Running amp without speakers? Good idea?

bozha · #1 06-20-2009, 11:03 AM

There is no way I can often use couple hundred watts amp+cabinet for practicing in my apartment. But still, I plan to use amp head DI for home recording and practicing with my headphones.

Is it absolutely necessary to connect speaker load prior turning the amp on? It’s a hybrid type of amp (Hartke LH500), and I found few opposite opinions, but I need to be sure, not to risk or damage anything.

Also, if I have to carry that heavy box up and down regularly, is it at least possible to keep it turned down silent all the time when practicing? Still don't want to try my chances with overheating and such…

many thanks!

RWP · #2 06-20-2009, 11:18 AM

Running an amp with tube finals is a huge NO NO. Without a load, voltages on the secondary of the output transformer can get so high they can arc and damage the transformer.

However, your amp has a solid state final and as long as you have head phones plugged in you are OK. Even without head phones plugged in it would probably be OK as most modern amps have open circuit protection built into the design. I would just make sure you run it with the head phones plugged in and not any louder than necessary.

bozha · #3 06-20-2009, 12:01 PM

It’s a bit of enigma with solid state final stage. Wish there is one definite answer…

Consider that this amp don’t have dedicated headphone output. Only DI for the mixer, which I plan to use. DI signal is not affected by EQ and master volume.

bmc · #4 06-20-2009, 12:07 PM

Drop $60-80 on a small Behringer 4 channel mixer, or similar cheap unit. They work great. Bought one for my daughter three years ago. I use it now.

B-string · #5 06-20-2009, 12:20 PM

Solid State outputs do not require a load, with no load no current is drawn so it will run happy with no load (speaker) connected. Tube amps a very different story you will need a load resistor twice it's reated output (just to be safe) and it will get hot so beaware of the fire danger. I have not seen a output transformer on a SS amp since the early 1960's so no worries there.

Bass_Pounder · #6 06-20-2009, 01:18 PM

Quote:

Originally Posted by bozha

It’s a bit of enigma with solid state final stage. Wish there is one definite answer…

Consider that this amp don’t have dedicated headphone output. Only DI for the mixer, which I plan to use. DI signal is not affected by EQ and master volume.

No enigma.........

You DO NOT need to be running a load on the amp.

BassmanPaul · #7 06-20-2009, 01:19 PM

Quote:

Originally Posted by bozha

It’s a bit of enigma with solid state final stage. Wish there is one definite answer…

There IS!

Running a SS amp that has no output transformer without a load, the vast majority, is perfectly acceptable. The amp will be quite happy working that way.

If you have a tube output stage then you mUST supply the amplifier with a suitable load.

There y' go.

Paul

billfitzmaurice · #8 06-20-2009, 03:00 PM

Quote:

Originally Posted by bozha

Wish there is one definite answer…

There is. Direct coupled SS power amps do not need a load.

bozha · #9 06-22-2009, 06:59 PM

I just got the same confirmation from Hartke customer service. This one is definitely solved.

Thank You all for answering!

JTE · #10 06-23-2009, 09:32 AM

To reiterate...

If it's a SS power amp that's direct coupled, then you don't need a load on the amp. If it's a tube amp, you MUST have a load on it.

At one Gallien/Krueger (or GMT) advertised amps that were apparently solid state amps with output transformers (way back in the dim dark days of information- I saw some ads in Guitar Player for them, and this was years and years before there were any bass rags). That's the only one I don't know about, but I'd assume that the output transformer needed a load on it.

jte

bovril · #11 06-23-2009, 03:26 PM

Hey, I just recently got a SVT and being my first tube amp, I was sure to learn all about proper use and was super anal about evertying, etc, only to come down the next day, fire it up, and try to play, and- nothing. I freak out, only to realize for some reason its not plugged into the cab. Did I do that? Why would I do that? No matter now, so I freak out more and turn it off. Give it a few minutes to recover, plug in and turn on again, and it seemed ok. Is it more likely that I got away with one or is there surely horrible damage that I dont know about yet? It was on for maybe 3 minutes with no cab...

RickenBoogie · #12 06-23-2009, 03:47 PM

You probably got away with one. I wouldn't do it again.

megadan · #13 06-23-2009, 04:19 PM

Running it for a minute without a load won't destroy it instantly. It's happened before, and it will happen again. Just try not to let it happen too much.

akaTRENT · #14 06-23-2009, 04:25 PM

I actually just did this by accident about 2 hours ago. I had my svt in standby for a minute and then realized there was no speaker load. But you dont have to worry when the amps on standby?

B-string · #15 06-23-2009, 08:16 PM

Quote:

Originally Posted by akaTRENT

I actually just did this by accident about 2 hours ago. I had my svt in standby for a minute and then realized there was no speaker load. But you dont have to worry when the amps on standby?

If the amp is in standby you have no worries, no high voltage to the output tubes or output transformer.