Questions on Power Amplifiers

[kratu]

My current system comprises of Acoustic Portrait Bookshelf speakers driven by Lyrita GM70 and Lync Pre. The speakers have a sensitivity of 89dB, impedance of 8ohms and recommenced wattage of 40-200w.

The power amplifier has output power of 20 watts. That’s around 20 watts less than recommended. I’m looking for a higher power amplifier to drive it well. At the moment, the low frequencies lack precision and attack.

I’m a low volume listener and listen to soft music; ambient and meditative kind. And that requires reproduction of finer nuances of sounds (micro-dynamics). I like large soundstage with expansive, fluid mids. Not to mention the warm, lush sound of a tubes.

Some noob questions:

What is the recommended wattage for the power amplifier considering my preferences?

Does higher wattage mean better SQ? What are the pros and cons of higher wattage?

How does one go about choosing a power amplifier? What factors need to be considered to short list them?

I’m planing to combine a SS power with a tube pre. What are the factors I need to consider (input sensitivity, gain)

 

[raghupb]

If considering SS amp look for something in the range of 50-100 W.
More watts does not translate into better SQ.
The assumption is higher the max wattage the first few watts are cleaner, leaving the rest as headroom.
Choose a design that can source high current; usually means big transformer in case of class A or AB designs.

Input sensitivity for most SS power amps these days is between 0.7V - 1.5V
Input impedance is important, it should be high enough so that it does not present itself as a load to the preamp.
Choose something that is 33K or 47K if retaining the Lyrita.
Gain is usually not a factor; even low gain amps (20-24dB) will work well.
Some amps have gain of 28-32dB. Higher gain amps also amplify noise; so some designs choose to be low gain implementations.

AP has an affordable SS power amp in their Swara line up. You may want to check it out.
Cheers,
Raghu

 

[prem]

Get the Lyrita GM 70 monoblocs frim Viren. That’s 35 watts per channel and better sounding than his 20 w stereo amp

Stick with tubes. Other options, if you have the budget, could be a Lyric or a Conrad Johnson or a VTL integrated/power amp

 

[kratu]

If considering SS amp look for something in the range of 50-100 W.
More watts does not translate into better SQ.
The assumption is higher the max wattage the first few watts are cleaner, leaving the rest as headroom.
Choose a design that can source high current; usually means big transformer in case of class A or AB designs.

Input sensitivity for most SS power amps these days is between 0.7V - 1.5V
Input impedance is important, it should be high enough so that it does not present itself as a load to the preamp.
Choose something that is 33K or 47K if retaining the Lyrita.
Gain is usually not a factor; even low gain amps (20-24dB) will work well.
Some amps have gain of 28-32dB. Higher gain amps also amplify noise; so some designs choose to be low gain implementations.

AP has an affordable SS power amp in their Swara line up. You may want to check it out.
Cheers,
Raghu

Thanks Raghu. Those are important metrics that I wanted to know. Especially the gain needs to be considered. Yes, I'm considering the Swara power amp. The audition is scheduled for this weekend.

I see that you have listed the Aksa power. How is it as far as the sound signature goes? Does it retain the tube warmth and just add the power? One of the FMs Jaibir offered to try it out.

 

[kratu]

Get the Lyrita GM 70 monoblocs frim Viren. That’s 35 watts per channel and better sounding than his 20 w stereo amp

Stick with tubes. Other options, if you have the budget, could be a Lyric or a Conrad Johnson or a VTL integrated/power amp

Thanks Prem. I've heard of GM70 mono blocks. I'm sure they would be better sounding. Yes, sticking to tubes makes sense. It would be hard to let go of the warm, lush sound signature.

It just the lower section of the frequency could be faster and precise. I'd like to try the tube pre + SS power route. Ideally, I would want the best from both the worlds. It is tricky get the amp that retains the tube warmth and yet adds that precision across the frequency range.

 

[raghupb]

Thanks Raghu. Those are important metrics that I wanted to know. Especially the gain needs to be considered. Yes, I'm considering the Swara power amp. The audition is scheduled for this weekend.

I see that you have listed the Aksa power. How is it as far as the sound signature goes? Does it retain the tube warmth and just add the power? One of the FMs Jaibir offered to try it out.

Yes, I picked up the combo from Jaibir. I am a noob when it comes to tubes.
I always wanted to try tubes and this combo literally landed at my place.
Good stuff, so decided to keep it, even though I have other components.

The AKSA amp has clean power delivery. The dynamics and depth of sound are something to be appreciated.
Actually, the AKSA by itself brings in a bit of that lusciousness. It is rated at 55W, but feels like its much more.
Paired with Lyrita DHT, I don't think it robs the tube goodness. I've read that 4P1L's are quite lively, no way "honey-dipped".
The only issue is the volume control usable range is very narrow. Something to do with it couple at output stage as per Jaibir.
Anyways it doesn't bother me as I am the only one at home who uses this chain.

Cheers,
Raghu

 

[kratu]

Yes, I picked up the combo from Jaibir. I am a noob when it comes to tubes.
I always wanted to try tubes and this combo literally landed at my place.
Good stuff, so decided to keep it, even though I have other components.

The AKSA amp has clean power delivery. The dynamics and depth of sound are something to be appreciated.
Actually, the AKSA by itself brings in a bit of that lusciousness. It is rated at 55W, but feels like its much more.
Paired with Lyrita DHT, I don't think it robs the tube goodness. I've read that 4P1L's are quite lively, no way "honey-dipped".
The only issue is the volume control usable range is very narrow. Something to do with it couple at output stage as per Jaibir.
Anyways it doesn't bother me as I am the only one at home who uses this chain.

Cheers,
Raghu

Thanks for sharing your view. As a low-volume listener who likes sweet sound devoid of sibilance or fatiguing sound, I personally prefer that the volume is at the narrow area.

I guess for my taste 55W is a sweet spot. Do you think it matches the parameters like input sensitivity, gain with the DHT? What makes them pair well, objectively?

 

[jai1611]

Have you tried any other amps with your speakers? That would be the first step to determine if the issue you are facing is amp related or not

The Aksa is a great amp. Unfortunately not a truly commercial product and only really sold in Australia

 

[raghupb]

Thanks for sharing your view. As a low-volume listener who likes sweet sound devoid of sibilance or fatiguing sound, I personally prefer that the volume is at the narrow area.

I guess for my taste 55W is a sweet spot. Do you think it matches the parameters like input sensitivity, gain with the DHT? What makes them pair well, objectively?

Oh ... It is not low volume by any stretch of imagination. It is just that the range of the knob turn is very narrow.
I usually set it a tad bit loud and control volume on my phone; my primary source is streaming.
It may be similar on the Lync pre too, don't know.
There is no sibilance or fatigue; definitely a plus when it comes to extended listening.

Lyrita literature says the gain on preamp is 12dB. So power amp input sensitivity match is not an issue.
Though I don't know the number on AKSA.

There is a faint hum when music is not playing; I can hear this when I put my ear against the woofer.
It does not impact the listening experience when content is flowing through or at listening position.
In my conversation with Mr. Viren Bakshi, he assured me that it is normal and nothing to worry about.

And volume control is coupled at output, as per @jai1611. Z-out is 1250 ohms but is said to be higher at times.
AKSA has a Z-in of 47K, so this is not an issue. As per my research, AKSA has 32dB gain; so yes high gain amp.

In terms of power, AKSA at stated 55W beats 200/300W, 70/100W, 90/150W (8/4 ohm) amps I am familiar with.
So much for the "more watts" theory. I don't know what AKSA is capable of at 4 ohms.
My speakers are 8 ohm nominal and 3.2 ohm minimum. Don't hear the amp complain.

Cheers,
Raghu

 

[kratu]

Have you tried any other amps with your speakers? That would be the first step to determine if the issue you are facing is amp related or not

The Aksa is a great amp. Unfortunately not a truly commercial product and only really sold in Australia

As of now, I haven't tried yet. I'm hoping to try AP Swara power amp.

 

[kratu]

Oh ... It is not low volume by any stretch of imagination. It is just that the range of the knob turn is very narrow.
I usually set it a tad bit loud and control volume on my phone; my primary source is streaming.
It may be similar on the Lync pre too, don't know.
There is no sibilance or fatigue; definitely a plus when it comes to extended listening.

Lyrita literature says the gain on preamp is 12dB. So power amp input sensitivity match is not an issue.
Though I don't know the number on AKSA.

There is a faint hum when music is not playing; I can hear this when I put my ear against the woofer.
It does not impact the listening experience when content is flowing through or at listening position.
In my conversation with Mr. Viren Bakshi, he assured me that it is normal and nothing to worry about.

And volume control is coupled at output, as per @jai1611. Z-out is 1250 ohms but is said to be higher at times.
AKSA has a Z-in of 47K, so this is not an issue. As per my research, AKSA has 32dB gain; so yes high gain amp.

In terms of power, AKSA at stated 55W beats 200/300W, 70/100W, 90/150W (8/4 ohm) amps I am familiar with.
So much for the "more watts" theory. I don't know what AKSA is capable of at 4 ohms.
My speakers are 8 ohm nominal and 3.2 ohm minimum. Don't hear the amp complain.

Cheers,
Raghu

Thank you very much.

I definitely agree that input/output gain matching could be important.

I've a headphone amp with adjustable gains meant to work with headphones with varying impedance. I found that lower gain tends to be sweet sounding and works well for quiet music. However, it lacks the muscle, when it comes to music with complex passages or fast transitions. The higher gain tends to have more muscle and energy. On the flip side, it lacks that sweetness mentioned earlier. Does this sound similar to what you've experienced? Having that perfect balance is important.

Considering that two amps are similar to each other except for the wattage, how do they differ sonically?

By any chance do you know of power amps that could work well in my case? Something on the lines of AKSA?

 

[raghupb]

Thank you very much.

I definitely agree that input/output gain matching could be important.

I've a headphone amp with adjustable gains meant to work with headphones with varying impedance. I found that lower gain tends to be sweet sounding and works well for quiet music. However, it lacks the muscle, when it comes to music with complex passages or fast transitions. The higher gain tends to have more muscle and energy. On the flip side, it lacks that sweetness mentioned earlier. Does this sound similar to what you've experienced? Having that perfect balance is important.

Considering that two amps are similar to each other except for the wattage, how do they differ sonically?

By any chance do you know of power amps that could work well in my case? Something on the lines of AKSA?

I do have an amp with gain control (Parasound); Have not experimented though. When you visit we can try.
In my rig, I feel the Parasound chain is very clean, easy going, laid back; great for background listening or long sessions.
The tube/SS is actually more of a "lively" combo; there is a certain fun factor at play here (can't exactly describe it though).
I use a sub-woofer/sub-bass unit from REL too, in the chain.

In terms of sonics, everyone looks for different things. Some of them are:
- Depth of sound, height of stage
- Separation, imaging and centering, though centering is more a speaker function
- Bass response (very room dependent); oomph factor
- Mids/Vocals; lush/lusciousness
- HF sparkle (or not); airiness
- Cohesiveness/balance; does one particular frequency range sound over or under whelming.
- Speed, dynamics, low volume listening, etc

In my limited experience, no single amp or component can get all of this right.
If the system can get close to ticking most of them, then it will be an enjoyable one.

The AKSA came home with the tube preamp. So don't what it would cost; never thought about, to be honest.
It has something different compared to many commercial amps/models I've heard.

Cheers,
Raghu

 

[kratu]

I do have an amp with gain control (Parasound); Have not experimented though. When you visit we can try.
In my rig, I feel the Parasound chain is very clean, easy going, laid back; great for background listening or long sessions.
The tube/SS is actually more of a "lively" combo; there is a certain fun factor at play here (can't exactly describe it though).
I use a sub-woofer/sub-bass unit from REL too, in the chain.

In terms of sonics, everyone looks for different things. Some of them are:
- Depth of sound, height of stage
- Separation, imaging and centering, though centering is more a speaker function
- Bass response (very room dependent); oomph factor
- Mids/Vocals; lush/lusciousness
- HF sparkle (or not); airiness
- Cohesiveness/balance; does one particular frequency range sound over or under whelming.
- Speed, dynamics, low volume listening, etc

In my limited experience, no single amp or component can get all of this right.
If the system can get close to ticking most of them, then it will be an enjoyable one.

The AKSA came home with the tube preamp. So don't what it would cost; never thought about, to be honest.
It has something different compared to many commercial amps/models I've heard.

Cheers,
Raghu

Sure, I agree that getting everything right would be a challenge (and very expensive at that). Perhaps, one can try two systems alternatively based on the need or the genre of music.

 

[raghupb]

Sure, I agree that getting everything right would be a challenge (and very expensive at that). Perhaps, one can try two systems alternatively based on the need or the genre of music.

Oh ... I'd warn you against it . I started with the goal of simplifying my system and ended up with 2 audio chains.
Cheers,
Raghu