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

[Potato Cakes]

I've just got a report back from another guy who also used the zeners from Mouser. His stereo unit developed a massive hiss when turning the release pot clockwise. He's now replaced those with 1N751s from Farnell (Multicomp) and the hiss is gone and the unit's working as expected.

It seems, most of the noise problems arouse from those Mouser zeners (Central Semiconductor?), although the symptoms may vary a lot...

I used a number of different brands of 1N751s from Mouser and Farnell and all gave me the higher noise I was fighting. I do not recall the brand 1N5231s that I used. I'll have to the look that up if people are looking for that info.

Thanks!

Paul

 

[ToBSn]

Hi Guys,

I've found a new 1n751a  zener from RND Comps. here https://www.reichelt.de/?ACTION=3;ARTICLE=223390;SEARCH=1n751a

@Paul
Thanks for your hard work. It seems i have to read a lot for the next few days.
Is your unit up and running?

 

[Potato Cakes]

Hi Guys,

I've found a new 1n751a  zener from RND Comps. here https://www.reichelt.de/?ACTION=3;ARTICLE=223390;SEARCH=1n751a

@Paul
Thanks for your hard work. It seems i have to read a lot for the next few days.
Is your unit up and running?

Yes it is indeed up and running. It's one of the many pieces that I've built for the reconfiguring of my studio. All the functions are working exactly as they should.

If you focus on building it exactly how it is says to do in assembly guide, you will have a properly working unit. There is quite a bit of off board wiring, so be prepared mentally for that. The boards are perfectly fine the way they are and the instructions explain very well how to customize your build with things like the hold function, etc. I just wanted people to be aware of what is going on when trying to do the stereo balance, which I would not have known about if I wasn't so obsessed with the noise I was hearing and hadn't spent all that time staring at a scope with audio passing through the unit.

Let us know how you go!

Thanks!

Paul

 

[dogvoid]

Hi

Finally I finished, well, the next month the input and output transformers, I think I'll put a switch to bypass these, I love how it sounds, it's wonderful!

In the end, the only zener that I have not given white noise problems I got in an old local store, and did not have many ...

After calibrating everything perfect, just following the pdf carefully.

The only problem is the baypass, I preferred to put relays with the pcb HWBP36 of Silent Arts and do direct bypass, when activating it sounds a "POP" is not a drama, but if someone knows some trick to eliminate them (they sound even with the volume to 0 input and output)

Thank you very much for offering this project, it is one of the best compressors that I have built (2 different SSL, one 1176, Gates Sta Level and Federal Compressor) sounds simply magical! I recommend it to everyone !!!

Abel

 

[Potato Cakes]

If the pop is from Volker's boards you should probably reach out to him. The pop using these boards is addressed in this thread.

Thanks!

Paul

 

[letterbeacon]

Looks like a great project!

How is everyone using this limiter? Is anyone using it across the mix bus?

 

[fripholm]

The TG1 can be pretty aggressive and coloured, kind of ‚in-your-face‘. Personally, I tend to use a more transparent compressor on the mix bus but depending on your needs this might work for you as well.

I love it on close mic‘d snare, it makes them pop!  ;D Have also used it for rock piano or clean electric guitar and it works great on some vocals. Maybe it‘s the right choice for mix bus compression on some electronic genres but haven‘t tried yet.

 

[MrBlomski]

@fripholm, what transformers did you use in you're build manual?
I have transformers from carnhill and I was figuring out how to use this in the stepped Elma switch version.

Cheers

 

[fripholm]

I'm using Haufe transformers for input and output. The one on the input is designated as '90468' and it's a 2:1 - unfortunately I couldn't find any more info on this. On the  output is a RK310/2 which has a turns ratio of 1:1.

Unless your using something different than a turns ratio of 2:1 you should be fine by using the resistor values for the input switch provided in the guide. For the output, the kind of transformer you're using is irrelevant for the values.

 

[warpie]

Does anyone know what is the input and output impedance of this circuit if I use a 2:1 and 1:2 in and out xfmrs? Thanks!

 

[fripholm]

Does anyone know what is the input and output impedance of this circuit if I use a 2:1 and 1:2 in and out xfmrs? Thanks!

The input impedance is about 3k which makes it about 12k when using a 2:1 transformer. The (simulated) output impedance of the output stage is less than 20 ohms which again is quadrupled (for an 1:2 xfrmr) at the secondary plus your winding resistance.

HTH

 

[warpie]

thanks fripholm 

 

[orangechili]

@Paul,

Would you happen to know what brand 1n5231 diodes you used? It would definitely be helpful as option for others to try who get the noise issue with zeners etc.

 

[Potato Cakes]

@Paul,

Would you happen to know what brand 1n5231 diodes you used? It would definitely be helpful as option for others to try who get the noise issue with zeners etc.

As I posted above, I do no recall and I cannot seem to find that order. They were either Vishay or ON/Fairchild.

Thanks!

Paul

 

[MrBlomski]

Hello everybody!!

Waiting for PCB

I found a very good option as audio transformers Carnhill

Input: VTB9046 2: 1
Output: VTB9070 1: 1.7

Does anyone know anything about it?

On the other hand, I have seen in other models a HI / LOW switch. I must review the scheme, but I think it is a switch that cancels or activates the pass through the input transformer, some information?

Thanks !!!

Did you realise this? I would like to know


Other stuff:
I am going for matched 1n5231b

Other question:
Could some people post some front panel designs for me for inspiration?
Thanks I am a noob at designing this.

 

[Hobbyist]

Did you realise this? I would like to know


Other stuff:
I am going for matched 1n5231b

Other question:
Could some people post some front panel designs for me for inspiration?
Thanks I am a noob at designing this.

Here is the idea for my unit.

 

 

[fripholm]

In case you didn't know, there's also an FPD file (for Front Panel Designer) with my design within the ZIP file from the first post.

 

[brewbacca]

Hi all, I built my unit about a year ago, but I was having an issue where the +28v rails would suddenly drop down to about 16v dc. I've been trouble shooting this intermittently ever since, but haven't been able to figure it out. Could there be a problem with my diodes?

I just replaced all the transistors on one of my boards and am positive the output transistors are installed correctly. But I'm still getting the issue, so I doubt it's a transistor problem.

 

[Potato Cakes]

Hi all, I built my unit about a year ago, but I was having an issue where the +28v rails would suddenly drop down to about 16v dc. I've been trouble shooting this intermittently ever since, but haven't been able to figure it out. Could there be a problem with my diodes?

I just replaced all the transistors on one of my boards and am positive the output transistors are installed correctly. But I'm still getting the issue, so I doubt it's a transistor problem.

Does it do this with nothing connected to the PSU? Are you using one or two boards? You're just going to have to do the process of elimination like everyone else has to do in this situation. PSU work properly without being connected to any TG boards? Yes - connect one board at a time and check again. No - double check your PSU soldering/component placement. Etc, etc....


Thanks!

Paul

 

[brewbacca]

The PSU holds the correct voltage without the boards connected. I've actually tried a few different LM317/337 PSU circuits and even perfboarded Fripholms circuit to make sure, and they all do the same thing when I connect to either board. I even tried different power transformers. Same thing. I've quadruple checked my soldering and component placement (not my first rodeo . I suppose something could be in the wrong place, but it seems odd that both boards do the same thing.

As noted above there are two boards with the same behavior and the voltage drop is worse when both are connected to the PSU.