Newbie question regarding amp filters versus crossovers for a bicycle stereo build

[jvossman]

85 mile bicycle charity ridethree of these thingsmanual

[jvossman]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

oh and one forum question, I had links in the post above to the bicycle ride, the batteries and the boss manual, but the links only show up when you hover over them. I guess I am a newbie at posting as well. Sorry.

[Taran]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

Tri-mode is where you bridge two channels to one for the sub and in the same 2-channels you also hook up stereo left and right. Bridging the amp to one channel for the sub and using 2 for the mains would work best, as you surmised. If you really wanted to tri-mode you would need 'passive crossovers (Just really inductors, capacitors, and resistors).I really think, however, that you should send back the tweeters and grab some full-range drivers. Running just subs and tweets will probably lead to a huge dip in the response... Yeah, you will drain your battery faster... do you have some kind of charging system off the wheels help out the battery?

[fbov]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

The BOSS trimode is just a poor man's way of getting 2.1 speakers to work with a 2-channel amp. Since all speakers are on the same amp channels, any internal filters would affect both sub and main speakers, thus the external crossover. Price the components and you'll find out why no one does this.

This amp has a fixed high-pass filter at 80Hz, and an adjustable subwoofer low-pass filter. For your purposes, use the diagrams on page 5, showing 4-channel and bridged modes. You want to wire 2 speakers like shown at the top, and wire the sub in bridged mode as shown at the bottom. The use the internal XO's to send the bass to the sub, the rest to the speakers.

I also understand what you're thinking with the Bluetooth module, but the bullet tweeters are a mystery to me. I assume you want to augment the highs from the Nissan pick-up speakers? You'll need some sort of XO here, too, if only to protect the tweeters. In effect, the bullets and pick-up speakers form a 2-way speaker, so you need a crossover of some sort to get them to play nicely together. At minimum, though, you'll need a cap on the tweeters for protection. Here's an example:
http://www.parts-express.com/project...ontent=Default

BTW, I could also show the link as Podzuma...

As to battery life, it's all in the losses - most of the battery power is going into heat, not music. Class A/B is not considered efficient (unless compared with Class A), but the PWM power supply may give you the benefits of an efficient amp design. Regardless, I'd expect better efficiency from a car amp than any AC-powered amp.

If you were doing a clean sheet design, I'd recommend
- class D amp, for efficiency
- high sensitivity speakers (like used in Podzuma) to reduce amp power needs
- high sensitivity sub/woofer, which won't dig low, but you can't get low outdoors without lots of power.
- sealed lead-acid batteries - cheaper and easily maintained

It looks a lot like this.
http://techtalk.parts-express.com/sh...ciency-speaker
or, for the power-hungry...
http://techtalk.parts-express.com/sh...boombox-design
and perhaps similar to this
http://techtalk.parts-express.com/sh...case-enclosure

Have fun,
Frank

[Whitneyville1]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

On a bicycle, you can easily get by with some 3-4" Tang Band full rangers and a Lepai amp running off a pack of AA LiPO's or a small gel lead-acid battery. I used a 20 watt per channel Blaupunkt car stereo on my motorcycle when I went to Yellowstone, the Tetons, Four Corners, Utah, Mexico, and Taos on one trip. Without the wind and engine noise, you'll scare the wildlife for a mile in every direction too. Have you thought about open back headphones so you can hear what's going on around you and hear your music too? I'd rather have snacks and water weight than all the music gear myself. Two 120 oz. Camelbacks in Flor-Aye-Da heat seem more important to me.

[jvossman]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

hi guys thanks for the excellent help and questions..

Here is a photo of the old system I am looking to upgrade.



As you can tell, not for my own sound enjoyment but for the 40 or so people behind me during a lonely 30 mile stretch in the Florida keys.
FBOV- thanks for the suggestion on the boss amp, will follow your instructions exactly.
Whitneyville1- you are right about the heat and snacks for my normal rides down here, but the MS charity ride is extraordinarily well supported, breaks every 10 miles.
Taran- no dynamo hub too much $$$, but these lithiumion battery backs serve double duty for my night mountain bike races. What full range speakers do you think can handle the wattage, I couldn't find any on partxexpress

Question, do I even need two speakers, to save weight should I just run one speaker and run the signal mono (I can select this on the phone/mp3 player.

Thanks again!

[Taran]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

hi guys thanks for the excellent help and questions..

Here is a photo of the old system I am looking to upgrade.

[ATTACH=CONFIG]37191[/ATTACH]

As you can tell, not for my own sound enjoyment but for the 40 or so people behind me during a lonely 30 mile stretch in the Florida keys.
FBOV- thanks for the suggestion on the boss amp, will follow your instructions exactly.
Whitneyville1- you are right about the heat and snacks for my normal rides down here, but the MS charity ride is extraordinarily well supported, breaks every 10 miles.
Taran- no dynamo hub too much $$$, but these lithiumion battery backs serve double duty for my night mountain bike races. What full range speakers do you think can handle the wattage, I couldn't find any on partxexpress

Question, do I even need two speakers, to save weight should I just run one speaker and run the signal mono (I can select this on the phone/mp3 player.

Thanks again!

I was actually going to suggest going mono. And don't worry about too much power --- you can always just turn the gain down.

[Whitneyville1]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

Feed the output from your I-phone MP3 player into a signal combining "Y" adapter or cord, and feed that into a mono amp or a "bridgable" stereo amp into one speaker. I'm a "weight-weenie" with a 26 lb. framed TREK 24 speed, but I like it more than my old Raleigh 14 lb. 10 speed stitch-on racer in the "real world". We won't even talk about shifters, brakes, gearing, suspension and frame geometry. A gel-seat is nicer on a 60-year-old **** than a leather covered monoposto IN it too.

[jvossman]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

WHitneyville1- unrelated to stereos, but once you find a seat you like, buy 3 because by the time you need a new seat, they might not make the original one anymore. As for speakers, if I run mono, then I might as well bridge both sides of the 4 x 90 RMS amp right? Then its 180 net to the bazooka and 180 to the Boss tweets? You are right, I'll need to turn the gain down, does doing that mean the amp itself is using less power? Finally for the tweeters I want to enable the HI PASS filter right, cause it lets the hi frequency sounds Pass through. Right? Or is the LOW pass.

Thx

jv

[Whitneyville1]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

I don't know if you can bridge the BOSS amp as you mention. I think you have it right on the high and low pass filters. People who know the BOSS amp can tell you much more.

[Taran]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil

WHitneyville1- unrelated to stereos, but once you find a seat you like, buy 3 because by the time you need a new seat, they might not make the original one anymore. As for speakers, if I run mono, then I might as well bridge both sides of the 4 x 90 RMS amp right? Then its 180 net to the bazooka and 180 to the Boss tweets? You are right, I'll need to turn the gain down, does doing that mean the amp itself is using less power? Finally for the tweeters I want to enable the HI PASS filter right, cause it lets the hi frequency sounds Pass through. Right? Or is the LOW pass.

Thx

jv

You have it correct on the filters.

[Brian Steele]

Re: Newbie question regarding amp filters versus crossovers for a bicycle stereo buil


So, basically you want something like this, but a bit smaller?