OB W-frame build

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mlundy57

Re: OB W-frame build
« Reply #80 on: 10 Apr 2017, 06:44 pm »
You can always look at it like this, if you like what you hear go for it. If at some point in the future you want to see what difference opening the back up makes, you can take the amps off and set them on the floor behind the cabinet for an experiment. This may be easier to accomplish when your wife is going to be away for the day.  :green:

Then if you can't tell any difference, put the amps back on the cabinet. If you can tell a difference and like the sound better with the back of the cabinets open, then it may be time to look for a solution that will let you keep the backs open and be acceptable with your wife.

Mike

Danny Richie

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Re: OB W-frame build
« Reply #81 on: 10 Apr 2017, 06:47 pm »
Danny, Were I closer I would bring them over so you could run tests on them. We could then see the impact that my foolishness has wrought.

While it is playing try moving it away. You are blocking about a 1/3rd of the air space on the back side with the amp. And it is also effecting the output on the front side.

Quote
Regarding the extra 3/4" in deciding the load it would present to the drivers, since it is also 3/4" out (from the center) I think it would act like a very short 45 degree horn. If that has an audible affect (on frequencies in the band pass), I would be very surprised.

Try moving it away.

Just laying it flat on its back behind the woofers takes up very little floor space and would hardly be seen.

Early B.

Re: OB W-frame build
« Reply #82 on: 10 Apr 2017, 06:55 pm »
If I cannot keep the amplifiers mounted, then I made a costly mistake, because that is where they will stay, or I will sell them and recoup some of my loss.

You're being given exceptional advice, and if you're not going to be receptive, then you should recoup your losses, and consider a more aesthetically pleasing option.

I'm not trying to give you a hard time, but I made a similar mistake when I built my W-frame. I made my own design changes, listened to Danny's advice, and to make a long story short -- I eventually bought a flat pack built to spec and it sounded much better. I also thought my wife would have an issue with the aesthetics, but once she sat down and listened to her favorite music, she was hooked and never had an issue from that point. In fact, she encouraged me to buy another OB sub! And I happily obliged.

   

Captainhemo

Re: OB W-frame build
« Reply #83 on: 10 Apr 2017, 07:10 pm »
You're being given exceptional advice, and if you're not going to be receptive, then you should recoup your losses, and consider a more aesthetically pleasing option.


I'm not  trying to hassle either but,   IIRC, this was all discussed  before you started this build.   Many of us suggested  that it was not a great idea to put the amp boxes onthe  cabientss, you chose to to  do so and tha's fine but  it now  is what it is.

I'd do what Mike suggested, go with it .... but, at least try and center the amps so that  each driver is loaded the same, mkae the most of what  you've got going. If at some point you chose to  try it without the amps mounted, great .

The bottom line is everyone wants you to get the most out of your new subs , people are passionate !

jay

aceinc

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Re: OB W-frame build
« Reply #84 on: 10 Apr 2017, 07:33 pm »
As I previously mentioned, I like the way they sound as is, but I can see moving the amplifiers up.

Having said that, I did run sweeps using REW, and an uncalibrated microphone on one, then the other then both subs. Things looked fair, considering I was using an uncalibrated mic and it was an in room measurement. There was a low peak (30ish Hz) & a high peak (60ish Hz), I used the built in parametric EQ to tame the 60hz peak.

The one thing I have not seen in this discussion is a quantitative or qualitative definition of what I could expect to see or hear by making the changes I made. If someone were to say, "By loading one of the woofers you will see a peak at 40hz." or "By changing the cabinet adding 3/4" of an inch the bass will sound muddy.", it would make understanding the issues/concerns easier.  Without this sort of input, how am I supposed to assess whether the changes I have made make a noticeable difference? Wiring them wrong sure made a difference :duh:

When I was young and went to church, I was a PITA to my Sunday School teachers, cause I would challenge everything. "Why can't we go to the movies? They show movies on TV." "Who created God?" :icon_twisted:

aceinc

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Re: OB W-frame build
« Reply #85 on: 10 Apr 2017, 07:44 pm »
Heck for all I know, my changes may have improved everything, and everyone else should jump on the bandwagon. :lol:

corndog71

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Re: OB W-frame build
« Reply #86 on: 10 Apr 2017, 07:46 pm »
Mine are laying on the floor behind my cabinets and you can't even see them.


aceinc

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Re: OB W-frame build
« Reply #87 on: 10 Apr 2017, 07:53 pm »
Part of my reasoning is functionality, I move my speakers testing and playing with stuff regularly. Having a separate box means more stuff I need to move, keep track of cables, etc.

aceinc

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Re: OB W-frame build
« Reply #88 on: 10 Apr 2017, 07:56 pm »
Corndog, I bet you have the rumble filter turned on when playing albums.

BobRex

Re: OB W-frame build
« Reply #89 on: 10 Apr 2017, 07:57 pm »
Here's a silly question - since you already have the amp boxes built, and you'll be placing some sort of satellites on the top of the woofer box, why not just stand the amps up on the woofer box and let them act as backstops for the satellites.  That should cause far less sonic "damage".

corndog71

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Re: OB W-frame build
« Reply #90 on: 10 Apr 2017, 08:14 pm »
Initially I had the amps up against the inner side of the sub cabinet so I could have easy access to the controls.  It took a bit of experimenting to get them to sound right.  Once I got that all figured out I didn't need to access them anymore so I laid them down and moved them behind the sub.  I would think screwing them onto the back would be more of a PITA. 

When it comes to Danny's designs he figures most of it out so all you need to do is build a cabinet to his specs, finish it however you like and enjoy.  Others have tried to improve on his stuff but only end up compromising the sound quality.  I've seen many other speaker designers do it differently (and cut lots of corners to make them cheaper) but Danny is all about providing the best sound for the money.

I do have the rumble filter on.

I suppose I should also add that I'm not married but I do have a very understanding girlfriend. 
« Last Edit: 25 Apr 2017, 09:51 pm by corndog71 »

aceinc

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Re: OB W-frame build
« Reply #91 on: 10 Apr 2017, 08:15 pm »
Bob, I am building an open baffle "enclosure" for the mids & tweets. I have thought about mounting the amp back there as well.

Of course I have the same poorly defined problem there of changing the loading on one of the midbass speakers. I say "poorly defined problem," because I haven't heard what kind of issues doing this will cause from a sonic point of view.

aceinc

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Re: OB W-frame build
« Reply #92 on: 10 Apr 2017, 08:26 pm »
Corndog (Rob?), I am not trying to improve on Danny's design from a sound point of view. I look at it as tweaking it to fit in my lifestyle.

Some (many?) people buy/build Danny's design to get incredible audio at a liveable price point. They are looking to get the best sound they possibly can. If I get 90-95% of that great sound, but I have something that meets my lifestyle and has my personal touches, that is why I am into this "hobby."

If I challenge people to think, "What actually will happen if I mount the amplifier on the back of the cabinet?" Instead of just saying "Everyone says it is bad it must be bad.", is that a bad thing?

corndog71

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Re: OB W-frame build
« Reply #93 on: 10 Apr 2017, 09:06 pm »
Corndog (Rob?), I am not trying to improve on Danny's design from a sound point of view. I look at it as tweaking it to fit in my lifestyle.

Some (many?) people buy/build Danny's design to get incredible audio at a liveable price point. They are looking to get the best sound they possibly can. If I get 90-95% of that great sound, but I have something that meets my lifestyle and has my personal touches, that is why I am into this "hobby."

If I challenge people to think, "What actually will happen if I mount the amplifier on the back of the cabinet?" Instead of just saying "Everyone says it is bad it must be bad.", is that a bad thing?

Well, they are "open baffle"  by design.  Perhaps you would've been better off choosing a sealed sub which you can still build with those drivers and amps.

aceinc

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Re: OB W-frame build
« Reply #94 on: 10 Apr 2017, 09:21 pm »
Nothing I am doing is changing them from open baffle. I am restricting the airflow some from one side, I don't see what all the hubbub is about. You'd think I was personally kicking someone's dog.

I already have a 15" Rythmik Audio sealed servo sub I built years ago. As well as a pair of sealed 10" subs, non-servo.

I also built a Danley Sound Labs TH-Spud clone once just to see what it would sound like, It was impressive, you wouldn't believe how much bass you can get out of two 8" speakers.

I think tonight I will try some hip hop or dub step, just for fun. I recently picked up a country hip hop CD (Jawga Boyz) for free at a garage sale, maybe I'll give that a spin to test the bass;

https://www.youtube.com/watch?v=ADC_6XFvIxk

S Clark

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Re: OB W-frame build
« Reply #95 on: 10 Apr 2017, 09:25 pm »
It's your stuff.  Do what you want with it.  I'm sure you realize by now that the designer has tested extensively to find the optimum enclosure.  You vary from that as you need to fit your parameters and live with the results.

Early B.

Re: OB W-frame build
« Reply #96 on: 10 Apr 2017, 10:00 pm »
If I challenge people to think, "What actually will happen if I mount the amplifier on the back of the cabinet?" Instead of just saying "Everyone says it is bad it must be bad.", is that a bad thing?

Yes.

Don't try to convince us that what you're doing is OK. It makes no sense at all to spend all of that time and money, presumably to get the best sound possible, then screw up the sound by being incredibly obstinate with such a minor issue as placement of amps behind the speakers where no one will see them.

mlundy57

Re: OB W-frame build
« Reply #97 on: 10 Apr 2017, 10:09 pm »
One of the big issues with open baffle is having enough distance between the driver and front wall (reflection point behind the driver) to achieve at least a 6ms delay between the direct radiated and reflected waves reaching your ears. If there is enough separation, the reflected wave adds an expansive aspect to the sound. The closer the speakers are to the front wall the smaller and more constrained the soundstage will become. If they are close enough so the delay will be too short for the brain to perceive the waves as two separate sounds the music will start becoming muddy and smeared.

This goes for all open baffle arrangements, mids and tweeter as well as bass. So blocking the back of the cabinets could have the same result as placing them too close to the wall. Only listening to both configurations will answer the question for you.

Mike

aceinc

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Re: OB W-frame build
« Reply #98 on: 11 Apr 2017, 03:03 am »
Early, it is my money and my time. I am not trying to convince anyone to do anything my way. I am interested as I stated earlier in what artifacts or anomalies I can expect by deviating from the norm. If I know what I might expect, I will look & listen for them.

But if all I see is folks saying this shouldn't be done because it may cause premature amp failure, or the loading of the drivers will cause some indeterminate audible anomaly, why should I not do what I want? The worst that could happen is I find why putting the amps on the back is a bad move. I then share that information, and idiots like me in the future will have concrete ideas as to what to expect should they try this. The best I can hope for is that it has little or no impact, and then it gives options to folks that read my posts.

Mike, I may be way off base here but at the wave lengths that we are talking about when dealing with < 100 Hz, having something that close blocking part of the opening would have little impact.

Sometime real soon I will pull the amps off, which I need to do to move them up to the middle anyway. When I do I will run an REW analysis with them off. I will then put the amps in the middle, and run the same analysis. Will this make everyone happy? Beware I am using the USB microphone from the Emotiva XMC-1 because my notebook does not have a microphone in jack. If someone has a calibration file for that microphone I would love to have it. I will be taking the measurements from my listening position about 12-13' from the speakers and will do 0-200 hz.

If anyone is in SE Florida and wants to join in the fun, PM me.

aceinc

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Re: OB W-frame build
« Reply #99 on: 11 Apr 2017, 03:16 am »
Danny, if you want to pop in with your test equipment, I would be happy to put you and your family up at my bungalow.

While this offer is genuine, I doubt that you will take me up on it, but if you have some tests you would like for me to do, let me know, and if I can do them I will try.