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Type E Mod / Driver Question


fromnowon

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Hello, I have a question, please!

 

About 4 mos. ago, I got brave and made changes to my Type E crossovers (schematic attached) based on what I learned on this forum, with help from several of you, and it worked out very well - holy cow, they sound tremendous in my Heresy's.  I am still amazed 4 months later after much listening.  I am glad I did it and I think you guys are the best Klipsch experts out there. 

 

So . . . I want to use the same modified Type E network in another horn-loaded 3-way application which has the same 700/6000 crossover frequencies.  

The squawker that I'm planning to use is in my new speakers is rated 8 ohms . . . I know that the K-55-V is rated at 16 ohms (however K-55-V squawkers that sound awesome with the modified Type E network test at 11 ohms with a multi-meter, disconnected).  

 

My question is:  should I change something in this modified Type E network for an 8-ohm squawker?  If so, what should I try?  Seems like the 21uF cap or the 11 ohm resistor are what could be affected by the change of drivers from 11 ohm (or 16, or whatever a K-55-V is) to my new 8-ohm compression driver.

 

Thanks very much for any comments.

 

(I barely feel worthy to post on this forum so I hope you'll go easy on me.)

 

 

Type E Mod2.JPG

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ha ha, thanks!

These were stock Type E's, so here is what I did to end up at the diagram above (there is also a lot of discussion about this mod in other threads on this forum):

- The woofer inductor was changed from 2.5mH to 2.2mH.  I splurged on a nice ERSE inductor after a recommendation from Bruce.  

- The Squawker taps were changed from 2 to 1.

- Tweeter connections were changed from tap 3 to 2.

- The 2uF cap in front of the autoformer was changed to 21uF (I used 2 caps in parallel to get to 21uF)

- An 11-ohm resistor was strapped across 0 & 5 taps.

  

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Thanks Dean!  I was hoping you'd see this question.

 

Here are the specs of the driver that I'd like to use with this Type E network/T2As:

Power handling: 75 watts RMS with recommended crossover of 500 Hz, 12 dB/octave slope • VCdia: 2" • Impedance: 8 ohms • Frequency response: 400-8,000 Hz • SPL: 107 dB 2.83V/1m

 

Also, I found a very relevant post that you wrote 10 yrs ago to explain why 11 ohms swamping resistor and 21uF capacitor:

 

"the goal is to create a somewhat constant impedance, with low pass and high pass sections somewhat equal in impedance.  The design assumes the K-22-E is 11 ohms at the crossover frequency (700Hz). To get the matching high pass section, and the proper resistor value for the autoformer -- we need to know the reflected impedance with the tap we are going to use. In this case, it's tap 1, and we'll go with 256 ohms (even though it's actually a little lower than that). At this point we bang on our resistor calculator until we find the value that gives us our closest match to the impedance of our low pass section at the crossover point. Using the calculator, we discover that if we parallel an 11 ohm resistor with 256 ohms -- we come up with 10.54 ohms. 11 ohms is close enough here, and we strap it across taps 5 and 0. Now we need the correct cap value for 11 ohms at 700Hz. That value is roughly 21uF. This design presents a benign, stable load to the amp --"

 

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I also found the tables below in an old post . . . instead of 256 ohms, I guess I'm looking for 128 ohms for Tap 1 . . . to maintain 700 Hz crossover frequency.  But maybe I'm only going to get -6 db of attenuation unless something else is done in addition.  (The woofers I picked for my project are Sensitivity = 93.8 dB 2.83V/1m, so it would seem that I need the whole -12db)

 

t2a at 16 ohm driver
tap attn multi impedance
4 -3 2x 32
3 -6 4x 64
2 -9 8x 128
1 -12 16x 256
 

t2a at 8 ohm driver
tap attn multi impedance
4 -1.5 2x 16
3 -3 4x 32
2 -4.5 8x 64
1 -6 16x 128
 

I appreciate any advice very much.

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When you measure a disconnected driver, you're measuring the resistance of the voice coil - which isn't the same as impedance. What we need to know is the impedance of the driver at the crossover frequency. So, you have an unknown.

 

Sensitivity and frequency response changes when you change horns. A manufacturer's spec sheet gives numbers which were measured while on a given horn. When you change horns, the numbers change. You now have another unknown. 

 

You are using a different woofer. Same problem. Change the driver and the box - and the numbers change. Another unknown. 

 

The schematic you posted was a network design for the Heresy, developed by John Albright. We know a lot about the Heresy, but very little about what you're doing. 

 

Tell us about the box and woofer.

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Sure.  Interior dimensions for the cabinets:
11.25 W
12.75 D
42 H
just under 3.5 cubic feet interior. I'll attach a picture.  I built them over the summer out of baltic birch - found a nice source for it and it makes them look Klipsch-like.  The two ports are supposed to tune them to about 32 Hz.
The woofers are 2-8” Dayton 295-377 4 ohm.  I intend to wire them in series to create an 8-ohm load.  

Hoping to get them to sound as good as possible and I like the idea of incorporating the T2As if I can.

Thanks again.

 

 

speakers.jpg

BB1.jpg

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Thanks guys.  I really don't have any right to expect this kind of help.  

 

It's the D250PH.  Very inexpensive but it gets into the midrange frequencies very well so I'm giving it a try.

 

Midrange driver:  http://www.parts-express.com/prv-audio-d250ph-s-1-phenolic-horn-driver-8-ohm-1-3-8-18-tpi--294-2825

PRV Audio D250Ph-S 1" Phenolic Horn Driver 8 Ohm 1-3/8"-18 TPI

Midrange horn:  http://www.parts-express.com/prv-audio-wg23-25-1-100-x-40-waveguide-1-3-8-18-tpi--294-2912

PRV Audio WG23-25 1" 100 x 40 Waveguide 1-3/8"-18 TPI.  Acoustically loads compression drivers down to 600 Hz.

 

Tweeter:  http://www.parts-express.com/dayton-audio-dt250p-8-1-polyimide-compression-horn-driver-1-3-8-18-tpi-8-ohm--270-406

Dayton Audio DT250P-8 1" Polyimide Compression Horn Driver 1-3/8"-18 TPI 8 Ohm

 

Tweeter horn:  http://www.parts-express.com/selenium-hm11-25-1-exponential-horn-60x60-1-3-8-18-tpi--264-306

Selenium HM11-25 1" Exponential Horn 60x60 1-3/8"-18 TPI.  Minimum frequency: 1,200 Hz

 

I know this is not a DIY forum.  Thanks again.

 

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1 hour ago, fromnowon said:

Thanks guys.  I really don't have any right to expect this kind of help.  

 

It's the D250PH.  Very inexpensive but it gets into the midrange frequencies very well so I'm giving it a try.

(snip)

I know this is not a DIY forum.  Thanks again.

 

 

Many of us here are DIY guys as well as Klipsch owners.  It's all good.  B)

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I believe the D250Ph is the same driver as D250X just branded with a different name. I have used and am currently using a D250X driver in a custom 3 way. I actually prefer the sound of the D250X over the k55v. It is more sensitive and and overall just sounds better to my ears. My custom 3 way consists of a 15 inch JBL E-140 woofer, D250X midrange, and D220Ti for a tweeter.. I replaced the D220Ti with a B&C DE110 and wow what a difference.. The DE110 is also more sensitive than the D220TI and sounds way better. I also use a modified Type E network. PM me if you want crossover info. 

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Hate to rain on the parade, but did you look at the curve of that PRV midrange driver?

 

http://www.parts-express.com/pedocs/specs/294-2825--prv-audio-d250ph-s-specifications.pdf

 

Transitioning at 700Hz isn't a problem, but you're not getting 6000Hz without considerable correction.   

 

Looks like the best place for a crossover point with that driver is 3kHz (it's 10dB down or more at 6kHz).  

 

How low will the Senium go?

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Deang, you are right, this mid will not reach 6000hz but there is no need to cross at 6k since his tweeter will play as low as 2000hz.. This would only be an issue if one were to attempt to use with a K77.. Thats not the case here.. I have crossed the D250X at 4000-4500hz. Sounds good and measures good.

 

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On ‎9‎/‎17‎/‎2016 at 0:35 PM, fromnowon said:

Sure.  Interior dimensions for the cabinets:
11.25 W
12.75 D
42 H
just under 3.5 cubic feet interior. I'll attach a picture.  I built them over the summer out of baltic birch - found a nice source for it and it makes them look Klipsch-like.  The two ports are supposed to tune them to about 32 Hz.
The woofers are 2-8” Dayton 295-377 4 ohm.  I intend to wire them in series to create an 8-ohm load.  

Hoping to get them to sound as good as possible and I like the idea of incorporating the T2As if I can.

Thanks again.

 

 

speakers.jpg

BB1.jpg

Really nice wood work. Wow

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Cool and pretty project - that reminds me that I have those PRV mid drivers, K700 - maybe make a 3 way with PYM1298 and a stubby "horn" port reflex? (that might be bad sounding -?)  I have less than zero carpentry skills so have to hire someone competent :D  -  I'll run a graph on the PRV/K700  not sure what value of cap to use (8uF ?)

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