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Forte III Impedance


Drumsbanger

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Hello, 

 

This is my first post here. I recently purchased a Decware Torri MK IV push-pull tube amp. I have owned a pair of Klipsch KG 4.5s since 1994. Up until the time I got the Torii  they had only been used with an Adcom GFA-535 solid state amp. When I hooked the KG 4.5s up to the Torii, there was an upper midrange glare that had not been there before. I am currently using a pair of Zu Omen MK II Dirty Weekends, but they are going back. I really would like to try the Forte IIIs with the Torii. I'm afraid that they will have that same upper midrange glare that the KG 4.5s had. I've spoken to the owner/engineer of Decware, and he mentioned that the Klipsch have a wild impedance swing that leads to that harsh, shouty upper midrange on non "ultralinear" tube amps. On the Decware forums, someone else posted about having the same issue with old Chorus speakers paired with his Torii. My question is, does anyone know if the new Fortes have the same issue, or has the new crossover addressed this problem of wild impedance swings? 

Edited by Drumsbanger
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The problem of impedance swings was due to the crossover implementation.  I would think that if Klipsch is still using autoformers in the crossover and not doing some type of impedance compensation, you will have the same problem with the newer Klipsch.  If they moved to L-pad resistors, then you may be in luck though not 100% sure that is the only issue with using that amp.

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He’s showing that the newer networks have no autoformer.

 

Classic Klipsch actually has a reputation for sounding outstanding with zero feedback amplifiers. 

 

Keep in mind that the absence of an autoformer does not guarantee a benign impedance curve. Klipsch seems to prefer series resistors instead of L-pads. 

 

Are there published curves of the amplifier?

 

There are treble cut knobs - they don’t help at all?

 

What preamp are you using? The front end is important. 

 

Try your new amp on some other speakers if possible.  

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Deang, the treble cut knobs are very subtle. I don't know that they would have any effect in the frequency range in which I'm hearing the harsh upper mids. 

 

I don't currently have a preamp in front of the Torii. It is being fed by my DAC and analog outs of the TV. 

 

I have tried Zu Audio Omen MK II Dirty Weekends. They are going back. The amp is still fairly new, and probably still in the burn-in process. Since the Zus are going back, I have just put the old KG 4.5s back in. After several weeks, I will be interested in listening to them to see if anything has changed since last hearing them in the system. 

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22 hours ago, Deang said:

He’s showing that the newer networks have no autoformer.

 

Classic Klipsch actually has a reputation for sounding outstanding with zero feedback amplifiers. 

 

Keep in mind that the absence of an autoformer does not guarantee a benign impedance curve. Klipsch seems to prefer series resistors instead of L-pads. 

 

Are there published curves of the amplifier?

 

There are treble cut knobs - they don’t help at all?

 

What preamp are you using? The front end is important. 

 

Try your new amp on some other speakers if possible.  

I kind of got that the pic was for reference that's why I brought up the crossover regions :D.  Could definitely be based on what someone likes in that region.  If the output impedance of the amp is high, that can create a several db variation in the crossover areas due to the impedance swings.

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