Bass amps for Live work

[Greg_L]

Cool. Glad to hear it. Avoid the buyer's remorse syndrome. I think I'm gonna like it.

So Steve, about this cab building thing.... I think I might have to start another thread...

I've got a lot of MDF laying around. Have you used that stuff with good results?? Or should I be looking at plywood??

I've got some drum shells you can use. A kick drum shell bass cab would be awesome.

 

[jonny deep]

Very generally speaking, I think solid state amps don't care what kind of speaker load you put on them. Bass amps are often solid-state or a hybrid with a tube pre-amp stage. The power section is SS. If the amp is rated for say 400 watts @ 4ohm load, if you connect it to an 8 ohm cab, you're only gonna get 200 watts out of it. 200 watts of bass power is not very much, so adding another 8 ohm cab will make the amp "see" 4 ohms and the power output will come up. Or something like that. I don't understand the electronics behind it. That's just how I've always thought of it.

Ah, so there's only one speaker output and the power drawn varies according to impedance, whereas on my amp there are two outputs for different impedances, which presumably tap in after a different number of windings on the output transformer, or something like that?!?!

 

[Greg_L]

Ah, so there's only one speaker output and the power drawn varies according to impedance, whereas on my amp there are two outputs for different impedances, which presumably tap in after a different number of windings on the output transformer, or something like that?!?!

I don't know, maybe. It depends on the amp. There are probably two speaker outs and you'd run two 8 ohm cabs with two cables going to the head to make the amp see 4 ohms, or just one 4 ohm cab. Some amps have different jacks for different impedences, some have a fewer jacks and an ohm selector switch, and some have a bunch of jacks and a selector switch. Like with your 15w head, you probably won't be running a wall of cabs like Yngwie, so you might only need one 16 ohm jack and one 8 ohm jack since those are the most common guitar cab ratings. If you have a cab wired correctly, you could daisy-chain two 16 ohm cabs together and plug the speaker cable into your one 8 ohm jack. An old 100w Marshall might have 4 speaker outs on the back and an ohm selector switch so you can run four 16 ohm cabs, set the amp to 4 ohms, and blow the building apart. My Marshall head has two speaker outs and an 8/16 ohm switch. I can run two 16 ohm cabs and set the amp at 8 ohms, or one 16 ohm cab and set the amp at 16. Some modern amps might have 5 outputs on the back. One will be a dedicated 16 ohm output, the other 4 will be switchable 4/8 ohms. It just depends.

I'm still half-asleep though, so that could all be nonsense.

 

[jonny deep]

I don't know, maybe. It depends on the amp. There are probably two speaker outs and you'd run two 8 ohm cabs with two cables going to the head to make the amp see 4 ohms, or just one 4 ohm cab. Some amps have different jacks for different impedences, some have a fewer jacks and an ohm selector switch, and some have a bunch of jacks and a selector switch. Like with your 15w head, you probably won't be running a wall of cabs like Yngwie, so you might only need one 16 ohm jack and one 8 ohm jack since those are the most common guitar cab ratings. If you have a cab wired correctly, you could daisy-chain two 16 ohm cabs together and plug the speaker cable into your one 8 ohm jack. An old 100w Marshall might have 4 speaker outs on the back and an ohm selector switch so you can run four 16 ohm cabs, set the amp to 4 ohms, and blow the building apart. My Marshall head has two speaker outs and an 8/16 ohm switch. I can run two 16 ohm cabs and set the amp at 8 ohms, or one 16 ohm cab and set the amp at 16. Some modern amps might have 5 outputs on the back. One will be a dedicated 16 ohm output, the other 4 will be switchable 4/8 ohms. It just depends.

I'm still half-asleep though, so that could all be nonsense.

Yes, well it is still horribly early over there! Makes sense, though.

 

[CoolCat]

Chili are you going to get a 8ohm 15" cab or a 4ohm cab? Is the 4x10 8ohm or 4ohm?

so....the 4x10 everyone seems to enjoy, is it a 4ohm cab? or a 8ohm cab?

preferably a 4ohm cab so it will squeeze into the backseat (smashing the drivers face to the window no doubt..but thats whats required sometimes)...

I'm taking the PF 350 back to GC this weekend, and to keep it a one cabinet setup for logistics reasons, the 1x15 8ohm isnt going to work either it seems, because it cuts the power in half on the cheaper amps.

the SVT 4x10HLF is $899!!!:

the SVT 15E is rated 8ohm 200watt rms 400watt program handling.

seems it would be cheaper to buy another 15" speaker like an Eminence 4ohm, for 450wattrms/900watt program for $125 than another cabinet?

I have a Carver Power Amp 12oowatt bridged, currently on PA thats only used 50% of the time (at small gigs.) Maybe thats the route to go for the head?

Hauling is a serious concern.

 

[Chili]

Very generally speaking, I think solid state amps don't care what kind of speaker load you put on them. Bass amps are often solid-state or a hybrid with a tube pre-amp stage. The power section is SS. If the amp is rated for say 400 watts @ 4ohm load, if you connect it to an 8 ohm cab, you're only gonna get 200 watts out of it. 200 watts of bass power is not very much, so adding another 8 ohm cab will make the amp "see" 4 ohms and the power output will come up. Or something like that. I don't understand the electronics behind it. That's just how I've always thought of it.

You got it right. It's all math, but basically multiple speakers lower the resistance. I think of it as a water hose. The more hoses the more water you can put on the lawn; if the water supply has enough pressure. That's why going below 4 ohms can cause problems, too much current can cause the voltage to drop and short out the final stage. Poof.

 

[Chili]

Chili are you going to get a 8ohm 15" cab or a 4ohm cab? Is the 4x10 8ohm or 4ohm?

so....the 4x10 everyone seems to enjoy, is it a 4ohm cab? or a 8ohm cab?

preferably a 4ohm cab so it will squeeze into the backseat (smashing the drivers face to the window no doubt..but thats whats required sometimes)...

I'm taking the PF 350 back to GC this weekend, and to keep it a one cabinet setup for logistics reasons, the 1x15 8ohm isnt going to work either it seems, because it cuts the power in half on the cheaper amps.

the SVT 4x10HLF is $899!!!:

the SVT 15E is rated 8ohm 200watt rms 400watt program handling.

seems it would be cheaper to buy another 15" speaker like an Eminence 4ohm, for 450wattrms/900watt program for $125 than another cabinet?

I have a Carver Power Amp 12oowatt bridged, currently on PA thats only used 50% of the time (at small gigs.) Maybe thats the route to go for the head?

Hauling is a serious concern.

Ha, that's why I can't look at Ampeg. At least not yet. Too expensive for anything bigger than a practice amp. If the kid keeps going with the bass, then he'll get Ampeg for his 16th bday instead of a car.

Cabs can be either 4ohm or 8 ohm. It depends on how the speakers are rated and how the cabs are wired. The Eminence 15" is available as both 4-ohm and 8-ohm variants.

For me, I will get a 15" 8-ohm speaker. The 4x10 I picked up last night is 8 ohm, so two 8ohm speakers in parallel will be a 4ohm load on the amp. That'll allow it to push more electrons out the door and into the cones!! yeah-ah-ah-ahhh

 

[Chili]

I don't know, maybe. It depends on the amp. There are probably two speaker outs and you'd run two 8 ohm cabs with two cables going to the head to make the amp see 4 ohms, or just one 4 ohm cab. Some amps have different jacks for different impedences, some have a fewer jacks and an ohm selector switch, and some have a bunch of jacks and a selector switch. Like with your 15w head, you probably won't be running a wall of cabs like Yngwie, so you might only need one 16 ohm jack and one 8 ohm jack since those are the most common guitar cab ratings. If you have a cab wired correctly, you could daisy-chain two 16 ohm cabs together and plug the speaker cable into your one 8 ohm jack. An old 100w Marshall might have 4 speaker outs on the back and an ohm selector switch so you can run four 16 ohm cabs, set the amp to 4 ohms, and blow the building apart. My Marshall head has two speaker outs and an 8/16 ohm switch. I can run two 16 ohm cabs and set the amp at 8 ohms, or one 16 ohm cab and set the amp at 16. Some modern amps might have 5 outputs on the back. One will be a dedicated 16 ohm output, the other 4 will be switchable 4/8 ohms. It just depends.

I'm still half-asleep though, so that could all be nonsense.

If I remember my old electronics training from the navy (analog computers!! ) a tube amp goes through a transformer before going out to the speaker. The transformer has multiple taps off the output coil to allow different impedance loads (speakers). The switches on the back of the amp are probably selecting which tap to use.

 

[Lt. Bob]

the SVT410HLF is a 4 ohm cab or at least mine is.


As for the amps ....... like a lotta things concerning tube amps it's not quite as critical as it's made out to be usually.
For example my Mesa's ..... I talked to their tech and he said ... "ummmm .... just try the different impedanced outs ...... they'll all sound different".
This was regardless of what the speaker is rated for.
Most amps you don't want to go below 4 ohms but some amps are rated for even 2 ohms.
A Fender Super Reverb is set up FOR 2 ohms.

In amps like my Orange where they have multiple speaker jacks for different loads, or my Ampegs where they have a switch to change it ...... they're tapping into the output tranny at different places in its windings.
This is about 'coupling' the amp to the speaker and getting the best power output from it.

It's less about not blowing up the amp. You're not likely to blow up the amp if you set it to 4 ohms and run it into an 8ohm load, but it's not gonna put out it's full power.
So with an amp like say, my Ampeg V2 ...... it's pretty much putting out 60 watts regardless of load because it has taps to properly couple itself to the various loads you can set the switch to. If you don't set the switch you won't be making that 60 watts if it's mismatched to the actual load. But as long as you set the switch right it'll pretty much put out 60 watts at any of its loads.

That's gonna be the case with any tube amps that have different tansformer taps (anything that has speaker jacks dedicated for different ohms or a switch to select different ohms). They'll pretty much put out the same power regardless of load because they have transformer taps for each load and thus, are efficient at each load.

But an amp like the Hartke doesn't have tranny taps ......so they just give it different power ratings at different loads.

All amps that don't allow switching the output for different loads are that way..... look at PA power amps ..... ALL of them have different power ratings at different loads .... Well, most of them do anyway ..... there are a very few exceptions but in general amps are set up where they'll put out the most into a particular load and it's not always the lower the ohms, the more power. You can have ratings where it goes up as the load goes lower and then suddenly goes down when you go even lower.

On guitar the amount of power going out isn't as important ..... if you have a 50 watt amp and it's only putting out 38 you won't hear much difference whereas if a bass amp puts out 500 watts and you get a load where it only does 300 ..... now you suddenly don't have enough to keep up with the drummer because bass needs a lot of watts and you've suddenly got 200 less.











.

 

[Greg_L]

Yeah I've heard that about Mesa's where you can basically just "hook up any cab" pretty much no matter what the ohm rating is. I've never tried it myself. I don't understand the theory or amp design enough to take that gamble with my Marshall - which while sounding awesome, they aren't the toughest amps on the block. Tiny little user errors tend to crater a Marshall.

 

[CoolCat]

yeah .... you really need 500 watts. I know that sounds daft but bass freqs take a lotta juice.
For one thing they have to physically move the speaker cones 20 times further than a guitar speaker moves ...... even more at some comparative freqs. It's just like moving a larger load in a car ...... needs more horsepower.

Did you see this I posted earlier?
$375 for 500 watts. Here's a review.
Overton Flyweight 500 Micro Amp Review - Premier Guitar

yes thats pretty cool and good size for a car. but like Chili, trying to keep the costs waaaaay down.

I have a rack-Carver pm175- 500watts bridged mono at 8ohm amp $90+ $50 case....just grabbed a Behringer $90 preamp VAmp Pro. so thats $230 for the amp. Also have a Carver PM1200 1200watts 8ohm bridged mono.

So I'm taking the PF350 back, and trade the 15" cab 8ohm SVT15E, and as I understand this past few days,
will try to get a 4x10 that can handle 400watts - 500watts at 8ohm... and also fit in the car.

Maybe try for a used SVT4x10hlf at 8ohm.(but probably wont be able to afford one..so 4x10 <enter brand here>)
Then I can take the old PA head, and Rumble and get it out of the loop...and reduce the loading of the car.
Will see how much I'm out of pocket in the end.

Chili, you got a great deal at $300 for a amp and cab, sounds great with a 15" cab too.

 

[Chili]

Chili, you got a great deal at $300 for a amp and cab, sounds great with a 15" cab too.

Yeah, I think i did. I was just playing around with it during lunch today (work out of the house) and it sounds good. Couldn't turn it up too much. About 3 was all I needed to bring the neighbor over wondering wtf. ha ha ha

I think the eq section is pretty flexible and I'll get most any tone I want. I placed my DBX 163x compressor in the effects loop and it really boosted volume. Had to turn it down to 1 to be comfortable.

No clip light either. The seller had the bass knob all the way up.
Happy camper.

 

[CoolCat]

yes it amazes me how loud and thunderous the bass gets and then for the band to say "its not loud enough".
very application specific, for sure.

for a good coffee shop acoustic-small drum set up, 250watts would be loud enough right? geeeezz
for a small practice room the walls shake with the PF350 + 8ohm, so I admit I'm a bit baffled?

it seems theres no point in even listening to this bass stuff in the store and just buy 400watt+ 4ohm or whatever cabinet will deliver the volume needed.

the band confirmed the little 100watt + 400watt/cabinet works....so whatever that equals to, in a single amp + single cabinet, I dont know...but thats what is needed for their application.

Lt. Bob has always said 400-500amp and the 4x10 works, so thats apparently plenty. In my case the added issue is loading the car issues too (so want one cabinet small as possible).

 

[Greg_L]

I'm thinking about getting a bass cab myself and tracking my bass through my Marshall head....like Lemmy! Bass destroys guitar speakers though, so I'm not going there with my current setup.

 

[Lt. Bob]

I'm thinking about getting a bass cab myself and tracking my bass through my Marshall head....like Lemmy! Bass destroys guitar speakers though, so I'm not going there with my current setup.

if it's for tracking a good 2x10 is basically one section of an SVT 8x10 since that cab is seperated into 4 2x10 sections.
Just don't crank a 500 watt SWR into a 300 watt 2x10 like I did a couple of weeks ago when I was too lazy to carry in the 410 or you might blow the speakers out in a suprisingly undramatic way like I did a couple of weeks ago when I was too lazy to carry in my 410.

 

[Greg_L]

if it's for tracking a good 2x10 is basically one section of an SVT 8x10 since that cab is seperated into 4 2x10 sections.
Just don't crank a 500 watt SWR into a 300 watt 2x10 like I did a couple of weeks ago when I was too lazy to carry in the 410 or you might blow the speakers out in a suprisingly undramatic way like I did a couple of weeks ago when I was too lazy to carry in my 410.

Lol. Nice. If I can get by with a 2x10, I might just build one myself.

 

[Greg_L]

Fuck that....
NEW B210 NEO

 

[Chili]

Lol. Nice. If I can get by with a 2x10, I might just build one myself.

Maybe it's time to start that cab building thread. Nah, I'm too lazy.

 

[CoolCat]

you got to get the cab going, the 4ohm is where you get into the full bass vybe. right?

i just got back form GC, returned the 350...they had a 8ohm 15 BS115 and I was just about to take it home and the 350 again, but the trade deal fell through. so only returned the stuff.

the sales guy was a bass player which was refreshing, and though he didnt say I needed the wattage as much as he said I needed to try the 4ohm (dual 8ohm) setup first. then he said a bunch of crap about speakers are really 200watt and the marketing guys post all that 600watt crap, and etc..etc.. I became confused again.

I'm done for now, but have a better understanding of what its going to take to get a loud/live bass rig going. 400-500watt@4ohm bass head and a 4ohm cab.

Im curious Chili, if and when you add the cab and get max wattage, what your opinion will be of the noticeable difference. good luck

 

[Chili]

I'm done for now, but have a better understanding of what its going to take to get a loud/live bass rig going. 400-500watt@4ohm bass head and a 4ohm cab.

That and money. But seriously, I think if you want to be loud, that is what you want; with a 4x10 cab, minimum.

Im curious Chili, if and when you add the cab and get max wattage, what your opinion will be of the noticeable difference. good luck

I'm contemplating my timeline on this. I have projects for the wife to do first. Plus, I won't be playing out anytime soon. The kid might.

Once I gett a second cab added, I'll let you know what I think. Resurrect this thread... it'll be a few years old by then.