Tube Amps Watts vs SS amp

In this particular case the 87 db spec is stated to be based on an input of 1 watt, rather than on an input of 2.83 volts. Also, as I mentioned in my previous post the brochure for the speaker states that an input of 8 watts results in an SPL of 96 db at 1 meter, which is consistent with 87 db/1 watt/1 meter. So if those numbers are accurate the efficiency is 87 db, rather than 84 db.

@almarg

Apparently it matters where you look. The specs I found stated 4 ohms and 87 dB Sensitivity; since the sensitivity spec is a voltage spec and not power, this translates to an efficiency as I stated. I’ve seen speaker manufacturers confuse efficiency and sensitivity before; is this one of those cases?

Under the power paradigm you want speakers of steady impedance and relatively high efficiency. How does Soundlabs achieve this with an electrostatic loudspeaker. My Acoustats drop perilously low at high frequencies.

@mijostyn Actually a steady impedance is not required of either paradigm. What is required is best put as the designer’s intention- and the behavior of the technology. In the case of ESLs, the impedance curve is based on a capacitance rather than a driver in a box (with its consequential resonance). On this account, ESLs have an impedance curve that essentially decreases as frequency increases. The Sound Lab for example is about 32 ohms in the bass but only 1.5-3.0 ohms (depending on the position of the Brilliance control) at 20KHz. The impedance curve of a box speaker maps out its efficiency with respect to frequency; with an ESL the efficiency remains constant despite its impedance.


One sign of a speaker that is a Power Paradigm device is that it will have controls in the crossover- like you see in the Sound Lab, but also like you see in vintage speakers like Altec, JBL, KLH and so on. These controls are not there to adjust the speaker to the room (although they are often used that way) they are there to adjust the speaker to the voltage response of the amplifier, which is an unknown. In the Voltage Paradigm the voltage response is a given; the idea was pioneered by MacIntosh and ElectroVoice in the late 1950s to assist with plug and play. The problem is to do so audible distortion in the form of brightness is usually introduced by the operation of the feedback loop in the amplifier, and one has to come to terms with the simple fact that no loudspeaker is actually flat in frequency response- so getting ’flat response’ is a bit of a red herring.


Add to that the fact that the ear/brain system interprets distortion as tonality (which is why we perceive the distortion added by feedback as brightness), often favoring it over actual frequency response, and you have a situation where you can often achieve greater neutrality without feedback. Crazy world, but we really can’t change how our ears perceive sound except by damaging them. So it seems pragmatic to come up with engineering solutions that take the human ear/brain hearing perceptual rules into account rather than ignoring them!

I would like to add,  compare a high power amp to a high horsepower car. Even at lower operating levels you can feel the power that is available. By this I mean it is much more responsive and effortless in its presentation.


ozzy

Atmasphere, I am certainly a believer in considering how the sensitivity of our ears changes with volume as were scientists long ago. Harvey Fletcher and Wilden Munson wrote their famous paper back in 1933. Loudness correction was a standard feature in preamps back in the day. The problem was that only one correction curve could be used which would only be accurate at one volume level. My processor uses a set of 6 curves pertaining to specific volume levels. The processor automatically blends from one curve to the next as volume increases, Dynamic loudness correction. The end result is that the music sounds the same regardless of volume. Bass and treble are automatically cut as volume increases. Under these circumstances I think distortion/clipping is more obvious as it stands apart from the high frequencies of the music. It also makes listening at high volumes magically comfortable. Violins and female voices do not cut your throat. The processor also does room control. IMHO the importance of room control is not in obtaining a flat frequency response as flat sounds terrible at most volume levels it is in obtaining exactly equal frequency response in both channels. The end result being laser imagining as frequencies don't shift between speakers. Any speaker's frequency response will change with position as well as two speakers of the same model will have slightly different frequency response. This technology is starting to become available in various iterations and I expect it will drift down to lower price points. None of the currently available units have dynamic loudness correction.

My understanding is that the concept of “bandwidth” is very important. Perhaps more important for tube amps than solid state. But I have a First Watt SIT-3 which is a low watt solid state amp. It apparently has some bandwidth to it because it drives my Magico A3s well. They have a sensitivity of 88dB, an impedance of 4 ohms and recommended minimum power of 50 watts. The SIT-3 drives them just as well as my Bryston 4B3, which has a lot more power. But what I would like to know from the group is: how is bandwidth measured? How do you calculate bandwidth? Thanks. 

I am driving 85 dB sensitivity speakers with 200 WPC of pure analogue tube power using 8 KT150s. I can drive these to 98dBA spl with little effort and NO clipping and more to go. It sounds better than the comparable powered SS amp that I replaced.


Rollin