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Adding tweeter to 8" full range?

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Posted on June 19, 2016 at 11:41:11
robertpeterson56
Audiophile

Posts: 36
Joined: April 2, 2005
 I could use some advice with a project I'm tinkering with. I have some 8" FR AlNiCo speakers mounted in wall cabinets with aperiodic loading. While nice and smooth in the midrange they lack the sparkle of the small Fostex drivers I have been listening to for a long time. I am looking at adding a tweeter with a series capacitor as crossover at 10k to 15khz. Should I be looking at tweeters with roughly the same efficiency as the FR? I am assuming I'l need some kind of pad as hitting just the rightl level match is unlikely without. Thanks in advance for any help offered.
Robert

 

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RE: Adding tweeter to 8" full range?, posted on June 20, 2016 at 08:00:06
krankkall
Audiophile

Posts: 296
Location: New Mexico
Joined: April 5, 2014
 I have a pair of old E-V 8" FR drivers, whose upper frequencies drop like a rock above 12Khz.
I added a pair of 1" VIFA soft dome tweeters, crossed over at 10Khz.
Much better now.............................................

My E-V's were 95db, while the Vifa's were 94 db....close enough for govt. work.

Steve

 

RE: Adding tweeter to 8" full range?, posted on June 20, 2016 at 08:05:23
Hornlover
Manufacturer

Posts: 2529
Joined: March 8, 2002
 Even a few db lower would be good. Better to be a bit lower than higher. Even -3 or -4 db lower would not be greatly noticeable, and would add that sparkle missing from the full range.

 

my time honored recipe, posted on June 20, 2016 at 10:20:03
mhardy6647
Audiophile

Posts: 16015
Location: New England
Joined: October 12, 1999
Contributor
  Since: October 23, 2016
 * Good, high sensitivity (super) tweeter.
* First order XO; very high (10 kHz or so) -- remember the slope is only 6 dB per octave!
* L-pad (variable).

Adjust to taste, then either

* Enjoy it

OR

* Measure the Rparallel and Rseries value of the variable pad and replace it with a fixed L-pad made out of good (don't over-think the choice!) resistors (Ohm's Law is your friend).


Here are a couple of serving suggestions; the nice thing about using a high-sensitivity tweeter is you have one more degree of freedom available to you for adjustment.

1) Fostex T-90A

IMG_0341
IMG_0340


final "implementation":


071

2) Radio Shack 40-1375:
This "leaf" (planar) tweeter (a "version" of a wonderful JVC tweeter of the 1980s) was/is very, very sweet sounding and fairly sensitive, too. I used a pair of these on my Altec Valencias, on and off -- they're not sensitive enough to keep up with the Duplexes, though.

40-1375

There are, of course, many, many many other good choices!

all the best,
mrh

 

by the way -- which 8" FRs? , posted on June 20, 2016 at 10:38:00
mhardy6647
Audiophile

Posts: 16015
Location: New England
Joined: October 12, 1999
Contributor
  Since: October 23, 2016
 I still think 8" is a sweet spot for so-called full-range (more accurately termed "extended range", methinks) drivers, FWIW.

Fostex made some nice 8" twincone FRs -- maybe they still do, I dunno; I just know they don't make the ones I have, and like (FE-207E).

I am also (stilL) quite enamored of the EV "Wolverine" LS-8. Sensitive, beautifully made, good sounding (yes, it drops like a rock over 10k or so, as noted by another response!) and plentiful & inexpensive.

all the best,
mrh

 

RE: Adding tweeter to 8" full range?, posted on June 20, 2016 at 12:02:13
merdy
Audiophile

Posts: 1625
Location: New paltz,ny
Joined: July 25, 2001
 you did not say what fr drivers other than alnico,i have experimented with every 8 inch vintage driver,and yes they could all use some help depending on the driver ,some can be crossed over at 6k onwards to 12k plus mostly only using a simple cap, L pads can rob some air if you are in the 99db area
you can measure and use a fixed hi quality resistor insted
matching spl is not mandatory and 3 or 4 db less sensitive can also be very pleasant
since its in the wall you could also add some ribbons, or horns or even a wave guide
sometimes i used a 2 inch sealed back alnico paper driver,or dome tweeter ,made a cardboard cut out in a kids shoe box and put it on top of the speaker with different caps to see whats best
you could make a card board speaker baffle and stick some pins or masking tape and 3 caps hanging from the terminal and experiment while listening

i am presently experimenting with a 3 layer damped sealed box with a Lafayette sk98 and a 4 inch ribbon,so far without the damping and testing caps(vintage oil) its delicious with some 45 amps
hope this helps

Silence is golden duct tape is silver

 

RE: Adding tweeter to 8" full range?, posted on June 20, 2016 at 13:00:13
robertpeterson56
Audiophile

Posts: 36
Joined: April 2, 2005
 The drivers I am using are Lafayette SK98 from the early 60s. If the catalog is to be believed the sensitivity is about 99dB. They are not mounted in the wall but in old timey on-the-wall cabinets. The cabinets are like the speaker in your schoolroom for announcements. Much to small, hence the aperiodic vent I cooked up for them. I have a powered sub to use with them so we aren't asking for any real bass just a smooth roll off. It is definitely
an eccentric experiment but I had everything in the basement so the stakes are pretty low.
Thanks for the advice everyone.
Robert

 

RE: Adding tweeter to 8" full range?, posted on June 20, 2016 at 20:17:37
Rod M
Web Geek

Posts: 16242
Location: So. California
Joined: March 1, 1999
Contributor
  Since: March 1, 1999
 It would be useful to measure your response and find out where the driver starts falling off. It may be a simple cap for 8-12K xover will work. If you get too much, add a resistor to the tweeter and/or raise the crossover point.

If you're like me, my hearing only goes to around 14K these days, so measuring is useful unless you don't care about cats howling for blocks away.

-Rod

 

The SK98/Pioneer PIM-20/PIM-8 is a cool driver, posted on June 21, 2016 at 03:53:26
mhardy6647
Audiophile

Posts: 16015
Location: New England
Joined: October 12, 1999
Contributor
  Since: October 23, 2016

a teeny-weeny Biflex :-) There was even a six-inch morph.

I have the misfortune to own... one... of the 8 inchers.
They tend towards the 'spensive (also unfortunately).


Pioneer LRE biflexes
all the best,
mrh

 

RE: The SK98/Pioneer PIM-20/PIM-8 is a cool driver, posted on June 23, 2016 at 23:50:16
nosmok
Audiophile

Posts: 208
Joined: February 3, 2002
 That 6-inch morph is actually 5" or so-- the PIM-5. I have a pair in factory cabinets, from some all-in-one system that I've never seen even a picture of-- the speaks have an rca plug input, and they are listed at 3 watts power handling.

Stand/sit close and they are the best overall sound I've ever heard. There's no extreme highs, lows, or louds but everything they do sounds right.

 

the ones I have are labeled PIM-6, FWIW (nt), posted on June 24, 2016 at 14:10:13
mhardy6647
Audiophile

Posts: 16015
Location: New England
Joined: October 12, 1999
Contributor
  Since: October 23, 2016
 nt
all the best,
mrh

 

RE: Adding tweeter to 8" full range?, posted on June 24, 2016 at 16:16:47
SimonYVR
Audiophile

Posts: 2
Location: West Coast
Joined: December 12, 2015
 Consider using an autotransformer rather than a resistor based method to balance out the sensitivities. Alternatively, I have heard some people have had good success just pushing out the crossover to a higher frequency and avoid any kind of resistor or transformer in the circuit.

Jensen Rp302 is a nice vintage super tweeter but it's popularity is now reflected in its ebay pricing. I personally like some of the more esoteric Japaese vintage tweeters from YL acoustics, Maxonic etc.

Simon

 

RE: Adding tweeter to 8" full range?, posted on June 24, 2016 at 16:29:23
SimonYVR
Audiophile

Posts: 2
Location: West Coast
Joined: December 12, 2015
 Here is an example of a nice Luxman transformer based attenuator

S

 

RE: Adding tweeter to 8" full range?, posted on June 24, 2016 at 17:12:19
hifipaul
Audiophile

Posts: 735
Location: NY
Joined: December 22, 2008
I use a 755c with a pioneer ribbon tweet with a 1.8uf cap in series. It adds just enough air, and does not call attention to itself.

 

RE: Adding tweeter to 8" full range?, posted on June 26, 2016 at 12:17:50
thetubeguy1954
Audiophile

Posts: 6112
Location: Orlando, Fla
Joined: January 7, 2001
 Hello Robert,

For about eight years I was using Sachiko double-back-loaded horns. I used these with various Fostex ---{FE206E, FE206ES-R & FE208ES-R}--- a Lowther DX4 and in the end the one I though sounded best a Dayton PS220-8 w/Rispoli modified cones. These "wide-range" drivers all had tweeters that I started with 12dB slopes, but changed after 2 years to a 6dB slope. I crossed the tweeters with a 6dB slope in at 8KHz so by 16KHz it matched in nicely with whatever the 8" "wide-range" driver I was using.

While others might disagree I attempted to keep the "wide-range" driver I was using and the tweeter's sensitivity ratings as close as possible. The tweeters I used were in chronological order:

1) Large dipole ESS Heil

2) Pioneer HW-7 ---{I think these are wonderful sounding, especially if you could locate them for $36/pr like this pair sold for on eBay: http://www.ebay.com/itm/Vintage-Pioneer-HW-7-Horn-Tweeters-Super-Tweeter-Rare-/161850106996}

3) The best I heard in my system Fostex T900a.

I hope that info helps you in some small way.




I'm listening to: Wild For You by Karrin Allyson




Thetubeguy1954 (Tom)

Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers


 

Congrats! looks like you got an inch on me then! , posted on June 27, 2016 at 22:10:36
nosmok
Audiophile

Posts: 208
Joined: February 3, 2002
 I may have gone off half-cocked here-- I have read about PIM-5's and seen pics and ePay ads, but have not actually pulled the back off my enclosures to see if mine might be PIM-6's. Of course, if you have them, they exist. My guess would be they sound great too.

The ones I'd like to experience are the PIM-10/25's, which are the biggest single coil ones (the PIM12/30 has a central small tweeter). Never even seen a picture.

 

RE: Adding tweeter to 8" full range?, posted on June 28, 2016 at 13:11:56
Inmate51
 It's like "WYSIWYG". Why do we need "Print Preview"?

If it's "full range", why do you need to add a tweeter?

:)

 

RE: "full range", posted on June 28, 2016 at 13:37:03
genungo
 "Flat" frequency response is another matter entirely.

 

RE: "full range", posted on June 28, 2016 at 20:09:50
Inmate51
 My post was tongue-in-cheek, as I think/hope you know.

:)

 

RE: "full range", posted on June 29, 2016 at 11:58:17
genungo
 Understood.

I do own a pair of *augmented single driver* speakers although I rarely use them anymore. The main driver crosses over to a supertweeter somewhere around 9 khz, smoothing out frequency response while maintaining efficiency and that seamless "full range" sound throughout the mids.

 

RE: Adding tweeter to 8" full range?, posted on July 9, 2016 at 06:45:58
thetubeguy1954
Audiophile

Posts: 6112
Location: Orlando, Fla
Joined: January 7, 2001
 Hi Paul! I'm sorry for breaking in to another member's question. But, what was the ohm rating of those Pioneer ribbons? And at what frequency did they cross in with that 1.8uf cap? Just curious because I've also been using "wide-band" drivers with "helper" tweeters for the past 7 or 8 years now and I found crossing these tweeters in at 8 KHz was ideal in my system. So I'm just curious as to what frequency your crossing in these tweeters to make them just add enough air, and not call attention to themselves?

I'm listening to: One More Once by Michel Camilo





Thetubeguy1954 (Tom)

Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers


 

RE: Congrats! looks like you got an inch on me then! , posted on July 9, 2016 at 06:51:50
thetubeguy1954
Audiophile

Posts: 6112
Location: Orlando, Fla
Joined: January 7, 2001
 Here's a photo of that Pioneer PIM12/30 you've never seen...








I'm listening to: One More Once by Michel Camilo





Thetubeguy1954 (Tom)

Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers


 

RE: Adding tweeter to 8" full range?, posted on July 10, 2016 at 15:13:11
hifipaul
Audiophile

Posts: 735
Location: NY
Joined: December 22, 2008
 Mike

At a nominal 8ohms the tweeter is rolling off at ~11khz, first order. The 755c rolls off at ~ 8k-9k. The gap, to me, is not relevant and may help the blending.

 

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