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Rod Elliott has a good article in this months Practicle Electronics detailing how to construct his 3 way active crossover. It is very thorough and well written; even to the point of allowing a first timer to build this unit.
Wow, cool! Thanks for the mention, I'll have to check it out.
MB, Is this article an expansion of Rob's Project09? http://sound.westhost.com/project09.htm
You know G-Man; this is a linkwitz-riley but it is a three way design. Last year I bought his original x-over board, his boards are only a couple bucks each but I haven't done anything with it yet and If I remmember without looking mine was the po9. I am leafing through the article but I can't find any reference to a model number. Let me search the thing; there has to be a model number somewhere. This article is a really complete and thorough build description with wiring shots and everything. It looks as if you can buy it as a kit but I don't see a source reference. I'll let you know. How's the chip amp project coming?
I think it's funny how you go all the way to Australia for your projects when you can get some world-class boards right next door from Marchand in Rochester. I'm working on several chip projects simutaneously. Rotating them depending on what parts have come in and what I'm in the mood for. Finished wiring up a Carlos-Snubberized PS and a pair of LM3875. Let me tell you. Stop playing around with your itzy-bitzy power supply from the "classic" GC design and move up to the big boys. Huge difference in the weight of your sound. Big improvement on the midbass and sub-bass with no ill-effect on midrange. I've also finished plugging 2 out the 4 LM3886-based boards I ordered from Marchand (2 channels per board). Tried them out on the Snubbed-PS and I love them. I'll give more detail as the project progress. g.
Hey; I'm open to all ideas. My mistake but I was always under the impression that Marchand was pretty pricey for their stuff. I'll check the catalogue. I only jumped in because I wanted to try GC's on the cheap. 90$ for everything is hard to beat. Looking forward to your results.
MB, Does the $90 include powersupply? If so, that's a great deal. Marchand's prices aren't pricey. I just looked at ESP's pricing for boards and they're in the same ballpark ($20-$30). What I can say is that Marchand's boards are very high quality. Thick and rigid, double-side and teflon coated. The brackets and heatsinks you can order with his amp boards are drilled and tapped to fit the boards perfectly. Marchand's version of the GC (PM21) is available as a stereo board for just $20. $100 gets you all the parts and the board. Sounds a bit pricey, but the design gives you the flexibility to run the amp with inverting, non-inverting, or differential inputs after it's been assembled. You can also get a power supply unit that includes a 160VA toriodal with 20,000uF per rail for another $100. I know this sounds like a commerical for Phil, but I think his stuff has been overlooked and underrated. g.
Well; here's the breakdown. The low-end kit runs 30$ and the audio-phile, Black Gate Cap Rikens etc goes for 69$ w/o transformer but with PS and parts. So I needed a trans which I used a Hammond toroidal that ran me 40$ but it is a good one. Then many of the connectors and wiring I had already so there's the 90$ something. The passive parts are pretty expensive if you buy them solo. The boards on Brian GT's amp are very high quality double-sided and well laid out. There is however no option for changing to an inverting config. So there we have the skinny on those. I like the idea of the swap capability and the what looks like bigger PS caps. Oh and the heatsinks are not included I had to get those. I amfamiliar with Marchand Quality; I had a active cross-over of theirs many moons ago when he was first starting out. So how did you set-up the whole unit?
No setup yet. What I would like to end up with is two 4-channel amps based on the four Marchand boards. I see these boards as a very cheap and easy way to build a set of high quality multi-channel amps that I can use to experiment with various set ups. Bridging, paralleling, active XO, home theater, etc. The second project I'm working on is an all-chip integrated amp, based on a pair of "classic" GC and opamp-based preamp with tone control and separate opamp headphone amp. The theme of this project is "how good can an all chip system be without using "boutique" components. g.
Good idea. The boutique thing is the most important since so many of the commercial amps now come with those chips the only way to improve on the sound for a DIY'er is to use them. Then see if there is a worthwhile difference. Any thoughts?
My thought is that I don't have the time, money, patience and listening skills to properly test different implementations and evaluate the merits of boutique vs common parts. I'm sure there are differences between the various types of coupling caps and resistors, but at $10/$20/$30 a piece, I'm not in the position to test for the hell of it. (Remember how all those resitors you bought from Angela's add up?) I think this is where the large manufacturers have an advantage. The serious ones set aside time and resource to test and refine beyond what most DIY'ers are able to do in their basement. (Then the accountants come in and tell the engineers to use the cheapest parts.) Because I can only afford (and allowed by my wife) to build a limited number of amps, I tend to stick to "tried-n-trues"
Yeah I placed those 7$ resistors on my workbench taped to the shelf so I can remind myself how easy it is to be a dumbass. I have to say though that Brian GT's amp sounds better with the Black Gates and really the values are such that they don't add up to that much. Now when I finish Rods P 32 pre-amp I will have a good handle on how much that difference is.
John, You still interested in getting together? We tossed the idea around a couple of weeks back. I'd like to make arrangements with Martinelli to pick up my bandsaw and I have my eye on Apr 22. Prairie Home Companion is taping a show on that Saturday in Rochester.
Re: Still interested in getting together?
No Kidding; I like that Garrison Keillor guy. "It was a slow day in Lake Woebegone this past week... I have to co-ordinate with the boss; I'll get back to you pronto. Rochester is 9 hours away; thats the only draw; it's a bit of a hike.
Just read the show details again and realized it's in Rochester MN, not Rochester NY. Unfortunately, no show. I still need to coordinate with Martinelli on the saw, but I understand that 9 hrs is a long ways away.
Rochester Minn. Close but no cigar. Too bad I would have liked to see him but thats a little too far. I have to examine the possibilities; it ain't over yet.
Talk about hot article, I was able to get tons of my questions answered through just reading this. Thanks!