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EL34, 300B and the KT150 sound differences


Flevoman

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7 hours ago, Flevoman said:

Is there a point where the EL34 outperforms the KT150 in your experience? 

Only when the EL34s are in a better amp than my MP-301. In the same amp, the KT150 always outshines the EL34 in a big way.

 

I haven't done a live KT150 vs 300b comparison yet. However, I have also listened to a KT120 vs 300b comparison on Youtube.  I couldn't tell the difference through my setup. I'm assuming the difference would be more noticeable with KT150s.

 

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What I have found in info about the 300b is that this is a very musical tube that shows a lot of detail. A more warm and laid back sound. Everyone is very enthusiastic about this tube. Musically and more detail appeals to me. But I found the 300b a bit too warm (too much hummmm in my opinion) and the sound could have had a bit more punch and dynamics. And this is what I could hear in the kt150

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I'm not sure how to interpret the class of an amplifier. At first I wanted to buy a SET amp. This is a class A amp. However, there is a good chance that it will be a Melody amplifier where the DPM80 is a class B and the AN300B is class AB1. It gives me the feeling that with Class AB I by definition buy a less good amplifier, and that this is especially the case with a class B amplifier. Is there a grain of truth in this? Will a class B amplifier always be subordinate to a Class A amplifier

 

Edit:What I can find information about class B amps doesn't sound very positive. I can't reconcile this information with a 6700 euro costing amplifier. 

 

"Class B amplifiers are much more efficient than Class A amps — 50% or so — but produce distortion as the two transistors switch on and off. This "crossover distortion" is so bad that very few if any manufacturers offer or produce an amplifier of pure Class B design."

 

 

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Hi @Flevoman,

 

I too have an amp with EL34s, a Cary SLI50. For more dynamics and precision and after trying EL34, EL34B, 6CA7 big bottle and KT77.

 

My preference is KT77 in 1st and 6CA7 in 2nd. In KT77 I currently use KT77JJ they are very dynamic and with fantastic highs.

 

You can already try KT77JJ on your Dynaco ST70 first before changing amps

 

jj-tesla-kt77-123254.gif

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18 minutes ago, mustang_flht said:

Hi @Flevoman,

 

I too have an amp with EL34s, a Cary SLI50. For more dynamics and precision and after trying EL34, EL34B, 6CA7 big bottle and KT77.

 

My preference is KT77 in 1st and 6CA7 in 2nd. In KT77 I currently use KT77JJ they are very dynamic and with fantastic highs.

 

You can already try KT77JJ on your Dynaco ST70 first before changing amps

 

jj-tesla-kt77-123254.gif

Thank you for this tip. 

I had the Dynaco modified to the kt88 tube before. I don't know why but I didn't like that sound at all. Recently I had everything built back to the EL34 and this sounds good again. Maybe it had nothing to do with the kt88 tube but the modification was not done properly. I don't have a clue. But the sound sounded dull with the kt88. But I can't just plug the kt77 tube into my amp I think. I think things have to be adjusted first. 

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If your amp is set for EL34, then you can put KT77 directly it's a replacement of EL34, you just need to change the 4 or 2 and do the Bias setting !

Attention KT77 has nothing to do with KT88 even if the writing is similar to KTxx

 

look here direct replacement for EL34 = 6CA7, KT77 ...

 

http://www.r-type.org/exhib/aaa0014.htm

 

https://dynacotubeaudio.forumotion.com/t3289-6ca7-or-kt77

 

 

😉

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2 hours ago, Flevoman said:

I'm not sure how to interpret the class of an amplifier. At first I wanted to buy a SET amp. This is a class A amp. However, there is a good chance that it will be a Melody amplifier where the DPM80 is a class B and the AN300B is class AB1. It gives me the feeling that with Class AB I by definition buy a less good amplifier, and that this is especially the case with a class B amplifier. Is there a grain of truth in this? Will a class B amplifier always be subordinate to a Class A amplifier

 

Edit:What I can find information about class B amps doesn't sound very positive. I can't reconcile this information with a 6700 euro amplifier. 

 

"Class B amplifiers are much more efficient than Class A amps — 50% or so — but produce distortion as the two transistors switch on and off. This "crossover distortion" is so bad that very few if any manufacturers offer or produce an amplifier of pure Class B design."

 

 

 

I feel a point where commitment to this beautiful hobby and music is reaching certain limits of technical understanding. Please don't misunderstand, this is not meant to be an offense, but to be honest I mean it as a protection, so that not too much money is spent on the basis and belief of half-knowledge and hearsay.
I respect any kind of personal taste and personal choice, philosophically it must even go so far that I respect any attitude, so even those who may enjoy that perhaps even knowing explanations are absolutely undesirable. For example, if someone has a hard job and has to make many decisions, then the hifi hobby should be exactly a soothing balance where you do not want and need to know and understand everything exactly, but you want to deal on the other hand gladly with the technology and the stories about it.

I think, however, if the interest, for example, about the differences of circuits (A, AB, B etc) is meant seriously then I would be happy if @captainbeefheart comments something about it because he is a real top expert in this field with an experience and knowledge and a background as a jazz guitarist as well who also feels the music and not only understands the tubes.

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3 hours ago, Flevoman said:

I'm not sure how to interpret the class of an amplifier. At first I wanted to buy a SET amp. This is a class A amp. However, there is a good chance that it will be a Melody amplifier where the DPM80 is a class B and the AN300B is class AB1. It gives me the feeling that with Class AB I by definition buy a less good amplifier, and that this is especially the case with a class B amplifier. Is there a grain of truth in this? Will a class B amplifier always be subordinate to a Class A amplifier

 

Edit:What I can find information about class B amps doesn't sound very positive. I can't reconcile this information with a 6700 euro costing amplifier. 

 

"Class B amplifiers are much more efficient than Class A amps — 50% or so — but produce distortion as the two transistors switch on and off. This "crossover distortion" is so bad that very few if any manufacturers offer or produce an amplifier of pure Class B design."

 

 

No way do you want a class B amplifier. You will have terrible crossover distortion. With a properly biased A/B amplifier crossover distortion is for all practical purposes eliminated. With our speakers, being so efficient an A/B amplifier may not ever leave class A. Bias is the term you may not understand but if means if you bias, turn up, the transistor or tube as far as reasonably possible, where it will not destroy itself, it will stay in class A. Then you will have a PP class A amplifier in it's power rating. Nelson Pass wrote and articled years ago called "Leaving class A".  https://www.passlabs.com/technical_article/leaving-class-a/

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1 hour ago, Flevoman said:

Thank you for this tip. 

I had the Dynaco modified to the kt88 tube before. I don't know why but I didn't like that sound at all. Recently I had everything built back to the EL34 and this sounds good again. Maybe it had nothing to do with the kt88 tube but the modification was not done properly. I don't have a clue. But the sound sounded dull with the kt88. But I can't just plug the kt77 tube into my amp I think. I think things have to be adjusted first. 

Kt88 is an excellent tube in a properly built amplifier. I have both a SE KT88 and SE El34 amplifier. Not a lot of difference in sound but more power. 

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So this is kind of my problem now.

0 in knowledge.. 0 in experience...and I will have to make a choice based on a short listening demo where I will only hear the most noticeable differences so quickly. There for I appreciate all the info I get from you that I can take with me with the second demo 👍🏻

 

On the first demo I thought the Melody with the KT150 sounded the best. This information (that it is a B amp, and then the info I read about a B amp) is confusing

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I also have a ST-70 along with two SS amps I have put on the shelf for backup if needed. I completely refreshed the ST-70 with a stock replacement 7199 driver board. I have 3 sets of strong testing RCA and Sylvania driver tubes. I used Takman carbon film resistors and CDE wmf series coupling caps on the board. I first listened with carbon comp and then metal film resistors. Yes they do influence the sound. The condition of the driver board, the components used and the driver tubes have a greater influence on the sound than the output tubes. Get that right first and then roll out EL34's, KT66 , KT77 and fat bottle 6CA7's and decide what sounds best in your system.

Give your ST-70 a fighting chance before investing in a completely different amp. When healthy with the right board configuration and tubes it is a very capable and sweet sounding amp. I use a tube preamp and my speakers are home built Cornwall clones at 100db sensitivity. Highs and mids are smooth, rich and detailed. Bass is clean, detailed and strong. BTW I have two strong testing sets of vintage Mullard xf2 power tubes. I couldn't be happier with my system....and won't spend thousands more chasing a unicorn.

 

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12 minutes ago, Flevoman said:

So this is kind of my problem now.

0 in knowledge.. 0 in experience...and I will have to make a choice based on a short listening demo where I will only hear the most noticeable differences so quickly. There for I appreciate all the info I get from you that I can take with me with the second demo 👍🏻

 

On the first demo I thought the Melody with the KT150 sounded the best. This information (that it is a B amp, and then the info I read about a B amp) is confusing

Whoever said it was a class B amplifier is mistaken or just a slip up in his review. I know of no consumer class B amplifier being sold. Possible in pro gear where distortion is sometimes wanted, guitars. I say trust your ears more than what you read. 

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1 hour ago, henry4841 said:

No way do you want a class B amplifier. You will have terrible crossover distortion. With a properly biased A/B amplifier crossover distortion is for all practical purposes eliminated. With our speakers, being so efficient an A/B amplifier may not ever leave class A. Bias is the term you may not understand but if means if you bias, turn up, the transistor or tube as far as reasonably possible, where it will not destroy itself, it will stay in class A. Then you will have a PP class A amplifier in it's power rating. Nelson Pass wrote and articled years ago called "Leaving class A".  https://www.passlabs.com/technical_article/leaving-class-a/

 


 I agree with you. In addition to the title of the thread, we are now moving to the level of amplifier circuits. This is a very important step. The circuit is the most important basis for everything else. On the one hand, the differences in principle, whereby circuit concepts such as Class A or A/B can be optimised specifically in each case. The same applies to push pull vs. single ended. It also applies to the amount of feedback. And once you have agreed on a basic concept then it can matter which tube is best suited to which circuit concept. Not coincidentally, it is often the case that historically certain types of tubes fit very well to the respective favoured circuits of their era.
Only the overall package of circuit and tube type can be seriously judged.

And then there are these prejudices, Class A sounds better than Class A/B...do people believe that because Class A is "first class" and when a B appears it is only "second class"? Of course not. The designation is just a historical list of when something was invented. (and of course it describes a different circuit technology*).
Then there is the prejudice that negative feedback could be a poor remedy and that a "noble true" amp does not need that. 
Then there is the prejudice that push pull is impure and that you only need it as a "compromise" if you want more than 8 watts of power.

Of course, this is all complete nonsense. Captainbeefheart once plausibly explained that a 45 tube, for example, has a lot of "built-in" feedback due to its design and that this is one of the reasons why it sounds so good in a SET even if it has no feedback loop in the circuit. In the end, the overall package of the amp also has to be chosen for a certain a speaker regarding impedance and sensitivity. 

I would just like to repeat what I said in another post...give the amp a chance to be technically "right" and then subjective taste will kick in. And it should because the hobby is all about our enjoyment and fun.
But let's be careful when one concept is elevated above another on a level of marketing slogans.

I am only a layman but I would guess that I prefer a tube amp that was built from the ground up for one type of tube than one that can be reconfigured for three types of tubes, e.g. because the transformers are also tuned for one type at best and so is the feedback. 

 

*Very roughly simplified (because I don't know any better myself:) others may correct me… With Class A, the tube or transistor is constantly supplied with the greatest possible current energy, regardless of whether you need the energy completely at a certain point in time or not. Therefore the heat in a sand amp Class A. Class A "can" lead to more "serenity" and the positive feeling of „torque“ in the sound like a V8 engine which must not struggle to move the car. With Class B, the DC energy of the power supply is supplied depending on the energy demand, i.e. less DC energy is demanded from the power supply when the music is quiet. This means, however, that the power supply must be very well integrated into a circuit because with Class B it works in time with the music and no longer statically supplies maximum power as with Class A. The advantage of Class B is the much lower wear and the much lower power consumption. Class A/B is something like a combination of both worlds. Regarding quietly played music it runs always Class A and it delivers this relaxing and pleasantly smooth and distortion free fundamental frame. Only when playing loud (using horns very loud) the circuit switches so that in addition Class B comes into play. But the low SPL is always very Class A which is also important when a loud signal „appears“ from nothing. In other words the subtle parts of a loud instrument which can give the impression of distortion keep clean.

 
 

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47 minutes ago, TubesGlo said:

I also have a ST-70 along with two SS amps I have put on the shelf for backup if needed. I completely refreshed the ST-70 with a stock replacement 7199 driver board. I have 3 sets of strong testing RCA and Sylvania driver tubes. I used Takman carbon film resistors and CDE wmf series coupling caps on the board. I first listened with carbon comp and then metal film resistors. Yes they do influence the sound. The condition of the driver board, the components used and the driver tubes have a greater influence on the sound than the output tubes. Get that right first and then roll out EL34's, KT66 , KT77 and fat bottle 6CA7's and decide what sounds best in your system.

Give your ST-70 a fighting chance before investing in a completely different amp. When healthy with the right board configuration and tubes it is a very capable and sweet sounding amp. I use a tube preamp and my speakers are home built Cornwall clones at 100db sensitivity. Highs and mids are smooth, rich and detailed. Bass is clean, detailed and strong. BTW I have two strong testing sets of vintage Mullard xf2 power tubes. I couldn't be happier with my system....and won't spend thousands more chasing a unicorn.

 

I can underwrite what you say very much in every aspect. BTW which resistors do you like more, CC or MF types regarding your ST70? 

 

Edit: Sorry I reread your post, so now you are committed with CF types? So am I when I replaced some resistors in a pre amp I was in the end happy to use KOA SPR, also carbon film types.

To come back to this thread, it can really be the case that e.g. the choice of resistors makes a bigger difference than another power tube or another brand of a power tube.

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I've played with different types of resistors a little bit. I really could not tell a difference. Maybe on paper but not on my ears. Carbon resistors change value with time for sure where metal film are very stable on value. It's called splitting hairs. 

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1 minute ago, KT88 said:

I can underwrite what you say very much in every aspect. BTW which resistors do you like more, CC or MF types regarding your ST70?

In order of preference for best sound in my system: Carbon Film - Carbon Comp (when all are within spec) and lastly metal film.

I suppose it goes against conventional wisdom not to use metal film as they are technically more accurate and with tighter tolerance. In my experience and in my system, a high quality carbon film like Takman just sounds sweeter. After spending time with them in my amp I installed them in the signal path of my preamp.

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3 minutes ago, henry4841 said:

I've played with different types of resistors a little bit. I really could not tell a difference. Maybe on paper but not on my ears. Carbon resistors change value with time for sure where metal film are very stable on value. It's called splitting hairs. 

I completely understand your feelings on this. I'm usually very skeptical with circuit component changes but for me the CF's took a bit of sharpness and edge off the upper highs. All metal film in my tube circuits tilted the sound towards a more sterile and brighter presentation. Yes splitting hairs...but I personally prefer the CF.

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7 minutes ago, henry4841 said:

I've played with different types of resistors a little bit. I really could not tell a difference. Maybe on paper but not on my ears. Carbon resistors change value with time for sure where metal film are very stable on value. It's called splitting hairs. 

 

May be it depends also on the circuit. My old Quad amps 34 and 306 use carbon film resistors by the factory simply because it was cheaper 35 years ago. I had to replace some resistors to change the input sensitivity. I first used Vishay metal film types and I was really shocked how harsh the sound became, at least regarding this amps. Then I went back to carbon film and the full smoothness was immediately coming back. It may all depend on the kind of added distortion. Metal film types will measure „better“ and perhaps it is the added first and second harmonic distortion with the carbon film which pleases me.

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