LETS COMPARE TUBE AND SS AMPS. TECHNICAL


I am seeking some very technically minded people to chat about differences in sound quality, dbs, and power ratings. I have not dived into this much yet but in my past study, I find that some SS amps are uniquely rated (lie about it). Maybe there is special "sound watt" used when comparing input fusing and wire size to rated output. When looking at tubes, their rating for power is much lower. 50-120wpc seems about right. However, I hear people say it comes down to "current" BUT, current and watts are directly related. Since the voltage or wave amplitude depends on the sound to be reproduced, it only makes sense that the only variable is the current, thus the wattage. I run a Rotel RB1080 on my RF-7s at 400wpc. I have to wonder the difference in dbs from a comparable tube amp.



Sure sounds like tube is way more expensive but can really give some nice sound. My experience with tube is only on guitar amps and I would not touch a SS guitar amp now!



Has someone compared tube with SS directly for dbs, accuracy, THD, etc??
viper6383

Showing 2 responses by marakanetz

First of all the Almighty set ALL watts to be equal to the product of Voltage and Current or physically Work per unit of Time.
The power P that is measured in Watts can be consuming and giving and the remaining power dissipates on heat.
Tube amplifiers and Class A SS amplifiers are only (approx)20% efficient since the remaining 80% of power goes onto heat.
The mentioned 'sonic watts' can be described as SPL that is measured in dB(usually guitar dudes know what it realy is). Decibel is a logarighmic relative value that compares no sound to the actual sound. SPL can be measured also at particular freequency and that's where all the Tube/SS confusion burried as the 'Holy Grail' for some folks arround here.
Normally tube output devices have very high output impedance and amplify voltage that suppose to be converted to current using the output transformer to satisfy nowdays speaker voice coils. Transformer is the device that converts variable electric field of an input coil into the variable magnetic field and the output coil has the induced electric field from the variable magnetic field. The input and output coils of the transformer are actually inductors that have variable impedance depending on frequency. As the frequency drops, the reactance is minimal and impedance of the inductor approaches actual resistance of the wire. In this case the voltage accross the input coil terminal becomes MINIMAL as well as magnetic field across the primary coil! Another words by nature there's hardly any lower-end extention and 'visible' spectrum of it is substantially less than corresponding SS amplifier. So placing 'in front of each other' 100W tube amp against 100W SS amp obviously SS will seem to sound more quiet, but if measured SPLs across the 'visible' frequency spectrum, SS will have it larger in both ends of a slope.
As to the speaker voice coils, lower frequencies should be hadled with much higher current than midrange.
In tube amp transformer would act rather as high-pass filter thus distributing a larger portion of an output power onto substantially smaller frequency range giving the 'illusion' of so called 'TUBE WATTS'.
Atmasphere, there's one important detail missing on your link mentioned by T_bone and which you perfectly might know as engineer is meaning of ideal source vs. non-ideal. It can also be explained in simple language to the public.

Tube or even transistor output devices can't be ideal by default: What device is closer to ideal source tube or transistor? The total impedance including impedance of the source should've been mentioned as part of the integrated source --> load circuit. There figures will come quite different especially in terms of current passing through the load.