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Tom Mobley

Heresy crossover mod, back from the dead

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Long time no type.  Hoping you are all well.

 

A long time ago one of the guys (John Albright?) posted up a crossover mod schematic for the Heresy.  I have my original untouched Heresys I bought new in 78.  I want to run this mod on them as I've always thought they were pretty shouty.  it calls for addition of .35mH inductors and and an 11ohm 20 watt resistor.  I"ve sourced the inductors but I'm having a little trouble finding reasonably priced resistors.   Anybody know how sensitive this mod is to the exact value of the resistor?  like what happens if I use an 8ohm instead of the 11?  Does the resistor need to be the non-inductive type?

 

Expiring minds want to know....

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4 hours ago, Marvel said:

You can put a 16 ohm 10 watt across the mid and just change taps.

 

http://www.soniccraft.com/product_info.php/16-ohm-mills-mra-10-p-4552

 

About $7.50 each.

 

It's the second schematic John posted in this thread. If you read it all he explains it

 

Bruce , this schematic was modified  twice by John Albright    -

 

  

  

On 1/29/2003 at 4:49 PM, JohnA said:

Al is correct. I wasn't thinking clearly. This was intended to be an easy mod and for a test, but the extra resistor should not be installed across the tweeter. I've uploaded a corrected version. We used to be able to delete files on the server. I can't figure out how, now.

post-2142-13819246217198_thumb.jpg

 

  

On 7/9/2006 at 3:39 PM, JohnA said:

Attached is the last version of the Type E xover. I have all 3 of

mine wired this way. They are much closer to the tone of my La

Scalas. I have discovered that a 2 uF tweeter cap will give

a smoother response curve, so, I'd recommend keeping the tweeter cap at

2 uF.

post-2142-13819304346714_thumb.jpg

 

  

 

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Here's what I have done.  The woofer inductor can be the 2.5 mH Klipsch used and it can be an iron core, but I'd go with 16 ga.  The squawker inductor is there to knock down the 9k response return of the K-55-V a few dB.  Use a 2 UF tweeter cap; it knocks down a 6k to 8k hump in the tweeter's response.  Note that the speaker is still bright with these settings; the woofer running at 93-94 dB, squawker at 95 dB and tweeter at 96 dB. 

 

 

TypeEModifiedR1.JPG

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9 hours ago, RandyH000 said:

 this schematic was modified  twice by John Albright    -

 

Yup, I know that, and John's 3rd version surely is smoother.  The single 16 ohm will let  you get a good taste and may be all you need. That's what my son Josh did, and felt it was enough, and easy to install across the terminal strip.

 

 

 

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Tom  - did you ever replace the capacitors in the E network  --- 44 year old capacitors must be leaking ESR ---and before you do any changes , or while you do them ,  make sure to freshen the caps ---

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ok - so , what I would do in disconnect the old caps , use  an ESR Meter and check the oil caps for ESR leakage since you cannot test them in circuit -

 

-mount the new caps  with newer wiring  and listen over a week for changes  using both the old and the new caps ,  on separate hookups , this will allow you to compare the sound in a live test -

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At the risk of being redundant,

 

On 9/21/2020 at 11:52 PM, Tom Mobley said:

So John, this schematic from earlier today with added .35mH inductor, is this the latest greatest?

 

Also, is this resistor OK?    https://www.mouser.com/ProductDetail/Vishay-Dale/RH02511R00FC02?qs=sGAEpiMZZMvNd0dY0Kymzl%2Bbo6xW4jof%2BQFxC8nWMjk%3D

 

does it want non-inductive?

 

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1 hour ago, Tom Mobley said:

At the risk of being redundant,

 

 

 

Non-inductive resistors are recommended, although the error of an "inductive" resistor will generally not be apparent in the audio band.

 

I can't see a reason why that resistor wouldn't work,  although I use these across the autoformer.  There is an 11 ohm version if that's what you want.

 

https://meniscusaudio.com/product/10-ohm-10-watt-mox/

 

Mike  

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16 hours ago, Tom Mobley said:

At the risk of being redundant,

 

 

Tom,

 

it just so happens that PE sent me an email today on some new products for them, non-inductive 1% copper capped and leads resistors, at reasonable prices.  Enjoy!

 

https://www.parts-express.com/promo/new_dayton_resistors?utm_source=bm23&utm_medium=email&utm_term=DA+Resistors&utm_content=NO+COMPROMISE+Crossover+Designs&utm_campaign=200924_DA+Resistors&_bta_tid=414917041621392152575322640043817355742246336352190723609828167684824389275593880272030593457832304484#!

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