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Bass head runing without a speaker load... harmful?
- Thread starter Jaruquin
- Start date
It is only harmful if you have a tube output section. You MUST have a speaker load when using a "tube" amp. SS, class D, do not need a load even if they have a tube preamp section.
Hi.
If it's the SM-900 in Your profile, then no, it doesn't need a (speaker) load.
As a rule of thumb, output transformer of some sort always means that a load is absolutely necessary for safe and correct operation.
Regards
Sam
If it's the SM-900 in Your profile, then no, it doesn't need a (speaker) load.
As a rule of thumb, output transformer of some sort always means that a load is absolutely necessary for safe and correct operation.
Regards
Sam
Hey B do most repair shops understand that all tube amps require a cab when the amp is on?
I took my 2nd hand tuber to a very busy repair facility and almost wanted to remind the intake guy, but realized that was meaningless since he did not even write much of anything down when I told him what was going on with the unit.
My local used gear store had a Mesa 400 non plus in good cosmetic condition and it was sitting unconnected to a cab in at least standby but maybe full on position. Price was great, but even after I confirmed it played loud I just could not deal with the thought of multiple wanker plug ins and clueless store jockeys leaving it on for days without a load.
Or is that an overstated worry.
I took my 2nd hand tuber to a very busy repair facility and almost wanted to remind the intake guy, but realized that was meaningless since he did not even write much of anything down when I told him what was going on with the unit.
My local used gear store had a Mesa 400 non plus in good cosmetic condition and it was sitting unconnected to a cab in at least standby but maybe full on position. Price was great, but even after I confirmed it played loud I just could not deal with the thought of multiple wanker plug ins and clueless store jockeys leaving it on for days without a load.
Or is that an overstated worry.
If the amp is in standby no load is needed. Off standby the high voltage is on and a load, either a speaker cab or a dummy load is a must with an OT (any signal even hum can cause output swing and damage may result). Any repair shop that handles tube amps will know this.
i have my old Fender Bassman 100 head turned on without a cab several times (accidentally, of course!) and nothing ever happened to it.
although, sme techs told me old Fenders have very resistant trafos so they can handle it.
But, either way it's not smart to do it
although, sme techs told me old Fenders have very resistant trafos so they can handle it.
But, either way it's not smart to do it
Would you please list those for us, so we know what not to do? I have a hunch it's going to be a very short list.
i have my old Fender Bassman 100 head turned on without a cab several times (accidentally, of course!) and nothing ever happened to it.
although, sme techs told me old Fenders have very resistant trafos so they can handle it.
But, either way it's not smart to do it
The first output jack shorts to ground with no plug inserted.
I don't think that is true. I seem to remember from a Bass Gear Mag review that even though the head has an impedance switch and puts out the same power into 8ohms and 4ohms, it is done using a compression/power management circuit, not a transformer.
I think anyway......!
The only SS amp bass that I am aware of that uses an output transformer is the Warwick Hellborg power amp(s)
Yes the list of SS amps with OTs is short, the list of OTL Tube amps is short. Very simple for a poster to mention the amp make and model instead of "can I plug in here"?
Terror Bass does not have an OT BTW that I have seen, the "impedance" switch is not connected to a OT secondary.
Ken, I figured as much as well, but I was curious and I pulled this off the Orange forum:
With no plug in the speaker jacks the amps output is shorted to ground (tubes are okay with this but will run very hot). Not all tube OT amps short the output like this, if they do not the OT secondary is an open circuit and damage is very possible.
