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KG2 - Impressed!


BadChile
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Many of my colleagues know I have a nasty habit of finding free or heavily discounted speakers usually which I fix up (surrounds / crossover rehab / add banana plugs / etc.) And either give away or keep.  So it didn't surprise me when a couple weeks ago a colleague mentioned he found a pair of speakers in his garage left behind by an ex-girlfriend seven years ago.  Once he sent a photo it took me a few minutes to ID as a pair of KG2 - no labels, no badges.  I had previously talked this colleague into picking up a pair of Heresy IIs in his hometown for cheap, and he's pretty happy with those.  But I said I'd recap the crossovers for free and proceeded to order parts (can always use parts!)

 

He brought them by on Tuesday evening for me to check out and do the work.  Before he unloaded them from the car he listened to my main system (Elekit TU-8200 into Heresy III with subs) and was blown away.  Then out came the KG2 pair.  These things were dusty as could be but were in good condition, even the dust caps of the passives were non-crushed. Shockingly, they did pretty well in the main system.  Highs were on the shrill side, no magical Heritage mid-range, but the bass held its own for the tiny "bookshelf" (don't fool yourself - these are mini-Heresy sized).  I liked 'em.  Unfortunately, so did my colleague who didn't even leave them for the recap - maybe he was afraid I'd never give them back.

 

I tried to even convince him to stick around so we could do a shoot-out against KG1s and KG4s, but like me when I find free speakers on the side of the road, he was in a hurry to leave before someone else grabbed his toys...

 

Summary: I now have parts for a KG2 recap but no KG2s.  Which can only mean one thing: time to hunt down some KG2s!!!!

 

 

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5 hours ago, BadChile said:

Before he unloaded them from the car he listened to my main system (Elekit TU-8200 into Heresy III with subs) and was blown away.

 

I really like those amplifiers especially for the money. One thing is I would trade the active auto-bias feature for either a interstage transformer or a follower circuit to drive the output stage into grid current as it drastically improves performance and you get more power out as a bonus.

 

With the KG4's do which mode do you find yourself listening to, triode, UL, or Pentode?

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16 hours ago, captainbeefheart said:

 

I really like those amplifiers especially for the money. One thing is I would trade the active auto-bias feature for either a interstage transformer or a follower circuit to drive the output stage into grid current as it drastically improves performance and you get more power out as a bonus.

 

With the KG4's do which mode do you find yourself listening to, triode, UL, or Pentode?

With regards to the first - that is well-beyond my knowledge/skill set - so I have no idea on where to even start there.

 

For the second I haven't run the KG4s on the TU-8200 in a few years.  I'll have to give it a shot.  With the Heresy IIIs  I usually run in Ultralinear but occasionally use the Triode mode.  I don't think I've ever even tried Pentode mode.  Any particular mode preferences that you have?

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Those were the first Klipsch speakers I ever purchased back in 1984.  I later traded them in for kg4, then Forte.  And so the Klipsch obsession began.  I recently got very nostalgic for them and wanted to hear them again.  So, even though I definitely didn't need them, I found and purchased a pair in very good condition off eBay for a good price.  They are in the same oiled oak finish as my original pair.  I even still had the solid oak stands that the deal sold to me with the speakers (built by a local craftsman the dealer worked with).  They had been gathering dust in the garage.

PXL_20211008_190654643_resized.jpg

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2 hours ago, BadChile said:

With regards to the first - that is well-beyond my knowledge/skill set - so I have no idea on where to even start there.

 

For the second I haven't run the KG4s on the TU-8200 in a few years.  I'll have to give it a shot.  With the Heresy IIIs  I usually run in Ultralinear but occasionally use the Triode mode.  I don't think I've ever even tried Pentode mode.  Any particular mode preferences that you have?

 

For the TU-8200 I was only saying I like the design of the circuit, much better than many much more expensive amplifiers. I wasn't suggesting to change anything, especially since it is all on a PCB it would be difficult to make the change. I was more or less thinking out loud that I would be over the moon for the amplifier if it ran Class A2 grid current mode. With low powered amplifiers even if you are listening at around 1 watt of power average, dynamic music needs headroom for the dynamic range and the transients or peaks in the music. General rule of  thumb is 20db headroom from average listening powers. Example average listening is 86db, that means you need headroom of 106db, with 94db like the Heresy that would equate to power of 16 watts of power. That amp in A2 operation would get you closer to the 16 watts power you need but more importantly if you run the amp closer to full power it will not go into grid clamping which causes a gross bias shift and blocking distortion, this takes the amp time to shift back into normal operation. With A2 operation none of that happens. I know tube rollers love the active auto bias so from a design perspective they most likely figured that would be a huge selling feature for customers to be able to change their own power tubes without worrying about having to re-bias. I would trade the auto-bias for A2 operation as it greatly enhances performance where the auto active bias does not, it is more of a convenience technology. One issue with the active auto-bias which has become very popular lately as a selling feature in tube amps they fail very frequently. When I purchase or build an amplifier I expect it to be bulletproof and last a long time before any need for repairs but I have been seeing a lot of these active auto-bias circuits fail prematurely. Nothing to stress about, I really think they did a great job with the amplifier design and I am only nit-picking at this point and like I said if it was A2 operation I would have the credit card out ready to purchase one!!

 

Sorry I messed up and meant to ask about the amp on the Heresy, the Heresy is a better speaker compared to the KG4 IMHO. Triode mode should be the best of all the modes and personally I would be listening to it like that the vast majority of time. As for Pentode vs Ultra-Linear I am not a fan of Ultra-Linear, it is grossly overrated because it tests well on a resistive load but under reactive loads it doesn't do so well. I have found that a different form of local feedback (instead of sending plate signal to the screen grid like ultra-Linear, signal from plate goes to the control grid) nested inside global feedback sounds a lot better in real world with speakers. Unfortunately the TU-8200 does not have the plate to grid local feedback in Pentode mode so that mode will not be at it's full potential but give it shot I am very curious what you think of Pentode mode vs Ultra-Linear mode. Another great engineering practice they followed was putting an RC Zobel network at the output to keep loading from reactive speaker loads from rising with frequency, it keeps it flatter for better performance and lower distortion at high frequencies. You would be surprised the vast majority of modern and vintage tube amplifiers do not add this inexpensive but very crucial addition. Since the TU-8200 has the Zobel networks it should be much smoother in Pentode mode than if it didn't. My hats off to Elekit!!

 

 

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