n00b here with some project q's

[umwingnut]

I am a hifi junkie from way back but have not dabbled much in 10 or so years. In my storage room, I have the following:

Polk RTi28 pair with a blown woofer in one cabinet, possibly the tweeter as well but I have not tested. I picked these up from a thrift shop for $8.99

Linn Nexus pair with KuStone stands. I bought these used from a local shop about 8 years ago, and the kids my wife babysat poked in the tweeters about 5 years ago. The tweeters also seem to be blown so I just plunked em in teh storage room until I had time to start some projects.

Sooo.....I am ready to dig into some projects now. I would like to make one or both sets into active, biamped sets using gainclones. I am trying to do this on the super-cheap, and just make some cool stuff with minimal investment. And I am not overly technical, I have a basic knowledge from selling car and home hifi from 1988 until about 2001. No real engineering or tech backkground, and most of my knowledge has evaporated with time.

My questions are:

1. replacement drivers for the Polk seem hard to come by short of striking gold on ebay, which may or may not happen. Is there any way to find the original specs and then find a subsititute, and replace both woofers (or even all drivers)? I have no issue trashing the crossover and going active. Or am I better off just making them into surrounds or giving them to my kid to mess with?

2. The Linns. I was furious and heartbroken all at once when I found them smoked, I really love those speakers. I am trying to avoid sinking 200++ into Hiquophons which are the correct tweeter, but if I have to I guess I can. I found a Seas that might work decently, the 19TFF1, which should drop right in, and seems to be a decnt performer. I have honestly not looked at the sonic differences though, so it could be a horrible match for the system. I'm hoping that by going active I may be able to open up my tweeter choices somewhat.

3. What is a good, inexpensive amp project for either or both? I would need 4 channels obviously. I've seem the 41hz as well as the chipamp.com and a few others, and they all look decent. Should I use somethiing different on teh tweeters? Should I go equal power to all drivers?

4. where can I find a decent active xover design?

My original idea was to build a whole new set of speakers from scratch with the amps and xovers in the cabinets, like the Meridian actives I used to love. But since I have these boxes laying around, I figured I would start by modifying them first and leave the electronics external. Then, maybe I will decide to build something from scratch that mimics the Meridians.

Please overlook any ignorance, and suggest away. I'm sure I have much but that will change. Thanks!

[wakibaki]

Originally Posted by umwingnut

My questions are:

1. replacement drivers...

2. The Linns...

Sorry, I cant help much with the drivers...

Originally Posted by umwingnut

3. What is a good, inexpensive amp project for either or both? I would need 4 channels obviously. I've seem the 41hz as well as the chipamp.com and a few others, and they all look decent. Should I use somethiing different on teh tweeters? Should I go equal power to all drivers?

4. where can I find a decent active xover design?

My original idea was to build a whole new set of speakers from scratch with the amps and xovers in the cabinets, like the Meridian actives I used to love. But since I have these boxes laying around, I figured I would start by modifying them first and leave the electronics external. Then, maybe I will decide to build something from scratch that mimics the Meridians.

Remember that 2 x 100W amps with active crossovers driving individual drivers can handle the same signal power as a 400W amp driving a passive (speaker) crossover.

You could do worse than build a 4-channel chipamp using LM3886s. The complication is that different drivers have different efficiencies, so even if all else were equal, different powers might be required. Have a look at Rod Elliott on bi-amping:-

BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 2

Linkwitz-Riley active crossovers are everywhere in pro audio, why not go to the source...

Active Filters

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