Amp Head shuts off, might be mismatched Ohms?

[Mikea59]

Hey guys, so I recently dug up my old amp head which is an Eden NA-600 Head. This head is rated at the following:

630W RMS @ 2 Ohms
435 Watts RMS @ 4 Ohms
270 Watts @ 8 Ohms

So, I went out and bought a cab. I ended up getting the Hartke VX410 which is rated for 400 watts @ 8 ohms.

Eden Docs: Invalid Link Removed

Hartke Docs: SamsonTech

The issue is that we started playing and after maybe 5 minutes the sound just stopped. The head was still on of course but no signal going to the cab. I was confused so I unplugged and replugged the cable into the input jack and the sound came back immediately only to cut out again in a few seconds. I tried shutting it off then back on, nothing seemed to actually keep the sound on permanently as it would come back and then cut out after 10 seconds at the most.

So, then I began looking at the power ratings and thought that it was a mismatch going on between the two. Now, if the cab is 400 W @ 8 ohms and the head only pushes out 270 W @ 8 Ohms than I would think I wasn't overloading the head, but obviously something is happening here. I suppose it could be my dirt pedals which add to the front load maybe?

I'm extremely confused as to the whole matching of Ohms, can someone please explain how this works to me? Given my cab, what kind of Power rating do I need to look for in a head that will give me the greatest amount of volume without damaging the speakers? For my current project, loudness is literally the only thing I am concerned with as I use so many pedals, I won't have to worry about having an authentically clean bass tone.

 

[Mushroo]

Your head should have no problem driving a single 8 ohm cab. There is no mismatch. Something else is wrong.

Did you test the cab at the store before you bought it? Can you borrow another cab and head from a friend, to test whether the head works okay with a different cab, or whether the cab works okay with a different head? Does the Eden head get warm to the touch before it shuts down? Is the fan operating correctly? Are you using a tested, known-good speaker cable (not an instrument cable)?

 

[Mikea59]

Oh right! I totally forgot to mention the critical part. I took this crappy little combo amp and then just connected the cab to it and it powered it just fine. That amp was, SWR WorkingMan's 15 (160/200W)

https://www.musiciansfriend.com/amplifiers-effects/swr-workingmans-15-bass-combo-amp

It was nice and loud like before the other head just crapped out on me. I went a full 2 hrs jamming at high volumes with ZERO issues when I set it up like this...

Also, I am pretty sure I was using an Instrument Cable in both case as above instead of as speaker cable. Maybe it's that?

 

[mmbongo]

Yes you definitely cannot use an instrument cable as a speaker cable. Fix that first then try again. That amp should be able to drive a single eight on cabinet all day long and not even get warm.

 

[Zooberwerx]

Doesn't sound like an impedance self-preservation shutdown...may be thermal but internal and not protection mode. Here's a quick & cheap litmus test:

Run a common T/S signal cable (instrument) between the FX sends and returns. Historically, they are notorious for the described anomaly.

Riis

 

[Mikea59]

I will try the above. It is worth noting though that in the past (talking 10 years ago) I had this same head with this same exact issue. The only difference was I was running an Acme B-4 Low cab and I was using those special connectors, can't remember the name where they lock in. But it was the same issue albeit it was happening after maybe 20 or 30 minutes of play time at high volume.

However, I just purchased the appropriate cable from amazon and will test out this theory this week at some point! Anything else I should look into?

 

[Mushroo]

If I understand correctly, your Eden head has been having this issue for 10 years?
If that is the case then no, a new speaker cable from Amazon probably won't solve the problem.
I'd take it to a tech.

 

[Zooberwerx]

I will try the above. It is worth noting though that in the past (talking 10 years ago) I had this same head with this same exact issue. The only difference was I was running an Acme B-4 Low cab and I was using those special connectors, can't remember the name where they lock in. But it was the same issue albeit it was happening after maybe 20 or 30 minutes of play time at high volume.

However, I just purchased the appropriate cable from amazon and will test out this theory this week at some point! Anything else I should look into?

The aforementioned speaker cable is "Speakon"...good call for any amp >< enclosure interconnect. You can trial the FX send/return with a common instrument cable.

Riis

 

[96tbird]

So you pulled an amp out that was broken 10 years ago, and it’s still broken? Seems about right.
¯\_(ツ)_/¯

 

[S-Bigbottom]

It is worth noting though that in the past (talking 10 years ago) I had this same head with this same exact issue.

Take the Amp to a Repair Shop and DO NOT USE IT ANYMORE, before it blows something more expensive inside it.
It did not heal itself during storage.

 

[96tbird]

Edit. Posted in the wring thread!!! Lol

 

[Zooberwerx]

So you pulled an amp out that was broken 10 years ago, and it’s still broken? Seems about right.
¯\_(ツ)_/¯

Riis's Rule of All Things Electro-Mechanical: **** that's truly broken doesn't repair itself.

Riis

 

[BogeyBass]

If the amp had no signal

Then you unplugged the INPUT
And then reinsert the INPUT and got signal

Then this would mean more than likely the input jack has issues and has always been the problem.

This is a common problem with alot of input jacks.

Either the interal contacts of the input jack are corroded or bent out of shape.

Or most likely it's a board mounted input jack. And unplugging, plugging into this jack. Works the solder connections loose.

The solder connections need to be touched up, or just replace the jack. Sometimes you can clean them but sometimes the actual connection taps inside the jack are just worked loose.

This is a 2 ohm stable amplifier.
A 8 ohm load would not cause it to overheat.

Unless of 2 things. The output jacks have the same problem as the input jack. The board connections need re solder or the actual jack is going intermittentant

Or if there is a disconnected driver like a tweet or a bad crossover component. Or again bad connections on the crossover board. This can present a load that is not 8ohms across all the frequency range.

Doubtful cause unplugging a input jack and reinserting will not make fault protection un trigger.

More than likely it's a poopy input jack.
Very simple easy common problem with many amplifiers.

 

[Slevage]

I will try the above. It is worth noting though that in the past (talking 10 years ago) I had this same head with this same exact issue. The only difference was I was running an Acme B-4 Low cab and I was using those special connectors, can't remember the name where they lock in. But it was the same issue albeit it was happening after maybe 20 or 30 minutes of play time at high volume.

However, I just purchased the appropriate cable from amazon and will test out this theory this week at some point! Anything else I should look into?

Broke 10 years ago and didn’t heal itself.

 

[frankie5string]

Hmmmm... I remember that Eden Nemesis head fondly. It had great tone no matter what bass I ran through it.
I see they never fixed the typo "Quazi..." in the manual. That always made me laugh.

That amp has an effect send/return that breaks the link to the power amp when you insert something into the loop. Have you tried running a cable from post to pre? Does that stop the cut-off? Also, try inserting and removing a cable from the post and pre plugs a few times. It could just be corrosion on those jacks causing the normal-on to fail from vibration.

 

[JoeWPgh]

So you unplug and replug the speaker wire and it works again for a bit? My guess is that the problem is the output jack

 

[Jaco who?]

Ten years worth of lint and dust clogging up the fan and the vents to cool the poor thing might be putting it into thermal protection after a few minutes of use. If the proper cable doesn't solve the problem, you might try removing the cover and carefully vacuuming it out. Even if the cable solves the problem, do it anyway.

 

[Al Kraft]

Also, I am pretty sure I was using an Instrument Cable in both case as above instead of as speaker cable. Maybe it's that?

Until you eliminate a known problem that can cause problems, there is no reason to go hunting for other issues IME.

 

[bassgrackle]

Sounds like heat issues. These heads have a safety cut off when they over heat. Is the fan running?

Hey guys, so I recently dug up my old amp head which is an Eden NA-600 Head. This head is rated at the following:

630W RMS @ 2 Ohms
435 Watts RMS @ 4 Ohms
270 Watts @ 8 Ohms

So, I went out and bought a cab. I ended up getting the Hartke VX410 which is rated for 400 watts @ 8 ohms.

Eden Docs: Invalid Link Removed

Hartke Docs: SamsonTech

The issue is that we started playing and after maybe 5 minutes the sound just stopped. The head was still on of course but no signal going to the cab. I was confused so I unplugged and replugged the cable into the input jack and the sound came back immediately only to cut out again in a few seconds. I tried shutting it off then back on, nothing seemed to actually keep the sound on permanently as it would come back and then cut out after 10 seconds at the most.

So, then I began looking at the power ratings and thought that it was a mismatch going on between the two. Now, if the cab is 400 W @ 8 ohms and the head only pushes out 270 W @ 8 Ohms than I would think I wasn't overloading the head, but obviously something is happening here. I suppose it could be my dirt pedals which add to the front load maybe?

I'm extremely confused as to the whole matching of Ohms, can someone please explain how this works to me? Given my cab, what kind of Power rating do I need to look for in a head that will give me the greatest amount of volume without damaging the speakers? For my current project, loudness is literally the only thing I am concerned with as I use so many pedals, I won't have to worry about having an authentically clean bass tone.

 

[Ekulati]

... this crappy little combo amp...That amp was, SWR WorkingMan's 15 (160/200W)

Ouch. Definitely NOT a crappy little combo amp.