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manual vs auto-biasing tube amp and the EL 34 tube/6CA7/KT88


derrickdj1

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I preferred manual biasing the amp.   It is easy at least on my amp.  Technology moves forward and offers auto-biasing.  Tubes normally operate in a narrow range and this may not be important ant to the SET crowd.  Ultaralinear provides the  best blend of SET  and low distortion.  Second or other harmonics is still distortion.  I, for one don't get into the second harmonics and low damping factor.  I   I am use to a black floor and no hum/hiss from the amp coming thru.  I am not use to and  also the requite  low 2nd THD.  Now, while saying this my amp operates in Class A most of the time even though it is not a total 360 range.  How audible is the difference?

  I

I ues an ultrelinear amp the operate in Class A most of the time and Class A/B  the rest of the time.  I don't like distortion 2nd order or not ant strive for a pure audio signal.  Many will not agree but, my background in SS is a permanent ingrain and introduction to tubes.

 

SS is excellent with music and yet different from tubes.  A lot has to do with what you listen to.  Rock and orchestral and and other complex music may not be best suited for a SET and ultraliner comes to mind.  Now we are dealing with Klipsch speaker which can take advantage of the low watts that most SET produce.  The people in this camp will hit you with the Heritage line and a iron glove in velvet.  

 

If you need the power the PP offers then ultarlinear amps provide what is needed for Rock and complex orchestra.  There are well executed design of both as well as, poorly executed designs.  So, no blanket statements can be made.  Even a PSET design is worth considering due to the headroom.  There should also be consideration give the 10 to 15 efficiency rating of operating an amp in Class A.  Beside a room heater, tube longevity.  I go fro 123 watts SS to 256 watts Class A with the tube amp.  It is not all bad  since I can heat up a plate of Nachos and melt the cheese.  What 's you thought s on the various types of amps, class operating zone and tube compliment.  

 

Is the shorten tube life and expense a must have for SET?  Is the extra power needed with our speakers from a Pentode or ultralinear amp?  Can a PSET match the power and preserve the fidelity.  I think it will be hard to find a one answer to fit all.  

 

For me, I will not be leaving my present amp till something definitively shows up at a  good cost to performance ratio.  The current enviroment favors more digital offering and the only analog is usually old and depends on the original mastering.  Where is one to go?  The KT 88 and EL 34 tubes have been a main stay for year since the advent of SS.  Many guitar amp use these tube due to the live like performance.

 

 

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Derrick, what kind of tube amp are you using that puts out 256 wpc (I may have misunderstood what you stated)???

 

Auto biasing is a very useful feature, especially for owners who are not technically inclined.  It makes the amp operate as a plug-and-play device as well as keeping each output tube set for the desired operating point (theoretically at least).  Another advantage is that it eliminates "bias obsession."  You can't imagine how many guys are so obsessed with bias that they check it on a daily basis and won't tolerate even a 1 milliamp drift (which can occur from normal line voltage variations).  Yes, it's worth keeping an occasional watch on it (like once/year after the first 100 hours of operation on the tubes) but it just isn't that critical.

 

Not everyone agrees about ultralinear combining the best qualities of triode and pentode operation.  It's a matter of personal taste.  To me, it's the opposite- I generally find that it combines the worst qualities of both.  One must experience it in their system to make a decision.  Since many amps can be switched between triode and ultralinear operation while music is playing, it's easy to get an impression of both.

 

There's no question about the inefficiency of triode operation.  However, triode amps are not necessarily room heaters (it all depends on the design, power output, etc.).  As to short tube life, that's totally design dependent.  I find no difference in tube longevity between my SETs and SEPs.  Distortion is also totally design dependent.  It is possible to have a SET with distortion figures which remain low over the entire operating range.

 

As to power needed with most Klipsch speakers, you yourself have measured that it doesn't require much to get blown out of the room.  It's a matter of selecting the needed power output to satisfy one's listening levels.  There's little to be gained by having an amp which can deliver 100X the maximum power required to handle the loudest level at which a person will listen.  

 

Maynard    

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I really enjoy single ended amps whether it be true direct heated triodes like the 2a3, one of my favorites, or pseudo single ended like a KT88 or 66. I say pseudo as the true single ended is DHT? Maynard, please inform and correct me on this if I am veering off course. It's when I get into higher power PP and/or UL tube amps that I see zero advantage over higher end SS amps, Class A in particular. I have owned several very well known PP and UL amps in the 25 to 60 watt range that were short lived in my rig. For me these higher power tube configurations sound like very good solid state, nothing more. I still own a couple single ended amps, a couple Class A solid state and tremendous sounding Class D but zero PP or UL tubes. I just don't see and in particular, don't hear,  any advantages with those designs.

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3 hours ago, richieb said:

I really enjoy single ended amps whether it be true direct heated triodes like the 2a3, one of my favorites, or pseudo single ended like a KT88 or 66. I say pseudo as the true single ended is DHT? Maynard, please inform and correct me on this if I am veering off course. It's when I get into higher power PP and/or UL tube amps that I see zero advantage over higher end SS amps, Class A in particular. I have owned several very well known PP and UL amps in the 25 to 60 watt range that were short lived in my rig. For me these higher power tube configurations sound like very good solid state, nothing more. I still own a couple single ended amps, a couple Class A solid state and tremendous sounding Class D but zero PP or UL tubes. I just don't see and in particular, don't hear,  any advantages with those designs.

To me, a triode strapped pentode is as much a triode as an actual triode.  It's the electrical characteristics which matter (a triode strapped 6Y6, for example, is a much better "triode" than some of the popular tubes which lack a suppressor and screen grid).  Others take a different view and only consider DHTs "true" triodes and that adding a cathode changes the definition.

 

As to push-pull pentodes (whether used in conventional pentode operation or ultralinear) I tend to agree with you.  I find that many push pull amps, even when biased for class A operation, lack the sonic appeal which makes tubes worthwhile.  If I needed much more power I'd probably go with SS myself as the differences between that and push-pull are small to my ears.

 

It's a matter of personal taste as with everything else in audio.  For me, single ended is the only way to go.

 

Maynard

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First I should clarify the 123 vs 256 watts.  This is the reading on the power console which has the avr, BDP, cable box and TV.  So, It is just the difference of powering the system with the SS, Acurus amp vs using the tube amp.  The Yaquin MC 13 S the vast majority of the time is operating in Class A.  

 

The wattage meter on the MC 13S is usually showing less than a few watts if that much.  It is interesting that at a recent GTG, I took my integrated MC 13S amp and there was another integrated amp, Master Sound Evolution 845.  The Master Sound is PSE configuration with four 845 power tubes.  At the GTG, I thought this amp would blow mines out the door, lol.  It did not sound any better to my ears and a few of the other guys.  Most people were interested in the Yaquin due to the price difference.  The Master Sound amp retails for $ 7,500.  It is suppose to be high end and boutique.  http://www.hifiplus.com/articles/mastersound-evolution-845-hi-fi-79/

 

I am fairly new to tubes with a lot more to lean. Correct me if  the Master Sound  is not PSE but, I did not pick up on any major difference ascribed to SE vs PP.  Maybe I just have old ears, lol.  Maybe I just need to hear some more SE amps.

We listen to some vocals, and jazz music.  The speakers were DIYSG 1099.  These speakers have a overall balance similar to the Forte I or II speakers.

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The Mastersound is apparently parallel single ended as you stated.  As to not hearing much difference between it and your Yaqin, it has nothing to do with the age of your ears!  Not everyone is sensitive to amplifier characteristics, and some music and speakers may be less revealing of differences than others.  I'd consider that a blessing as it keeps you from chasing your tail trying to find amplification which covers all the bases with all kinds of music.

 

Maynard

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I just could not truly tell much difference between the $7,500 amp and the $500 amp.  Now, I have heard Amp Sound and some McIntosh tube amps that sounded much better than the $7,500 Master Sound amp.  The McIntosh was the best tube amp I have heard.  I don't need the best, just close, lol.  This forum has taught me that it is not what something cost that makes it good!  

 

This amp may be a gem in the rough for it's price point.

 

For comparison, I’ve compiled a list of EL34 integrated amplifiers that share similar characteristics: the Yarland M34-IV-EU ($1,499.00 CAN); the Jolida JD 202BRC ($1139.00 CAN); the AudioSpace AS-3i -EL34 ($2100.00 CAN); the PrimaLuna ProLogue Classic ($2300 CAN); the Antique Sound Lab AQ1003 MARK II DT ($1600 CAN); and, the Line Magnetic LM-211IA El34 ($2200 CAN). If I were to do a comparison review of any of these EL34-based integrated amps, I wouldn’t hesitate to throw the Yaqin MC13S into the evaluation. http://wallofsound.ca/audioreviews/amplification/review-yaqin-mc13s-stereo-integrated-amplifier/

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  • 2 weeks later...
On ‎11‎/‎1‎/‎2017 at 7:31 AM, tube fanatic said:

There's little to be gained by having an amp which can deliver 100X the maximum power required to handle the loudest level at which a person will listen.  

 

Depends on the speakers, the room, and the dynamic range of the source material. If the goal is to reproduce the intensity and dynamic range of a live classical performance in a 4000 cu. ft. room, 1 watt average power into Khorns and 20 dB dynamic range (100 watts) is about what you want to have. Outdoor usage needs more power for the same acoustic output.

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