Passive preamp for Logitech Transporter

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omega

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Passive preamp for Logitech Transporter
« on: 21 Apr 2012, 12:44 am »
Hi,
I wanted to built a passive preamp for Logitech Transporter. I really like what Bent Audio offers and wanted to use them for this project. I am not a professional just an enthusiast.

What I am looking for:
1) Transformer based passive pre (Don't know what it means, but that is what I heard is better)
2) One XLR input and one XLR output
3) Some display to show where the volume level
4) Transporter has IR in and out I wanted to control the unit using it. I also want the IR capability and remote but some type of IR in would be great
5) 12 v Trigger out to switch the amp
6) Physical knobs or buttons to turn volume up or down.

Seeking direction... I have not set the budget as I have no clue what I need to buy to this happen

TiA


John Chapman

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    • http://www.bentaudio.com
Re: Passive preamp for Logitech Transporter
« Reply #1 on: 25 Apr 2012, 12:27 am »
Hello!

I will do my best to answer in-line below. If you can shoot me a phone number via email we can discuss the project on the phone too. My email is johnc@bentaudio.com .


1) Transformer based passive pre (Don't know what it means, but that is what I heard is better)
I like them better myself. I think they perform particularly well used passively and the physics of how they treat impedances leads to that result. They give an easy load to the source while at the same time having a nice low output impedance to drive cables and the amp input. Just what you want in a preamp.

2) One XLR input and one XLR output

That is nice and simple. XLR connections work great with them - I use one that way myself. The downside for true balanced operation is that you need 4 autoformers to do it right (adding to parts cost). The plus is that it gives a true balanced fully differential signal path. 

3) Some display to show where the volume level

That can be either the wide front panel pcb or the smaller prm-1 pcb or module. The choice is dependant on how your case plans develop. We can pin that down together.

4) Transporter has IR in and out I wanted to control the unit using it. I also want the IR capability and remote but some type of IR in would be great
5) 12 v Trigger out to switch the amp

Both 4 and 5 might get a bit tricky - I do not know the specs of those IR signals or the trigger.... It is possible and I will look into it for you once we get to where it looks like the overall design is going to suit your needs.

6) Physical knobs or buttons to turn volume up or down.

The larger front panel pcb has a knob in the centre and the PRM-1 has buttons for up down or can alternately be fitted with the optical encoder to let you use a knob.

Seeking direction... I have not set the budget as I have no clue what I need to buy to this happen

The full set of parts not including a case would be about $1800 + shipping. The bulk of that cost is for the 4 autoformer modules - if you only needed RCA connections then you only need 2 of those and the price for parts would drop way down to about $1000 or so.

Hope that is a start anyway!

Thansk!

John



« Last Edit: 25 Apr 2012, 06:42 pm by John Chapman »