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EL34, 300B and the KT150 sound differences


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Sorry for kidnapping your thread again, Flevoman. It is not meant so. It shows only that many different parts can influence the sound beside the choice of tubes.

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1 minute ago, KT88 said:

 

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.

I believe any changes made to the original components in a 60 year old circuit be they resistors or capacitors when in the signal path, can and do influence the sound. CC resistors when in spec are going to sound different than metal film...maybe very noticeable, maybe not so much. Depends on your equipment and your ears. For me, I've settled on carbon film for my tube gear. I wouldn't tear into a new solid state amp and change out original metal films though, just for the hell of it.

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2 hours ago, henry4841 said:

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. 

This is what they say on the official Melody site :

 

"The Melody DPM80 integrated tube amplifier is the power house in our mid-range amplifiers. This tube amp offers an output power of 2x 75 watts strong Class B amplification. The DPM80 is our mid-range integrated amp and for this price range you can expect quite a punch. The amp is as such made for music lovers who love a tight bass."
 

Or do I misunderstand things now 

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1 hour ago, KT88 said:

Sorry for kidnapping your thread again, Flevoman. It is not meant so. It shows only that many different parts can influence the sound beside the choice of tubes.

Np at all.. For me, everything is interesting information. 

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51 minutes ago, Flevoman said:

This is what they say on the official Melody site :

 

"The Melody DPM80 integrated tube amplifier is the power house in our mid-range amplifiers. This tube amp offers an output power of 2x 75 watts strong Class B amplification. The DPM80 is our mid-range integrated amp and for this price range you can expect quite a punch. The amp is as such made for music lovers who love a tight bass."
 

Or do I misunderstand things now 

First one for me. Possible a language problem in translation but if not they have somehow solved the problem class B has with crossover distortion. If true I would be reluctant to purchase myself. An amplifier I used for decades went into class B at high power levels but it was mainly produced for pro applications. The Crown DC300a. 

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7 hours ago, henry4841 said:

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. 

 

 

McIntosh made a lot of class B amps and you can't say they're bad 😉

 

 

 

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2 minutes ago, mustang_flht said:

 

 

McIntosh made a lot of class B amps and you can't say they're bad 😉

 

 

 

Learn something new every day. Hard to figure out why when all one has to do is bias the output devices up a touch. The engineers at Mc know what they are doing. Must be the same with the Chinese built Melody's. 

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☺️👍

 

Example and Explications the MC2255 :

 

http://www.hifi-classic.net/review/mcintosh-mc2255-284.html

 

The output stages of the MC 2255 operate in class-B, but a unique biasing system completely eliminates the crossover distortion usually associated with class-B operation. This being the most efficient mode of linear amplifier operation, the total power consumption of the MC 2255 from the 120-volt a.c. line is only 0.7 ampere at idle (or normal playing volume) and 12 amperes at full output. The input and driver stages form a complete class-AB low-power amplifier which drives the front-panel headphone jack as well as the power stages. Switches connect the input sections for mono operation. In the mono/parallel mode the right-channel input drives both output sections in phase, and for the mono bridge mode the other input section is used as a phase inverter so that the outputs can be driven 180 degrees out of phase.

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2 hours ago, mustang_flht said:

☺️👍

 

Example and Explications the MC2255 :

 

http://www.hifi-classic.net/review/mcintosh-mc2255-284.html

 

The output stages of the MC 2255 operate in class-B, but a unique biasing system completely eliminates the crossover distortion usually associated with class-B operation. This being the most efficient mode of linear amplifier operation, the total power consumption of the MC 2255 from the 120-volt a.c. line is only 0.7 ampere at idle (or normal playing volume) and 12 amperes at full output. The input and driver stages form a complete class-AB low-power amplifier which drives the front-panel headphone jack as well as the power stages. Switches connect the input sections for mono operation. In the mono/parallel mode the right-channel input drives both output sections in phase, and for the mono bridge mode the other input section is used as a phase inverter so that the outputs can be driven 180 degrees out of phase.

I do not understand why they would design a class B amplifier or what the advantage of doing so would be. Above my pay grade. 

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17 hours ago, mustang_flht said:

☺️👍

 

Example and Explications the MC2255 :

 

http://www.hifi-classic.net/review/mcintosh-mc2255-284.html

 

The output stages of the MC 2255 operate in class-B, but a unique biasing system completely eliminates the crossover distortion usually associated with class-B operation. This being the most efficient mode of linear amplifier operation, the total power consumption of the MC 2255 from the 120-volt a.c. line is only 0.7 ampere at idle (or normal playing volume) and 12 amperes at full output. The input and driver stages form a complete class-AB low-power amplifier which drives the front-panel headphone jack as well as the power stages. Switches connect the input sections for mono operation. In the mono/parallel mode the right-channel input drives both output sections in phase, and for the mono bridge mode the other input section is used as a phase inverter so that the outputs can be driven 180 degrees out of phase.

I just found out the MC 2255 is a 40 year old amplifier that was sold only for a couple of years. There are always exceptions to every rule when it comes to electronics. Marketing and selling a class B amplifier to audiophiles was a hard sale even for McIntosh. I am sure it was is a fine sounding amplifier but why when an A/B is so much easier to design. I would never pay good money for a class B amplifier just because of how it operates. 

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No ! For 2255 it was an example, there were many other class B at McIntosh: power advantage, low consumption and cold amp!

 

Even their valve classics MC60, MC225, MC275 ... were class B, many of their modern ones are still with this class B

 

their Solid State are also class B, old or modern: MC2505, 2255, 2125 .... MC7270 ... MC501 ...

 

😜

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19 hours ago, mustang_flht said:

No ! For 2255 it was an example, there were many other class B at McIntosh: power advantage, low consumption and cold amp!

 

Even their valve classics MC60, MC225, MC275 ... were class B, many of their modern ones are still with this class B

 

their Solid State are also class B, old or modern: MC2505, 2255, 2125 .... MC7270 ... MC501 ...

 

😜

Again, there are always exceptions to every rule when it comes to electronics and members here are quick to point them out. It is what happens on social media forums. Still not common on consumer electronic amplifiers. Class B was dropped decades ago by most designers considering A/B the better and simpler way to design amplifiers. All I can say about McIntosh is good for them. 

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For those that do not understand or really care to know the differences in the classes of amplifiers being discussed here a very simple explanation is in class B operation the transistors cut off and on when amplifying the positive and negative portions of the audio signal. There will have to be other components added to manipulate the signal to not have what is called crossover distortion inherent in class B operation. In class A the transistors are operated full on never cutting off and on or slowing down not needing other components to defeat the associated crossover distortion. Many consider less components as better as I do. This is the reason class A is considered the most linear of all the classes of amplification and engineers like Nelson Pass have devoted his life to class A. The exception to every rule comes into play again with this statement about Nelson Pass. He has designed other classes as well but his main function has and is class A operation. 

 

All this does not really matter if an engineer can make and sell a product that sounds good enough to make a profit no matter how he achieves it. Personally I would hesitate buying an amplifier I know to be class B no matter who makes it. It just does not taste good to me knowing it is being operated in class B no matter who makes it when there are many others to choose from. But this is just me. I use to snub my nose up on class A/B until I built the diyaudio product called the Honey Badger which has many components and is operated in class A/B designed by everyone in a joint effort by members from all over the world. In class A/B the transistors are biased up where they never cut off and on but are not run full on either. Outstanding sounding amplifier. But I still listen mostly with my many class A amplifiers both tube and SS. 

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  • 3 weeks later...

I don’t think I saw the KT120s mentioned, so thought I’d throw in for consideration.

 

I haven’t heard the 300s or the 150s, but have tried various EL34s, KT88s and now KT120s in my PrimaLuna.

 

The 120s are more dynamic but smoother than the 88s with a bit of that EL34 mid range magic.  They punch lower and cleaner too.  I very rarely use my sub with my Cornwall IV when listening to music.  

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  • 2 weeks later...
On 5/19/2022 at 3:01 PM, henry4841 said:

I am at the opposite of KT88 when it comes to tone controls. Have not had or used in a decade or more. It takes a lot of effort adjusting your speakers to your room but when done correctly tone controls are just another form of signal manipulation. More components in the audio signal path. It does take a lot of effort, time and expense to conform your room to your speakers. I am the camp of less is better. I have multiple amplifiers and preamps. None with tone controls. The one I use the most is a simple buffer with no amplification. The Nelson Pass B1v2. 

 

Pass B-1 does sound good, sounds delicious loud. Surprisingly, reminds me of the FET-10 phono preamp I had years ago.Who designed the Fet-10? Yeah Nelson Pass.

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