Using multiple amps with one set of speakers....

[Alco]

How do you guys set yourselves up when you're using more than one amp in your listening room with just one set of speakers ?

Do you use some kind of switching rig ? Or perhaps just swich the wires manually ? I've got some pretty good main speakers with my 5.1 setup that I would like to use with my recently acquired SCA-35. I would love to leave my contemporary 5.1 home theater wired up for use with the TV, and keep the SCA wired to those same speakers for use with music.

Whilst I'm asking about speakers.....Do any of you use modern powered subwoofers with your tube amps ? Are there any special considerations or crossover setups involved ?

[Geek]

Hi, Welcome!

An A/B switchbox is your friend. Just wire it so it switches between amps and not speakers.

But frankly, you're better off making one with binding posts and a nice big DPDT toggle (assuming common ground) instead of the really crappy ones found in the stores.

But "audiophiles" prefer the hard way... swapping wires. I dunno, I can't hear the difference.


As for subs, totally depends on application. If you're using horn speakers, subs are pretty much mandnatory.

Most of my friends keep the sub off for music listening, then turn it on for TV/DVD's

Hope this helps.

Cheers!

[Alco]

thanks Gregg,

that's pretty much what I suspected. I think I'll be swapping wires, or maybe breaking out my old bose bookshelf speakers. I love the idea of an A/B switch, but I would hate to see my SCA 35 get fried when its speakers get switched off and its xformers are left pumping into the void. It's not fair to my friends and housemates to set up a booby trap like that. Unless I make a switch with a load bank !

thanx again Gregg

[msmpe]

Hi Alco

Those old Bose may not be efficient enough for the SCA-35. You could consider putting the Bose in the HT, as there is usually a + 5dB (or more) equalizer in the HT resceiver set-up. Then you could use your fave speakers for the tube amp where the real sound is!

[Alco]

Hi Mike,

Good thought. In fact thats just what I wound up doing.

I found a pair of 1988 Klipsch KG 4 speakers on craigslist for $200. So I got those guys hooked up to my SCA-35 (which btw, I just finished refurbishing: all new caps, all new metal resistors, sds power supply board, and all wiring and soldering mistakes rectified). The old reliable Bose I hooked into the 5.1 system where they sound much better than the old KLH towers, which are now pulling their weight at Goodwill.

The Klipsch speakers sound much better than the Bose, no surprise. But the Bose are not bad, and they are about the same efficiency. The Klipsch are rated as 94db. Both are plenty loud for me with the SCA-35 in my medium sized living room.

I just ordered new dayton 1% caps for the Klipsch and am looking forward to seeing what kind of improvement recapping a 21 year old crossover network brings.

[msmpe]

Hi alco,

How'd those xovers sound with the new caps?

[Alco]

Hi Mike,

The difference is surprisingly huge, like putting new power supply caps in a vintage amp, or even pulling some coton out of one's ears. The audio range seemed to extend on both ends and what was in between seems both cleaner and has a greater dynamic range.

I replaced three caps: a 33 uf 100 volt non polarized electrolytic that the guy at parts xpress said functioned as a bass rolloff. And two metallized polypropalene that direct the sound to the proper driver. One was 8.2 uf the other 3.0, each was 250 volt. I ordered the 1% Dayton caps from parts xpress just because they gave me some advice. In the future I'll probably buy solen caps locally because thats what my local speaker store stocks.

It would be fun to try some of the super expensive caps one day to see if there is a difference. I suspect that the most important thing is to have fresh well functioning caps and that after that differences can become subejective and sometimes hard to discern.

The guys on the Klipsch forums say that the KG4's came with cheap caps to begin with, plus mine were 21 years old !

It seems to me that the best source for bargain potentialy awesome speakers is yard sales and thrift stores, especially if you're will to dig in and refresh things. I'm certainly keeping my eyes open.

Reduce, reuse, recycle: vintage rocks !

[msmpe]

[kevco]

I just added a Niles DPS-1 A/B switch box to my system today. I'm using it to switch between my Dynaco ST-70 and Marantz 2275 feeding my Klipsch Forte II's. I'm very pleased with it so far. No noticeable noise is added to the system and connection was very easy and clean. The unit is small and well built and is rated for 14 gauge cable, but 12 gauge will probably work if the wire strands are well twisted. It can also be reversed and used to toggle two sets of speakers to one amp. I'm assuming, however, that I need to make sure the switch set is properly before I fire up the Dynaco, so that there is a speaker load on the OPTs? I grabbed mine for $69 on Ebay, new in the box.
http://www.jr.com/niles-audio/pe/NIL_DPS1/

[EWBrown]

Either the Dayton or the Solen caps are a vast improvement over any non-polarized electrolytic. 150V rating is more than sufficient, don't waste your money on 400 or 600V rated caps.

The old paper and beeswax, and aged film caps really should be replaced.

The crossover inductors should be OK as is, though they could be replaced with some of the newer "tape wound" inductors, though the amount of improvement won't be as dramatic as with replacing the caps.

Any tweeter or midrange level pots are always "suspect" and should be replaced if there is any apparent intermittency. Old AR speakers were notoriously bad in this regard.

Just my dos pesos' worth...

/ed B in NC