Can i run a solid state head without cabinet ? Vox Pathfinder.

[Thin white duke]

Hi, up until now nothing happen but i want to be sure.

Basically i want to try to use the Pathfinder 10 head as a preamp.

I plugged the last pedal in the input of the head and from the line out of the amp into a D.I. box with the cab. simulation, i really like what i'm hearing from the home stereo.

I know that you can't do that with tube amps but this is a solid state so can i do it or will i burn the head ?

Thanks a lot.

 

[mkdaws32]

Generally, this is a no no. You can cook power transistors as easy as power tubes. Many modern amps have a built in protection load that allow you to safely run without a cab so check your manual to see if it is safe with the Pathfinder.

 

[Thin white duke]

Generally, this is a no no. You can cook power transistors as easy as power tubes. Many modern amps have a built in protection load that allow you to safely run without a cab so check your manual to see if it is safe with the Pathfinder.

Ok thanks a lot, unfortunately the manual doesn't say anything about it, but for example, if i couldn't do it, would the head burn immediatly o it will damage little by little ?

 

[mkdaws32]

It could work for weeks and then just pop. Burning smell and the whole bit. Heat is the enemy of solid state electronics and when there is no speaker load (or too low of a load), the power amp runs hot.

 

[mkdaws32]

Seen it happen with solid state PAs and Bass amps mostly, but it applies to any solid state amp.

Email VOX - I’d be almost surprised if a Pathfinder doesn’t have a built in dummy load when no speaker is connected. Tech support can tell you for sure.

 

[printer2]

No, you can run them without a load. It will not hurt anything. Tubes have an output transformer that is the problem. SS amps generally do not care. If there is no current flowing (through the speaker) they do not pass any current through the transistors other than the idle current. The Pathfinder uses a chip amplifier that has protection circuitry anyway.

 

[printer2]

Seen it happen with solid state PAs and Bass amps mostly, but it applies to any solid state amp.

Email VOX - I’d be almost surprised if a Pathfinder doesn’t have a built in dummy load when no speaker is connected. Tech support can tell you for sure.

Do you recall which amps?

Generally, this is a no no. You can cook power transistors as easy as power tubes. Many modern amps have a built in protection load that allow you to safely run without a cab so check your manual to see if it is safe with the Pathfinder.

I am also not familiar with SS amps having a load inside the amps to protect itself from a no load condition. If you can indicate ones I would really love to view the schematic.

 

[DeepDangler]

Using the direct out feature won't burn out the head. It will disengage the speaker when the direct out is on. You just have a really big amp for just using it for a head.

The Vox MV50 AC will get a similar sound and works as a head and a DI box. It's about the size of a double pedal.

 

[Thin white duke]

No, you can run them without a load. It will not hurt anything. Tubes have an output transformer that is the problem. SS amps generally do not care. If there is no current flowing (through the speaker) they do not pass any current through the transistors other than the idle current. The Pathfinder uses a chip amplifier that has protection circuitry anyway.

Oh thanks man, that's a good news, i've read about output tranformers in a couple of forum, the guy said the same thing basically, i don't know if the Pathfinder has it.
Just a few people said that i will burn everything so i was afraid......

 

[schmee]

I've wondered this before using powered PA heads as just a mixer? What really gets you wondering is "can I just plug into one side of the PA head instead of both outputs?"
The manuals never seem to say anything about it.

 

[Thin white duke]

Using the direct out feature won't burn out the head. It will disengage the speaker when the direct out is on. You just have a really big amp for just using it for a head.

The Vox MV50 AC will get a similar sound and works as a head and a DI box. It's about the size of a double pedal.

Thanks a lot, very helpful, what i did i took the head off from the cabinet and it's not that huge, i can put it underneath the pedalboard, i really like the Pathfinder, i don't know if the MV 50 sounds as great......

 

[mexicanyella]

I have used a few small SS amps as line-out devices, with speaker disconnected, and haven’t had a output stage pop yet. I was also under the impression that if the speaker is not connected, I.e. open circuit, that in itself keeps the current flow stress and heat out of the output transistors.

I was first told this by the amp repair guy I knew, who was laughing at me for building a load resistor so I could use a solid state amp for silent recording! I thought I was all slick with this idea...

 

[Thin white duke]

I have used a few small SS amps as line-out devices, with speaker disconnected, and haven’t had a output stage pop yet. I was also under the impression that if the speaker is not connected, I.e. open circuit, that in itself keeps the current flow stress and heat out of the output transistors.

I was first told this by the amp repair guy I knew, who was laughing at me for building a load resistor so I could use a solid state amp for silent recording! I thought I was all slick with this idea...

Great, thanks a lot, i'll probably do that then.....it won't explode.

 

[printer2]

I've wondered this before using powered PA heads as just a mixer? What really gets you wondering is "can I just plug into one side of the PA head instead of both outputs?"
The manuals never seem to say anything about it.

If it is SS you can run one channel.

And as far as my opinion goes and being just some guy on the internet, I had an Electronics License as well as a few more qualifications that said I can work on stuff and not blow it up (or if I blow it up I can repair it, you know, stuff happens). Retired now and did not bother paying for the licenses as WORKING FOR A LIVING SUCKS. Well, it wasn't so bad, I like this better though.

 

[mkdaws32]

Do you recall which amps?


I am also not familiar with SS amps having a load inside the amps to protect itself from a no load condition. If you can indicate ones I would really love to view the schematic.

I used to do SS amp repair years ago on the side, so nothing recent - I have a 2-year community college diploma in electronics engineering, but went a different direction with my main career . I've seen this happen with some old peavey power amps (CS series) - one particular CS-800 had a massive failure, shorting out several power transistors after having it running for months with a 2 ohm load. I think it was rated for 8 ohms. Also I recall a Yamaha B100 that failed in the same way. The guy had a number of cabinets cascaded reducing the load way below spec and blew out the power transistors. Car audio amps too.

I just assumed, based on my experience with larger solid state amps, that newer lower watt amps that allowed operation without a connected cabinet would need a dummy load. It's entirely possible that todays devices have a higher heat tolerance and that this is less of an issue with lower wattage amps. I still wouldn't run any amp without a load unless it was specified by the manuafacturer.

 

[nojazzhere]

Hi, up until now nothing happen but i want to be sure.

Basically i want to try to use the Pathfinder 10 head as a preamp.

I plugged the last pedal in the input of the head and from the line out of the amp into a D.I. box with the cab. simulation, i really like what i'm hearing from the home stereo.

I know that you can't do that with tube amps but this is a solid state so can i do it or will i burn the head ?

Thanks a lot.

I'm gonna say....YES....go ahead and do it (a lot!) Then please report back to us periodically as to how it goes. This way, we take the guesswork out of the equation next time this question is asked.....
.....and thanks for doing the "heavy lifting".

 

[printer2]

I used to do SS amp repair years ago on the side, so nothing recent - I have a 2-year community college diploma in electronics engineering, but went a different direction with my main career . I've seen this happen with some old peavey power amps (CS series) - one particular CS-800 had a massive failure, shorting out several power transistors after having it running for months with a 2 ohm load. I think it was rated for 8 ohms. Also I recall a Yamaha B100 that failed in the same way. The guy had a number of cabinets cascaded reducing the load way below spec and blew out the power transistors. Car audio amps too.

I just assumed, based on my experience with larger solid state amps, that newer lower watt amps that allowed operation without a connected cabinet would need a dummy load. It's entirely possible that todays devices have a higher heat tolerance and that this is less of an issue with lower wattage amps. I still wouldn't run any amp without a load unless it was specified by the manuafacturer.

Those Peaveys are usually quite reliable. The Yamaha I will have to look up the schematic, I have their 220W PA amp, it spent two years on the road. Yamaha is also a manufacturer that is usually pretty reliable. Car amps, that is the wild west as far as I am concerned, anything goes. I took a 2 year program, went into Instrumentation the second year. Took me some interesting places to work. My brother did the Electronics course and had been doing design for 35 years. A different game now days, almost like everything is disposable. I hope some of the manufacturing comes back here.

 

[Thin white duke]

I'm gonna say....YES....go ahead and do it (a lot!) Then please report back to us periodically as to how it goes. This way, we take the guesswork out of the equation next time this question is asked.....
.....and thanks for doing the "heavy lifting".

Thanks for supporting me man , i'm gonna go ahead and do it, if i'll fry the head i will lose 50 Euro, not a big deal .
Today i played this way for about one hour, nothing strange happened, let's see tomorrow what's gonna happen.....

 

[printer2]

The right hand corner triangle is the IC power amp, a TDA2030. It has been used in countless products, heck, I got a few downstairs.

 

[printer2]

Thanks for supporting me man , i'm gonna go ahead and do it, if i'll fry the head i will lose 50 Euro, not a big deal .
Today i played this way for about one hour, nothing strange happened, let's see tomorrow what's gonna happen.....

Yours was an easy one. I already knew what was in the Pathfinder.