Common Questions: SpeakOn types and "Can I use my amp without a cab"?

[groovaholic]

I've talked to a few people here and on Facebook about these questions, so I thought I'd share here:

SPEAKON TYPES:
SpeakOn plugs are all upward compatible; you can connect an NL2 cable into an NL2 or NL4 jack - an NL4 cable can go into an NL4, but not an NL2 jack.

There's also an NL8 that's much more common in pro-audio than instrument amps, and IIRC an NL4 plug can also connect to the center of an NL8 jack, but I'm not aware of any bass gear that has NL8 connectors.

Because of this, a cable with NL2 ends can go into ANY SpeakOn connector - but an NL2 jack can only accept NL2 plugs.

Most cabinets might accept an NL4, but they're generally only using 2 of the conductors, so the NL2 is all you need...and a cable with NL2 plugs is guaranteed to work into any bass amp or cabinet with Neutrik connectors.

GK used the NL4 originally because their amps (700RB, 1001RB, Fusion 550) were bi-amp capable and actually needed all 4 conductors; the woofer signal was on conductors 1+ and 1- and the tweeter signal was on 2+ and 2-.

When they got rid of the bi-amp feature, they went to NL2 on the amps.
To an engineer like Bob, it made sense to get rid of an unnecessary feature - but GK got an earful from their customers because the SpeakOn cables the customers had bought for their earlier GK amps no longer fit.

So GK went back to NL4, even though the newer amps only use 2 of the conductors.

Since I'm not doing any biamping or bridging, I've installed NL2 on all my speaker cables to ensure I can use them on most gear.
Installing NL2 ends is (IMO) as easy as replacing the plug on a toaster or table lamp.

"Can I use My Amp Without a Cabinet Attached?"
The only amps that ever require a speaker to be connected are amps with an output transformer - and 99% of the time that means amps with tubes in the power amp; Ampeg SVT, Mesa Bass 400+, Orange AD200, etc.
[The 1% are solid-state amps with an output transformer like larger McIntosh amps or the Warwick Jonas Hellborg power amp]

The output transformer is what turns the voltage in the amp into the current that moves the speakers.
Without a speaker, all that voltage goes into the transformer but can't get out, which can destroy the output transformer - and that output transformer is generally the most expensive single component in the amp.

So if your amp has power tubes, you need a speaker connected when the amp is on. There are exceptions, but that's the general rule.

A solid state amp, and amps that just have tubes in the preamp (like Ampeg SVT3/4/6/7Pro, Mesa WD800/TT800, Orange Terror Bass) will be fine without a speaker connected because solid state power amps are current-driven.

Ohm's Law tells us that V=IR (voltage = current x resistance)

So when a solid-state amp has no speaker plugged in, the resistance in the output section is infinite and the current and voltage go to zero.

That's why solid-state amps are fine with no speaker connected.

 

[agedhorse]

NL-2 jacks have no place on bass amps, cabinets due to their almost universal incompatibility with the rest of the industry.

The reasons given for how amp failure occurs in tube amps with output transformers is incorrect.

Just more examples of bad internet information and why AI results can be misleading.

 

[abarson]

@agedhorse we now know that the Markbass 58R and Ampeg Venture series of amps are now using NL2, regardless of the vast majority of the industry adhering to NL4. It's still a mystery to me what their motivation was in making the change. So much for "industry standards".

 

[agedhorse]

@agedhorse we now know that the Markbass 58R and Ampeg Venture series of amps are now using NL2, regardless of the vast majority of the industry adhering to NL4. It's still a mystery to me what their motivation was in making the change. So much for "industry standards".

It's just more confusion in an already absurd industry where some manufacturers don't follow decades long established standards.

I wish Neutrik would simply discontinue the NL-2 jacks except for special applications. It would help all of us in this industry.

 

[40Hz]

It's just more confusion in an already absurd industry where some manufacturers don't follow decades long established standards.

I wish Neutrik would simply discontinue the NL-2 jacks except for special applications. It would help all of us in this industry.

Going back to my days in finance with a scientific instrument manufacturing company, I suspect there were either issues with the NL4 supply chain at one point -or- someone in accounting (or an industrial engineering type who bills himself as a "manufacturing cost specialist") asked: "Why are we buying plugs and jacks that provide four connections when our speaker cabs only require two? We can save $X if we use NL2 rather than NL4 SpeakOns for an annual projected cost savings of $XXX."

And upper management, who have incremental costing down cold (but generally have zero understanding about the technology in their products or a clue about long term reliability and serviceability) smile approvingly and send a directive down to purchasing.

Sometimes they even copy manufacturing and engineering on the memo - after they make their decision.

Fortunately, the company I once worked for before I transitioned to IT had engineers who were also MBAs still running the show. That cut way down on the usual boneheadedness you find in many companies.

My dad was a mechanical engineer. He designed transmission systems for gas turbine aircraft engines. He used to say if you made a brilliant innovation that improved an engine's performance you'd get a letter of commendation and a plaque plus a picture of the company president shaking hands with you in the company paper. But find a way to save twenty bucks on the cost of an $18K engine and you'd get a raise and a promotion.

 

[tadawson]

"So if your amp has power tubes, you need a speaker connected when the amp is on. There are exceptions, but that's the general rule."

Another statement that misses the mark. It needs a suitable *LOAD* connected . . . . There is nothing that mandates that the load be a speaker . . . .

 

[seamonkey]

"Can I use My Amp Without a Cabinet Attached?"

Consult the manufacturer's guidelines.

Ohm's Law tells us that V=IR (voltage = current x resistance)

So when a solid-state amp has no speaker plugged in, the resistance in the output section is infinite and the current and voltage go to zero.

Voltage stays much the same. Ohm's Law applies in circuits with a complete path for current. With an open circuit (no load), the current drops to zero, but an ideal amplifier tries its best to maintain the voltage output within its capabilities.

 

[groovaholic]

bad internet information and why AI results can be misleading

No AI was used here - I was trying to explain things in layman's terms based on 40 years of my own mistakes and things I've learned the hard way (often by releasing the "magic smoke")

Another statement that misses the mark. It needs a suitable *LOAD* connected

Again, I was trying to explain this in layman's terms.

Consult the manufacturer's guidelines.

I've seen the question about using a hybrid amp without a load connected dozens of times.
For example, until recently, the manual for the Orange Terror Bass said that it "must not be used without a speaker connected" - but when people called Orange to confirm that, they were told the amp would be fine with no load.
Sounds like whoever wrote the manual just cut and pasted that section from another amp's manual.

 

[seamonkey]

I've seen the question about using a hybrid amp without a load connected dozens of times.
For example, until recently, the manual for the Orange Terror Bass said that it "must not be used without a speaker connected" - but when people called Orange to confirm that, they were told the amp would be fine with no load.
Sounds like whoever wrote the manual just cut and pasted that section from another amp's manual.

Orange should update the PDF manual.
Amps with autoformers may not need a load, unless the manufacturers guidelines say so.
Some tube amp switch in a resistive load if the speaker is disconnected.
And your explanation on the output transformer isn't correct. The correct answer is too lengthy and easy to simplify to "Follow the Manufacturer's Guidelines"
...

 

[groovaholic]

Orange should update the PDF manual.

Orange has corrected it now:

I agree that people should start with the info that the manufacturer has provided, but unfortunately people seldom read their manuals.

Also, plenty of TB responses demonstrate that folks here tend to read headlines and ignore the rest.
All of which suggest it was a misguided notion to post this thread...

 

[Gigas444]

Orange has corrected it now:
View attachment 5457660
I agree that people should start with the info that the manufacturer has provided, but unfortunately people seldom read their manuals.

Also, plenty of TB responses demonstrate that folks here tend to read headlines and ignore the rest.
All of which suggest it was a misguided notion to post this thread...

hello, this is true for the "new" terror 500, but for the old one with impedence selector in the back the manual stated:
"IMPORTANT: A speaker cabinet of suitable impedance and power handling must be connected to the amplifier's speaker outputs even when the DI Output is in use."

which in my opinion means: do not use it without a cabinet connected, I had a terror 1000 and I remember I had to attach a cabinet even during "silent" recording sessions, I have searched now for the old manual becuse I knew it was there , I think they changed the power section in some way into new models, but I wait for more technical people to clear my doubt in a more specific way

 

[groovaholic]

this is true for the "new" terror 500, but for the old one with impedence selector in the back the manual stated:
"IMPORTANT: A speaker cabinet of suitable impedance and power handling must be connected to the amplifier's speaker outputs even when the DI Output is in use."

Exactly my point - you are correct that that is definitely what the manual stated.
Many users were confused by that statement since it contradicted what they know of bass amps with a solid state output section.

The earlier Terror Bass amps may have had a proprietary Class D output section, so it may have been accurate for that model, but there are many current Class D amps with impedance switches on the back (my Genzler Magellan, Mesa D-800+ and GK Legacy all have impedance switches) that operate safely with no load connected.

It seems possible that Orange (who sell more amps with tube than with solid state power sections) copied over that warning from the manual of an amp like the AD200 for which it was 100% applicable.