Started my new custom SDA's today

ben62670

I feel pretty... Oh so pretty...
OK well I am just happy. My XO's worked very well the first time. Well not really. First I tried running them with the same amp as the stereos. Too much highs. So I hooked them back up to the GFA-7500. Excellent match. I have not done a sweeps yet, but the way I set it up I only have to makes a change to the main cap, and inductors like Polk's. I mess with the values a little. A resistor in series with signal is wasted power. The caps are new so I only expect it to get better. This setup is much better than having to deal with driving the highs hard with the active XO. There are no phase, lobing issues that I had at close range like before. I can't wait till the caps break in. When i am completely satisfied I am going to upgrade to a better cap for at least the main cap. I may parallel 2 8's or 2 6's for better power handling. I love these Morels. I so can't wait till they are broken in!

lightman1

Tip o' the hat Ben. It's a labor of love.

ben62670

lightman1 wrote: »

Tip o' the hat Ben. It's a labor of love.

Thanks. I always appreciate encouragement, and I love to share what I have learned

dudeinaroom

bah, frankenpolks

jpowell

Trying to refresh my sda srs's. Getting all new drivers and tweets. Any advice?
Jeff

ben62670

jpowell wrote: »

Trying to refresh my sda srs's. Getting all new drivers and tweets. Any advice?
Jeff

Welcome to Club Polk!
Most likely your woofers are good. I would look hard at getting the RDO tweeters. They are silk domes, and remove the high pitched spike at 12khz.
Stick around, and learn about the upgrades that can make them much better than new.
Ben

lightman1

How are the "Home Brew" Speaks going?

ben62670

Ya know that country song "What was I thinking"? Man that song was going through my head today moving them from one room to another. I only had to go 30 feet, and under one door, but man what a job, and I had someone helping me! 7 feet is too tall for an indoor speaker. You have to lean it so far over to get it under a door its not funny. I am dreading the day I need to move them up stairs or down for that matter. I had to move my RTA15TL's too, but they felt like book shelves after the biggins! Well when I hook them back up, and get my ears on again I will not whine, but smile.

engtaz

Ben, That's 1 of the reasons I offered my help.

Take care and God bless,
engtaz

ben62670

engtaz wrote: »

Ben, That's 1 of the reasons I offered my help.

Take care and God bless,
engtaz

So you could hear them, or so I wouldn't get squished:D

engtaz

Both LOL

engtaz

Gempler

Months after your last posting, but just read this whole thread from top to bottom... Congrats on your success and thanks for the play by play.

ben62670

Well I may have found my new tweeters for my speakers. With domes a single tweeter is much better than an array. With the array if you move around the room L/R, or up/down you can really hear the phase issues. Yes in the sweet spot its damn good, but else where there are issues. These issues are very apparent with sine waves. The tweeters I found have great off axis performance, power handling(200wrms), and 92.5db rating. These should be able to handle transient peaks up to 122db. The ones I had before survived system peaks to 126db. Those were rated at 90db, and 120wrms.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=277-072
I'm certainly not getting these any time soon, and will go back to using two tweeters for now. Just dreaming a little here, and excited about the new model.
Ben

Edit BTW the 2 tweeter array had by far the best sound stage/made the speakers disappear effect of all. The Morel have a nearly identical phase/impedance characteristics to the SL3000's from 2k on up.

obieone

Ben, you need help! Professional f*cking HELP! BTW, when you get settled in GA, I may have a SMALL project for you.

zingo

Those tweeters look like the perfect match for duty on your SDAs, and no you don't need help. None of us do... :cool:

ben62670

Well I was working on them again today. I put about another 10hrs in. I did the tweeter wiring over again. I replaced the cheap stuff with silver 16ga. I ran every single wire from the inside out. No tweeter XO components are inside the cab anymore. I can tweak the XO very easily without removing anything. I will post pics after the little get together we are having here. I have a "magic box" that I have designed for XO components for the woofers in both dimensional, and stereo arrays. Matt Polk sent me an email a while ago with some ideas for my design. I felt like I had been blessed by God

ben62670

Well I found another major improvement. A cheap Technics TT. The SQ isn't the greatest(kinda hollow/tinny), but I was listening to Queen's greatest hits, and I was just floored! I felt like I was being lifted out of me seat. The bass dynamics were great. It felt like my speakers were even bigger if that makes sense(they are over 7'). I am using an Outlaw 990 phono in which probably isn't the greatest. Thats all I need is the stinken vinyl bug. I am picking up a DAC Sunday. I hope this cures the upgraditis for a while. BTW the SACD player I thought I was going to get fell through. I took it as a sign. Sell amp first to get SACD player, or I will just keep the amp, and starve myself!

ben62670

I don't know man. I have been eye balling one of those Marantz 8260's for a bit. If an SACD layer is 5.1 only can an SACD player still put it out in 2 channel?
Ben

ben62670

Sal can you have your honeymoon at my house:D

ben62670

Well I did some playing with the SDA's, and I explained that the Dims were at 4ohms, and the stereos were at 4 ohms. With the newer XO styple(P/B) the outers needed to be 4ohms with the inners at 8 ohms. I was thinking of adding another driver to make the stereos 8 ohms, and the dims 4 ohms. I sent an email to the man the other day, and he sent me a reply pretty quick.

Quote:
Ben -

When you get a moment please sketch out a diagram of the crossover and SDA circuits you are using. I might have some ideas that would help.

The reason you're not getting a really wide SDA soundstage is the impedance of the SDA drivers is the same as the Stereo drivers. Because the two SDA driver arrays are effectively wired in series the SDA signal is seeing 8 ohms, not 4 ohms. This means that the SDA signal is about half as loud as it should be. A nice experiment would be to disconnect 4 of the stereo drivers on each side leaving just the four in the middle wired series-parallel to give you 8 ohms. This will drop the stereo signal level to match the SDA signal and will also reduce beaming.

Give it a try and let me know.

Good luck!

-msp

---

Original Message

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From: ben williams [mailto:ben62670@yahoo.com]
Sent: Thursday, August 14, 2008 10:32 PM
To: Polk, Matthew
Subject: RE: DIY SDA builder

Well I have saved your email for quit some time now. I have been playing with them, and making lots of changes. I now have them actively crossed over at 2250hz. The top end consist of either one, or two tweeters running. I am using Morel's for the tweeters. When using two tweeters I just run one out of phase. I know it sounds overly simple, but it seems to work very well in my environment. I never did implement a 300hz XO on the bottom, and top sets of MW's. Where I am now like you said the mids are beaming pretty bad. I get a big bump in the 300 region, and I was thinking of a 6db XO point at 250(inductor). This would throw off phase a bit, but might actually play nicely with the PR's. Some input would be appreciated. I hope to see you at PF-08. Here is a recent pic of the system as it sits now.
http://www.polkaudio.com/forums/show...1&postcount=65
The little wood box in the center contains two 15mh inductors for the SDA effect. I know this isn't the best setup for my array seeing that both arrays are running 8 8ohms drivers at 4ohms, but I just couldn't afford to get 16 4ohm MW's to get things right. It works, but the sound stage isn't as wide as I would like. Someday I will ave the coin to get it right Have you ever played with the idea of over sized SDA's?

Thanks
Ben

Well I never thought of running just 4 stereo drivers, and 8 dims. I'll have to get back to him(those who know... know who him is), and see.
Pretty excited about the new idea. I just can't pull it off with that many mids in that small of an area. We were to the point of nailing up blankets to the walls!
Ben

ben62670

Well a little experimentation has been taking place today. I have disconnected 4 of the stereo drivers per cabinet to yield an 8ohm load on the stereo, and kept all the dims at 4ohms. The beaming upper mids are very reduced, and the sound stage is wider for sure. Before I had to have the speakers less than 6 feet apart, and now they are at 7'6" with my head 11' away. This is what SDA's are supposed to sound like... almost!
Ben

Please donate 8 MW6511's to Ben's kids care of ben62670:D

zingo

ben62670 wrote: »

Please donate 8 MW6511's to Ben's kids care of ben62670:D

Is that Brad Pitt's new charity?

sswilson

Ok, that's absolutely sick!!!!

Amazing job. I never would have thought it could be pulled off, but looks like you got both the audio and the looks just right.

ben62670

Thanks. I am never quit satisfied, and after the move in the new environment it's needed a little tweaking. Today is a good for for them:)
Ben

ben62670

Well I am pissed, and happy at the same time. Jerry came over today with his LSI 15's. We did an XO upgrade. I was pissed. The LSI's had better SQ after the upgrade than mine. My mids just weren't as sweet compared to his when I did a side by side. He told me to put the Vifa's in mine. I thought that was nice, but wasn't the problem. Its my mids. Well we did it. The Morels are going. I am getting the Vifa's now. Well when I can afford them. At least I know I can bring them to the next level. The Morels imaged a little better, but the trade off with the Vifa's mids just creamed the Morels. The Morels just can't hang as low as the Vifa's, and the Vifa's are way more forgiving to bad recordings.
Ben

ben62670

The Morel's are better off axis on paper, but it is minimal, and at the upper ranges, and after 12k my hearing isn't there like many others:(
Ben

Face

Told you Vifas are the shiznitz.

F1nut

ben62670 wrote: »

I don't know man. I have been eye balling one of those Marantz 8260's for a bit. If an SACD layer is 5.1 only can an SACD player still put it out in 2 channel?
Ben

All SACD's have a default 2 channel hi-rez layer.

ben62670

Face wrote: »

Told you Vifas are the shiznitz.

Well some people are stupid and look at numbers instead of relying on their ears:o I am very lucky my friend came over with those nippled tweeters!

Face

ben62670 wrote: »

I don't know man. I have been eye balling one of those Marantz 8260's for a bit. If an SACD layer is 5.1 only can an SACD player still put it out in 2 channel?
Ben

Wait for SA-8001's to come down in price, many of the 8260's were troublesome. The 8001 can be had new for a little over $700(750 locally), used prices should come down soon.