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Re: 4Pi with feet [message #78239 is a reply to message #78127]

Wed, 30 October 2013 17:45

Matts
Messages: 359
Registered: May 2009

Grand Master

Yeah, if they're used speakers, they should be broken in. I don't think sitting around would matter. Only re-coning would start the process over. What kinds of music do you listen to?

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Re: 4Pi with feet [message #78240 is a reply to message #78127]

Wed, 30 October 2013 18:29

lucasmateo
Messages: 43
Registered: October 2013

Baron

They are breaking in? Or something happened.

I changed the cables to a better one, I'm not really a cable fan, but maybe is this?

They sound great, amazing, better than anything I had before. They are truly record dependant, I hear from tom waits to kusturica, some jazz, some modern (james blake...) It depends on my humor.

Some records have great tight defined bass with great extension, some others lack it. I'll listen to them for some weeks, and then try less insulation. This way they sound great, better that I expected.

This photos are from now, its quite late so I have bad light, on the weekend I'll post some nice shots, I used to be a photographer...

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Re: 4Pi with feet [message #78251 is a reply to message #78127]

Thu, 31 October 2013 18:01

Matts
Messages: 359
Registered: May 2009

Grand Master

Sounds like your speakers are doing fine. A lot of records, especially rock, are engineered for the booming tight boxes, and sometimes people interpret that boominess as bass, when it's a distortion. Kind of a quality vs. quantity issue. Also, many rock records don't really have much happening below 60-70Hz, and bass sounds lacking when you listen on a system that goes an octave below that. The Pi4's don't go super deep, but I can rattle my windows with them, even with 2A3's, when I put on Tupac's greatest hits....

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Re: 4Pi with feet [message #78253 is a reply to message #78251]

Thu, 31 October 2013 19:27

lucasmateo
Messages: 43
Registered: October 2013

Baron

You are right. And I think the suspension on the JBL were a little stiff the first time I connected them. Now they are sounding great, I'm listening to everything I have again! Now greatful dead is on. It's incredible how loud can they go with just a little set amplifier.

I don't have a weight in my home, but I travel quite often and I can tell that this creatures weight probably more than 50kg each!!! (More than 110lbs each Smile

)

They are really heavy, actually I have to move to another place soon and it will be quite hard to move them. I should have used wheels instead of legs.

I used double front face mdf, plus the veneer is solid wood 3mm thick. The legs might weight 2kg too.

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Re: 4Pi with feet [message #78268 is a reply to message #78253]

Sat, 02 November 2013 22:15

my0x
Messages: 23
Registered: October 2012
Location: Philadelphia, PA

Chancellor

Nice build - I hope you are enjoying them!

I found that the crossover and the compression driver needs to break in for a while before things start to gel. It's really hard to wait for that to happen after putting in so much effort to wrap them up and get everything together...expectations escalate! My woofers, which were also used (and at one point I thought were trashed) came alive one evening about 2 weeks in.

The other issue I found was that placement makes a big deal with these speakers - proximity to rear and side walls, height and angle.

I've had to stash mine for a little bit while I renovate the living room - so I'm envious yours are up and running.

Good luck,

Matt

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Re: 4Pi with feet [message #78269 is a reply to message #78268]

Sat, 02 November 2013 23:27

lucasmateo
Messages: 43
Registered: October 2013

Baron

Matt,
You are right about placement. My speakers like to have some air around, and I don't know if my ears are getting used or if they are breaking in, but every day they sound better and better. I don't want to change anything until I see they stop changing. Other thing I noticed is that sometimes my ears get tired after some time of listening, but after I love them this stop, so I have some bad reflections somewhere.

It's a pleasure to listen to them, it's quite a difference from other speakers I had, different design approach. I listen about 2-3 hours a day and I'm really enjoying the big babies.

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Re: 4Pi with feet [message #78272 is a reply to message #78127]

Sun, 03 November 2013 16:52

lucasmateo
Messages: 43
Registered: October 2013

Baron

Some numbers, I made this graphs with REW 5.0 and the laptop internal microphone, so I guess its not very precise, what do you think about this?

Any way I can measure them without expensive equipment?

Then I made this other graphs with Fuzzmeasure, again with the crappy internal mic of my laptop. With and without smoothing.

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Re: 4Pi with feet [message #78273 is a reply to message #78272]

Sun, 03 November 2013 22:52

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

It's a little hot above 1kHz. I'm not completely comfortable with the measurements because the graphs show more top-octave rolloff than I would expect and that's common with uncalibrated measurement systems and microphones.

But then again, putting aside the top-octave rolloff, the chart looks about right except for that amplitude shift at 1kHz. So that makes me wonder if the woofer is a little low or the tweeter a little high.

What compression driver are you using? What resistor values are installed in positions R1 and R2? Are you sure your woofers have genuine JBL cones with 8Ω voice coils?

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Re: 4Pi with feet [message #78274 is a reply to message #78127]

Sun, 03 November 2013 23:07

lucasmateo
Messages: 43
Registered: October 2013

Baron

The compressor is a B&C DE250, the XO is the one you sent me (by mail you said it was made for the B&C, but I didn't check it). I bought the JBL used and I don't know if they were reconed, maybe you can know looking at the pictures.

I'm finding them a little fatiguing after some hours. But the place were they are is not the best.

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Re: 4Pi with feet [message #78275 is a reply to message #78274]

Mon, 04 November 2013 00:28

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

I'm not really sure what compression driver you listed in the notes on your crossover order, but I can check tomorrow. Then again, that doesn't matter really - Please double check the values installed on your boards. The R2 resistors (four closest to the edge of the board) should all be 16Ω values and the R1 resistors (next four in) should be 20Ω and 30Ω values. Please verify that.

If the R1/R2 values are right, then I know what your tweeter SPL is, and that leaves only the woofer. You can't tell the condition of the woofer by looking at it - Some third-party recones look very much like OEM parts, but they're not. Some are really bad, to be honest, with horrible breakup and other nasty things. Yours don't look that bad, but they do look like they are less sensitive than they should be, by about 6-8dB from your charts.

I'd like to see absolute SPL values, as measured on an LMS system at a known distance and drive voltage. I'm sort of assuming the compression driver is good, since it's a new part. Under that assumption, I can sort of use the tweeter as a baseline, since I know what it does. I suppose it is possible that the compression driver is abnormally "hot", but I find that extremely unlikely. And even if the R1/R2 values were set for the PSD2002 instead of the DE250, that would only explain 2dB shift, not the level we're seeing in your charts. So I am leaning towards woofers being out-of-spec at this point.

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