Hi,
A friend of mine has been asking about a light portable bass amp that he can lug with him and use for around 4 hours. I want to build this as a christmas present.
So far I have come up with the following:
Using 4x 60W/hr 6 cell notebook batteries for the supply
Using 1x 60W/hr 6 cell notebook battery as a reserve supply (switchable)
Using a 45-55 litre max fibreglass enclosure with a 10" driver and 4" mid
Using 2x 41hz.com Amp 11 (60w RMS@32V) (one for a switchable backup with a 2 ohm resistor in series with the speaker as a "limp mode" backup).
I know this will not blow the house down, but with a speaker around 92db 1w 1m am I safe to assume it will be quite loud? Also it has to have bass extension to 41.2hz.
Can anyone suggest a suitable speaker? Is there anything that screams failure in this project?
Are the 41hz amplifiers up to this task, if someone unplugs a guitar and it makes a high level pop sound will the ampifier take it? Should I add input protection (such as 2 lots of opposed polarity banks of 3x diodes in series to clamp the input level)
Thank you for your help with this.
A friend of mine has been asking about a light portable bass amp that he can lug with him and use for around 4 hours. I want to build this as a christmas present.
So far I have come up with the following:
Using 4x 60W/hr 6 cell notebook batteries for the supply
Using 1x 60W/hr 6 cell notebook battery as a reserve supply (switchable)
Using a 45-55 litre max fibreglass enclosure with a 10" driver and 4" mid
Using 2x 41hz.com Amp 11 (60w RMS@32V) (one for a switchable backup with a 2 ohm resistor in series with the speaker as a "limp mode" backup).
I know this will not blow the house down, but with a speaker around 92db 1w 1m am I safe to assume it will be quite loud? Also it has to have bass extension to 41.2hz.
Can anyone suggest a suitable speaker? Is there anything that screams failure in this project?
Are the 41hz amplifiers up to this task, if someone unplugs a guitar and it makes a high level pop sound will the ampifier take it? Should I add input protection (such as 2 lots of opposed polarity banks of 3x diodes in series to clamp the input level)
Thank you for your help with this.
What type of use would be most normal? Indoors or outdoors?
Bass extension to low E is a pretty big task for a single 10" woofer indoors, outdoors it's next to impossible. What driver do you have in mind?
Bass extension to low E is a pretty big task for a single 10" woofer indoors, outdoors it's next to impossible. What driver do you have in mind?
Intended Application
Hi,
He does a bit of street performing. I do see what you are getting at and my choice in woofer would be:
http://www.eminence.com/pdf/legend-bp102-4.pdf
If required I will use 2x 41hz AMP11 with two of these speakers, I may use mild equalisation to bring the bottom end up (3db centred at 60hz). If I use 2 amplifiers and speakers I will be using 6x 6 cell liion (from 60W/hr notebook packs) for 360W/hr energy storage capacity.
At the moment I am seeking advice with regards to the sound output level and speaker selection - I haven't had to build a bass guitar speaker before, Would using a sensitive 4R home hifi woofer / car subwoofer be better at the expense of a small degradation of sound quality?
Hi,
He does a bit of street performing. I do see what you are getting at and my choice in woofer would be:
http://www.eminence.com/pdf/legend-bp102-4.pdf
If required I will use 2x 41hz AMP11 with two of these speakers, I may use mild equalisation to bring the bottom end up (3db centred at 60hz). If I use 2 amplifiers and speakers I will be using 6x 6 cell liion (from 60W/hr notebook packs) for 360W/hr energy storage capacity.
At the moment I am seeking advice with regards to the sound output level and speaker selection - I haven't had to build a bass guitar speaker before, Would using a sensitive 4R home hifi woofer / car subwoofer be better at the expense of a small degradation of sound quality?
Any type of electric guitar will use distortion as a musical effect, so you shouldn't be concerned with how good the driver sounds - rather with how sensitive and how tough it is. Avoid high excursion drivers in such an application, they will sound muddy.
This is a bit of an oxymoron.
A good bass combo is heavy and large.
This looks like a good (cheap) battery: DealExtreme: $12.70 Mystery 11.1V 2200mAh Lithium Polymer Rechargeable Battery
I haven't tried this battery, but I have bought other lithium batteries from DX with no problem. The Amp 11 will be OK with 3 of these if you get the version with 50V caps (#28)
You've also got a charging problem. You might want to look at something like this balancing charger: Inwood Models : LIPRO QUAD 6 BALANCER CHARGER [FCH005] - £109.99
...you'll need some switching to break the battery down into 3 individual packs unless you can find a charger that will cope with them in series. I think the pack shown has connections for charge balancing, but this is something you need to check. You can probably source a charger closer to home, electric flight is the source for this one.
I'd go for a more efficient speaker, I see some Celestions out there with 99dB, this is more than twice as loud, or the same volume for less power, which is a significant consideration.
Fibreglass may be light but you'll probably find it easier to construct a resonance free cabinet with MDF.
w
Your friend is probably thinking of the classic small bass combos like the Gallien-Krueger MB150 or some of the Genz-Benz stuff. I suspect both makers use proprietary drivers to get things so ridiculously small, but maybe you can find some info on the driver used in the MB150 over the years-- it has a strong cult following.
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