Heresy and SET

[Tom Mobley]

he's in Yucaipa, Ca. it's SE of San Bernadino north of I-10. Not far from Redlands, where I lived for a few months as a wee tyke.

[Deang]

With the Premier Series on the horizon -- going titanium on Heritage seems silly at this point.

The Heresy II does not lend itself well to extensive modifications since the autotransformer does not allow for adjustable tap settings. There is a work around -- but it ain't cheap.

[Erik Mandaville]

Hi, Pixpop:

In a medium sized room at moderate listening levels, the Heresy will do very well with a single-ended triode amplifier -- 2A3 based, or as Leo indicates, possibly a 300B. I've used all of the 2A3 amps I have built with speakers in the 90db efficiency range, and even they can sound quite good. I have known a number of Heresy owners who, as mentioned above, have been and are very satisfied with the quality of sound and output power of single-ended triode amps.

Regarding modifications and output levels of the midrange horn, a very simple and effective solution is to use a variable L-pad. I use them in my Klipschorns, as does a friend of mine, and they work extremely well. It's far more straightforward than using various combinations of input and output tap settings on the traditional Klipsch autoformer. Moreover, one can directly listen to the difference as the control is turned up or down, which in my opinion is more accurate and immediate than trying to remember what the different output tap settings sound like.

Good luck!

Erik

[Deang]

From the archives:

An autotransformer...

"...holds a constant attenuation to spite a varying load...

...holds the amp's damping factor to the driver, which an L pad won't do ...

...is more efficient electrically because of tighter coupling of the magnetic field...

...in step down acts like a resistive voltage splitter due to the shared resistance in the turns..."

[Erik Mandaville]

Thanks for responding, Dean.

I'm not going to argue about this, since we are both entitled to our own opinion. I will say that the majority of networks I have built and many more I have studied in books use either fixed or variable L-pads as a means of matching drivers of differing efficiency. I have found autoformers far less frequently used.

I also appreciate your sharing some of the qualities of autoformers, which might be helpful for those who are not aware of them. Having used both in a few different networks I have built for my Klipschorns -- and in the last case built entirely from scratch, having calculated the values of parts I would need for the various capacitors and inductors, I will maintain that the variable L-pads I am now using sound just as good to me as the autoformer. More importantly, they are much, much easier to use in terms of taming the output of the midrange. If there was some obvious anomoloy or very poor sound quality, it would have been absolutely simple and nothing at all to just put the autoformer back in.

Autoformers, as far as what I have seen in my own experience, are actually less frequently used for attenuation of drivers than fixed or variable L-pads.

If one has the opportunity to compare an L-pad in place of the autoformer, and based on the comparison decides that he or she prefers the autoformer, I don't know of any hard and fast rule (do you?) that says once the change is made, there is no going back.

On the other hand, if no sonic difference can be detected, yet the added flexibility and ease of use of the L-pad is there, why should someone feel obliged to use an autoformer?

Once again: An L-pad is a very effective way of controlling the output of the midrange horn (or tweeter, if someone happens to change to a different and very efficient driver), and will function very well in place of an autoformer. I used them on an AK-3 network, which like the Heresy above also did not have output tap options, and they work perfectly.

Modifying an output-tap-less autoformer on a Heresy (or any speaker, for that matter)does not mean that the crossover subsequently does not lend itself to modification. Sure it does. Sometimes that requires breaking from what one has been used to, but the possibility is still there. Anything can be changed. But if the change does not sound as good as what was formerly there, then what was formerly there can always be put back into service.

I have used the L-pad in a total of four different networks in Klipschorns -- the 'A', the Ak-3, the AL, and the second order networks I built for myself from extra parts I had on hand. I could not hear a difference, but the output was as easy as turning up the volume on a preamp. In light of this, why should I go back to the autoformer? Moreover, the person I did this for in the first place, who has much more experience listening to and playing live music at a professional level than I, liked the L-pad because of its flexibility.

Each to his own. Neither is right, neither is wrong.