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

[fripholm]

Does anyone have any clips of this unit working hard on various sources...drum room, acoustic guitar, vocals? Cheers.

Here are a few quick tests on different sources: HQ-MP3s 256kBit

These are not necessarily examples for tasteful compression - just me abusing the units I have 8)

The 'Drums' and 'Acoustic Guitar' files have been processed with my stereo unit. The clicks you're hearing within these files is me actually toggling BYPASS while audio is running. I change a few settings in between; input, attack, (auto)release etc., and activate the compression again on the next downbeat. Note that the room mic is not active in the drums example, just the overheads and close mics. No additional processing apart from a bit of EQ here and there. The files are not level matched.

For the vocals I have used my mono desktop unit on Comp, Lim and THD settings - the original is included as well. Again, except for a bit of EQ and reverb, there's no additional processing - but I've tried to level match them as good as it gets.

 

[desol]

Thanks Fripholm! That's exactly what I was looking for.

The unit sounds pretty good actually. I was a bit skeptical at first but, hpmh...not bad...and I know these are just basic examples to start.

Cheers and thanks!

 

[JCN1218]

Hi everyone!

First of all, thanks to fripholm for this project. Just placed the order for my boards and now I'm trying to get my ducks in a row in the mean-time by putting together some mouser carts and whatnot.

My questions probably have obvious answers. I've built a few kits so far, but I'm still somewhat a beginner and want to make sure I'm getting the right parts.

First question, is this a suitable power transformer for American voltage/ current?
https://www.parts-express.com/avel-lindberg-y236653-250va-30v-30v-toroidal-transformer--122-630
I know from the BOM that it needs 2x30V secondaries which this has, but I'm unfamiliar with transformers as of writing this post, so the rest is greek to me.

Second, also dealing with transformers, this time the input/output. I'd like to use Sowters if only because I have no gear that uses their transformers. There are other posts in the thread that mention which Sowters to use, but I just figured if anyone had any suggestions or advice, I'd love to hear it. I'd also be interested in Cinemag or Ed Anderson transformers as a substitute.

Lastly, regarding the BOM for the power supply, I have no idea what kind of bridge rectifier to get. I'm very unfamiliar with this kind of component, and I'm having little luck with google searches.

Thanks in advance! Really looking forward to this build, I'm hoping to have all my parts sourced by the time my boards get here.

 

[ToBSn]

First question, is this a suitable power transformer for American voltage/ current?
https://www.parts-express.com/avel-lindberg-y236653-250va-30v-30v-toroidal-transformer--122-630
I know from the BOM that it needs 2x30V secondaries which this has, but I'm unfamiliar with transformers as of writing this post, so the rest is greek to me.

Second, also dealing with transformers, this time the input/output. I'd like to use Sowters if only because I have no gear that uses their transformers. There are other posts in the thread that mention which Sowters to use, but I just figured if anyone had any suggestions or advice, I'd love to hear it. I'd also be interested in Cinemag or Ed Anderson transformers as a substitute.

Hi JCN1218,

250VA (4.17A) is a lot and is´s not needed.
Try to find one between 50VA and 120VA and save money.
Like 546-1182K15

If you want to go with the sowter´s.
I think this guy´s will do the job:
For input 2:1 (High-Z) 9165 or 1380
For output 1:1 1460

 

[JCN1218]

Thanks, ToBSn!

I thought that that number on the power trafo, seemed high, I just didn't know what to make of it.
I'll be sure to check out those sowters too.

Thanks again! Really appreciate the quick reply!

 

[fripholm]

Lastly, regarding the BOM for the power supply, I have no idea what kind of bridge rectifier to get.

This one should get you started: Through Hole KBP Bridge Rectifier

 

[JCN1218]

Awesome! Thanks so much, Fripholm. Now I'll be ready to order the PSU components when the boards arrive. I'll have to start putting a cart together for the rest of the materials soon.

 

[JCN1218]

Hi again, back with some more questions as I await the arrival of the boards.

I've been doing a lot of research and some comparative shopping regarding input/ output transformers. David from Cinemag has gone above and beyond as far as customer service is concerned. He recommended the CMOB-2S for output, which seems to fit all the requirements. He then said this about the input transformer:

"The input stage, I think comes through C3/R1 (???  I cannot quite make out the part numbers) at the upper left-hand corner of the schematic.  It looks like there is a 3.8K resistor across a level pot which then goes to C1/2.2u.  That creates a fairly low input impedance.  To do that right, you need a pretty big input transformer such as the CMLI-4x150D.  $111.14  If R3 could be eliminated, you could use the CMLI-15/15B which is $53.04.  Keep in mind that it looks like the design calls out this network for pre-emphasis purposes."

Just wondering if those suggestions would fit the bill. I'm leaning more toward cinemag at the moment since the cost would be considerably lower.
I was also doing some research and I found a pic of the Chandler TG1 opened up. I saw that it was using Carnhill VTB9046 input transformer as well as Carnhill output, though I couldn't clearly see the model number. Anyway, I was wondering if anyone has used Carnhills in their TG1 build.

I also noticed a lot of mention of the Sifam AL20 mirrored meters a few pages back in the thread. I was wondering if anyone has managed to get them to work with this build yet, since I was thinking about getting a pair myself, but I'm hesitant to drop that kind of cash if they're not going to function correctly.

So that's it for now. Sorry if I'm asking too many questions, I just want to be as close to 100% sure as I can get before a buy anything for this build. Thanks again to everyone in this thread for being so helpful so far, I really appreciate it!

 

[fripholm]

You don't necessarily need a BIG input transformer - big, as in size - you need one with a turns ratio of 2:1 or even 4:1 - not 1:1, as recommended by Cinemag. If however, the secondary of the CMLI-4x150D can be wired in parallel (primary stays in series as per the datasheet) you would have a 2:1, which is fine.

He's right, the input impedance is rather low but one of the purposes of the transformer is to raise the impedance as 'seen' from the outside. Impedance ratio of a transformer is turns ratio squared, so 2:1 makes for 4 times the impedance - 3.8k-ish times 4 is more than 15k - exactly what you want.

Another purpose of the input transformer is to lower the signal (by 6dB for a 2:1) to an acceptable level. This particular circuit either distorts heavily or will be in extreme compression most of the time, when the level is too high.

The Carnhill might be a perfect fit as it can be wired for both 2:1 and 4:1 - personally I would go for the M-version with the mu-metal can. But as it doesn't have mounting holes, it needs to be mounted to a PCB or perfboard with a 5.08mm (0.2") spacing.

HTH

 

[TwentyTrees]

Side-note on the Carnhills, they're excellent and I've just finished a 2254 build stuffed full of them. They actually have mounting holes on the opposite side to the pins - just undo the screws on the top and there you go!

 

[JCN1218]

Awesome! Can't thank you guys enough for how helpful you've been. I think I'll go Carnhills then for this project. I was just using them in my EZ1290 build, so I'm pretty familiar with how they work too. Plus it'll also save me some funds for other parts of the project.

 

[ToBSn]

Hi,

Side chain pcb´s available here [Black Market] 


Edit:

Some additional infos:

To calculate your own frequencies you can use this tool: Calculator RC
RC-Filter 51kΩ [R48,R49] and Cap = Corner frequency.
I think the following values make sense.
You can also increase the frequency spacing, is a matter of taste.


Off and 5 selectable frequencies:
 

	Off​	1​	2​	3​	4​	5​
	-​	47nF​	33nF​	22nF​	15nF​	10nF​
@ -3db​	-​	~70Hz​	~100Hz​	~150Hz​	~200Hz​	~320Hz​

 

 

	Off​	1​	2​	3​	4​	5​
	-​	68nF​	47nF​	33nF​	22nF​	15nF​
@ -3db​	-​	~45Hz​	~70Hz​	~100Hz​	~150Hz​	~200Hz​

 





6 selectable frequencies + Off with extra dptp[on/on] to switch the high pass on/off:

 

	1​	2​	3​	4​	5​	6​
	68nF​	47nF​	33nF​	22nF​	15nF​	10nF​
@ -3db​	~45Hz​	~70Hz​	~100Hz​	~150Hz​	~200Hz​	~320Hz​

 

 

	1​	2​	3​	4​	5​	6​
	100nF​	68nF​	47nF​	33nF​	22nF​	15nF​
@ -3db​	~30Hz​	~45Hz​	~70Hz​	~100Hz​	~150Hz​	~200Hz​

 



ToBSn

 

[JCN1218]

Hi,

Side chain pcb´s available here [Black Market] 




ToBSn

Awesome! Would love to have some more side-chain options. PM sent

 

[MrBlomski]

Side-note on the Carnhills, they're excellent and I've just finished a 2254 build stuffed full of them. They actually have mounting holes on the opposite side to the pins - just undo the screws on the top and there you go!

Do I see the DB54?

 

[TwentyTrees]

You certainly do! I'll do a proper build report at some point in the DB54 build thread, but it's a very enjoyable build and sounds fantastic.

I've not got going on this zener limiter yet, but I'm looking forward to two apparently very different flavours of diode compression!

Do I see the DB54?

 

[MrBlomski]

You certainly do! I'll do a proper build report at some point in the DB54 build thread, but it's a very enjoyable build and sounds fantastic.

I've not got going on this zener limiter yet, but I'm looking forward to two apparently very different flavours of diode compression!

I am also building them

 

[Hobbyist]

Hi,

Side chain pcb´s available here [Black Market] 




PM send 

 

[Potato Cakes]

Making progress!

I am waiting on push button switches and a fancy IEC inlet. I have everything else.

Thanks!

Paul

 

[kante1603]

Making progress!

I am waiting on push button switches and a fancy IEC inlet. I have everything else.

Thanks!

Paul

Very nice.
I see squared holes for the pushbutton switches,are these the ones from frank or can you tell us the type?
For the meters,are these the ones from DonAudio?Did you get them to work already?
Best regards,


Udo.

 

[Potato Cakes]

Very nice.
I see squared holes for the pushbutton switches,are these the ones from frank or can you tell us the type?
For the meters,are these the ones from DonAudio?Did you get them to work already?
Best regards,


Udo.

Those are for the switches from Don Audio. Same with the meters. I haven't been able to power anything up as I forgot to order the IEC inlet and I used the switches I had for a GSSL I sold.

I did ask Aaron about using these meters in place of a 1mA version that this design uses, and he said to use a VU meter driver that are commonly found on ebay. I have a pair of VU meter buffers that I built from JLM audio but never installed, however I don't think it's the same thing. I'd have to look over that particular schematic some more and see if it will work. Hopefully will have this finished at the end of next week.

Thanks!

Paul