Running amp heads without speakers

[graham1945]

OK, showing my ignorance here, after fifty years of gigging. Could probably get the answer elsewhere, but it is good value to see where this thread goes!!!
I read somewhere that you should never run a valve amp without speakers, however, does the same apply to all transistor and the new class D amps? In other words could I use a class D amp as a preamp only without connecting it to speakers?
Thanks,
Graham

[Mr. Foxen]

It isn't the class, it is the presence of an output transformer that means an amp needs a speaker load. So for the most part any solid state amp you encounter will probably be fine without a speaker. Only exception I can name is the Warwick Hellborg sig power amp, which has an OT, but others exist.

[paul_5]

+1. Hybrid amps (valve pre, solid state power) such as the Hartke LH and HA stuff, SWR 220, Ampeg SVT3 and 7 Pro etc... are all fine without speakers.

As a general rule of thumb - if it's REALLY HEAVY then it needs a speaker!

[graham1945]

Cheers fellas, great response! Pity the manufacturers don't mention this in their manuals.
Thanks again,
Graham

[bassmachine2112]

I,ve just got an Orange terror bass head and cab-500 watt one
you can put it on standby and the DI line will give a signal to mixing desk for recording/PA whatever,pretty neat trick that

[Mr. Foxen]

A standby should cut the HT to the valves, which should disable the preamp. So either it isn't a standby, or the DI signal isn't going through the valves.

[Bassman Steve]

Curiously the Mesa Bass 400 and 400+ can be run without speakers with the master volume on 0 - according to the manual. Not sure I'd actually do it but it says you can.

[Dad3353]

[quote name='Bassman Steve' timestamp='1369045581' post='2084130']
Curiously the Mesa Bass 400 and 400+ can be run without speakers with the master volume on 0 - according to the manual. Not sure I'd actually do it but it says you can.
[/quote]

Any (or, at least, most...) valve amps can be run without speakers if there's no i/p, or volume at 0. Not a good idea, of course, and no point if you want to hear something, or use the pre-amp section. Can be useful for technicians on the bench, but not recommended in 'real life' situations. Don't be tempted, it's not worth it if it goes wrong.

[flyfisher]

[quote name='Mr. Foxen' timestamp='1368870432' post='2082420']
It isn't the class, it is the presence of an output transformer that means an amp needs a speaker load. So for the most part any solid state amp you encounter will probably be fine without a speaker. Only exception I can name is the Warwick Hellborg sig power amp, which has an OT, but others exist.
[/quote]

That's also my understanding, but there's a lot of confusion about it - probably because hi-fi amps (mostly solid-state) always seemed to state that they should not be operated without speakers connected. So, having been brought up with such advice it just doesn't seem 'right' to me to operate any amp without the speakers connected.

[BassTractor]

[quote name='flyfisher' timestamp='1369055379' post='2084292']
hi-fi amps (mostly solid-state) always seemed to state that they should not be operated without speakers connected.
[/quote]

Indeed, they sound better with speakers than without.
Seriously though, I have not met this in my Hi-Fi years. Regular Hi-Fi amps "love" operating without speakers, as they are very lazy, and not having to deliver any Ampere is a great, relaxing state for them.

best,
bert

[Dave_the_bass]

I can't speak for all amps out there, but I own a shuttlemax 12.2, the one with two 600W at 4ohm power amps.

The manual states that it's a 375W in to 1 8ohm cab, this is how the head runs in the practice room, with no load on the other power amp.The manual also says that it can be used without a cab and just headphones plugged in to the headphone socket for silent practice, I did this once when I first got the head, no ill effects but it felt wrong!

So it would seem that some amps are fine while others are not. If in doubt, don't risk it!

[gsgbass]

My class D, TC Electronic RH450 posts on the back of the head, ok to run without speakers. Not all heads will work without a connection. When in doubt, contact the manufacturer.

[graham1945]

Just an update on my original query, I've just bought one of the new Ampeg PF800 amps and in the manual it specifically states that it can be run without loudspeakers connected - (for practice purposes using the headphone and music input sockets). Thanks Ampeg, very helpful, along with all of the advice in this thread.

[Bill Fitzmaurice]

[quote name='graham1945' timestamp='1368869585' post='2082400']
I read somewhere that you should never run a valve amp without speakers, however, does the same apply to all transistor and the new class D amps? In other words could I use a class D amp as a preamp only without connecting it to speakers?
[/quote]Valves need a load, SS doesn't. Most valve amps short the output just in case you forget to plug speakers in, to prevent damage.