Green Pre Questions?

I've been putting together a parts list from Mouser for a pair of Green Preamps for a few months now (newbieness) and am all most done but have a few questions.

Can I put a VU meter on the Green? if so how? I would think it would be simple but I've read a few post here or somewhere that it could cause distortion unless I have some sort of buffer? ( I have no idea what I'm talking about I hope you do)

Are the LEDs something needed for the circuit? Can I just leave them off?

Which part from Mouser do I need for the 100k flat/multiturn trimmer?

I've been learning as I go along. I hope it all works in the end. It may end up being an expensive soldering lesson. :razz:

I enjoy this forum very much and read it everyday.
Thanks,
Harold

Hi & welcome,

Can I put a VU meter on the Green? if so how? I would think it would be simple but I've read a few post here or somewhere that it could cause distortion unless I have some sort of buffer? ( I have no idea what I'm talking about I hope you do)

Are the LEDs something needed for the circuit? Can I just leave them off?

Click to expand...

You deliberately want to have a VU and not the LED-bar ? OK, I don't know the exact Green-LED-circuit, but figure you can skip the related IC (339?) and the LEDs.

W.r.t. VU-meter introduced distortion, best would be to give the VU its own dedicated buffer (unity gain configured opamp). Could be added on a small piece of perfboard since you'll need only the additional opamp and perhaps a decoupling cap. because it's unity gain no additional resistors needed.

Bye,

Peter

Are the LEDs something needed for the circuit? Can I just leave them off?

Click to expand...

If you have the V14 PCB, leave out the TL074, the LM339 & all the related components

Peter

So no TL074 or LM339? I just posted a query about this in another link, but does this mean that neither of these ICs are necessary to the circuit if you are not using leds? What if these ICs and "related components" are on the board, but I just don't have the leds hooked up? Is this bad?

What, specifically, are the "related components"?

Jacob

Just remove the IC's from their sockets and you will be fine TL074 or LM339.

Matt

I must have missed this thread cos I asked exactly the same question the other day
I looked at the PCB (and with Peters comment of removing everything ont he right hand side of the PCB) and to my uneducated eye - I am leaving out everything (apart from the pots etc..) that are..

To the right of the parallel vertical PCB tracks going down the PCB about 2/3 to the right.
ie no jumpers.. (going left to right from those tracks), no transisitors bottom right, no ICs, no loads of caps and resistors etc..

If you remove the IC's and Jumper once you stuff the board you should still be okay, I ran my pres like this when I chose not to use the metering...

Matt

To the right of the parallel vertical PCB tracks going down the PCB about 2/3 to the right.
ie no jumpers.. (going left to right from those tracks), no transisitors bottom right, no ICs, no loads of caps and resistors etc

Click to expand...

Everything to the right of the meter select jumper excluding the 3 toggle switches & output trim pot can be left off if there is no need for the metering.

You could also just leave off the LED's or take out the 2 IC's, up to the user.

Peter

sorry to resurrect this thread but a quick question about leaving the metering out:

if leaving all the components off after meter select traces, is there still need for the jumpers?

also, i am using off-board switches to wire up the pre, but the pcb mount ones have 3 leads instead of two, this only matters on the HPF, how do I wire that up?


thanks alot for helping a new diyer!

[quote author="Luke"]sorry to resurrect this thread but a quick question about leaving the metering out:

if leaving all the components off after meter select traces, is there still need for the jumpers?

also, i am using off-board switches to wire up the pre, but the pcb mount ones have 3 leads instead of two, this only matters on the HPF, how do I wire that up?


thanks alot for helping a new diyer![/quote]








Bump..


:roll:

[quote author="Luke"]sorry to resurrect this thread but a quick question about leaving the metering out:

if leaving all the components off after meter select traces, is there still need for the jumpers?

also, i am using off-board switches to wire up the pre, but the pcb mount ones have 3 leads instead of two, this only matters on the HPF, how do I wire that up?


thanks alot for helping a new diyer![/quote]

You can leave the jumpers off that feed the meter circuit, but not the ones that feed the HI PASS Filter.

Not sure I understand the question RE the off boards witches... again a picture says more than a thousand words... help us help you :thumb:

Cheers

Matt

The HPF needs to switch between 2 points, it is not an on/off switch. So it needs 3 terminals. i.e. it needs to be a changeover switch & not an on/off type of switch.

SO, in this position it needs to be a SPDT (single pole double throw) switch.

Peter