuit?

Jay x

I don't know,
but it's a very simple transistor circuit.
Current Draw will be pretty small, probably smaller than 50mA