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Make me a stereo system! (poof!!)   

Posted by kurtster - Jan 25, 2016 - 10:39am
So I got the refoaming of the sub done successfully and couldn't be happier and relieved all at the same time.  It was pretty simple.  Here's the video from the company that I went with.  Didn't remove the dust cap and shim like others have.  The technique explained in the video worked fine.

The results are stunning.  I really don't know when I finished blowing out the surround.  I have some suspicions, but, it was obviously a long time ago.  The change was gradual though.  About a year or so ago, I flipped the sub on its side and had it aiming at the wall behind it instead of firing down as designed.  I guess I just figured it was the acoustics in the new place and was something I would just have to live with.  

So here's what I think I learned from all this.  First, speaker repair isn't all that difficult, although reconing has yet to be tried, but evidently its also a not too hard diy project if necessary.   All the digging for a powered sub told me it was a crap shoot unless you could pony up at least $400 for something close to real.  Thought about the Dayton kit.  But I'm broke.  So for $19, I had to try.

Into the weeds...
During the two weeks that the sub was totally disconnected, I lived with the two ways I had running after the sub to see if I could live with them if I had to.  I don't have a home theatre rig up and working, just plain stereo.  But the receiver is a 7.1 THX certified Onkyo 24 bit DAC box I got more for the inputs that anything else.  Everything is played flat without eq of any kind through a dedicated XP computer using Foobar as the backbone media player with an optical input to the receiver keeping things as accurate and noise free as I guess is possible.  All wav files including the turntable via a USB preamp 16 bit DAC, unless listening to innernet radio.

So first go round, hooked them up and played the usual super familiar tunes for testing.  Full bandwidth signal.  Really ?  No way this was gonna work.  Looked up the specs for the speakers and bottom end claimed was 50hz.  So I set the cutoff frequency to the speakers to 50 and gave it a listen.  Better, but ...   Ran the Audessy setup on the receiver, got better yet and it was beginning to sound doable.  But the mid was muddy and the bottom was there but thin.  So one more look at new subs and the fix.  The sub has a 120 hz crossover to the speakers behind it.  Critical and the reason for the sub in the first place.  The 2 ways are now liberated from having to deal with anything below and the difference is stunning.  

I think I have a better understanding of what break in for a speaker means.  Its the surround that has to break in.  It has to flex and conform to the cone movement within the frame which takes many hours to happen.  Last week I had two 5 plus hour wake and bake sessions of good old fashioned listening and I could hear the sound constantly improving.  Reached the point of the music being pretty again and just sitting back with eyes closed satisfying.    I had a listen to the sub by getting on the floor, next to it.  Didn't sound real good, even though the immediate overall sound improvement was like night and day.  Groan again.  Hmmm.  How about I set the bottom cutoff in the receiver to the speakers at 40 hz ?  I don't know about movie soundtracks, but for music recordings, in all the years of remastering or what ever it is, I saw that there is virtually no signal below 40 hz.  In fact there is not a lot going on below 60 hz in most recordings.  That is what gave me some hope in living with the 2 ways.  But there is a traffic jam between 100 hz up to about 700 hz.  That is where all the complex music really is.  So WTF, set the cutoff to 40.  No reason trying to reproduce what isn't there which is mostly hum and meaningless distortion.  Immediate improvement.  After all these years, it makes sense.  The reason for the sub, is to liberate the mids from doing what they can never do.  Same holds true for a sub or a woofer in a 3 way like my old retired Vega's which have 12" woofers.  

Back in the day, I had a 10 band eq that was pretty decent, but IIRC the bottom slider was at 36 hz and the next one up was around 60 or so.  But iffen you slid the bottom slider down, the bottom was diminished too much to really want to do it.  So never went there.  So hmmmm again.  Someone gave me a macdaddy 17 band Pioneer eq about 5 or so years ago.  The bottom sliders are at 15 hz, 25, 40 and 63.  Never used it, didn't have a need for it.  But if I had it back when and know what I know now, I would have set the 15 and 25's all the way down and cutoff all of that to the bottom end.

If you're still reading, you know that bass eats up the most watts trying to reproduce the lowest frequencies, so why try and deal with the garbage found below a certain point ?  Same idea as a crossover to keep the mids from trying to work in places they lose there ability and have no business in trying.  If I had a powered sub, I don't know of any way to cut off the sub below a certain point, without an inline piece of hardware like an eq or wired crossover / low pass filter.  I don't think very many people have given any thought to a lower limit for the lowest of frequencies and it would be an extremely exotic function of a receiver.  Because my sub is a passive inline type, the receiver allows me to make it think its running a powered sub and set the crossover cutoff to the mains at 40.  The settings for a powered sub have an upper limit, but no lower limit.

From all the sound engineering, I've seen visually as well as having heard how when a lower frequency is boosted it washes over the higher frequencies and lifts them up in the process.  It does not work in reverse.  When ripping vinyl, the preamp has a 40 hz cutoff for turntable noise, but listening to the 2 choices of the same song, its better to keep it off and get everything, regardless of what it is and deal with it later in the mastering process or playback.  This becomes more meaningful with the rebirth of vinyl and the re introduction of turntable noise to the foodchain.  Digitally, an engineer could arbitrarily cut off all frequencies below a certain point making the need for a low filter unnecessary, but in the analogue realm its all different.  Mastering vinyl is different than digital because of the limits of the medium and needing to work with the RIAA eq curve.  Its all subjective as hell; more dependent on the ear and experience of the engineer than anything else.  

So if you play lot's of vinyl, the preceding thoughts apply more to you than anyone else.  Some of you have built and used attenuaters for different cartridges, so its not a stretch to add this stuff to the thought process.

These are the thought and conclusions of this whole process.  I thought that maybe my hearing was going bad at some point along the way.  It wasn't and I was getting used to the gradual degradation of the speakers.  Those of you who have said that your hearing isn't good enough anymore to listen to and appreciate high fidelity music are settling and giving up.  Having worked on hundreds of songs and seeing them on a vertical spectrum analyzer that covers from 40hz to 22khz, I have seen where the music lives.  Reached the point where I can kinda of see music as well as hear it now.   Nearly all music is happening below 10khz which is where AM radio stops.  Stuff recorded in the 70's and later gets up to 15khz which is where FM stops.  Occasionally I've seen some recordings that actually have something over 20khz but damned if I can hear it.  In the age of fizzy 128 cbr mp3's and lord knows what kind of crappy vbr rates, its hard to care as much about quality and clarity, but even they can sound better, at least to the point where you can actually hear the fizz.  But if you still have quality sources, its easier to get quality playback these days than back in the old days.

All 2 way main speakers need a sub and it has to be properly set up.  Its a beautiful thing when it is.  A 3 way with 12" or bigger woofers will also benefit just as much with a low frequency cutoff.  If you see an old passive unpowered sub at a garage sale or on Ebay for $25 or 30, grab it, knowing that it will likely need a refoam which ain't that hard to do.  Like the tech at the speaker place I spoke with said, tossing out a speaker with a blown surround is like getting rid of a good car simply because it has a flat tire.  Maybe this spring, I'll dig out the Vega's and fix them.  The wife is real nervous about this possibility, cuz they are huge.  With them fixed, I could actually get a proper 7.0 system up and running with just having to do some wiring.  The cat's are already not liking how loud the stereo get's again.  They did not like the sessions last week very much cuz the whole place was loud.  But the wife did.  I am so lucky to share the same musical tastes with her, at least most of the important ones ...  This retirement thing just might work out.  It is still all about the music, period end of story.

And Bill if you're reading this, the 320k stream is simply awesome after being able to give it a proper listening to.  It was always better, but now I can hear how much better.  {#Notworthy}

{#Cheers} y'all
7 comments on this journal entry.    [ add yours ]

FourFortyEight Avatar

Location: The Dirty South

Posted: Feb 3, 2016 - 6:08pm

I love SPAM.

kurtster Avatar

Location: drifting

Posted: Jan 30, 2016 - 5:42am

 bokey wrote:

You takee 21 dollah?
No, I work for spam ...

I haven’t seen the Democrats this mad since we freed the slaves
bokey Avatar

Posted: Jan 29, 2016 - 8:25pm

You takee 21 dollah?
Free-Range DJ
BillG Avatar

Location: Left Coast

Posted: Jan 27, 2016 - 7:46am

Interesting stuff, Kurt.   & thanks for the kudos on the 320k stream.
Shine On.
Coaxial Avatar

Location: 543 miles west of Paradis,1491 miles east of Paradise

Posted: Jan 26, 2016 - 5:26am

Nicely done. {#Dancingbanana_2}
Single, unwanted, unloved eccentric, crusty ol' fart with cats
DaveInVA Avatar

Location: In a hovel in effluent Damnville, VA

Posted: Jan 25, 2016 - 12:21pm

Glad the refoaming went smoothly!

miamizsun Avatar

Location: (3261.3 Miles SE of RP)

Posted: Jan 25, 2016 - 11:09am

 good for you and jam on brother