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Dean's Super AA


jwc

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i'm glad i decided not to solder yet, otherwise i'd be screwed. it may look as though the woofer inductor lead is not connected to anything, but it is.. it's just hard to see in the crappy photos. i apologize, but a cameraphone is all i have.

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I use the soldering iron. Make sure the tip is clean when you start. Stretch out the lead, and then put something heavy on it a couple of inches back to stop it from moving around. Lay your tip on the end and rub back and forth -- you're going to melt it off. When you hit copper you will feel the tip scrape a bit -- start feeding solder. Stop for a second and clean your tip again. Back to the lead and keep feeding solder. I usually go until it starts dripping off and takes most of the enamel with it. Solder will not stick to the enamel, you know you're done when the quarter inch or so you've been working 'holds' the solder. You don't want a big glob on the end of the lead, so after you remove the iron give the lead a little flick with your finger to knock off the excess solder. Wear saftey glasses, and keep the kids away. Let it cool a couple of minutes and clean the end with alcohol. It took much longer to write this than it takes to do it.

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O.K. JC -- it took a while but we have a DBB Cornscala filter. Al finally convinced me the series connection just ends up being a step back. The small gain in sensitivity (if any) doesn't bring any real rewards for the effort you put into the build/concept. So, parallel it is. My issue here of course is the extremely low impedance, and I remembered from the other thread that you wanted to try tubes someday. I ended up reading through that whole thread again before I called Al, and he agreed with one of the posts in the thread that indicated the impedance would actually be more like 3 ohms. Al ran simulations while I drank coffee and annoyed him as much as possible:) Al sees the whole thing coming in more like 3.5 ohms and I suggested a filter based on four ohms. We started with modifying the Cornwall ALK (4 ohm filter) with a 400Hz crossover. After several interations it became a modified Universal Type A. You will be able to run this off the 4 ohm taps of any tube amplifer without any trouble. Squawker level is adjustable as opposed to fixed, and the tweeter section assumes a K-77 is used. If you use a different driver you need to use an L-pad, another autoformer/swamping resistor, or Al's tweeter attenuator.

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Let me take a time out to be a little mushy. I can't thank you guys enough for doing this for me. I am a newbie trying to have fun and you guys (yall) just make this more fun. I've been on this forum one year now and and it has been one great roller coaster ride.

People reading this need to realize what an asset it is to have such great contrubutions to audio.

Ok. I'm out of tissue now.

I will order those parts. I sure as heck am going to build it since "yall" spent the time to help me. The tweeter will be the JBL2404. No experience with the Lpads. May run it as is and then add the attenuation later.

It will be hard for me to sleep tonight.

jc

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Yes Al. I assumed that. Thanks again. Can't wait to try it.

I have circled the parts I don't have right now. It takes me forever to get them from Solen. Do you all have these on hand for me to purchase? I also need one 1.5mH 14 awg litz inductor and one 10 watt 20ohm resistor.

jc

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(2) x http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=027-946&DID=7

(2) x http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=027-952&DID=7

(2) x http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=266-904

(2) x http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-428&DID=7 (peel back to 1.6)

(2) x http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=004-6

So, two each of the following:

027-946

027-952

266-904

255-428

004-6

The 1.6mH value is in 18 AWG and does not need to be litz. I think the Janzten 1.8mH 15AWG coil peeled down to 1.6 will work nicely.

20 ohm resistor assumes -3dB on the tweeter. This works with my Beymas but may not be enough for the 2404. What is that things sensitivity anyways?

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Great. I was thinking I had to use the Solen stuff to get it right. Partsexpress can get that stuff to me in no time.

Good question on the JBL

8 Ohms<?XML:NAMESPACE PREFIX = O />

Frequency Response

3k Hz - 21.5kHz

Continuous Program Power

40 Watts

Dispersion

100° x 100°

Minimum Cut-off Frequency

3k Hz

or higher w/ 12dB slope

Sensitivity (SPL)

105dB


This is all I got for specs.

Dean. I have that JBL unattenuated right now and it sounds great on a Type A design. I was thinking I would need only about 1-2dB attenuation if any. I can't get that with a type T2A can I?

How do you unwind the inductor to 1.6mH? I don't have a way to measure inductance.
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One goof on the schematic guy's you should include two woofers in parallel on the schematic.

Now I have a question. If a guy was so inclined to want to run dual Lascala bass bins with a single Lascala top section would this crossover work for that application?

Craig

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