Why tube phono stages? Because…no tubes, no magic!
When it comes to analog, I love designing tube phono stages! But why tubes? First of all, “No Tubes, No Magic”.
Tube simply provide tone, celebrate harmonics and produce sound that is organic and to my ears, sounds like music. By comparison, a SS phono stage sounds to me like the information has been processed, bleached, amplified and feedback so much, that quality of sound is lost. The amplified signal sounds sterile and lifeless to my ears.
I have always been very pleased with our phono creations. We began with the SWP 9.0SE (phono), the SWLP 9.0SE (Line phono), the PH 150 (phono) https://www.modwright.com/products/ph-150/ and most recently the PH 9.0/X/T https://www.modwright.com/products/ph-9-0-ph-9-0x-ph-9-0xt-tube-phono-stage/ series of tube phono stages. I also designed a tube phono upgrade board for the 6SN7 based LS 100 tube preamp https://www.modwright.com/products/ls-100-tube-preamp/. It offers amazing analog playback to an already sweet sounding tube preamp! All of these designs share similar circuit topologies, and all of which used tubes for voltage gain.
Many of you know that I speak both ‘tube’ and ‘transistor’. I like them both and they have their respective strengths. I do tend to prefer tubes in line level components, hence my history of tube mods in digital gear. I also tend to prefer transistors in power amps and power applications like this. But, I have used tubes in power amps and SS in line level applications. I have my preferences today, based on past experience.
The biggest reason for wanting to use SS in power applications, is because transistors amplify current, and tubes amplify voltage. Current translates directly to power in a system. Power is a product of the ‘square’ of the current with the impedance of the speaker. More power means A LOT more current is needed for products like our KWA 99 Mosfet monoblocks https://www.modwright.com/products/kwa-99-monoblocks/ and our soon to be released, KWA 300 Reference stereo power amp.
As for tubes in line level applications however, there is really no need for power. There is still current and voltage, the product of which IS power. But, because we are talking about Gain levels in source gear, we are really talking about voltage, not current.
Tubes allow for clean, elegant and simple circuits. SS designs are necessarily more complex and have a much higher parts count. This is not necessarily bad, but if we think about the path that the music signal has to travel, from the the needle to the phono output, it is VERY fragile. Any noise present is further amplified A LOT and there are many noise sources along the way, including interelectron interactions, etc. In short, I believe a simpler and shorter signal path is deal.
It is all of course a matter of personal preference and we all prefer different things. For phono stages and most line level applications, it will always be tubes. For power, I do like solid state for current amplification.
And remember… ”No tubes, no magic.”