Bugle Mono Switch on output side

0 Members and 1 Guest are viewing this topic. Read 1829 times.

OcdMan

  • Jr. Member
  • Posts: 7
Bugle Mono Switch on output side
« on: 8 Apr 2015, 01:10 am »
What is the proper way to put a mono switch on the output side of the original Bugle? Could someone walk me through it? Please and thank you. It's more than just tying the signal leads together with a SPST switch, right? Don't I need to add a resistor somewhere? I know it might be simpler to just tie the inputs together but I understand that will alter the cartridge loading and might introduce some hum.

hagtech

Re: Bugle Mono Switch on output side
« Reply #1 on: 14 Apr 2015, 04:11 am »
It's not a good idea to install a mono switch on the outputs.  Inputs ok.  For true MONO you don't have to do anything except use one channel.  With a STEREO cartridge, you can fake it by strapping inputs together.  For an example of this, download the CORNET2 user manual from my website. 

jh

OcdMan

  • Jr. Member
  • Posts: 7
Re: Bugle Mono Switch on output side
« Reply #2 on: 14 Apr 2015, 04:57 am »
Thank you for the response. Then summing the channels at the inputs is the way to go then. I considered using only one channel but half of my old mono LPs aren't in great shape and so much of that noise is canceled out when I sum the channels.

I found this on www.rane.com:
Quote
Outputs are low impedance and must only be connected to high impedance inputs -- never, never tie two outputs directly together -- never. If you do, then each output tries to drive the very low impedance of the other, forcing both outputs into current-limit and possible damage. As a minimum, severe signal loss results.

So that's the problem with tying together the outputs of the Bugle, right? I had read something like that before but then I've been seeing people touting putting simple mono switch boxes (summing the channels with nothing more than a switch and RCA jacks) between the phono stage output and line stage. It looks like a proper channel summing switch box would be more complex than that in order to do it properly.



hagtech

Re: Bugle Mono Switch on output side
« Reply #3 on: 16 Apr 2015, 07:57 am »
Technically yes, that's the problem.  The Bugle circuit does work ok strapping outputs together, but it's best if you increase the output resistors to 1k or more.  Then the output will be an average (summation) of the two.   Without those resistors it would be a mess, having high feedback circuits fighting each other.  For me the better choice is to just strap inputs together. 

jh

OcdMan

  • Jr. Member
  • Posts: 7
Re: Bugle Mono Switch on output side
« Reply #4 on: 17 Apr 2015, 05:53 am »
I'll try the switch on both sides just to see how it goes. But if the switch on the input side is hum and noise-free, I should probably stick with that. The output resistors are at R7 and R25? Changing them to 1k should make no significant difference when in stereo mode, right? Could I put a resistor between the two channels that's only in the signal path when the switch is engaged? Or would that not have the desired effect on the output impedance? (Novice stuff here.)

hagtech

Re: Bugle Mono Switch on output side
« Reply #5 on: 17 Apr 2015, 06:07 am »
Don't add any extra resistors.  You don't want to tie outputs together, you merely want to average them. 

jh

OcdMan

  • Jr. Member
  • Posts: 7
Re: Bugle Mono Switch on output side
« Reply #6 on: 18 Apr 2015, 01:27 am »
Thanks for the help. Eventually this will go to my father when he finds a place for his turntable in his new house and I'll move on to building a Bugle2. But for now I'm having fun with it.

I noticed in the Bugle that R12/30, R11/29, and R9/27 are 1k Ohms, and R13/R31 is 316. In the Bugle 2 they are all 332 Ohms. Would changing these to 332 in the Bugle yield any improvement? Lower noise perhaps?

hagtech

Re: Bugle Mono Switch on output side
« Reply #7 on: 18 Apr 2015, 06:14 am »
Quote
Would changing these to 332 in the Bugle yield any improvement? Lower noise perhaps?

Nope.

jh