[CButterworth]

Having got my preamp working, I am now decommisioning my passive preamp.  My new preamp is tube-based and so far has one input and one output, and a stepped attenuator volume control.  My original plan had been to install extra inputs and an input selector.  However, I am loathed to do this and have a possible alternative.

My tuner is actually a Sherwood 100Wpc amp.  I never used the amp side of things, and took the tuner output into my AKSA 55N.  The Sherwood has a number of other inputs such as DVD, TV, etc.  As I really don't think that vacumm-tubes and AKSA are really going to enhance our TV, radio, and DVD enjoyment, I was thinking of using this amp for these items, leaving my tube-preamp and AKSA for CD's.

Right now, I have speaker cables running from my AKSA to my speakers.  They are not biwireable.  Would it be sonically detrimental to have another set of speaker cables connecting to the speakers - these comming from the Sherwood?  Of course, I would only have one amp turned on at any one time.

I'd appreciate opinions, as my guess is that there should be no problem at all on doing this.

Charlie

[avahifi]

Whoops!  Connecting two amps to one set of speakers is blowup city because each amp sees the low output impedance of the other amplifier as the load, through the shared speaker cables.

Don't ever do this, even with a switch, because the switch will always be inadvertently misused, turning into an amplifier destruct button.

Been there, seen it happen.

Regards,

Frank Van Alstine

[CButterworth]

Frank,


Cr*p!  I was hoping that I could get this to work.  I wonder what other folk have done?   I was really wanting to avoid having to drill my preamp chassis for a selector switch.

OK, what if I do the following:

[CButterworth]

How do I attach images????

[CButterworth]

OK,

What about this?

[AKSA]

Charlie,

Frank is spot on.  Don't do it......

Your second option is fine, should work very well.  Do keep the switch electrostatically shielded by placing in an earthed box.

Cheers,

Hugh

[CButterworth]

Hugh,

Good, I'll consider the pros and cons.  My current passive -preamp  is in a metal box, with input grounds bussed to the chassis.  I expect that I would not connect the cd/preamp input to chassis-ground at all, and ensure that the output is not grounded to the chassis.

What precautions would I have to take to avoid damage if the preamp was switch on without being switched to the output to the AKSA???

Maybe it simply would be easier to play everything through the preamp afterall.

Charlie

[AKSA]

Hi Charlie,

You wrote:

What precautions would I have to take to avoid damage if the preamp was switch on without being switched to the output to the AKSA???

It would be fine;  preamps do not need to be loaded.  But be sure that the switch has low capacitance, so as to avoid crosstalk!  You would be amazed what you can hear through a switch if the parasitics are high......

Maybe it simply would be easier to play everything through the preamp afterall.

Certainly, that might be true, but do you really want the easy solution, Charlie?  Come on now - we all like the more complicated solution - it's the human condition!!     (Sorry, a little British humour - note spelling - 'Brahms Third Racket' if you recall your John Cleese!)


Cheers,

Hugh