Jump to content

Dialing down the midrange in KLF 20s


Recommended Posts

I've had an L pad on my midranges for a few years now but I've recently been reading posts about attenuating drivers by a certain value like -3db for example.  i had no idea how much i have attenuated mine but I'm curious to actually measure.  I have a hand held db meter.  Should I just download a test tone app?  What frequency should I use for the midrange?  Do I just hold the meter in front of the midrange driver or should i disconnect the other drivers as well?  I'm obviously not very technical here, so could someone please outline the procedure?  

I also know I have Ti tweeters but not sure what midranges I have.  The tweeters were replaced by the previous owner and for all I know the mids could be Ti too.  I do remember ordering Crites midrange drivers a few years back only to realize that they sounded a bit dull compared to what I have in there.  I will snap some pics and post them up her so maybe you can help me identify them.

 

Thanks

 

Jon

Link to comment
Share on other sites

cant comment on the L pad or attenuation on klf's or the proper way to measure them with a meter... but its very easy to tell if mid diaphragms are TI, they will be a shiny looking metal vs black or dark reddish plastic/phenolic.  shine a flashlight in the mid horn & should be able to see what it is made of.  

Link to comment
Share on other sites

2 hours ago, Klipschtastic said:

 

I had no idea how much i have attenuated mine but I'm curious to actually measure. 

 

 

Hey Jon

 

The best way would be with a true rms multimeter.  I'd actually measure a few things...

 

Play a test tone, say 1000hz.  It doesn't have to be real loud, as you are just creating a voltage that can be measured.

 

Measure the voltage across taps 0-5 of the T7A autofomer (input).

 

Measure the voltage across taps 0-2 of the T7A autoformer (output).  This should measure around .316 times the voltage across taps 0-5, or -10db.

 

Measure the voltage across the wires connected to the squawker.  The difference between this voltage and the voltage across taps 0-2 is the attenuation created by the lpad.

 

If you are curious about the difference in db, you can enter the measurements here...

 

http://www.sengpielaudio.com/calculator-amplification.htm

 

I hope this is what you are after.

 

Mike
 

Link to comment
Share on other sites

3 hours ago, Klipschtastic said:

Mike, I did actually shine a light in there the other day.  Tweeters are shiny metal.  Mids are black plastic looking.  Thanks!

 

Mboxler, that does help. I'll have to dust off my multimeter. Thank you!

Probably pretty hard to see the titanium diaphragm without removing the horn, not sure. 

127122-frontrs.jpg

53dia.jpg

Link to comment
Share on other sites

9 hours ago, Klipschtastic said:

attenuating drivers by a certain value like -3db for example

 

Typically in the context of the bigger, vintage Heritage stuff. You can change the attenuation value using the autoformer, and adjusting the capacitor value to keep the crossover point the same. Your autoformer only has a single, fixed setting - so not something you can readily do.

Link to comment
Share on other sites

I was able to see into the midrange horn well enough to spot the Amber colored material of the diaphragm.  It looks like they are the originals.  Oh well, they sound good to me.  I just can't believe they actually sound better than the Crites replacements I ordered a few years back but they did sound better and clearer to me.

Link to comment
Share on other sites

I think there are phenolic-people and titanium-people and "ne'er the twain" (at least until you hear the other thing when it doesn't bother you).  Preferences are one thing, but I've noticed (read:  no hard data, just my observations) people with tinnitus (like me) seem to often lean non-Ti. 

  • Like 1
Link to comment
Share on other sites

23 hours ago, Klipschtastic said:

Mike, I did actually shine a light in there the other day.  Tweeters are shiny metal.  Mids are black plastic looking.  Thanks!

 

Mboxler, that does help. I'll have to dust off my multimeter. Thank you!

 

my names not mike... but youre welcome. glad the flashlight trick worked for you. 

Link to comment
Share on other sites

Thanks for the insight, mboxler!

 

 

On 1/10/2022 at 12:49 PM, mboxler said:

 

Hey Jon

 

The best way would be with a true rms multimeter.  I'd actually measure a few things...

 

Play a test tone, say 1000hz.  It doesn't have to be real loud, as you are just creating a voltage that can be measured.

 

Measure the voltage across taps 0-5 of the T7A autofomer (input).

 

Measure the voltage across taps 0-2 of the T7A autoformer (output).  This should measure around .316 times the voltage across taps 0-5, or -10db.

 

Measure the voltage across the wires connected to the squawker.  The difference between this voltage and the voltage across taps 0-2 is the attenuation created by the lpad.

 

If you are curious about the difference in db, you can enter the measurements here...

 

http://www.sengpielaudio.com/calculator-amplification.htm

 

I hope this is what you are after.

 

Mike
 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...