TG1 - advice from any one who has built it...

[SLB]

Here is a picture of my build. I'm waiting on a couple of components and then it's calibration time. I think I have worked out what the calibration procedure is and if I'm right I'll post it here.

Regards,
Brezo

 

[baadc0de]

Very Snazzy brezo. Looks righteously good! Which transformers and transistors are you using in the output section & have you found any abnormalities like me and warpie are having?

 

[SLB]

I'm still deciding on transformers but will most likely be going with the Carnhill VTB 2281 for in and outputs. That way I'll have +6dB in and out but most importantly input as the comp needs a decent level to get it working. On the flip side you play with AOT 3 and 4 to change the threshold of the comp mode and AOT 5 and 6 for limit mode.

I'm using 100% original semiconductors as per 1969 schematic.

I'm only doing preliminary testing at the moment with no transformers, OP amps configured for +6 in/out  and output going to headphones as I would not want to destroy my Apogge converters if something went wrong. The compressor sounds great, no unbelievably good.

Now my thoughts on the resistor that keeps burning out is that because you are driving a low impedance output of the transformer primary more current is need to for a given dB level. I have no problem with resistor temp at the moment a I'm driving a high impedance load. Does the resistor burn out only when you have the iron switched in. I have been smashing the unit with dance music (big bass) for hours now with no issues.

I'm also using a 10K lin hold pot and R115 jumped.

More details to come as I finish off this project.

Regards,
Brezo.

 

[SLB]

Hi desol,

your inbox if full and I can't PM you.

I designed the panel myself and got DIY racked to make it for me. I have the design as a pdf in http://www.ladislavbrezovnik.com/diy/TG12413/ as well as other info.

Regards,
Brezo

 

[desol]

Thanks! I hadn't noticed!

 

[SLB]

Here are my AOT resistor settings.

AOT1 620r
AOT2 not used
AOT3 47K
AOT4 not used
AOT5 3K
AOT6 510r (Make the unit work limit more in limit mode)
AOT7 33K
AOT8 68K
AOT9 10r
AOT10 not used

Time for some audio samples. I have attached a track that I’m recording of a mate’s band. It’s only drums and guitar at the moment. I have the TG12413 on the drum bus. The drums where recorded in a room not much bigger than a bedroom.
This is done without transformers as I have not ordered them yet.

http://www.ladislavbrezovnik.com/diy/TG12413/audio_samples/The_Gate_%28TG12413%29.mp3 With Compression

http://www.ladislavbrezovnik.com/diy/TG12413/audio_samples/The_Gate_%28No%20Comp%29.mp3 Without Compression

I'm using a 25-0-25 30VA power transformer with the powersupply PCB that came with the boards with no trouble. The main PCB draws 80mA and the Bypass PCB with relays in draws 42mA. So a total of 122mA per channel.

Regards,
Brezo

 

[desol]

Nice sound quality...they need to work on their timing tho...they're all over the place.

Compressor sounds good.

 

[SLB]

Here is some only drums samples.

Drums TG Out http://www.ladislavbrezovnik.com/diy/TG12413/audio_samples/Drums%20TG%20Out.mp3
Drums TG In http://www.ladislavbrezovnik.com/diy/TG12413/audio_samples/Drums%20TG%20In.mp3
Drums TG In Hard Limit http://www.ladislavbrezovnik.com/diy/TG12413/audio_samples/Drums%20TG%20In%20Hard%20Limit.mp3

Regards,
Brezo

 

[haima]

Thanks Brezo - so rare that people actually post samples from their DIY gear.

The TG1 definitely hardens up the attack of the drums in a useful way. I think it would also be really great in parallel on drums, or on just room mics etc... really seems like it will be a useful mix tool. Can't wait to find the time to finish mine!

 

[SLB]

It's great on the room mic as well. It's also good on individual drums. I had the attack set to 8mS and the recovery set to 47mS with the HPF set to 80HZ to let more of the kick through. This is the best compressor I've built because it is a creative tool not just a mix tool. Another awesome compressor I built is a modded RS124. It has amazingly quick attack and release times for a variable mu tube comp. Info Here. http://www.ladislavbrezovnik.com/diy/RS124/

Regards,
Brezo

 

[alexc]

Way, way nice SLB  ;D

And thanks for your descriptions of the aot and other less obvious things.
I'm going to be doing my one soon and I think you helped!

Cheers

AlxC

 

[SLB]

I never thought I would get the TG to work as it is the most complicated transistor build I've done, but it worked first go thanks to festers great PCB. I am very happy with the results. I'm still waiting on the output vol switches, once they arrive I'll take some detailed pics. If you run into any issues I'll do my best to help.

Regards,
Brezo

 

[warpie]

BTW, what fuse do you guys use for a single unit?

 

[SLB]

500mA for 240V mains.

 

[SLB]

I also made a recall sheet to suit the case I made but you should be able to use it. http://www.ladislavbrezovnik.com/diy/TG12413/TG12413%20Recall%20Sheet.pdf

Regards,
Brezo

 

[warpie]

Thanks SLB. Is that for a single unit that draws around 125mA?
I'd think that a slow blow 250mA at 240V would be sufficient? Or maybe not? 

 

[SLB]

The mains fuse is to protect the power transformer not the circuit. The fuse would have to very small to protect the circuit but big enough not to blow on the in rush current when you first turn the power on.

Regards,
Brezo

 

[warpie]

So for a dual unit you double the value, don't you (ie. 1Amp at 240V) ?

 

[SLB]

500mA is for the 25-0-25 30VA transform I used. Bigger VA bigger fuse as the transformer can supply more curren on the secondaries.

Regards,
Brezo

 

[warpie]

I see.. So in my case (25-0-25 50VA) the fuse needs to be of a higher value.
Thanks