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Forte III and Decware Torri MK IV Amp


Drumsbanger

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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? 

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3 minutes ago, Schu said:

Issue... I have an issue with that characterization. There are a few issues to address besides the poorly designed speaker scenario.

May I ask what tubes you are using?

I am using new production Gold Lion KT66 outputs, NOS (Matsushita) 7DJ8 inputs, and NOS RCA 5U4GB rectifiers. This is a dual mono design. 

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6 hours ago, Drumsbanger said:

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? 

Never heard that before, wild impedance swing that affects the upper midrange on Klipsch speakers. One has to remember that people with accredited engineering degrees have disagreements especially when it comes to sound reproduction. Every speaker graph I have seen might show some impedance swing on the bottom end but were pretty steady on the upper spectrum. Drivers used with Klipsch speakers were, are the ones anyone can purchase without being branded Klipsch and do not have a wild swing of the impedance. Also the horns are designed using the industry recognized standards for their specific purpose. I would not think the engineers at Klipsch would design a speaker crossover that would contribute to a wild impedance swing. Possibly some synergy problem with the marriage of said amp and speakers but I would not call it a wild speaker problem. Sounds like trying to blame the speaker rather than the amp myself and I have one of his amplifiers and am a believer in his products and designs. Some L-pads on the drivers will work wonders taming what you are calling shouting. As Nelson Pass says, there is no such thing as a perfect amplifier for everyone. I now have 7 up and running Firstwatt clones and some sound better than others with my LaScala's. 

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I had Forte IIIs a few months ago. I was driving them with a Line Magnetic SET. There was a sharpness in the midrange on some recordings, but firing them almost straight ahead with only a slight toe in seemed to go a long way in controlling it. Very good speakers IMHO.

 

I moved on to a pair of Klipschorns and was not completely convinced in the LM/Khorn pairing. I bought a Decware Torii II and have found that to be a beautiful match. Although I didn't get to hear the Fortes with this amp, I think you would be absolutely thrilled with your Mark IV driving a pair.

 

I read somewhere that Steve Deckart keeps a pair of Klipschorns around for testing with his amps, so he knows how they pair with horns.

 

Shakey

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Steve Deckert has no KHorns that I've ever seen, but it's been a long time since I lived in Peoria.  He does have some corner horns of his own design which utilize a single "full range" driver.

 

Virtually all speakers, including Klipsch, are designed assuming a near zero output impedance from the amplifier.  Any amp that has slightly higher than zero output impedance, such as your Torii, will invariably result in frequency response aberrations (linear distortion) when facing a wildly swinging impedance load.  The aberrations are really not that much.  On the old networks that used autoformers it amounts to a db or two (which I have measured), which is enough to skew the tonal balance of the speaker.  On fIII, which don't have those swings up to 100 ohms+ in the midrange, would fare better.  

 

Linear distortion can be corrected by either a crossover network / drivers that present a fairly flat load (think zobels here, although they do come with insertion losses and are contra to high sensitivity), thus sidestepping the problem, or by upstream equalization (which needn't be heavy handed, as the aberrations are not great).

 

The Torii amps are very good IMO, pp that preserve a large chunk of that SE sonic personality but with significant balls.  

 

 

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Thanks for the responses. I think I will order the Forte IIIs. I have a 60 day return window, so if they have the harsh midrange, I will send them back. 

 

Apparently, Klipsch is not using autoformers in the newer speakers. The KG 4.5s I used were from the mid '90s, and a much lower line than the Forte, so hopefully I'll be good. 

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10 hours ago, Drumsbanger said:

Thanks for the responses. I think I will order the Forte IIIs. I have a 60 day return window, so if they have the harsh midrange, I will send them back. 

 

Apparently, Klipsch is not using autoformers in the newer speakers. The KG 4.5s I used were from the mid '90s, and a much lower line than the Forte, so hopefully I'll be good. 

Forte's are and have been considered as one of the best designed speakers in their price range by many satisfied customers for decades. I can assure you if there is a harsh midrange it is not in the speaker. There is no magic in horns themselves, they are used in most every concert that has amplified music and are certainly not considered harsh. Bad rap by sellers of conventional home speakers. If there is a problem with sound I can almost guarantee it is in the amplification. There is one thing horns do, show any imperfection with amplification or source. The better the horn, and driver,  the more it will show. There is one fault of any push pull amplifier, crossover distortion. All PP amplifiers have it, some more than others. It cannot be eliminated entirely but only kept to such a low value not to be heard. Just give it some thought, one transistor or tube handles the positive part of the sound wave and another tube or transistor handles the negative part of the wave,  crossover. More than likely the Torri amp is an A/B PP tube amplifier instead of class A PP by the amount of power stated which inherently  has more crossover distortion than a class A PP amplifier. Not saying this is your specific problem but just in general terms. Not unusual for one person to hear it whereas someone else would not. I hope you do not have a problem since you have already bought but you may want to consider a quality single ended class A amplifier. The most linear of all the forms of amplification. The Torri is probably a very good amplifier with more forgiving, conventional speakers. 

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I would ask Steve what the output impedance of the amp is.  It could be fairly high since he is not using any negative feedback.  Also his frequency response plot, which he says is into an actual speaker, is amazingly good.  I'm curious as to what speaker he used to make that measurement.  His comment to you about non-ultralinear amps makes me wonder a bit as it suggests that the Torii isn't capable of handling "wild impedance swings" which are very common.

 

 

Maynard

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I used the amp in my signature with the Forte's and loved it.  It is high quality without the bells and whistles and a modest price.  This amp has been to GTG's against amps up to $7,000 and held it owns.  This is an ultralinear pp amp that operates in Class A the 99% of the time with normal listening habits. I have not ever thought twice about replacing this amp.  It will be with me a long time.  It sounds like the amp the op has may not be the right amp for him.

  

 

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Kevin Deal at Upscale Audio has a nice little video about the Forte III, which he sells of course on Youtube.  He discusses and dismisses the brightness issue.  Just worth a listen and of course he is into and sells PrimaLuna as well as many other brands.  Very funny video as well.   

 

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wdecho, the Torii is a class A1 amplifier. Not placing "blame" on speaker or amp, but perhaps an incompatibility/synergy issue. I already have the amp, so I want to be reasonably sure that the F3s do not present the same problem I had with the KG 4.5s. Since the F3s are a 24 years newer design, plus much higher in the Klipsch food chain, I think I may give them a shot. 

 

Shakey, I'm glad to hear that your Torii works so well with the Khorns. Are they old or newer? I just wonder if they have changed the crossover design in that speaker in more recent years. 

 

Tube fanatic, Steve generally prefers crossoverless full range designs, or simple two way designs, with a cap on the tweeter. That's more than likely the type of speaker he made the measurements with. Those are probably they types of speakers he has in mind when he designs his amps. 

 

derrickdj1, I didn't see what amp you used in your signature. Was it the Torii? 

 

dbomberger, I've seen that video. I've spoken to Uncle Kevvy about my issue, and he offered me a "great trade in" on my Torii. Ha! I can't see that happening. I'm sure I'll love the amp with the right speakers. 

 

I'll probably end up ordering the Forte 3s, since the only way I'll find out if they work in my system is to try them. Crutchfield offers a 60 day trial. I can return them if they don't work for me, with a $75 shipping charge back. If the F3s don't work, I'll probably go to Decware and get one of Steve's speakers. 

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2 hours ago, dbomberger said:

Kevin Deal at Upscale Audio has a nice little video about the Forte III, which he sells of course on Youtube.  He discusses and dismisses the brightness issue.  Just worth a listen and of course he is into and sells PrimaLuna as well as many other brands.  Very funny video as well.   

 

 

Every time I watch Kevin in a video I make sure my wallet is still in my pocket. 

 

He's a tad over the top..

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Haha but his PrimaLuna line sounds SOOOOO good.  Every time I hear tubes being talked about here, I refrain from mentioning my experience with his products.   They are KILLER.   I have tried many.   If you want a taste, try his primaluna prolpgue 3 preamp. Oh BTW, he has a RIDICULOUS hone where you can audition anything in a PREMIUM area in CA.  just my 2 cents.   Super nice guy.  I have spent too much money with him..... FWIW

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53 minutes ago, Westcoastdrums said:

Haha but his PrimaLuna line sounds SOOOOO good.  Every time I hear tubes being talked about here, I refrain from mentioning my experience with his products.   They are KILLER.   I have tried many.   If you want a taste, try his primaluna prolpgue 3 preamp. Oh BTW, he has a RIDICULOUS hone where you can audition anything in a PREMIUM area in CA.  just my 2 cents.   Super nice guy.  I have spent too much money with him..... FWIW

Thanks for the info.  I have yet to hear a PL, but am going to the Rocky Mountain Audio Fest in 10 days and will hear them (and many others) there.  Unless I'm dissuaded by something else while I'm there, I'll be ordering one when I get back.  Been meaning to drive over to his place, but it is 500 miles.  I'm sure I'll get there sometime. I might even decide to go pick up what I buy to avoid any delivery disasters-though I know they are well packed.  

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11 hours ago, Drumsbanger said:

Shakey, I'm glad to hear that your Torii works so well with the Khorns. Are they old or newer? I just wonder if they have changed the crossover design in that speaker in more recent years. 

 

Mine are from 1976. However, I do have Volti Audio xovers in them now, no autoformers. I didn't have the Torii amp when I still had the AAs in them.

 

Shakey

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12 hours ago, Drumsbanger said:

wdecho, the Torii is a class A1 amplifier. Not placing "blame" on speaker or amp, but perhaps an incompatibility/synergy issue. I already have the amp, so I want to be reasonably sure that the F3s do not present the same problem I had with the KG 4.5s. 

I did not research the amp but it is good that it is class A but not all class A amps sound the same. I can only speak on class A PP SS amplifiers being that I only have one class A PP tube amplifier but all do not sound the same. Case in point is the Firstwatt F5. It is a SS class A PP amplifier which is not my favorite SS PP with my speakers. Very unforgiving on speakers and source used. There are no culls in Firstwatt amplifiers but each and every one does sound different. Perhaps there is something in the crossover with your present speakers or maybe they just need some more attenuation in the mids or tweeter. Never the less I hope your Torri and Fortes make a good marriage. 

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