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Dave A

KP-904 questions, crackle in HF

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2 hours ago, windashine said:

@Dave A - can you display a picture of your HF crossover board ?

Later, heading out for a welding job right now.

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1 hour ago, davis419b said:

I have had the 904's for several years. They came with 510 horns and BEC DE75 drivers. They were too hot for what I liked so a forum friend of mine made me some jumpers to tone them down and it worked well. Later I went to the 402 horns with pAudio BM-750 drivers and have enjoyed them with no issues.

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I will try this. 402's still needed PEQ's here but they are stellar when set up right.

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In my house Klipsch speakers must stand on their own 2 feet ! I have been a member here for 12 years and still don't know what a PEQ is.

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On 1/10/2020 at 8:50 PM, Dave A said:

There is a crackle that comes out of the 510's with the stock crossovers in some music and less when I bi-amp these with recommended PEQ cinema settings.

I had that cracking problem many years ago when I was using the RCA (analog) outputs from my Oppo DV-980H disc player, and only on certain discs (like Dave Grusin's Now Playing--Movie Themes CD).  When I switched to HDMI (and I had to ditch a brand new AVP that I bought from Outlaw Audio that didn't have HDMI inputs, and buy a refurbished Onkyo AVP...that I still use), the problem immediately disappeared. 

 

I'd check your signal stream--like your sound card (if you're not using digital output from your computer that's serving your music files). 

 

On 1/10/2020 at 8:50 PM, Dave A said:

I wonder if the latest B&C DE75 drivers Klipsch uses have also been switched out to the new SLA build phase plugs.

This could also be the source of the problem--quite easily.

 

On 1/10/2020 at 8:50 PM, Dave A said:

The other thing I am wondering about besides the EQ aspect is if these were made to work behind screens and thus a little hot what could I change on the crossover to tame the HF down and possibly reduce the crackle?

Likely a problem.  I'd push down the HF SPL response above ~5 kHz by about 3 dB/octave.  The figure below shows screen attenuation of two different types of "MicroPerf" screens.

 

Defining-the-Difference-in-Perf-Screens5

 

On 1/10/2020 at 8:50 PM, Dave A said:

The third thing is I have begun to wonder if my music files have been hurt with too much tinkering through Audacity and considering starting over from original source material. Some of these just sound a bit unnatural now and I have to say I really hope Chris A can spend some time in Hope with Audacity best practices.

We'll discuss this at SWAG, but note that I've been going back to the CD shelf to re-read the original tracks from the discs on many of my oldest Audacity edits--and the reason for this is that I've learned to dial in the Jubs better (especially the phase flattening thing that I've talked about).  When I made improvements in the SPL and phase response of the Jubs, I found that I needed to re-edit the Audacity-edited tracks.  This was a fairly mild thing until last May 1, when I found out how to flatten the phase, then everything changed--dramatically.  We'll talk about this, and perhaps listen to the differences in using low-phase-growth crossover filters vs. steep slope.  That was the most dramatic change that I've experienced in the sound of the edited tracks.

 

On 1/10/2020 at 8:50 PM, Dave A said:

...the Xilica crossover frequencies I am using are HF 900hz and LF 920hz which is what the Klipsch literature said but that seems a bit high to me.

That's the frequency at which a 15" woofer will approximately match the polar coverage of the K-510 horn (at least horizontally).  Below that frequency, a 15" woofer will progressively lose polar directivity.

 

Chris

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On 1/20/2020 at 6:50 AM, Dave A said:

Anybody with this setup care to answer?

Dave, sorry but no help. Using 904's with stock crossovers and NO "crackle" at all. Actually like the 510's a little hot ... but they are probably a bit tuned down as I have speaker grilles on them.

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I have a set of K510 horns with DE75 drivers B&K Enterprises is making me some crossovers with an L Pad on them for taming down the HF, this was their recommendation.

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@rmlowz, please share these with us when you get them.

 

maybe even dedicate a separate post to it (for sure)

 

I think an L-pad would be just the ticket for the K510

 

some recordings are perfect, others too hot

 

 

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Hi all, not ignoring but out of town on a job. Back today and achy so I will respond to new comments tomorrow.

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On 1/22/2020 at 11:44 AM, Chris A said:

I'd check your signal stream--like your sound card (if you're not using digital output from your computer that's serving your music files). 

 

The problem is with the 510 and DE75. Other speakers work just fine off my system.

 

On 1/22/2020 at 11:44 AM, Chris A said:

This could also be the source of the problem--quite easily.

 

This was a comment of curiosity thinking of how much improvement there was with the phase plug update on 1132 drivers. The DE75's on the 510's have what appears to be the same phase plug as the old 1132's and most definitely are not the new versions.

 

On 1/22/2020 at 11:44 AM, Chris A said:

Likely a problem.  I'd push down the HF SPL response above ~5 kHz by about 3 dB/octave.  The figure below shows screen attenuation of two different types of "MicroPerf" screens.

I figure this is the likely culprit and will work on this aspect first.

 

On 1/22/2020 at 11:44 AM, Chris A said:

We'll discuss this at SWAG

I look forward to doing so. It will be nice to meet the face behind the comments and help.

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On 1/22/2020 at 11:07 AM, davis419b said:

In my house Klipsch speakers must stand on their own 2 feet ! I have been a member here for 12 years and still don't know what a PEQ is.

All I can say is hearing will make a believer out of a skeptic. I have a test case here and it is the 904KPT with factory crossovers and then the Xilica and bi-amp. While not dialed in all the way yet the electronic DSP stuff is the clear winner. I fought "unneeded" complications until I built the S-MWM's and will not ever go back.

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On 1/22/2020 at 3:53 PM, geoff. said:

@rmlowz, please share these with us when you get them.

 

maybe even dedicate a separate post to it (for sure)

 

I think an L-pad would be just the ticket for the K510

 

some recordings are perfect, others too hot

 

 

I tend to think the right way is to use something like Audacity to fix the music and not have to change settings for different songs. I look forward to Chris and Audacity 101. Audacity is a required tool in your toolkit for audio as far as I am concerned.

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As a possibly relevant side note:

 

I am using 315LF's and not 904/940's so according to the active literature we've been discussing I would need to attenuate my HF -2dB, which I originally did when I started playing around with this setup by inserting a single series resistor prior to the + input of the network. I considered this solution simple and effective for what I was attempting and this method appears to be commonly used in current Klipsch networks. As an example this Jubilee/402 network supplied by Roy allowed the owner to insert a value 0-4ohm (0 to -3dB) inbetween the network and the K69A driver "to taste".

image.thumb.png.26c0bd5c1eaf0e2d1df4d354b45249d9.png

In any case, I found that the -2dB suggested was not quite enough and end closer to double that using a 5ohm resistor. This experiment would make me wonder if those using the 904/940LF might not want to try using a 1-2ohm resistor (-1 to -2dB) in the same manor. 

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7 hours ago, CANT said:

As a possibly relevant side note:

 

I am using 315LF's and not 904/940's so according to the active literature we've been discussing I would need to attenuate my HF -2dB, which I originally did when I started playing around with this setup by inserting a single series resistor prior to the + input of the network. I considered this solution simple and effective for what I was attempting and this method appears to be commonly used in current Klipsch networks. As an example this Jubilee/402 network supplied by Roy allowed the owner to insert a value 0-4ohm (0 to -3dB) inbetween the network and the K69A driver "to taste".

image.thumb.png.26c0bd5c1eaf0e2d1df4d354b45249d9.png

In any case, I found that the -2dB suggested was not quite enough and end closer to double that using a 5ohm resistor. This experiment would make me wonder if those using the 904/940LF might not want to try using a 1-2ohm resistor (-1 to -2dB) in the same manor. 

I am saving that one and had not seen this before. Thanks for posting it. That thing is way more complicated than the very basic 904 HF-LF crossover.

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@Dave A Did you ever get this resolved?  I also have the the same speakers but no crackle.  Everything is currently stock but feel something is missing and am leaning towards the digital crossover vs getting a new passive for it.  When I run REW it seems the HF is not hot, but then again I watched a video on REW (still learning) and they said anything over 500-700HZ you should disregard in a home environment.  Not sure how much truth there is to that though.

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I have not done a thing yet except get some brackets burned and bent for mounting the 510 horns on the bass bins. I intend to dig into this further soon since I have a pile of these to make right.

 

  I am going top try an HF crossover like the ones on the KPT-456 since I have the material on hand to build some. Those 456's were stellar and with all the good things I have heard about the 510's it is just a matter of finding out what works.

 

  Active crossovers are something I am learning about  along with REW and I am kind of waiting until SWAG where I hope to learn much more about these tools. I think the very best sound is with actives but better sound than I currently have can be had with passives to.

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5 hours ago, risingjay said:

...but then again I watched a video on REW (still learning) and they said anything over 500-700HZ you should disregard in a home environment.  Not sure how much truth there is to that though.

Which video...? 

 

I can't say that statement is valid at any time, unless they're referring to taking measurements farther from the loudspeakers than 1 m, and the loudspeakers have little or no directivity.  Then you're measuring the direct+early reflections in-room.  If you're taking the measurements at 1 m and are using a good amount of absorption on the floor from the loudspeaker front baffle to the microphone, and about 1m wide, then you'll have no problems using the measurements from 100 Hz--20 kHz.

 

I would be really careful about what is said in YouTube videos--in general.  I've heard a lot of false information there.

 

Chris

 

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@Chris A

 

This what I was watching Chris.  I'm trying to get educated on REW somewhat before asking any questions so I don't sound dumb......to late.  

 

At least you clarified that for me.  Now I can take that and run all new measurements this weekend!  Thank you for your help.

 

I try not to burden the forum with dumb questions.

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Not dumb questions...important questions.

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He's using REW like someone uses "room correction software" like Audyssey or YPAO.  I've found that these measurement techniques only work for setting channel gains and time delays.  Trying to set EQ using a microphone at the listening position is not a very good way of correcting the individual loudspeaker SPL responses. You really don't want to flatten SPL response with the room's early reflections mixed in with the loudspeaker direct arrival energy.  Instead, you take measurements at 1 metre in front of each loudspeaker.

 

Measurement at the listening position is only done to smooth peaking response below about 200 Hz (and 100 Hz for larger home theater-sized rooms).  (Note that I don't use measurements at the listening position.) Here you're only wanting to find peaks in bass and midbass response, then apply attenuating PEQ filters to flatten the peaks in response--not the dips (which typically cannot be corrected due to the non-minimum-phase nature of those dips, which are typically room mode cancellations).

 

Chris

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If you were to find yourself at the SWAG on 3-4 April in Hope, this is the type of stuff that we'll be talking about, except that the BS would be cast by the wayside (and there was a fair amount of BS in that video).  I'd just get used to the basics, such as the following tutorial (without the Equalizer APO portion at the end--which you can ignore):

 

 

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