I messed up.

[Mike Caldwell]

Check the simple stuff first. I was at a gig this past summer where the band sent someone out to pick up an emergency amp from a friend a few towns over. I went up on stage and they had the cabinet wired like this:

View attachment 4986674

For what it's worth those are a perfect example of knock off Speakon connectors.

 

[CPB2019]

For what it's worth those are a perfect example of knock off Speakon connectors.

And here I had no clue. They came with the cab, which I bought used.

 

[MCF]

This chart gets posted over in the Subway Club when this question of ohms, amps and cabs comes up.

 

[HolmeBass]

How many 8-ohm min. amps do you think are on planet earth, like right now. Even just the functioning ones….

That’s a large number.

This seems such a weird conversation.

I do like semantics conversations. That’s my wheelhouse. EE, not so much — I dropped out of engineering in undergrad.

Numbers are only large/small in comparison to one another.

The number of 8 ohm minimum load bass amps (I know of none) is absolutely smaller than 4 ohm minimum load amps. It is also smaller than 2 ohm minimum load bass amps.

In fact, why don’t you lay one on us. Like I said, I know of none.

 

[Stylee Mousse]

I have no dog in this fight but the Ampeg b40 (a 70s SS). Is 8 min

of course it’s an odd bird being a transistor amp with an output transformer
It’s the only one I’ve ever seen

 

[MCF]

For what it's worth those are a perfect example of knock off Speakon connectors.

Wow. Don’t know what else to say.

 

[agedhorse]

View attachment 4987572 I have no dog in this fight but the Ampeg b40 (a 70s SS). Is 8 min

of course it’s an odd bird being a transistor amp with an output transformer
It’s the only one I’ve ever seen

I’m familiar with this, it’s a conventional (and classic) power amp topology (current source supplied diff amp and voltage amp, double darlington output stage), no output transformer. It’s also 50 years old and quite rare. Gibson also made a few (amps) like this in the earliest days of solid state. I doubt there are many survivors.

Taking another look at the schematic because it looked so familiar, there's no surprise that the power amp used this conventional topology because it was designed by (the late) Bill Hughes who was my supervising engineer while we worked under the Fender umbrella. Bill is best known for the SVT but designed a lot of different models and was an engineer's engineer.

This was a state of the art topology in the 1970's, a very early use of constant current sources that were originally developed for IC op-amps because it's easier to implement on a silicon die.

 

[Stylee Mousse]

Thanks ‘horse! I somehow got confused. Probably by a 50# SS head with a big power transformer….
It really is a rare bird I got for free and the cost of new power supply caps that I knew enough to install safely

anyway not an attempt to derail just pointing out that one of a few unicorns do exist.

 

[Standalone]

Numbers are only large/small in comparison to one another.

The number of 8 ohm minimum load bass amps (I know of none) is absolutely smaller than 4 ohm minimum load amps. It is also smaller than 2 ohm minimum load bass amps.

In fact, why don’t you lay one on us. Like I said, I know of none.

I get where you’re coming from and all that, but it seems to me that you’re ignoring some important context things, failing to read what I wrote (I listed two models in my first post — I “laid” two on you but you still “know of none.”), and imo are oversimplifying the “meanings” of numbers.

EE and amp design are not my professional and credentialed wheelhouse, but words are, and number theory is sort of a longtime hobby. I enjoy a good respectful debate about them, and love to be proven wrong because I like to learn stuff.

People seem to be arguing this a lot based on their own reading of two indeterminate things. First is the word "many," which is indeterminate. And chosen intentionally, for reasons I've explained but can explain more clearly below. Also indeterminate is the phrase “bass amps.” I did not say “models of bass amp,” though I listed two, including one of the most famous and well-regarded amp models of all time.

This is a thread discussing failure modes rather than a “what should I buy” thread. To pretend otherwise in order to argue semantics ignores the idea of context that you say matters.

I’d not tell someone asking about what amp to buy that there are “many” 8-ohm minimum amps. But in a thread where I want to be warning people that they’re out there, I’m likely to state my warning briefly and strongly.

“There are many rattlesnakes in the Pennsylvania woods. Careful not to step on one or put your bedroll next to one!”

Sure, there are far more non poisonous snakes out there, but the word makes sense in a warning context.

And since we are talking math, shouldn’t we consider how much more statistically likely a newbie is to be making do with cheap random old cast-off amps or be tinkering with a combo designed for 8-ohms. Heck, we used the mic inputs of old 1970’s silver face stereo stuff in the 90’s when I was starting out. Finagled speaker wire to connect to whatever instrument cabinet we could scrounge. “Many” people have done stuff like that.

 

[Standalone]

The number of 8 ohm minimum load bass amps (I know of none).

In fact, why don’t you lay one on us. Like I said, I know of none.

Here is one from a fairly recent TB thread. Crate BX-80 Speaker Swap 4 ohm load

My first “real” amp. I used it for “many” years. Well, only four. But they sure seemed interminable. The amp stank, and the Peavey TNT 130 that I replaced it with was many times better. How many? You may ask. I don’t know but many people would agree.

Would you still say that there are “absolutely” more 2-ohm stable amps floating around out there than the Wall-E sized piles of student combos etc.?

I used the word I intended to, and while there is obviously room for an editor’s debate about its usage, I don’t think I’m wrong to use it.

I like these kinds of debates even more than ones about bass gear or technique, but many if not most folks don’t, so I’ll leave this at that.

 

[HolmeBass]

Here is one from a fairly recent TB thread. Crate BX-80 Speaker Swap 4 ohm load

My first “real” amp. I used it for “many” years. Well, only four. But they sure seemed interminable. The amp stank, and the Peavey TNT 130 that I replaced it with was many times better. How many? You may ask. I don’t know but many people would agree.

Would you still say that there are “absolutely” more 2-ohm stable amps floating around out there than the Wall-E sized piles of student combos etc.?

I used the word I intended to, and while there is obviously room for an editor’s debate about its usage, I don’t think I’m wrong to use it.

I like these kinds of debates even more than ones about bass gear or technique, but many if not most folks don’t, so I’ll leave this at that.

Those are combo amps, which this thread is not about. A combo with no external speaker jack is a null example because it was never intended to be anything other than a self-contained unit.

 

[HolmeBass]

I get where you’re coming from and all that, but it seems to me that you’re ignoring some important context things, failing to read what I wrote (I listed two models in my first post — I “laid” two on you but you still “know of none.”), and imo are oversimplifying the “meanings” of numbers.

EE and amp design are not my professional and credentialed wheelhouse, but words are, and number theory is sort of a longtime hobby. I enjoy a good respectful debate about them, and love to be proven wrong because I like to learn stuff.

People seem to be arguing this a lot based on their own reading of two indeterminate things. First is the word "many," which is indeterminate. And chosen intentionally, for reasons I've explained but can explain more clearly below. Also indeterminate is the phrase “bass amps.” I did not say “models of bass amp,” though I listed two, including one of the most famous and well-regarded amp models of all time.

This is a thread discussing failure modes rather than a “what should I buy” thread. To pretend otherwise in order to argue semantics ignores the idea of context that you say matters.

I’d not tell someone asking about what amp to buy that there are “many” 8-ohm minimum amps. But in a thread where I want to be warning people that they’re out there, I’m likely to state my warning briefly and strongly.

“There are many rattlesnakes in the Pennsylvania woods. Careful not to step on one or put your bedroll next to one!”

Sure, there are far more non poisonous snakes out there, but the word makes sense in a warning context.

And since we are talking math, shouldn’t we consider how much more statistically likely a newbie is to be making do with cheap random old cast-off amps or be tinkering with a combo designed for 8-ohms. Heck, we used the mic inputs of old 1970’s silver face stereo stuff in the 90’s when I was starting out. Finagled speaker wire to connect to whatever instrument cabinet we could scrounge. “Many” people have done stuff like that.

No, we should not be considering combo amps, especially ones without an external speaker jack, in a thread about a stand-alone amp where the user must understand something about how impedances combine in parallel.

Totally off the wall thing you brought up just to be “right”.

How about an example of a stand-alone bass amp with an 8-ohm minimum load, since that’s what we’re talking about.

Also any really salty bassist doesn’t use the word amp to mean anything other than a stand-alone amp. There are amps, cabinets, and combos. Calling a combo or a cabinet an amp is a newb position to stake out.

 

[ctmullins]

Check the simple stuff first. I was at a gig this past summer where the band sent someone out to pick up an emergency amp from a friend a few towns over. I went up on stage and they had the cabinet wired like this:

View attachment 4986674

Glad you were able to help them out. Did the amp survive or need servicing?

(sorry for going off-off-topic…)

I’m pretty sure this is a harmless mistake. While this setup will obviously produce no sound, it shouldn’t cause any harm to the amp. Nothing is connected that isn’t already connected inside the chassis.

If this were one of those older tube amps that shouldn’t be powered up without a load attached, that would be a problem. But this looks like a modern, probably Class D, most/all of which don’t have this limitation.

 

[Stylee Mousse]

Semantics war!

In my innings we pretty much used these terms, defined this way:

AMP - complete system whether a combo or head and cabinet, eg “what amp are you bringing out this weekend”

HEAD - also amp head. Preamp and poweramp, either combined in one unit or racked components. Eg “I need a head for the gig, my SVT is in the shop”

CABINET - speaker system. eg “why do we have to bring your SVT cabinet AGAIN!?”

COMBO - integrated amplifier and speaker combination eg “when I perform with my hiphop polka trio I bring my SWR Silverado combo because it slaps”

regional variations are, of course accepted. In fact, I’d love to hear about other ways to name gear bits.

 

[HolmeBass]

Semantics war!

In my innings we pretty much used these terms, defined this way:

AMP - complete system whether a combo or head and cabinet, eg “what amp are you bringing out this weekend”

HEAD - also amp head. Preamp and poweramp, either combined in one unit or racked components. Eg “I need a head for the gig, my SVT is in the shop”

CABINET - speaker system. eg “why do we have to bring your SVT cabinet AGAIN!?”

COMBO - integrated amplifier and speaker combination eg “when I perform with my hiphop polka trio I bring my SWR Silverado combo because it slaps”

regional variations are, of course accepted. In fact, I’d love to hear about other ways to name gear bits.

You seem to use amp as an equivalent to rig. I feel like that is just wrong. A bass rig is the combination of amplifiers and speakers. It can be a combo amp or separates that are impedance and wattage matched.

To some “bass rig” further includes their pedals and bass, but that is more of an individualistic reference rather than a reference to backline equipment. I do not use the term that way.

Amp is obviously short for amplifier - itself short for integrated amplifier - the electrical component that amplifies the very low voltage bass signal (or really any input signal) to a much higher voltage, with ability to support the current draw when connected to a load. It has nothing to do with speakers.

I think combo amp is fairly descriptive, but if I am lining up backline for a show and someone calls a combo an amp, or worse a speaker cab an amp, to me that’s a red flag that they don’t really understand bass amplification.

I feel like the sloppy terminology here creates a barrier to bassists learning about impedance matching, wattage, and to learning how you can use a separate pre-amp and power amp as a rig. None of which is that complicated, but it does require some precision and orderly analytical thinking. The sloppy terminology makes it harder to figure out.

 

[CPB2019]

(sorry for going off-off-topic…)

I’m pretty sure this is a harmless mistake. While this setup will obviously produce no sound, it shouldn’t cause any harm to the amp. Nothing is connected that isn’t already connected inside the chassis.

If this were one of those older tube amps that shouldn’t be powered up without a load attached, that would be a problem. But this looks like a modern, probably Class D, most/all of which don’t have this limitation.

The picture I posted was not of the actual amp / cap (it was mine to illustrate), but it was indeed a class D and you are correct that there appeared to be no harm, as they played the gig after correcting the wiring.

 

[Stylee Mousse]

Bass rig. I like it. I’ll use that going forward.

 

[StereoPlayer]

Semantics war!

In my innings we pretty much used these terms, defined this way:

AMP - complete system whether a combo or head and cabinet, eg “what amp are you bringing out this weekend”

HEAD - also amp head. Preamp and poweramp, either combined in one unit or racked components. Eg “I need a head for the gig, my SVT is in the shop”

CABINET - speaker system. eg “why do we have to bring your SVT cabinet AGAIN!?”

COMBO - integrated amplifier and speaker combination eg “when I perform with my hiphop polka trio I bring my SWR Silverado combo because it slaps”

regional variations are, of course accepted. In fact, I’d love to hear about other ways to name gear bits.

Back in my earliest day, we also used top—meaning heads, bottom—-meaning speaker cabinet.

 

[BassyBill]

I accidentally ran an 8 ohm amp into my 4 ohm cab

That’s where the confusion started, right there in post#1. THERE IS NO SUCH THING AS AN 8 OHM AMP.

Ohms are a measure of impedance, or how much one or more loudspeaker cabinets will resist / restrict the flow of electrical signal into it/them from an amplifier. Loudspeaker cabinets have an impedance of typically 4 or 8 ohms. An amplifier will be designed to operate with one or more loudspeaker cabinets with a (combined) stated impedance of say, 4 or 8 ohms. Saying an amp is designed to work with an eight ohm cab does not mean it’s an eight ohm amp. Put as simply as possible - the cab has ohms, not the amp.

If you use a cabinet or two cabinets with a total impedance lower than the amp is designed for, the output signal from the amp won’t be IMPEDED enough for correct operation and yes, damage to the amp may result.

I hope that helps some folks understand ohms a little better. If you’d like me to add a supplementary post about watts (power output of an amp and power handling capacity of a cab) and how that relates to ohms, I can add that later.

 

[agedhorse]

IMO, 3 or 4 or 5 models out of thousands is not many. That’s how I see it.