are class a amps really that much better in terms of sq?

[nology 0]

Here's my dilema... I've got a few soundstream class a amps all of which are 2 channel amps with a seperate gain for each channel. I recently picked up a rubicon 555 5 channel amp and could use the 4 channels to run my front actively. I've got a class a 6.0 going to my fronts now. Would I really be able to tell the difference??? This is just for personal use and not competition.

[Adrian_D 520]

IIRC, pure class A amps are very very inefficient. Me thinks diffrences between pure class A and AB aren't worth thinking about. Again, IIRC, AB's work in 2 stages : on low levels they work as a class A (inefficient) and as you increase the level they work as a class B.

I'm not sure those Soundstreams are actually pure class A.

[nology 0]

They would only be running @ 4 ohms. Except for the 10.0 which be running a sub @ either 2 or 1 ohm.

[JimJ 11]

I love mine

In a vehicle, though...the inefficiency is going to be killer on the electrical system.

[Adrian_D 520]

I love mine

In a vehicle, though...the inefficiency is going to be killer on the electrical system.

Tubes shouldn't count

[nology 0]

It shouldn't be that ineficient if I'm running the amp @ 4 ohms though right? The 10.0 might not even go in my car. I plan on running a svc 4 ohm exact 12 so I will probably end up using a reference amp on that.

[audio-neon 34]

You will most likely only notice that your class A amps are substantially hotter than your class D amps.

[JimJ 11]

It shouldn't be that ineficient if I'm running the amp @ 4 ohms though right?

Inefficiency is inefficiency no matter what impedance you're talking about.

If it's a true class A, 25% efficiency is the absolute maximum it's ever going to get to. I don't know if those SS amps are true class A's, will leave that for someone who knows those amps better...

[nology 0]

Class d? the only amps I own are the pre-sellout soundstream amps.

[shizzzon 461]

25%!! Wow!, that's hella inefficient.

Off of 13.8v, to output 300w at 85% efficiency(class d typical @4ohm), power draw would be 25.58A of current.

Off of 13.8v, to output 300w at 20% efficiency(class a example), power draw would be 108.7A !!!!!

With 109A of draw on class d amp at 85% efficiency, you could output - 1270w+!

That's a big difference!

[nology 0]

If these amps are so inefficient what makes them hold their value? I've seen some of these class A soundstream amps go for insane $$$

[JimJ 11]

If these amps are so inefficient what makes them hold their value? I've seen some of these class A soundstream amps go for insane $$$

Inefficiency is not in itself a bad thing, just something that has to be taken into consideration...

More power is not always needed, the relatively low power output of a Class A amp wouldn't matter for something like an Image Dynamics HLCD because you simply don't need that much power on them anyway

[Tirefryr 1,742]

The Soundstream Class A amps are not what their name implies. They are A/B amps.

[audio-neon 34]

If these amps are so inefficient what makes them hold their value? I've seen some of these class A soundstream amps go for insane $$$

Inefficiency is not in itself a bad thing, just something that has to be taken into consideration...

More power is not always needed, the relatively low power output of a Class A amp wouldn't matter for something like an Image Dynamics HLCD because you simply don't need that much power on them anyway

Can you say ear piercing loudness with 12-14 watts per hlcd.

They are truly amazing.

[nology 0]

hmm.. Maybe I'll just try a few different setups and see what works. I'm putting in some polk mm465s and A/D/S 335ims in the car.. I'm losing my mind trying to set this car up.

[sqguy 0]

They just work in A at low volumes, like most class AB do. I doubt you (or me) could tell the difference from a pre buy SS to another far as quality. They might have used other higher quality parts inside not sure, or even colored it a little different, the right tech would know. Class A is marketing in cars, you just can't do much power at all in pure class A. They say some day all car amps will be class D/T/etc.

[///M5 2,833]

Meh, in particular in a moving car I am on Richard Clark's side. An amp is an amp, if you are hearing a difference you will also be susceptible to all sorts of other placebo effects.

**please do not translate this into go ahead buy a piece of crap as they can introduce noise, fail, and don't do what they are supposed to.

[todd.brust 29]

Meh, in particular in a moving car I am on Richard Clark's side. An amp is an amp, if you are hearing a difference you will also be susceptible to all sorts of other placebo effects.

**please do not translate this into go ahead buy a piece of crap as they can introduce noise, fail, and don't do what they are supposed to.

I'll Agree with that(from my personal experiences, read below though) I would think that the speakers being used and the installation are going to have more influence on how the audio sounds rather than the amplifiers.

But then again I don't know. I have had a number of car audio amps on the same speakers and never heard a noticeable difference. And that's the way it is in car audio. But Home stuff is completely different. There are all kinds of people who swear that tube amps sound better(regardless of some of their higher THD when compared to SS) than any solid state(one of the reasons I decided to restore my own tube amp) and then there are the people who say there are not an audible difference between solid state and tubes.

This whole thing is completely debatable. I can see where both sides are coming from. Class A are truly linear amplifiers meaning that the transistors or amplifying devices are conducting for the full 360 degrees of a sine wave whereas a Class AB conducts for half that and is susceptible to crossover distortion. Some people think that the more linear the sound is the more natural it is in comparison to lets say someone actually playing an instrument right in front of you. But the crossover distortion is so low in commercial amplifiers that i don't think it is possible to hear and audible difference. When Class D amps can send high and low pulses to make a sine wave with THDs as low as .001%, I find it hard to believe that a truly linear amplifier will sound that much different when compared to any other well designed class AB or D.

When comparing THD numbers they can both have good and bad ratings. Now this has gotten me thinking. I want to hear Class A vs. AB. vs. D with the same THD ratings. I would be surprised to hear any difference.

I'd like to hear more opinions on this topic. And to elaborate a little more, Tubes vs. Solid State. JimJ, I know you're a big tube guy. I saw some of your old posts on ForceAudio. What's your take on Tubes vs. SS? Why do people prefer one to another?

Enough with this ramble. I'm going to get some food and head to bed hopefully. Early class tomorrow

[///M5 2,833]

You did note the beginning of my post....the noisefloor of the moving car will be way higher than any of the amps. And considering SQ has way more to do with installation and eq settings that is where the difference will be anyways. From a mobile audio standpoint there will be no discernible difference.

[todd.brust 29]

Yes i did see it but then I started to think in generalities. (My mind wanders because of a little thing call ADHD, oh sweet, Prigles) I have never really listened to a specific amplifier vs another amplifier with differing topology in similar listening conditions just to compare the sound.

Still interested.

[helotaxi 46]

The SS "Class A" amps were actually fairly efficient as they approached full power. They were not Class A amps, but were rather fairly high-biased Class A/B amps with a Class A input stage. What they were was amazingly quiet (CSR measured s/n of 90dB ref 1 watt IIRC and that was just on one of the Reference line, not the Class A line which used tighter tolerance components.).

[Adrian_D 520]

Meh, in particular in a moving car I am on Richard Clark's side. An amp is an amp, if you are hearing a difference you will also be susceptible to all sorts of other placebo effects.

[creyc 1]

It's funny, I always figured a record player would be the ultimate source unit in a car, since the noise floor of the car environment more closely matches that of a turntable.

I personally am at odds with "car" and "sq or hi-fi" in the same sentence. Everything about the car environment, from road noise to bumps to big flat plates of glass and other resonant surfaces just screams out that I'm wasting my time trying to achieve truly amazing sound.

Now I'm of the opinion "just get it close". Save some money, a lot of time and headache and focus on things which will truly make the most difference in a car, the install.

[JimJ 11]

I always figured a record player would be the ultimate source unit in a car, since the noise floor of the car environment more closely matches that of a turntable.

If you're talking about a moving car, I'd say that's one broken turntable/phono stage

Phono preamps aren't that bad

[creyc 1]

Well, there are a few setbacks we would need to solve first, of course Jim!