UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Audio (record players, hi-fi etc)

Notices

Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

Reply
 
Thread Tools
Old 25th Jan 2023, 2:55 pm   #21
Phil__G
Hexode
 
Join Date: Mar 2011
Location: North Yorkshire, UK.
Posts: 431
Default Re: Using a speaker switch

How about this, no breaks, no 2 ohm parallels, no resonating...
This is one channel, repeat for the other...
Attached Thumbnails
Click image for larger version

Name:	IMG_20230125_145315.jpg
Views:	49
Size:	29.2 KB
ID:	272153  
Phil__G is offline   Reply With Quote
Old 25th Jan 2023, 3:14 pm   #22
Nickthedentist
Dekatron
 
Nickthedentist's Avatar
 
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 16,901
Default Re: Using a speaker switch

Agree with David et al.

I too would never switch speakers on a transistor amp without switching off (and ideally waiting a couple of seconds) first. It's just not worth the risk, especially as genuine vintage replacement transistors are now almost impossible to source.
Nickthedentist is online now   Reply With Quote
Old 25th Jan 2023, 3:44 pm   #23
lesmw0sec
Octode
 
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,317
Default Re: Using a speaker switch

I would suggest that all that is required, is to turn the volume down to zero when changing over. Turning the amp. off should not be necessary.
lesmw0sec is online now   Reply With Quote
Old 25th Jan 2023, 3:48 pm   #24
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 20,886
Default Re: Using a speaker switch

Many amplifiers are DC coupled and give several milliamps DC into a typical speaker. If not well adjusted this can be quite a bit more. Low risk, but not zero. Unlikely enough to be a killer.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline   Reply With Quote
Old 25th Jan 2023, 4:09 pm   #25
mhennessy
Dekatron
 
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,108
Default Re: Using a speaker switch

I have an Arcam Alpha 2, which uses the same power amplifier as the 3.

It has current limiting and "catch" diodes, as well as output fuses. I would have no concerns about using it "live" with a speaker switch. I routinely change speaker connections without powering down amplifiers, and have never had an issue. No competently designed amplifier should be bothered by sudden disconnection or accidental short circuit when silent or playing quietly. Remember; a just a couple of volts is a lot of noise given that speakers generally produce anywhere between 80 and 90dB when driven with 1 watt.

In the highly unlikely event that the Arcam does suffer, it's an easy amp to repair as it mostly uses transistors that are easy to source (TIP2955/3055, BC547, etc). The exceptions are the drivers, VAS and VAS current load, being FST239/240 and MPSA056, but it won't be impossible to find substitutes.

Obviously, I have this viewpoint because I'm able to do a repair if necessary, so the "consequence" part of the risk assessment (likelihood-times-consequence) is just a minor irritation for me. If you have to pay someone to repair an amplifier that fails, the consequence is higher. But as the "likelihood" side of the equation remains vanishingly small, it's still a very low risk, whatever your position.

It's worth saying that power-cycling amplifiers is not completely risk-free either...

And please don't wire speakers systems in series! Remember that the impedance varies wildly with frequency, so they won't sound anything like the designer intended. Parallel is fine. I used that Arcam to power a 4 ohm subwoofer for many years - it never complained.
mhennessy is offline   Reply With Quote
Old 26th Jan 2023, 10:28 am   #26
Diabolical Artificer
Dekatron
 
Diabolical Artificer's Avatar
 
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 6,922
Default Re: Using a speaker switch

I had one of these speaker switch boxes, it lasted about a month before the switches failed. I now use 4mm banana jacks with a "U" shaped patch to sw between my various amps, no issue's so far.

Some of the lads over on DIY audio have built quite complex speakers sw's using relays, no idea if they're any better than the speaker sw boxes comercially available.

Andy.
__________________
Curiosity hasn't killed this cat...so far.
Diabolical Artificer is offline   Reply With Quote
Old 26th Jan 2023, 3:45 pm   #27
Edward Huggins
Dekatron
 
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 7,730
Default Re: Using a speaker switch

I hope that this does not appear as too intrusive, but noting Martin's comment in his Post #5, surely using two other speakers as speaker "stands" is not the best possible way to enjoy decent stereo sound?
__________________
Edward.
Edward Huggins is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 1:17 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2023, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.