Amp trouble/ am I wrong?

[Prosebass]

This one is going round in circles now.
I think what has been established is that provided a cab (cabs) is matched to an amp correctly no harm should come of it.
With modern solid state amps, running at 8ohms as opposed to 4ohms puts less electrical strain on the amp. (lower wattage / lower current flow)
Amps sometimes fail (for various reasons)
Mathematics dictate volume/loudness (SPL) not hearsay or witchcraft.
High efficiency speakers (sensitivity in dB) can double (10dB) the loudness of an amp.

If we bring valve amps into the equation it gets much more complicated.

[Maude]

Sidestepping the bickering for a moment ,
@ the OP, I assume the band uses a PA, another option would be to run into the PA and just use a smaller amp as a monitor.
This is what I do, I use a Line6 X3 Live and run an output to the PA and an output to my amp, I only use an Ashdown Perfect10 Minirig which is a 60w head into two 10" cabs.
When playing gigs this works well as you can turn up or down the Ashdown to hear yourself but it won't change the sound out the front which is through the PA.
At rehearsals I can hear perfectly well running the amp at half volume competing with two guitarists, one using a Rickenbacker and Jam fetish so loud and 'spiky', and a very hard hitting drummer.
If your amp, or one you get, doesn't have a DI output then a Behringer BDI21 will do the job very well for around £25/£30.
It's just an option and will save you a lot of money on expensive amps, but where's the fun in not buying big amps eh?

[0175westwood29]

[quote name='xgsjx' timestamp='1394274174' post='2389725']
I know never said running a single 4 ohm cab is rubbish, I just advised that it puts an extra strain on the amp.
You do realise that most bass amps are effectively 2 amps? There's the pre amp & the power amp. If you've set the volume on your bass quite low & set the input gain to just under clipping, then turning the instrument up would cause the pre amp to clip, which could damage the cab's drivers.
Increased current draw increases the chance of the power amp clipping.
I never said it would cause the amp to fail (though it could, especially if the amp is 2nd hand), but more likely to need serviced sooner.
If someone is given advice to get a single 4 ohm cab, don't you think it's wise to know the pros and cons?
It's like telling someone with a car that it's good to run upto the red line before changing gear as you'll get there quicker.
[/quote]

no problem keep believing that people would sell things that even doing what there designed to do may go wrong.

[Musky]

[quote name='0175westwood29' timestamp='1394279937' post='2389801']
no problem keep believing that people would sell things that even doing what there designed to do may go wrong.
[/quote]
Ampeg PF500, Ashdown Superfly?

[Prosebass]

[quote name='Musky' timestamp='1394287651' post='2389915']
Ampeg PF500, Ashdown Superfly?
[/quote]

And many others. The forum is littered with amp fail threads.
[topic='185862'][/topic]

Edited March 9, 2014 by Prosebass

[Guest bassman7755]

[quote name='Musky' timestamp='1394287651' post='2389915']
Ampeg PF500, Ashdown Superfly?
[/quote]

If a particular amp model if know to have reliability problems when operating with its alleged design parameters then its not an amp Id want to rely on under any circumstances as it implies its not a robust design in the first place and/or its being built with underspecified components.

Or to put it another way: if an amp has a marked increase in failure rate between 8 and 4ohm then its failure rate at 8 ohm is probably still significant (even if lower than at 4).

Edited March 9, 2014 by bassman7755