Aric Audio 300B amplifier

[henry4841]

Glad to see you as well Aric Audio. Using 8 300B tubes and only getting 1.5watts confused me as well. In my SET 300B amp I believe I reached around 7 watts only biasing the tubes around 80%. 

 

By the way if anyone wants to check the 1 watt window with a scope to see if they exceed the 1 watt level it is easy to do. With a signal generator set it with a 1K signal at 2.83V's AC and adjust the scope where the sine wave is between two lines on the scope. Then without turning off the scope attach the scope to the back of the speaker and see when listening at a very loud level if the sine waves ever exceed the lines on the scope. I have never done the test myself believing Nelson knows what he is talking about using what I believe are Tannoy speakers rated at somewhere around 95db Nelson uses when testing his new designs for PassLabs and Firstwatt. At what most call too loud for conversation in his listening room. I trust he is telling the truth. I have done the simple test with a VOM at my speaker seeing if the signal ever reaches 2.83v's which is 1 watt. I only have seen a couple of volts myself on peaks at my listening level. Most of the time never seeing 1v ac let alone 2.83v's. Our speakers are fantastic only needing a few good clean watts. PWK said when tubes ruled 5 watts the sweet spot. Another giant in the audio field I consider who knew what he is talking about. When one is using only a few watts on peaks with our horns I see no need for wasting money on watts that will never be used buying an amplifier purely on their watt rating. More sounding better is a myth spread by manufactory's hyping their product to fool the masses. When one reaches another level in their audio journey they begin to cut through the hype and seek quality amplifiers rather than overhyped large watt ones. Called audiophiles, whatever that truly is. 

 

By the way I could be happy with just my Little Sweetie 1 watt amplifier designed by our own Maynard, tubefanatic, if need be. At the level I now listen at it is plenty enough. Great sounding little amp along with my diy built Zen clone with 2 watts. There are many on this forum praising the sound of that little Decware Zen. 

[Aric Audio]

Thanks henry4841 and Shakeydeal, much appreciated!

 

Hey, I'm a firm believer in whatever works for the individual. That's why there's SET amps, Push Pull amps, SS SE and PP, and class D, T, AB, etc. Same with why there's Harleys, Triumphs, Hondas, Kawasakis, and dozens of other brands of bikes. If one was "perfect", we'd all ride that one, but that's not the case as it's all subjective. Back when I was mostly building speakers in the late 90's my "Go to" was a QSC MX1500A which produced 500 watts RMS per channel @ 4 ohms, or 750 WPC @ 2 ohms. I would often drive my speakers until the clipping lights flickered, or sometimes stayed a steady red on the QSC amp- and that made me happy. Eventually I built a tube preamp and connected that to the frontend of the QSC and I thought that was "IT"- nothing could sound better. Well, it took quite a bit of the digital "edge" off of the leading hips of the notes and softened up a screaming singer (did I mention I listened to mostly metal and jam-band rock?). I was in the camp that tubes were my grandfather's tech and they were over priced and produced high distortion because I only READ about them and thought folks were crazy to buy a tube amp. Flash forward and there aren't many SS amps I can stand listening to, and yes my hearing is just fine. It's just a different presentation that satisfies me to where I don't need to listen at 105+ db unless I want to crank one song. Headroom is good too, but I honestly rarely need more than my 300B SET for my 97 db efficient speakers. When I do, I pop in my EL34 based Push Pull amplifier. Strangely enough, I had an SPL solid state 225 wpc here in house for a spell as I needed to tweak the balanced outs of my ML XL line-stage, and I was amazed how little power it seemed to have- clip lights were coming on, bass was decent- but didn't blow me away. Then I swapped in my Super 211 SET which produces around 30 watts per channel and the speakers suddenly sounded larger, more realistic and the soundstage opened up beyond the confines of my room. I didn't take my own word for it either, I had several other "untrained" music lovers come check it out. Each person thought the 211 SET had more power than the SPL amplifier. Why is this? I don't know for sure....there's lots of theory and papers on the subject, but they're all conjecture. All I can tell is sometimes there's more to a watt than a simple measure of power. Take that with a grain of salt too, but it's the best description I've got. 

 

Aric

Edited October 7, 2023 by Aric Audio

[henry4841]

Talking about 8 300B's producing just 1.5watts, Roger Modjeski at one of his lectures said one should expect 1/3rd power out from what you bias the tubes at. If not something is not right. 

[Aric Audio]

Absolutely. A single 300B can and will do 10 watts at relatively low distortion if you bias it in the linear part of its curves, and overcome grid current which occurs at around 5 watts. This is why I use an interstage transformer to avoid the time constant of a coupling cap. You can also use a cathode follower with a negative tail which would do double duty as a fixed bias method. 

Edited October 8, 2023 by Aric Audio