folkdeath95 Posted January 5, 2011 Share Posted January 5, 2011 Hello, Like many people here, I found my Heresy rather on the "treble side". I discovered on this forum that the Type E crossover could be modified to change this. So I decided to try this mod: The result was a "smoother", more quiet treble, as I expected, but I found that the squawker was attenuated too much. So I thought about pluging the squawker back on tap 2. But, there will be two drivers connected on this tap and I don't know if the T2A can work like this... Hence this question: Is it possible to connect two drivers on the same tap of a T2A? Thanks. Quote Link to comment Share on other sites More sharing options...
folkdeath95 Posted January 11, 2011 Author Share Posted January 11, 2011 Nobody have an answer? Quote Link to comment Share on other sites More sharing options...
moray james Posted January 11, 2011 Share Posted January 11, 2011 Not sure about your desired configuration. You said the speaker was too bright. Why don't you try a 39-40 ohm resistor parallel with the tweeter and put the midrange back to stock position. See what you think, this should smooth things out. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
pzannucci Posted January 12, 2011 Share Posted January 12, 2011 Since you will be going back to almost stock as far as the crossover for the mids, you may have to swap back out the higher cap for the lower since the impedence will change on the midrange circuit. The tweeter is likely of minimum consequence since it has a cap in line with the tweeter raising it's impedence so it should minimally affect the midrange crossover. Going back to stock for the mids may make the mid/high to hot again which would force you to play with the resistor and crossover cap (because of the impedence change). Quote Link to comment Share on other sites More sharing options...
folkdeath95 Posted January 12, 2011 Author Share Posted January 12, 2011 Not sure about your desired configuration. You said the speaker was too bright. Why don't you try a 39-40 ohm resistor parallel with the tweeter and put the midrange back to stock position. See what you think, this should smooth things out. Best regards Moray James. Sorry if I haven't been clear. The midrange is already back to stock position (tap 2) and I'm still trying to attenuate the tweeter. That's why I thought about pluging it on the tap 2 too. What will be the goal of the resistor in parallel with the tweeter? Quote Link to comment Share on other sites More sharing options...
folkdeath95 Posted January 12, 2011 Author Share Posted January 12, 2011 Since you will be going back to almost stock as far as the crossover for the mids, you may have to swap back out the higher cap for the lower since the impedence will change on the midrange circuit. With the swanping resistor, changing the position of the driver on the T2A doesn't affect the impedance seen by the amplifier, so the value of the capacitor can stay nearly the same. Going back to stock for the mids may make the mid/high to hot again which would force you to play with the resistor and crossover cap (because of the impedence change). With the squawker back to stock position, the midrange is not too bright (to my ears). Only the trebble need to be attenuated. When plugged on tap 2 (with the squawker) it's OK, but I'm not sure it's safe to have two drivers plugged on the same tap (that was my main question). Thanks to both of you for your answers. Quote Link to comment Share on other sites More sharing options...
pzannucci Posted January 13, 2011 Share Posted January 13, 2011 Safe, as in load? The only safety problem is with the crossover points and shifting down the crossover lower than it should be and toasting a driver. Since the cap on the tweeter is after the autoformer, it should have minimal impact. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted January 13, 2011 Share Posted January 13, 2011 These work real well. They are from ALK Eng. Quote Link to comment Share on other sites More sharing options...
folkdeath95 Posted January 13, 2011 Author Share Posted January 13, 2011 Safe, as in load? The only safety problem is with the crossover points and shifting down the crossover lower than it should be and toasting a driver. Since the cap on the tweeter is after the autoformer, it should have minimal impact. Thanks.[] Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 13, 2011 Share Posted January 13, 2011 I think there is not a problem. If you look at the effect of the 21 uF cap and the load it is looking into: It will work as a first order crossover with a crossover of 700 Hz if the total load is 10 ohms. The great part of that is the resistor of 11 ohms. How much that is lowered depends on the taps, let me say, output taps, on the autotransformer. But when you're using the lower ones, it may well work out to 10 ohms. I believe there should not be a problem with the power demanded through the windings of the autotransformer. One reason for this is that the tweeter as fed through it's cap (a high pass filter) is only loading any part of the system, specifically the autotransformer, on any tap, above 3000 to 6000 Hz. Probably at the high range. Also the midrange is not really loading any part of the system, again the autotransformer, above the range of 3000 to 6000 Hz, probably at the low range. This is because the mid driver has a voice coil inductance which is essentially choking it off -- another way of saying there is an effective low pass filter. Essentially you could put an inductor in there to remove the highs, but the voice coil is already doing it. I'll wax complicated here. Let's leave the autotransformer out of picture and just consider a classic first order crossover system where we have two 10 ohm drivers. The 10 ohm tweeter is fed through a cap. The 10 ohm woofer is fed through an inductor. If you look at it you might think . . . heck . . . does not these two drivers add up to a 5 ohm load? This is because we know that two equal resistances in parallel, result in half. The answer is no. This is because we have to look at why the cross over filters work. We are used to thinking that high pass filters don't pass low freqs to the tweeter (correct). And low pass filters don't pass high freqs to the woofer (correct). It is as if there a frequency dependent switch in the filter (and this is pretty much true). But think about the switch analogy. If a switch is "off" it allows no current to flow. Essentially, this is a very high resistance or impedance. So, a high pass tweeter filter works because it is switched off at low freqs and its input impedance is high and can't draw current from the amp or autotransformer). Similarly, a low pass woofer filter works because it is switched off at high freqs and its impedance is high and it can't draw current from the amp (or autotransformer). This is a difficult concept. So let me say it again. A good way of thinking about why simple filters work is not only what they pass through by some magic. Rather, it is how they present a rising input impedance to the amp. To be crude. Suppose you had two Christmas tree light bulbs (old screw types) wired in parallel fed at many different freqs, One blue (to which you want to send low freqs) and one red (to which you want to send high freqs). What to do? The answer is that that you when a high freq signal comes along, you unscrew the blue and leave the red connected. When a low freq comes along, you unscrew the red and leave the blue connected. The two are never on at the same time. And the unscrewing process is a filter. As you can see, what is passed through, and not passed through, is mostly a matter of disconnection. Smile, WMcD . Quote Link to comment Share on other sites More sharing options...
pzannucci Posted January 14, 2011 Share Posted January 14, 2011 WMcD, Excellent expansion on why I provided my answer. You always have a good way of explaining things. I make too many assumptions and you always lay it out. Quote Link to comment Share on other sites More sharing options...
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