Small Valve amps vs Big Valves amps

[Jozua_2019]

Hi

I have recently acquired a 75 watt valve amp to supplement a 150 watt valve amp. Both amps were made by Audio Research and basically follow the same design topology. The 75 watt unit has two KT150 valves per channel vs the four KT150 valves per channel in the 150 watt unit. The 150 has a larger power supply whereas the 75 watt unit has a smaller power supply than the 150watt amp but with the same power rating as the power supply used the 110 watt ARC amp that uses four KT120 valve per channel.

I also have a 35 watt Dynakit valve amp.

All three amps excel in driving my small ribbon speakers. In fact the 75 watt unit has power meters that seldom indicate more than 10 watt output.


150 watts provides:

1. More Dynamics- forceful - the amp controls the speakers- the music just pulls you in.
2. The LF is exceptional- no need for a sub.
3. Greater Emotional involvement in the music - this is the main difference that draws me to valves vs solid state.
4. Massive output transformers close to another.

75 watts provides

1. Exceptional finesse and transparency- it does not have the emotional involvement of the 150.
2. LF is good but not as deep as the 150 - slightly thinner sound compared to the 150.
3. Very sensitive to the stand used and isolation - weight is 50% less than the 150 unit. Placing the unit on rollerballs added significantly to sound quality.
4. Output transformers are smaller and wider spaced compared to the 150. I often wonder about cross contamination when output transformers are closely placed to another?

Dynakit = 35 watts

1. Very musical and enjoyable - the sonic signature is similar to the Synthesis valve amps - full bodied and enjoyable.
2. Very good bass- possibly a bit bloated compared to the 75
3. Midrange is full bodied but lacks the absolute spatial finesse of the 75.
4. EL34 valves compared to KT150 in the 75/150
5. (I am tempted to experiment with replacing the stock caps and signal wires with boutique replacements in the hope of optimizing the amp - for what it is with stock standard components, it truly offers exceptional value. Compared to other low powered valve amps, what makes the Dynakit so exceptional ?)

In essence- al three amps sound radically different - each one has it own magic. What I am looking for is the knowledge how to extract the best from each. The goal is not to have them sound identical.

I do realize that the above comments refer to subtle and subjective observations - I am looking for some guidance how to optimize the unknown key variables?


Questions for the valve and non valve experts and especially people who have experience with these products:

1. I am somewhat intrigued by why the two ARC amps sound so different? Could it be the ease of valve matching in the 75 that provides the finesse? Are we underestimating the importance of valve matching vs the risks of random tube rolling?
2. Isolation - are we underestimating the importance of vibration control with small amps? How often do you see a valve amp placed on a cupboard? Could the sheer weight of the 150 minimize the need for isolation?
3. When listening the meters seldom exceeds 10 watts output. That immediately raises the question why would the more powerful 150 be so much more emotionally more involving but lacking in finesse? Would HE speakers make a bigger difference with the 75?
4. Aka does the above suggest that a 250 watt valve amp will provide more overall satisfaction? The reviews seem to suggest it will although the current running cost makes this a no go option and;
5. Lastly - are there any known specific best practices to follow with these products, aka cables, isolation interconnects etc. versus the current experimental approach?

 

[juan]

 

[Ingvar Ahlberg]

 

[Jozua_2019]

 

[SeanS]

 

[marantz123]

 

[udwadia]

 

[udwadia]

 

[Baseline]

 

[mahleu]

 

[Jozua_2019]

 

[Air]

 

[handsome]

 

[marantz123]

 

[Jozua_2019]

 

[jerkyaudio]

 

[fredeb]

 

[Air]

 

[AlleyCat]

 

[Jozua_2019]