Portable class D Bass Guitar amp/speaker design

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#63
The purpose is to show how loud a 5 watt tube amp and efficient speaker really is.
Click to expand...

And that clip is a perfect example of one of the key issues in loudness discussions:
Yes, a 5W amp can loud enough to be heard over the drums. Even a 1/2 watt amp can be that loud.

BUT

- The amp in the clip is already pushed into severe distortion. There's no headroom left and it is evident that the same amp at clean settings would not be loud enough to be heard over the drums. - At least not nearly at the same magnitude.
- The recording is drums + guitar only. What happens when you throw in a bass, perhaps a second guitarist and the vocals? Will the amp still cut through the mix? It's very possible that it actually gets drowned out by the other instruments. Drums are somewhat bad to compare because of their transient nature. Throw few sustained bass notes in to the mix and things get very different.
- With all respect, the drummer does not seem to be hitting the kit very hard. Things get way different when you have a heavy-handed drummer doing metal-ish blast beats over fast double bass. Again, the amp would get pretty much drowned.
- What if you want to amplify PA or bass guitar (of which this thread is about anyway) with that 5W amp? With those low frequencies and the clarity required the outcome is only distorted mush and farting sounds. You suddenly realize that you need at least a 100W amp (likely even something more powerful) to cut through the mix cleanly, though the perceived loudness doesn't really change that much.

So, the output power in regards to loudness is often immaterial. Output power in regards to headroom and overall clarity of the signal on the other hand is not.
 
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#64
teemuk said:
And that clip is a perfect example of one of the key issues in loudness discussions:
Yes, a 5W amp can loud enough to be heard over the drums. Even a 1/2 watt amp can be that loud.

BUT

- The amp in the clip is already pushed into severe distortion.
Click to expand...

As well it should be.😀 Clean is for sissies.😴 Or PA or Bass.

I happen to have a 1/2 watt solid state amp and it doesn't get loud enough to play with drums even when played through the same efficient 12" speaker. Besides, the distortion sounds horrible.

I have recorded clips with the drums, bass and guitar and it sounds about the same as the clip you listened to. The guitar is not less prominent because of the bass.

Of course a 5 watt tube amp is not really gig worthy unless you mic it up. In that case, the cleans would be loud enough.

I have built a 50 watt clean tube amp based on the Fender Twin schematic. That amp just collects dust because it doesn't distort until the volume is almost full up. At that point, you can't even hear the drums. You would need to mic them.😕

BTW, I have that clip on a CD. The difference between listening to it on CD vs an internet MP3 file is amazing. It's like a 10 fold decrease in audio quality! Maybe it's because of my cheap 30.00 Logitech computer speakers?

Don
 
#67
Having tried some Bose stuff before (never bought), they shouldn't be difficult to beat.

Those Fostexes would certainly be better. Perhaps look on ebay/whatever to see if there's any of the next size up (5" midbass instead of 4") for a similar price. You'd get more dynamics etc.

Chris
 
#68
I play bass too and was wondering about the same thing- battery powered amp with decent output. (I am listening to a 5 watt per channel tube decware amp through 98 db speaks. Plenty o db sans clipping. I still think tube amps subjectively sound louder than SS even without pushing them. Not sure why.)

I think class D is optimal for portable bass/PA simply becasue you are wasting less power as heat. The trick is a loudspeaker that can be efficient without any room loading.

I was tempted on this little piggy since the price is good.
http://www.amazon.com/Pignose-PB-30-Keyboard-Acoustic-amplifier/dp/B002JCSQ62

Pyle Pro, Samson, Carvin all make self contained portable battery included PA and they would probably work so so for bass.

But I would like to do is find a class D (or class T) amp amp module and mount it into an 8" or 10" Bazooka. Sure, they don't sound all that great as subs IMO but they are light and efficient. I guess they are making FR enclosures now. I like how the port faces front. I wonder if the powered marine version can be modded using the smaller 12v battery from the other designs. The Korg Pandora series make fine battery powered preamps, sound good and have stereo RCAs in addition to std. phono.
I think MCM or PE sold a PA plate amp at one time, but that was for AC. THe stock drivers in the bazooka could probably be swapped for decent neo Bass guitar drivers. Just don't know anything about the TS tuning.

Amazon.com: Bazooka MBTA8100 8-Inch 100-Watt Marine Amplified Tube: Electronics

I am having a custom U-bass made, a bass guitar with a 20" scale and dub central. Want to play it at beach at drum circle. Remember the Ashbory bass anyone?
 
#69
Here's the recipe for a Class D bass :
a stratoblaster buffer ,
blaster schematic
2 Preamps that you'd like .
100w x 2 or so Class D if you'd like ,
some nice JBL GT-82's ( though they are 93db efficient only ) if you can find them .
An externally hosted image should be here but it was not working when we last tested it.

Full size
Horn loaded , preferably .
2 x mid rangies
Pyle Pro PDMR5 5-1/4" Sealed Back Midrange << i root for them
An externally hosted image should be here but it was not working when we last tested it.


There you go , it's quite portable isn't it ?
But it isn't very cost-friendly 🙁
unless you can find 4 80+ Watt Hours Laptop batteries , go with SLA's they will save your life .
And you need some violent voltages 😀
Who likes cliff burton ?
 
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