[BUILD] fripholm's TG1 Zener Limiter boards - support thread

[Potato Cakes]

Hi guys,

I'm about to start this build and I'd like to install the AL 20 vintage mirrored meters like the ones that Chandler use on their TG version. What resistor values need to be changed ?

Thanks for your help.

Would to love to know as well. I am using these same ones in my build.

Thanks!

Paul

 

[fripholm]

I'm about to start this build and I'd like to install the AL 20 vintage mirrored meters like the ones that Chandler use on their TG version. What resistor values need to be changed ?

As far as I know, the original used an Ammeter with 2.4mA full scale deflection which was connected across diode D5. If Chandler really used VU meters (as opposed to an Ammeter) for their units then I would think there might be more involved than just the tweaking of some resistor values. Maybe there's some additional circuitry for the meters?! I don't know.

This is an older post of someone trying to use VU meters which seemed like a lot of hassle:
https://groupdiy.com/index.php?topic=37400.msg754309#msg754309

 

[fripholm]

I've just tried it with a standard Sifam AL29 VU meter and it works - kind of...  8)

With the currently implemented metering circuit, the needle of the AL29 maxes out at about the third of the scale with more than 20 dB of compression. Connected across D5 (as in the original), the needle's travel is even lower. At least it moves with the compression 

There might still be a way to use a VU meter, but you definitely have to come up with a custom scale and replace the original one. As it is, the voltage drop across diode D15 is too low for full scale deflection but if you connect two diodes in series it might be enough. A shunt resistor/poti across the meter could be used for fine tuning. It works fine when simulated but still needs to be tested in the actual circuit.

Are the AL20 really available as a mirrored version, I mean mechanically mirrored?

 

[kante1603]

Are the AL20 really available as a mirrored version, I mean mechanically mirrored?

Hello,


yes,but very expensive,here's a link:


https://www.don-audio.com/Sifam-AL20-6-7-Retro-VU-Meter-Set


Best regards,


Udo.

 

[fripholm]

yes, but very expensive.

Thanks and yes, that's a lot of money - but very nice nevertheless. They even have a custom scale.

 

[kante1603]

Yes,looks like they're the replacement parts for chandler limitters.

 

[Ilya]

Yes,looks like they're the replacement parts for chandler limitters.

I doubt Chandler uses VUs. Should be mA meters. And yes, these are a hell of a price.....

 

[kante1603]

I doubt Chandler uses VUs. Should be mA meters. And yes, these are a hell of a price.....

Not sure if these are vu meters.On the manufacturers page there are quite a few meters from the series "20" to find.When going through the options (use the meter selector "ALL") you'll find some of them to be available as VU,A,mA,dc etc.Same for direction,you can choose the zero position to be left,centered,right etc.
The inlay must be done yourself of course.
DonAudio just writes that these are VU,but they state them to be replacements for Chandler.Maybe ask them......?

Just thinking......

Best regards,

Udo.



Edited because of font size issues.

 

[Ilya]

I'm not a VU-meter fetishist 
I'm using LED meters in my build for both level and GR. Much cheaper and less internal "real estate".

 

[Aniol1349]

Really excited with this project. I'm just waiting for a new batch of PCBs

Have anyone actually finished a unit? Maybe someone could share some photos/audio.
and yes I would be tempted to get myself a pair of those beautiful meters!

btw. really well documented build guide as well

Take it easy everyone!

 

[Potato Cakes]

Not sure if these are vu meters.On the manufacturers page there are quite a few meters from the series "20" to find.When going through the options (use the meter selector "ALL") you'll find some of them to be available as VU,A,mA,dc etc.Same for direction,you can choose the zero position to be left,centered,right etc.
The inlay must be done yourself of course.
DonAudio just writes that these are VU,but they state them to be replacements for Chandler.Maybe ask them......?

Just thinking......



Best regards,

Udo.



Edited because of font size issues.

I emailed the guys at Don Audio to get some further information and I'll let you all know what they say. I have already ordered a set and are in the pile of parts I have for this project. Still a month out from finishing it up.

Thanks!

Paul

 

[Potato Cakes]

Response from the Aaron at Don Audio is a VU driver circuit is needed to get these particular meters to work with a design that uses 1mA.


Thanks!

Paul

 

[Ilya]

I wonder if removing the internal bridge rectifier and stuffing some resistors in series/parallel will do the trick...

 

[fripholm]

Have anyone actually finished a unit? Maybe someone could share some photos/audio.

I'm curious as well! Any finished units out there or photos of your work in progress?! ???

 

[ToBSn]

I'm curious as well! Any finished units out there or photos of your work in progress?! ???

Here is my WIP in a very early state

 

[Potato Cakes]

I'm curious as well! Any finished units out there or photos of your work in progress?! ???

I just ordered transformers so it will be a couple of weeks before I finish. I have the boards populated with case, switches, and connectors on standby till I get home.

Thanks!

Paul

 

[fripholm]

Within the last weeks it has come to my attention that someone has been making and is selling clones of my boards. And yours, ToBSn, seems to be one of those. I'm in contact with a couple of members who purchased copies, which had been offered at another forum outside of GDIY. And occasionally, I have seen some of the clones showing up here in the Black Market again.

I was never asked for permission nor permitted the cloning of my PCBs, but I really hope they are electrically okay. If you find out you have a clone and they are not okay, please don't blame me!

From ToBSn's photo I can tell that the silkscreen looks slightly fuzzy and the solder pads seem somewhat irregular (maybe from scanning?!). But the most obvious difference is the rotation of R90 by 180 degrees (it's upside down) and one of the PCB manufacturer's imprints is in the free space around the output stage. Mine never were that way! Maybe the cloner deliberately rotated the resistor to be able to differentiate clone from original. This person must have had at least one original, as I've never sent out the Gerbers to anyone. And as I said before, the fine quality of my boards allowed for some abuse of the solder pads for testing around with different values. Obviously, wether this is also true for the clones can't be judged from a photo...

I have only ever offered the boards here on groupdiy and I will keep it that way. If you find these offered anywhere else and/or in larger quantities, they are most likely clones.

Just wanted to let you guys know. Take care. 

 

[kante1603]

Oh no,not again!
Thanks for letting us know,and please decent fellows: Do not support thieves!


Best regards,


Udo.


Edited central point to bold letters....   

 

[rock soderstrom]

 

[TwentyTrees]

Dang, that's awful! Poor show, mystery thief, poor show.