Amps, heads, cabs, combos....... ??

[Rayman]

So embarrassingly, after 40yrs of using combos, I have a question. Proof that you're never too old to learn...

 

I just can't keep lugging my Ashdown ABM combo around anymore. We live in an upstairs flat, and it's getting impossible to hump it up and down the stairs.

 

So I'm looking to move to separates, a lightweight head and 1 or 2 cabs instead.

 

How does the Ohm thing work?  Can I use a 500W rated head with a 300W cab? 

 

Thanks for your assistance

 

 

[Lozz196]

You can, just be mindful of the ohms thing. In all likelihood the amp will be 500 watts at 4ohms, and there`s a good chance that the cab will be 300 watts at 8ohms (but do check).

 

If this is the case then the 500 watt amp would deliver approximately 250, maybe 300 watts to the 8ohm cab so this should be ok, but obviously keep your ears finely tuned to make sure you`re not overloading it. 

 

If the amp is 4ohms then you can connect two 8ohm cabs to it or one 4ohm cab (I know, whoever made this up did it on purpose to be confusing).

[nige1968]

52 minutes ago, Rayman said:

How does the Ohm thing work?

 

 

 

Exactly what to choose will depend on the kind of places you're playing, but here's an idiot's guide (ie written by an idiot -- apologies for any egg-sucking unwittingly foisted on any elderly relative)

 

First, amps

 

These are classified by the power stage output. Class A and AB are your traditional ones with massive heavy transformers (and allegedly more of a subjective quality known to bass players as 'heft'). Class D amps are more recent, often featherweight amps with a decent output for the size. These seem to be taking over the 'everyday' market.

 

The power of an amp is usually expressed as, for example, 500w at 4ohms/300w at 8ohms. That would mean the amp delivers 300w to an 8ohm speaker, or 500w to a 4ohm speaker.

 

Ohms refers to electrical resistance (aka impedance). In general, the higher a speaker's resistance, the more electrical power is needed to move the cone.

 

If the amp above has two outputs you can connect two speakers in parallel; in this case, two 8ohm speakers give 4ohms total resistance (thought I knew why but it turns out I don't). What you can't do is connect two 4ohm speakers to this amp -- that would give you a 2ohm total resistance, drawing twice the current the manufacturer has specced for, and things would likely start melting and burning.

 

So to cabs

 

Amp power isn't the same thing as loudness. While more power will push a speaker harder, much depends on the efficiency of said speaker, and how many of them you have. Fortunately, speakers can be made much lighter by things like clever cab design or lightweight (neodymium) magnets. Markbass, Barefaced, Vanderkley and Bergantino all have a good rep in making lightweight cabs; GRBass makes them from carbon fibre. Alas, lightweight does not equal cheap.

 

If you run a low-powered amp into a high-impedance speaker, you risk overheating the amp (bad).  Equally, running a high-powered amp turned up full into a lower-rated speaker will create unwanted distortion and risks blowing the speaker. Therefore, you ideally want a speaker set matched to your amp's power output, or slightly less, so that there's enough power available to create a clean sound at the desired volume.

 

If you're still around, here's the tl;dr: Unless you're playing the Albert Hall, get yourself a class D head and a lightweight 1x12 8 ohm. Enjoy the continued feeling of being able to stand up straight without it hurting. Hope it helps; otherwise someone who actually knows what they're on about will no doubt be along soon.

 

 

 

Edited December 19, 2023 by nige1968

[Rayman]

Fabulous.... thank you 👍

[BassAdder60]

If you get a 500w ( choose wisely as some are not loud for claimed 500w) and add a single 8ohm cab you will get around max 250w power. Just about enough to gig with if it’s a decent cab.

Or buy a single 4ohm cab and get the full head power which if 500w would be ample to gig with

 

A decent cab (4ohms ) or two (8ohm) cabs will make the world of difference 

 

My advice is get the largest you can comfortably carry. Go too puny and most sound boxy and struggle unless it’s high end stuff 

[Dan Dare]

If you're looking to save weight, modular - several smaller, lighter boxes, rather than one large heavy one - is the way to go. 

[Merton]

If you need volume more drivers is better than going for a single 4 ohm cab “to get the maximum from the head”.

So as @Dan Dare says, several smaller, lighter weight boxes. A small 500-800W head, two small, lightweight cabs.

You can then take one or both cabs as the mood/situation dictates.

[BassAdder60]

1 hour ago, Merton said:

If you need volume more drivers is better than going for a single 4 ohm cab “to get the maximum from the head”.

So as @Dan Dare says, several smaller, lighter weight boxes. A small 500-800W head, two small, lightweight cabs.

You can then take one or both cabs as the mood/situation dictates.

Although I agree but a decent lightweight 2x 12 4 ohm cab is all you need but the challenge is getting a reasonably priced lightweight cab. 
Two small 1 x12 8 ohm cabs are easier for carrying if you find a decent make / model 
 

Everything is relative to what each person considers a weight to carry as acceptable. My Ampeg SVT212AV cab is 30kg approx and it’s an easy carry if you are strong but I wouldn’t want to carry it up flights of stairs ! 
 

At the end of the day the budget will determine how good and how light 

Edited December 19, 2023 by BassAdder60

[Merton]

3 minutes ago, BassAdder60 said:

Although I agree but a decent lightweight 2x 12 4 ohm cab is all you need but the challenge is getting a reasonably priced lightweight cab. 
Two small 1 x12 8 ohm cabs are easier for carrying if you find a decent make / model 
 

Everything is relative to what each person considers a weight to carry as acceptable. My Ampeg SVT212AV cab is 30kg approx and it’s an easy carry if you are strong but I wouldn’t want to carry it up flights of stairs ! 
 

At the end of the day the budget will determine how good and how light 

Agreed. The irony with my previous post is that I’ve just bought a Super Twin so I can use my Trace TE1200 with a single cab on loud gigs, because I’m lazy and don’t want to carry two cabs, an amp, basses and a pedalboard 🤣🤣

Edited December 19, 2023 by Merton

[Merton]

So yes. Depends on budget and what cabs you can get…

[Rayman]

Also in the mix, is that I’m an Ashdown guy, have been for years, and we’re a loud original heavy rock 3pce. So I need grunt……..light, grunty and affordable , not asking for much like.

[BassAdder60]

37 minutes ago, Rayman said:

Also in the mix, is that I’m an Ashdown guy, have been for years, and we’re a loud original heavy rock 3pce. So I need grunt……..light, grunty and affordable , not asking for much like.

Ashdown Neo cabs or RM series ? 

[Merton]

7 minutes ago, BassAdder60 said:

Ashdown Neo cabs or RM series ? 

My thoughts exactly.

 

RM800 and then either Pro Neo or RM cabs.

 

That said there’s a Genz Benz Streamliner in the classifieds for a frankly ridiculously low price of £220 which is well worth a look.

[Lozz196]

1 hour ago, Rayman said:

Also in the mix, is that I’m an Ashdown guy, have been for years, and we’re a loud original heavy rock 3pce. So I need grunt……..light, grunty and affordable , not asking for much like.

Same here, I use the RM500 and it’s a very good amp, the gruntiest Class D amp that I’ve used. I pair it with two of their PRO NEO ABM210s - or at least would but every gig since I’ve had them has had a provided backline.

[Downunderwonder]

2 hours ago, Rayman said:

Also in the mix, is that I’m an Ashdown guy, have been for years, and we’re a loud original heavy rock 3pce. So I need grunt……..light, grunty and affordable , not asking for much like.

At least you are cognizant of the trades that are made. Mostly you wind up trading money for lightness. See video of the Barefaced guy holding his 310 up in the air like he could throw it across the room no problem. If you can afford one of those you should be set.

 

An Ashdown Ant could make quite a racket with a 100dB cab like that.

 

If you ever had a hankering for a tube amp now is probably the time. Although a little bit heavy the box size is easy enough to manage on stairs. You need to be still steady on your feet not needing the handrail. At that stage you can go micro.

[Rayman]

39 minutes ago, Downunderwonder said:

You need to be still steady on your feet not needing the handrail. At that stage you can go micro.

I’m not quite there yet lol…. and only a couple of years ago during lockdown I was solo lifting washing machines into the back of a van. Couldn’t do that now.

 

I’ve seen a tiny 500W TC BQ class D head…. my only experience of TC is that I’ve blown two of them to bits…. but it’s small and powerful…. plugged into a 2x12 it might work 

[warwickhunt]

I think the ohmage and wattage thing is covered but be aware not all cabs are created equal.  This pic might look ridiculous but I'm presently testing various rigs and cab combinations.  I can tell you that all of these combinations present 4 ohm loads to the amp (the 2x12 cab is 4 ohms, all other single cabs are 8 ohms) and one of these set ups is way louder than the others, while one set up is particularly quiet (no setting changes on the amp).  This is all down to sensitivity of the cab(s) and... one of the single speaker cabs is exceptionally clear and carries the top end with more projection.  

 

Oh and this little test absolutely destroyed the urban myth that you get more top end from 10's and 15's give you more bass/bottom end!    

 

[Rayman]

Oh right….. please do tell us your findings 

[Rayman]

So as I’m in a rush, and I wanted something for the next gig, I’ve gone for a temporary measure. A used TC BQ500 and a Peavey 2x12 4ohm 350W cab. I understand that the TC output is probably realistically closer to 400W anyway. So that’ll do as a temporary setup, but the search for a proper rig will continue in the New Year

[warwickhunt]

33 minutes ago, Rayman said:

...a Peavey 2x12 4ohm 350W cab. 

 

Not sure I've ever seen one of those!  

[chris_b]

The volume difference between an 8 ohm cab and a 4 ohm cab is minimal.  The difference between 1 cab and 2 cabs is huge.

 

There are heavy and light amps and cabs. You've got to the stage in life where weight is important, so do this job properly.

 

There are 20-30lb 112 cabs out there which will blow "standard" 40-50lb 212 cabs out of the water. I haven't heard a bad D class amp yet.

[Rayman]

1 hour ago, warwickhunt said:

 

Not sure I've ever seen one of those!  

Me neither….. hopefully it’ll work. It wasn’t expensive at all, but then this is a cheap temporary set up. 

[Rayman]

3 minutes ago, chris_b said:

 I haven't heard a bad D class amp yet.

Well I’ve gone for a modest D class to start with, the reviews are good, and it’s small, so it ticks all the boxes for now.

[asingardenof]

Also worth mentioning that the value the amp gives is going to be for when it's going flat out, so if you're never getting the volume past halfway then having a cab with a lower wattage rating than the amp isn't necessarily a cause for concern. If you are then just add another cab  

[Merton]

12 minutes ago, asingardenof said:

Also worth mentioning that the value the amp gives is going to be for when it's going flat out, so if you're never getting the volume past halfway then having a cab with a lower wattage rating than the amp isn't necessarily a cause for concern. If you are then just add another cab  

But also… the volume control does not necessarily correspond in any way to the output power, coz of the various ways manufacturers build things and make all the volume in the first 1/3 of dial movement (for example…)

Edited December 20, 2023 by Merton
Clarity