Single source > two amps

[btrancho]

My current system is a Squeezebox Touch into a Prima Luna Prologue II and out to DIY bipole Microtowers.  I have just ordered a Crack that I will use with my Beyer DT-880s.  I'd like to be able to switch the Touch from one amp to the other without repeated unplugging/plugging cables.  Though this is somewhat the opposite of the situation that calls for a preamp, I'm sure I'm not the first to try to figure the best way to do this.

I suppose that a passive preamp like the Goldpoint could work in reverse but my budget doesn't allow for that kind of expenditure.  I am very leery of degrading the signal with a simple A/B box such as this:  http://www.amazon.com/Cables-Go-28750-Composite-Selector/dp/B0032ANC8M/ref=dp_cp_ob_e_title_1 .

Any advice/experience will be greatly appreciated.

[Jim R.]

First, welcome to Bottlehead!

Does your main amp have a tape monitor out?  If so, that could work, but honestly, I think the best way to go is an AB switch box, and if you're worried about the quality of the switch on amazon, just build your own with a better switch, wire and RCAs, as it's just the bestt solution -- meaning better than y cables or constantly swapping cables, which can be hard on the connectors and shorten their life.

I honestly think this is your best bet (unless there is a tape monitor out on the amp), and what I'd do in the same situation.

HTH,

Jim

[Laudanum]

What about the Quickie?  The more technically inclined members can chime in to help but I imagine the Quickie could be fitted with a 2nd pair of outputs.  If im not mistaken, FPIII does it by simply placing a resistor across the two outputs.  Couldnt this be done easily with Quickie as well?

[btrancho]

Thanks for the welcome and the replies!

The Prima Luna doesn't have tape out so I dug into the old parts boxes and drawers and cobbled together a few RCA jacks and a DPDT switch in an old Radio Shack project box.  Even though the jacks were pretty cheap and somewhat mismatched as to brand and build, it seems to work pretty well.

I'll have to wait until later this evening or tomorrow when the house is more quiet (no dishwashers, clothes driers, TVs, etc) for a more critical listen but right now I don't hear any hiss or hum on the speakers or via the headphones connected to an old Pimeta headphone amp I built a few years ago.  So far, so good.

As to the Quickie, I suppose it could be modified with a second selector switch for two outputs, but then I really don't need volume control nor do I want to be changing batteries regularly.  I'd rather put the $99 into the Speedball upgrade.

I'll live with this until my Crack arrives (I wish Doc would update the delivery status page to something more recent than October) and is built and then see how they all play together.  If all is good I'll rebuild the switch with better parts and put it in something that isn't as plug-ugly as the RS box.

BTW - would a 3PDT switch make more sense so as to isolate each ground?

Thanks again
Bob

[Doc B.]

We've had a rather astounding breakdown of three different computers in the past week. My plan was to update the delivery status today, however the hard disk that has my web software on it is currently in the process of being recovered - excruciatingly slowly. I'll try to get an update ASAP.

Our backlog on Crack is at about the 3rd of November. We had an amazing number of orders October and November, and we are awaiting a large shipment of chassis panels in order to get caught up. Hopefully we'll see them the end of this week or the beginning of next.

[btrancho]

Thanks for the update Doc.  I was formerly in IT and appreciate the aggravation that computers can cause, especially in a business environment.  As I used to tell users in my organization - "That's why they call it a cursor!"

As I just placed my order on Nov. 30, I guess that I shouldn't expect to see it for a while.

Thanks again.  I look forward to posting some pics when it is done.

[Jim R.]

Bob,

Sounds good so far, but you probably mean a 4pdt switch, don't you?  2 signals and 2 grounds?  IMO, that is the best way to do it.
-- Jim

[btrancho]

Jim,

I thought a 3PDT, wired as below would work.  I star wired the grounds with the DPDT.  This would keep them separate, no? 

out1R   inR   out2R
out1G   inG   out2G
out1L   inL    our2L

How would you wire a 4PDT? I've built several SS head amp kits and an integrated Tripath amp but will admit am woefully ignorant of anything but the most basic electronics so I'd certainly defer to the expertise of the members of this forum.

[Jim R.]

Bob, Sorry, yes that will work fine, I just prefer to keep the grounds separate too, but I have no proof that that makes an actual difference, though that is the same switching scheme BH uses in the stereomour (a 4p3t rotary switch), and I believe the same thing for the Foreplay III.  Your plan will keep the grounds of the power amps apart, so that's probably just fine.  I'd go with what you have, and if ground loop noise becomes a problem, then maybe try the 4pdt scheme.

-- Jim

[btrancho]

I've been thinking of eliminating the switch box I connected previously and simply using a pair of these RCA Y adapters from my DAC to the amp and Crack instead.  Is there any downside to this?  Is it possible (or inadvisable) to feed both at the same? 

I'm getting really tired of sitting down, putting on the cans and then realizing that I forgot to throw the switch from the amp to the Crack.

[Doc B.]

It won't damage anything to try it. You would just have to try it out to see if it changes the sound.