TREX and TREX2 Transistor regulator kit

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mylesgm
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Re: TREX and TREX2 Transistor regulator kit

Post by mylesgm »

That 470r resistor was all that was needed! Which means a real thumbs up for the smoothness of your standard 3 and 5 rail power supply because I've never needed that extra resistor and lots of previous, trouble free builds.
Cheers...

dane999
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Re: TREX and TREX2 Transistor regulator kit

Post by dane999 »

Hi !
I'm currently thinking about racking 2 Studer 900 input channels. The rails needed are +/- 15v, 48v, -6v, -24v. Some people experienced hum problems when getting all the rails from a single transformer, so I plan to get the audio dedicated rails (+/-15 and 48v) from an ACDC kit, and the logic rails from a reversed TREX2 via a 48v 15w 315mA SMPS. Do you think this would work ? (Along with 2 regurgitators after the -10dB pre-fader output…)

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Joe Malone
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Re: TREX and TREX2 Transistor regulator kit

Post by Joe Malone »

dane999 wrote:Hi !
I'm currently thinking about racking 2 Studer 900 input channels. The rails needed are +/- 15v, 48v, -6v, -24v. Some people experienced hum problems when getting all the rails from a single transformer, so I plan to get the audio dedicated rails (+/-15 and 48v) from an ACDC kit, and the logic rails from a reversed TREX2 via a 48v 15w 315mA SMPS. Do you think this would work ? (Along with 2 regurgitators after the -10dB pre-fader output…)
Yes you can build a trex2 reverse with PNP TIP125, 126,127 and reverse polarity on all caps (and zeners if using them) to make 2 negative rails which will work fine.

There should be no problems using one transformer as long as you pick the correct ac windings which will be preferably 2 x 22 to 25vac windings into the AC/DC due to the -24v rail. You may be able get away with 1 x 22 to 25vac winding but 2 windings is better for full wave rectification.

Wire the roughly -35vdc unreg at the negative solder pad of C8 on the AC/DC to the TREX2 in and set -24vdc and -6vdc. To get to -24v you may need to make the 10k resistor 4k7 or 5k1 on that rail on the TREX2.

If you haven't ordered yet mention the reverse trex2 in comments at the end of ordering and we will make up a reverse TREX2 kit for you.
Joe :-)
JLM Audio
Capturing Audio without Injury

dane999
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Re: TREX and TREX2 Transistor regulator kit

Post by dane999 »

Thanks a lot for those explanations ! I'll order within the next week I think, so thanks (again) for the reverse TREX2 option !

dane999
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Re: TREX and TREX2 Transistor regulator kit

Post by dane999 »

Okay, I'm finally trying to get this done.

So what I need is an AC/DC and a reversed (and modified for -24V) TREX2, fed by C8 negative leg. Am I right ?

About the power transformer, I found a 40VA 230V to 2x24vac (http://www.conrad.fr/ce/fr/product/7103 ... 4?ref=list), the calculator asks for about 30VA, will this be ok ?

Thanks a lot !

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Joe Malone
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Re: TREX and TREX2 Transistor regulator kit

Post by Joe Malone »

dane999 wrote:Okay, I'm finally trying to get this done.

So what I need is an AC/DC and a reversed (and modified for -24V) TREX2, fed by C8 negative leg. Am I right ?

About the power transformer, I found a 40VA 230V to 2x24vac (http://www.conrad.fr/ce/fr/product/7103 ... 4?ref=list), the calculator asks for about 30VA, will this be ok ?

Thanks a lot !
Yes will work fine and the transformer above will also work.

We have a new V6 power supply coming in 4 to 6 weeks which has 3 positive and 3 negative rails for pairs of SSL, Neve 88, Neve VR, Studer channel racking which has super smoothing cap bank on it.
Joe :-)
JLM Audio
Capturing Audio without Injury

dane999
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Re: TREX and TREX2 Transistor regulator kit

Post by dane999 »

Ok, thanks for the answer. That V6 PS seems to be a very good alternative, maybe for a cleaner build, so I think I'll wait for it, as I have some other studer channels on the way. I'll check for its availability, thanks again !

mybishi
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Re: TREX and TREX2 Transistor regulator kit

Post by mybishi »

Can I run 2 trex's with one of them having its polarity reserved (with tip126, caps and zener reversed) off of the same 48v input?

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Joe Malone
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Re: TREX and TREX2 Transistor regulator kit

Post by Joe Malone »

mybishi wrote:Can I run 2 trex's with one of them having its polarity reserved (with tip126, caps and zener reversed) off of the same 48v input?
You can make a reversed TREX as you describe but you CANNOT run if from the same 48v that runs a normal TREX as the same time.

Best to let me know what you power rails you are after and I can suggest the best way to do it.
Joe :-)
JLM Audio
Capturing Audio without Injury

mybishi
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Re: TREX and TREX2 Transistor regulator kit

Post by mybishi »

For this project I need 15V+ and 15V-, around 70ma out. I'm powering 8x THAT 1280's and 2x OPA627's. I've tried the zener approach but in prototyping, one mistake leads to blown Zeners. (For example, nicking the chassis with a multimeter probe and shorting the power supply in). What would you suggest? Thanks!!!

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Joe Malone
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Re: TREX and TREX2 Transistor regulator kit

Post by Joe Malone »

mybishi wrote:For this project I need 15V+ and 15V-, around 70ma out. I'm powering 8x THAT 1280's and 2x OPA627's. I've tried the zener approach but in prototyping, one mistake leads to blown Zeners. (For example, nicking the chassis with a multimeter probe and shorting the power supply in). What would you suggest? Thanks!!!
Ok I see. If you fit 16 to 18v zeners instead of trim pots to the normal TREX and the reverse TREX you should be able to make a much stronger virtual ground +/-15v to 17v power rails from the one 48v SMPS. So yes your idea should work.
Joe :-)
JLM Audio
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mybishi
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Re: TREX and TREX2 Transistor regulator kit

Post by mybishi »

Joe Malone wrote:
mybishi wrote:For this project I need 15V+ and 15V-, around 70ma out. I'm powering 8x THAT 1280's and 2x OPA627's. I've tried the zener approach but in prototyping, one mistake leads to blown Zeners. (For example, nicking the chassis with a multimeter probe and shorting the power supply in). What would you suggest? Thanks!!!
Ok I see. If you fit 16 to 18v zeners instead of trim pots to the normal TREX and the reverse TREX you should be able to make a much stronger virtual ground +/-15v to 17v power rails from the one 48v SMPS. So yes your idea should work.
Ok, awesome! I already ordered the TRez PCBs so this is good news. So, I just need to split the incoming 48v from the SMPS and connect the leads to the two TREX's and ground the TREX outputs to chassis along with all of the components' grounds?

Thanks Joe,
Nick

mybishi
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Re: TREX and TREX2 Transistor regulator kit

Post by mybishi »

Also, you are saying I should replace the trim pot with a zener? Should I also install the zener indicated by the circuit board or should I jump that connection?

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