2 outputs instead of 2 inputs?

Loquah · 2273

0 Members and 1 Guest are viewing this topic.

Offline Loquah

  • Sr. Member
  • ****
    • Posts: 507
  • Accidental Tube Addict
    • Passion For Sound
on: October 18, 2013, 12:18:03 PM
Just wondering if I could use the input selector switch as an output selector switch? (I.e. Quickie would have a single input only and two outputs)

My biggest concerns are whether this is possible (i.e. can the switch work in that direction) and whether it will negatively impact the sound quality.

The reason I need this is that if I just passively split the output with a Y-split cable, my active speakers will be always on as they detect input signal to come out of standby (no dedicated power switch).

Possible?

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 19353
Reply #1 on: October 18, 2013, 12:32:10 PM
Possible, yes, easy to do, not really.

You can add a DPDT switch to switch the outputs, then drill another pair of holes on the chassis plate for the second pair of outputs.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Loquah

  • Sr. Member
  • ****
    • Posts: 507
  • Accidental Tube Addict
    • Passion For Sound
Reply #2 on: October 18, 2013, 07:55:39 PM
So does that mean I can't keep the current layout, but just wire differently?

Without looking at the plans in detail, I was wondering if I could wire the inputs direct (ie not via the switch) and using the single pair of output RCA sockets, and then wire the provided selector switch into the output circuit to send signal via what is normally the input RCAs.

I know this might sound odd, but is it possible without degrading SQ? 

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Bonzo

  • Sr. Member
  • ****
    • Posts: 251
  • My name is Marco, best known as Bonzo
Reply #3 on: October 18, 2013, 08:02:57 PM
You can reverse input and output RCAs, but as Paul said there is a problem: you have to hook the output capacitors directly on the switch, and add a resistance to each rca out (and remove the ones on the input).
A bit tricky considering the layout but not so hard to do!
PS: will you ever publish a review of the quickie as a headphones amp?  ;)

Ciao!

Bisogna avere orecchio!


Offline Loquah

  • Sr. Member
  • ****
    • Posts: 507
  • Accidental Tube Addict
    • Passion For Sound
Reply #4 on: October 18, 2013, 08:30:40 PM
Thanks for the info Bonzo. It sounds like I should build it stock while I order extra resistors for the second output and then modify later.

Unfortunately I have no plans to modify it for headphone use, but I will be thoroughly reviewing it in its role as a pre-amp so hopefully that will at least grant some insight to its transparency and any colouration, etc.

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Loquah

  • Sr. Member
  • ****
    • Posts: 507
  • Accidental Tube Addict
    • Passion For Sound
Reply #5 on: October 18, 2013, 08:54:50 PM
Hmmm... just doing some more reading and think I should hold off on saying no headphone mod. I'm wondering if I could mod the Quickie for IEMs. More reading required...

Edit: Scratch that. High impedance only so no point really given I have a Crack w Speedball already. Sorry.
« Last Edit: October 18, 2013, 08:57:04 PM by Loquah (Passion for Sound) »

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 19353
Reply #6 on: October 19, 2013, 08:20:46 PM
This is the kind of modification that is possible, but if you do it, you can't really get any tech support on the forum if it doesn't work out, as everything will be changed around.

If you started with a working Quickie, it might be easier to modify a working unit into what you want.  Pop off the coupling caps that go to the output jacks, wire the output jacks to the potentiometer.  Send the output signal of the coupling caps to the rotary switch.  Install resistors on the output jacks to bleed off the coupling caps.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Loquah

  • Sr. Member
  • ****
    • Posts: 507
  • Accidental Tube Addict
    • Passion For Sound
Reply #7 on: October 20, 2013, 01:40:01 AM
Thanks all.

I've just finished the stock build and will get to know it before I mess with it.

I might have also found an alternative route rather than modifying the Quickie, but I have a question in relation to the solution. My new DAC has a 2V RCA out or a 6.8V XLR out. I want to use one with the Quickie and one direct to the S.E.X. now and Mainline later. Would I be better running the high voltage output to the Quickie or the S.E.X. (adapted to stereo RCA of course)?

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Bonzo

  • Sr. Member
  • ****
    • Posts: 251
  • My name is Marco, best known as Bonzo
Reply #8 on: October 21, 2013, 07:39:00 AM
I don't know if there are aprticular issues about SEX input sensitivity, but in my opinion it's better to send the weakest output (rca) to the Quickie.
Ciao!

Bisogna avere orecchio!


Offline Grainger49

  • Hero Member
  • *****
    • Posts: 7175
Reply #9 on: October 21, 2013, 08:42:34 AM
A number of Bottleheads have found that an active stage between sources (matching impedances) is beneficial.  I had a passive pre, much like the volume control in a SEX or Stereomour before putting a FP 2 between my sources and amp.

I preferred it.



Offline Loquah

  • Sr. Member
  • ****
    • Posts: 507
  • Accidental Tube Addict
    • Passion For Sound
Reply #10 on: October 21, 2013, 01:57:47 PM
What do you mean by matching impedances, Grainger?

I asked in another thread if the addition of the Quickie is just complicating my signal chain so maybe your comment about impedance matching is the answer. I'd be really appreciative of any explanation you can provide.

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Grainger49

  • Hero Member
  • *****
    • Posts: 7175
Reply #11 on: October 22, 2013, 05:58:57 AM
For the most part an input should have high enough resistance (impedance) to keep the source from going into current limit.  Anything from 20K to 100k is good. 

An output needs a low impedance to drive cables and not have high frequency roll off due to the parallel equivalent capacitance of the cables.  A passive preamp, a stepped attenuator or a pot will not typically have these impedances.

Very often through the years I have been on the board I have read of someone inserting an active preamp and finding greater drive from his system.  It often gives better PRAT as well as dynamics.

As always, YMMV!