Amplifier circuitry-4 ohm vs 8 ohm
Obviously there are different wires leading into the four or eight Ohm taps on the back of an amplifier from the one amplifier. The single amplifier at some point splits the signal going into either one of these Ports. What differences are there in the circuitry?
Maybe this will help me better understand the difference between these two taps. I believe 4 ohms is a wider more open path for voltage to flow. So when you're speaker attempts to go lower, which requires more power, the 4 ohm more easily allows this to happen with a better outcome. Or maybe I got this wrong.
@atmasphere -- I understand that OTL tube amps have been around for years, but they are their own thing, with specific design considerations and tube selection, typically needing multiple output tubes to get the needed current. You just don't take a tube amp with transformers and hot-wire around the output transformers. But, you already know all that! Many others don't. But, OTL amps weren't really the focus of this discussion. |
@emergingsoul In my experience, not very many! But I am playing a class D amp at home that has the same distortion spectra as you expect to see in a tube amp. It is at a lower level however. Most solid state amps look distinctly different when you look at their harmonic distortion. |
And there in lies the challenge. I believe tubes represent a more even profile of the harmonics, elevating the harmonics in the upper range better than solid state. So the richness of tubes and benefits of improved gain at lower levels makes them very attractive. However, powerful tube amplifiers generate a ton of heat and this is disappointing. It's like having a portable heater unit set to low continuously while you operate a tube amplifier, as I have learned. Unfortunately most of us don't live in a room with very high ceilings which would be a great place for heat to be accumulated without impacting the humans. Maybe A more efficient speaker would be more desirable when working with a tube amplifier that uses less watts. ie, Full benefit of tubes without all the heat. Hopefully I got all this right |
This is incorrect. Tube amps tend to make more the lower ordered harmonics, the 2nd and 3rd, which is the source of their 'richness'. These two harmonics are at a high enough level in tube amps that they are able to mask the higher ordered harmonics, which are heard otherwise (if not masked) as harshness and brightness. The class D amp I'm playing at home does exactly the same thing, and since the distortion signature of any amplifier is the way that amplifier sounds its not a surprise that this amp sounds exactly like a very good tube amplifier. |
I have ARC amps from 1995, 2018 and 2023, and they all have 16, 8 and 4 ohm taps. My ELS speakers impedance curve indicates about 30 ohms at 20Hz and 3 ohms at 20kHz. The 16 ohm taps sound excellent. The 8 ohm taps do too, but with a different balance and therefore dynamic. @emergingsoul: I doubt any two amps, especially a tube amp and a class D amp, sound "exactly like".... |
