Combining -ve lead - two pairs of speakers and one Quad 303 amp?

[surv1v0r]

Would there be any problems associated with combining the -ve signal leads from two pair of speakers (not joining left and right) - i.e.
Quad 303 Amp Left -ve to -ve Left speaker 1 and Left speaker 2
and
Quad 303 Amp Right -ve to -ve Right speaker 1 and Right speaker 2 -ve
The +ve leads would be routed through a pair of single pole double throw (SPDT) light switches.

This is a temporary measure to allow quick and dirty comparison between two pairs of speakers. In theory it would allow me to set the switches such that I could listen to Speaker Pair A Left and Speaker Pair B Right; in practice I would typically be listening to either Speaker Pair A Left -or- Speaker Pair B. - IT IS NOT INTENDED AS A PERMANENT SETUP.

[The Barbarian]

http://www.ebay.co.uk/itm/QED-MA17-Two-way-Speaker-Switching-unit-/271736918619?pt=UK_Sound_Vision_Other&hash=item3f44c8525b

[StanleyB]

If you want quality then a better suggestion would be a TC-7220 MKII. (http://www.homehifi.co.uk/S/tc-7220.htm)

[surv1v0r]

Thanks for the suggestions, I know that commercial solutions are available, some are undoubtedly very good, some may not be quite so great. However, Ideally I would just like temporarily to use what I happen to have lying about (e.g. alight switch and some electrical "chocolate block" connection strip - so long as it does no harm!

[The Barbarian]

wiring speakers in series or parallel from one power amp will not let you analise the sound difference between each pair.

[struth]

I would have thought that it would work ok. There will be some degredation through the switch but as only the negs are connected it shouldn't harm anything

[surv1v0r]

Well, I made up the crude DIY speaker switch as described in the opening post and it works absolutely fine :)

13855

[cloth-ears]

To be honest that’s not a good way to compare speakers. In order to make a realistic comparison both sets of speakers would have to be played at identical volume levels. Different speakers have different efficiency’s. The same one watt would sound louder or softer depending on many factors within the speakers design such as cabinet size, impedance, and so on. In many cases the loudest pair would initially sound better. The only good way to compare would be to use two identical amplifiers sharing a common input source

[The Barbarian]

+1

[Reffc]

Be aware that by doing this, you're essentially wiring the speaker loads in parallel, so it the speakers are nominally 8 Ohms, the amp will see a 4 Ohm load. That might be ok as the 303 has quite a stable output circuit, but if the speakers are a 4 ohms, load, you will be asking quite a lot of the amp. It was designed to run the ESL57, which was a notoriously difficult load (82dB/1w/1m and a minimum impedance of 1.8 Ohms (HF)). However, it's not really up to spending most of its time driving a low frequency load of a few ohms as you could end up pushing it into clipping which wont do the amp or speakers any good. It all depends on the speaker loads.

Edit: just seen that you'd fit a switch so you could flick between speakers...in which case, it should be ok.

[The Barbarian]

I dunno if anyone is the same but i can hook a pair of speakers up listern disconnect them wire another pair up & still have the ability to hear the difference..Ive never understood this critical A/B Listerning thing..

[walpurgis]

I dunno if anyone is the same but i can hook a pair of speakers up listern disconnect them wire another pair up & still have the ability to hear the difference..Ive never understood this critical A/B Listerning thing..

Exactly! :exactly:

[Barry]

I dunno if anyone is the same but i can hook a pair of speakers up listern disconnect them wire another pair up & still have the ability to hear the difference..Ive never understood this critical A/B Listerning thing..

+1 , there is no need to have instantaneous change over.

[Marco]

...there is no need to have instantaneous change over.

Unless you’ve wet yourself with excitement in the process of discovering an improvement ;)

Marco.

[Barry]

Unless you’ve wet yourself with excitement in the process of discovering an improvement ;)

Marco.

One thing I do have is a strong bladder. :lol:

[struth]

Aye but some folk like old mentally damaged guys like me dont have a memory that stretches longer than .....what was I saying.............:doh:

[zanash]

ditto

[The Barbarian]

I even have the ability of a sound recollection of certain amps from 30 years ago..must be wonder boy or summert

[Marco]

Aye, but can you remember what happened yesterday? ;)

Marco.

[The Barbarian]

:lolsign:

[walpurgis]

I even have the ability of a sound recollection of certain amps from 30 years ago..must be wonder boy or summert

Ditto. I can recall how just about every bit of gear I ever had sounded, even the differences I heard between cables.

[surv1v0r]

Well, I have made this DIY speaker switch (the +ve leads routed through a pair of single pole double throw (SPDT) light switches) and it has worked perfectly well for weeks.

14296

[Firebottle]

Excellent, it doesn't need to be complicated :thumbsup: