Amp for a Bongo?

[Bubba Love]

Hi everyone, I have a few questions about amps to use with Bongos.

I currently have a Pearl Blue HH Bongo 4 string on order, which should be with me early january, until then I have to put up with my Squier P-Bass special (which is falling apart). My current amp is a Laney HCM160B, and after doing a gig at my college to a hall of 150-200 people, it came to my attention that it just doesn't cut it anymore.

The Bongo has a low end the size of a small house, and I like that, so I'm going to want something that will give me a nice fat, defined bottom end, while still maintaining clear mids and highs. Which would be better in your opinion, a 1x15 or a 4x10 cab? 1x15 is the answer that springs to mind, but they can tend to be a little muddy, and I've heard that 4x10 cabs provide big low end as long as the enclosure is well built. Can any of you tell me which cabs in particular have these qualities (Bearing in mind I'm a student, and I wouldn't want to spend any more than £400-£500 on the cab).

And how about wattage of the amp? I've been looking at something like the Peavey Firebird 700 II, which cranks out 475 watts at 8 ohms. How big a venue will this suffice for (I play in a fairly loud bluesy rock band)? More importantly, do any of you know if this is a good amplifier?

And my last question is, what is all this nonsense about Ohms? How does having a lower resistance affect the sound of the amplifier (apart from the increased power to the speaker)?

If you read all that, I commend you. If you answer all those questions, you are a living legend and deserve to live in a house made of money with a key to the fountain of youth.

 

[element]

I read it all but cant answer it. Do I still get a runners up prize?

 

[Aussie Mark]

Which would be better in your opinion, a 1x15 or a 4x10 cab?

In most cases, a good quality 4x10 will be a much better option than a 1x15. Smaller speakers are more responsive, which is better for attack and projection, and 4 of them in a well designed box will handle the lows as well as a 15" or an 18".

And how about wattage of the amp? I've been looking at something like the Peavey Firebird 700 II, which cranks out 475 watts at 8 ohms. How big a venue will this suffice for (I play in a fairly loud bluesy rock band)?

With bass amplification, more is always better, but 475 watts should be adequate for smaller venues as you described. Since that rating is at 8 ohms, you can also add a second 8 ohm cabinet, which would drop the impedence to 4 ohms, and suck around 600 watts from the amp, which would give you more volume if needed, because the extra speakers will be moving more air, even though 600 isn't much more than 475 in practical terms).

And my last question is, what is all this nonsense about Ohms? How does having a lower resistance affect the sound of the amplifier (apart from the increased power to the speaker)?

Here's a good way to understand ohms (which measures impedence, or resistance as you put it). Imagine your amp is a water tank sitting on top of a stand, with a hose fitting attached to it. If you connect a 2" diameter hose to the fitting, the water will flow much faster and in larger volumes than a 1" hose, because there is less resistance.

To apply this concept to amps and speakers, assume the 2" hose is a 4 ohm load, and the 1" hose is a 8 inch load. Your amp (the water tank) can pump more power into a bigger hose. For ohms, a smaller number means a bigger hose.

Hope this helps

 

[Bubba Love]

Thanks a lot man, that's really helpful.

How ambitious do you think I have to be with this amplifier? All things considered, if it would do the job, I'd rather ditch the Peavey idea and go with an Ashdown MAG300H head (link: http://www.soundslive.co.uk/moreinfo.asp?ID=3074 ). Would 300 watts be enough to handle a small, loud gig situation?

Also, this has a minimum impedence of 4 Ohms, would that mean that if I bought one of Ashdown's 8 Ohm cabs, I'd only have, say, 200W of power going into it? Would I have to buy either a 4 Ohm cabinet or two 8 Ohm cabs to harness the full 300W?

 

[Aussie Mark]

You're right, the Ashdown would only put out 200 watts into an 8 ohm cabinet. If you added a second 8 ohm cab, you'd have a 4 ohm load, but the 300 watts of power would be split 50:50 to each cab, so each would get 150 watts. To me, the Peavey head looks like a much better option. Besides, it's always best to have more power than you need, so you can avoid of running your amp at full throttle and possibly sending a clipped signal to your speakers (a square signal means death to speakers).

 

[TheDirtyMoocher]

can there be any damage done to either the amp or speaker if the amp isnt powerful enough to push the speakers as hard as they could be pushed?

 

[Aussie Mark]

can there be any damage done to either the amp or speaker if the amp isnt powerful enough to push the speakers as hard as they could be pushed?

In theory, speakers can't be damaged by being driven with less than their rated power handling capacity. However, damage from underpowering is definitely possible if you run the amp full throttle until it clips. This is the single biggest cause of blown speakers. That's why the rule of thumb is to use an amp with 1.5-2.0 times the RMS rating of the speaker.

The simplest example of this is someone with a 100w combo trying to be heard over two Marshall stacks and a double kick drum. He turns his amp up full bore and still can't hear himself, and next thing he knows, his speakers are dead.

 

[cgworkman]

FWIW (and to show off) I run 2400watts into 4 ohms - Both cabs are "rated" 600 watts.

 

[Aussie Mark]

FWIW (and to show off) I run 2400watts into 4 ohms - Both cabs are "rated" 600 watts.

Bingo, a perfect match. Each cab is getting 1200w, or twice their RMS rating. Good job!

 

[TheDirtyMoocher]

so it would probably be bad to have a g-k 400rb 210 combo and run a home made cab with a cerwin vega 187 (18" speaker, i havent found out the rms of it yet but i think its around 400 watts) ...i havent done this yet because i have yet to buy the combo or build the cabinet but it was my plan

 

[Aussie Mark]

so it would probably be bad to have a g-k 400rb 210 combo and run a home made cab with a cerwin vega 187 (18" speaker, i havent found out the rms of it yet but i think its around 400 watts) ...i havent done this yet because i have yet to buy the combo or build the cabinet but it was my plan

Looking at the specs, that combo delivers 180w into 8 ohms or 280w at 4 ohms. The two internal 16 ohm speakers are an 8 ohm load, so adding an 8 ohm extension cabinet would give you a combined 4 ohm load. This would mean that the 2x10 would get 140w and the extension cab the other 140w. That should be plenty in a rehearsal room or a small gig, but you'd be easily overwhelmed by two guitar stacks and a drum kit in an average sized club. Plus, that 18" will suck up a lot of wattage just to get the voice coil moving, so it won't be very efficient.

 

[Bassplyr]

Thanks for the lesson in ohms Aussie!!!

 

[TheDirtyMoocher]

thanks

 

[tiffles]

WOW my head is still spinning.... so is the 18 ohm pre amp in the bongo a good thing..? or is the ohms thing a whole different kettle of fish in regards to pre amps..? (it is an 18 ohm pre amp isnt it )

 

[dlloyd]

WOW my head is still spinning.... so is the 18 ohm pre amp in the bongo a good thing..? or is the ohms thing a whole different kettle of fish in regards to pre amps..? (it is an 18 ohm pre amp isnt it )

Volts?

 

[tiffles]

hell yes that would make sense...2 times 9 volts. urgh long day at work. i was a christmas elf today...could explain the lack of common sense

 

[vonfog]

RMS vs. "program"

Bingo, a perfect match. Each cab is getting 1200w, or twice their RMS rating. Good job!

What about cabinets that give their ratings in "program" watts? I was talking to one manufacturer who doesn't use RMS ratings.

Thanks,
Adam

 

[Aussie Mark]

Program is generally twice RMS. So, if you match the amp output with the program rating of the speaker, you'd be spot on.