Taps on the Autoformer (reduce squaker output)

[DrWho]

Well the title pretty much says it all...

I remember reading a few times about using different taps on the autoformer that allow you to adjust the output of the squaker and tweeter. I always glanced over them because I never had speakers to which that applied. But I've got a heresy center channel now and the squaker is just ripping my ears off so I'm now interested in changing out the taps.

I've done some searching, but can't seem to find any of the threads I remember reading. Does klipsch provide this information somewhere or does someone know what taps to use?

Or would I be completely better off going with the L-Pad route?

[colterphoto1]

Mike,

Check mods columns. I think you lose something else when using an L-pad. It's resistive and has impedence so I think that changes the frequency response somewhat. (sorry if I have this wrong, I'm trying to learn, really I am). I think DeanG or Bob would have the definitive answer for you.

Michael

[dbflash]

I don't know where the post is.

I don't remember who wrote this, but this may get you started. I never tried it, so I can't tell you anything more about it>

Danny

Background: I have been enjoying Klipsch speakers since I heard my first pair of K-horns back in the 70's (instant addiction). However, until a year ago I had only had experience with the large Heritage Klipsch speakers and had never owned or listened to a pair of Heresys, so I bought a pair off Ebay.

They are 1980 Heresy I's with a K22-E woofer, K55-V squawker, K77-M tweeter, and a Type E balancing network.

I have owned and been listening to a pair of Cornwall I's (100% stock) for years and I am in love with the sound - I expected the same for my Heresy's. However, when I heard the Heresys, I didn't want to admit it, but they were just too bright and sounded to me nothing like the K-horns, Cornwalls, or La Scalas (lots of listening experience with each). The Heresy tweeters were just screaming loud compared to the squawker. In my Cornwalls, the tweeter plays at about the same level as the squawker when you put your ear by each one. This is also true of the K-horns and the La Scalas. I was contemplating getting rid of them and dismissing them as "not real Klipsch speakers." This sentiment was coming from one die-hard Klipsch fan too. My feeling was that the Herseys sounded decent, but not great. With all the Heresy modification posts here, I assume there are many who feel like I do.

Anyway, enough background, on to the good stuff, read: solution. After careful listening, I decided that the problem was definitely a tweeter problem, not a squawker problem, no need for a P-trap, or some caulking dope. After a quick search, I found a schematic for the Type E network on this BB and copied it down (search T2A, then read "The great inductor face-off"). The T2a transformer provides the attenuation for both the squawker and the tweeter. Each tap (six of them in all) is a 3dB increment. Note: the tap #'s on this BB's schematic is hard to read, the numbers should be 0,1,2,3,4,5 for the bottom tap to the top tap.

Anyway I figured "Hey why don't I just change the attenuation by trying different taps?" So I opened up a Heresy and unsoldered the wire from the #3 tap on the T2A (which goes through a 2uF cap then on to the negative terminal of the tweeter on the crossover). And here's what I found. (A copy of the schematic will greatly help you follow what's going on, even though it's quite simple.) Also, the #'s of the taps is written right on the T2A, so there is really no chance of making a mistake.

1. First I tried tap #4, which is unused. This brightened the tweeter up a lot (by 3dB, I guess). No dice.

2. Next, I tried tap #1, which is also unused. Dramatic attenuation of the tweeter, however, 6dB was too much attenuation. By the way, I'm using alligator leads for the tests. Also, I'm doing A/B comparisons with my vintage Alnico Cornwall I's for reference.

3. Finally I tried tap #2 which is the same tap used by the squawker's negative lead (so basically I just loosened the screw on the negative terminal of the squawker on the crossover, put the bare wire under it, and tightened the screw - piece of cake). This lowered the output of the tweeter by 3dB and was perfect! The voicing of these Heresys now very closely match the sound of my Cornwalls and other big Klipsch (less some low bass) and I must say I am thrilled with the results. These speakers now sound like "real Klipsch" to me. The Heresys also sound way better loud than they used to - they sound more like a big speaker. The bass and midrange are greatly improved because they are not being drowned out by the overzealous tweeter. My goodness, now THESE speakers have beautiful midrange too! Hail Klipsch!

I hate modifying anything from the original, but this was an exception. The results from this are also very apparent, none of that "deepened the sound stage" or "fuller bouquet" stuff - we're talking real results. Somebody else please try this modification and write back to this BB and post your opinion/findings.

Couple other things. 1) this modification is easy, FREE, and 100% reversible. I printed my modification on a piece of masking tape and taped it to the T2A for future reference (Although I'll never change it back, unless deep shag rugs come back in style and rob 3dB of my highs). You may or not like the mod as much as I do, but it sure is an easy way to change the tweeter attenuation, in both directions. Another benefit is that with 3dB of attenuation, you cut 1/2 of the power going to the tweeter (but with only a perceptable difference in loudness) thus protecting it from burnout.

One last point. I also tried stuffing one cabinet loosely with some damping material and compared it to the other speaker. The damping material definitely robbed some punchyness from the woofer and, in my opinion, was not an improvement - I removed it instantly. Also, any thoughts on my modification would be appreciated - I haven't read of anybody trying this, have you?

Tom,

I think this modification is just what your looking for because the story your telling about the room postions and the tone controls were exactly what I was doing - until recently.

The mod is very, very simple. All you have to do is: Note: This applys to the E Type crossover (not E-2 or others).

1)Remove the back - just take out the screws and don't overtighten on reassembly. The wires will still be attached to the back - just leave them alone.

2) Locate the T2A on the crossover. It looks like a transformer and has brown paper wrapped around the core. On CLOSE inspection of the brown paper you will see little numbers by the little taps (0,1,2,3,4,5).

3) The negative lead of the tweeter should be soldered to tap #3 (after it passes thru a 2uF oil filled metal-can capacitor). You'll see the number "3" on the brown paper.

4) Disconnect the #3 tap lead with a soldering iron (or, if you don't have a soldering iron, you can snip it, just leave about an inch of wire so you can reattach it if you don't like the mod).

5) Loosen the screw on the crossover which goes to the negative (white and black wire) side of the squawker (also makes it's way over to the T2A TAP 2) and put the wire under the screw and tighten it up (you will need to strip a little insulation off the wire to get good contact). Everything is clearly marked inside. Note: red is positive, black is negative. !!!Make sure you can trace your hook up wire back to TAP 2 on the T2A - you do not want a short! You can use a meter acoss the terminals to make sure you do not have a short, BEFORE listening tests.

6) Your done. Put the back on and listen to the results.

7) recap: Move tap #3 wire to negative side of midrange on the crossover (this will correspond to using tap #2 on the T2A - check it out when your inside the speaker). Make sure you can trace your hook up wire back to TAP 2 on the T2A! Use a meter across the inputs to make sure your not shorted.

8) post results here when done

9) VERY IMPORTANT: THESE INSTRUCTIONS APPLY TO THE E-TYPE BALANCING NETWORK. MAKE SURE THAT WHEN YOU HOOK THE TWEETER WIRE UP THAT IT IS EITHER DIRECTLY HOOKED TO THE T2A TAP 2, OR IF IT IS HOOKED TO THE CROSSOVER, MAKE SURE THE TWEETER WIRE CAN BE TRACED BACK TO THE T2A TAP2! IMPORTANT NOTE: The E-2 crossover has the POSITIVE side of the squawker going to the T2A, NOT THE NEGATIVE, so if you put the TAP 3 tweeter wire under the negative squawker screw with the E-2 network - YOU WILL BE SHORTED.

10) This modification is indeed simple, but requires some basic wiring knowledge and a little common sense. If you are unsure of what you are doing, DON'T do it, because I don't want anyone to short out their amplifier. Different crossover types are wired differently - so make sure (also somebody may have rewired something in the past - unknown to you). Before you hook your speaker up to an amplifier, use a meter to make sure your not getting a dead short - should be somewhere around 8 Ohms (I don't know the EXACT value, but it's NOWHERE near ZERO).

11) Make mod at YOUR OWN RISK, I am not responsible or liable for your actions.

Klipschguy

P.S. I have a feeling your speakers are going to sound a heck of a lot better.

My Heresy modification of switching tap 2 to tap 3 in the negative leg of the tweeter circuit does a pretty admirable job (by my ears) of balancing out the tweeter and the squawker levels. But by looking at the Cornwall circuit, there may be another way to match the tweeter level - and that would be the addition of an appropriate choke in the tweeter leg of Heresy crossover while likely leaving the taps in their stock positions.

J,

The T2A looks just like a transformer and is mounted to the crossover board (not to be confused with the woofer choke/inductor). By the way John, excellent explanation regarding the T2A function.

You will notice on close inspection of the T2A that it has small numbers printed next to the taps where the individual wires are hooked up. The LOWER the number, the GREATER the attenuation of the driver, be it squawker or tweeter (woofer doesn't use the T2A).

IF your crossovers are like mine, the neg lead of the squawker will be hooked up to tap 2. The tweeter negative lead will be hooked up to tap 3. My mod is simply move the neg lead of the tweeter from tap 3 to tap 2 (which is also used by the negative lead of the squawker in my E type balancing network). This will serve to attenuate the tweeter output, but will not affect the frequency response of the tweeter.

[DrWho]

Hey thanks, that gives me the courage to try out different taps I'm thinking I'll end up putting the squaker and tweeter down one tap and see what happens. Is it all in 3dB increments?

[BEC]

Let me suggest that if you haven't replaced the caps in the Heresy crossover, try that before changing the taps. I think that it is important to get them sounding like the factory had them once before getting into mods. You might like them when you hear them with new parts.

Bob Crites

[3dzapper]

I went the L-pad route, I made new, reinforced rear panels for them. It doesn't alter the impedance like changing taps on the autoformer and gives me the flexibility to adjust output with different amps. I am playing them now on the Jolida 302 and Foreplay. Just as sweet a loudspeaker as one could ever want especially with the SW-15 cut-off at 60 Hz.

Rick

Edit: Bob's right do the caps first. I did but forgot to mention it.

[Deang]

You can't just drop down to the lower taps. It would be great if it was that simple, but it's not.

Tap 4, -3db, x2 the impedance of the driver

Tap 3, -6db, x4 "

Tap 2, -9db, x8 "

Tap 1, -12db, x16 "

You're starting out with an 8 ohm tweeter, and a 13 ohm midrange driver. As it is (with taps at 3 and 2), and using the above, you can see that you now have a 32 ohm tweeter, and a 104 ohm midrange driver. The network components are loosely based on these numbers. If you drop taps, two things happen: 1) the crossover points shift, and 2) the impedance on those drivers go to 64 and 208 ohms respectively.

Now, you could cut the cap values in half to keep the crossover points the same, but you're still left with the extremely high impedance values. The proper "fix" is as follows:

Drop the tweeter to tap 2, and the squawker to tap 1

Connect a 10 or 11 ohm resistor between taps 0 and 5

Change the primary cap value from 2uF to 21uF

Change the tweeter cap value from 2uF to 3uF

The cap values change because you are now designing for what amounts to basically being an 8 ohm network. The 10 ohm resistor sitting between taps 0 and 5 acts to swamp the autoformer, and is the same as paralleling it with the drivers. So, it looks like this:

Tweeter, 64 ohms with 10 ohms = 7.1 ohms

Squawker, 208 ohms with 10 ohms = 9.5 ohms

[Erik Mandaville]

I'm not going to get in on the variable L-pad vs autoformer debate -- it's ancient. They are both different paths to the same objective, and whether one sounds better is completely subjective. Variable L-pads can be purchased which maintain the impedance seen by the amplifier regardless of the position of the wiper on the resistive element, and as Rick mentions, do not require capacitor value modifications. Regarding the use of a swamping resistor, it might be important to address an appropriate power rating.

The autoformer could actually also be used as a sort of 'stepped' attenuator. I've mentioned this in the past, but it would not be difficult to setup up a switching system that works very much like a stepped attenuator volume control. The switch would simultaneously switch between various tap combinations on the autoformer and the required value of capacitance. A make-before-break switch would allow for quiet switching, on the fly, while listening to music, which for me was an easier and more straightforward way of finding the desired level of attenuation. It would also be possible to use an adjustable L-pad on the tweeter and continue to experiment with the taps on the autoformer for the midrange.

Good luck!

Erik

edit: Again, for the record, I'm not saying one is better than the other. The L-pad was just easier for me in a user friendly sense, but that fact alone does not mean it's the right way to go for everyone. One might experiment with both in order to make a determination that was independent of the advice offered here, including what I said above.

[djk]

The correct way to set a type E network for center channel use is to move the K55V to tap 1 and the K77 to tap 2 and install a 15 ohm resistor in parallel with the K55V. A 10W resistor is adequate for up to a 100W amplifier.

The added resistor keeps the crossover points the same.

The K22E is about 95dB/2.83V/1M in 2Pi (half space), the stock taps work best in 1Pi (floor-wall or corner at ear level).

[DrWho]

Ok, so what's the end result difference between DeanG's method and djk's method? Is it just two different ways to skin the cat?

And would this be the right resistor?

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=016-15

[djk]

Dean's method is OK, but have you priced a 20µF Hovland or Mundorf vs a 2µF one? About $125 a pair more.

The PE $0.39 resistor will work OK, I like the $1.00 Eagle non-inductive resistors that Madisound sells. The Mills resistors PE sells are good too, but a bit expensive at $4 each.

[DrWho]

Wow, I can't believe I never heard of madisound before. Thanks for the heads up, you rock.