The Audio Gods are tough but fair-Have you had the "Curse of the 300B" ?
Thanks Charles, I wasn't aware of those. I know what you are really planning is to buy these 2 300Bs https://tubedepot.com/products/nos-western-electric-engraved-base-300b-black-plate-late-1930-s-match... |
I am a believer in the church of 300B. That said, I'm highly contemplating trading in my SETs for a push pull tube amp. I know full well I may go on to regret it...but I am at a place where I need more power 30-40% of the time, and I want to make the move to floorstanders. Nonetheless, 300bs have been a revelation, in what can be accomplished by modern stereo systems. I swapped out a McIntosh solid state integrated amp for the Allnic A-6000s, which with 300b xls tubes pump out 60 watts of SET glory. They make magic. If only we could have 200 watt 300b SETs...why oh why not!? |
If only we could have 200 watt 300b SETs...why oh why not!?Its the output transformer- with SETs its very difficult to get bandwidth as power is increased. This is true of push-pull too, but you don't run into problems until you have about an order of magnitude more power (+70 watts or so). What gives SETs a lot of that magic is the ultra low distortion at lower power levels. Most push pull amps can't do that- they have a minimum distortion at a certain low power level and below that power the distortion actually increases. It is possible to build a push pull amp that has a very low distortion signature at low power like an SET but to do that the amplifier must be fully differential from input to output. If the amp has a single-ended input combined with a phase splitter circuit its common to run into problems. |
The High End ndustry norm seems to be 85 to 88 db sensitivity and a 4 ohm nominal speaker impedance.Yeah- I don't get that. It doesn't matter what kind of amp you have, if you make it work hard its going to make more distortion, and with **any** amplifier tube or solid state the distortion is always higher driving 4 ohms as opposed to 8 or 16. Speaker cables are more critical on 4 ohms too. I always thought high end audio was about making the playback sound like it was real, but so often it sounds like being able to weld with your amplifier is more important. |
In the High End community/sector there are certain numbers often and proudly presented to presumably impress audiophiles. Very high amplifier output wattage Very high current (amperage) peak capacity Very low output impedance of amplifiers Very low THD i.e. 0.001range Very high damping factor i.e. 1000 and higher. When it comes to actual sound quality and listening to music I don’t believe that the above stated parameters are necessarily shown to be beneficial. Charles |
Charles, it took me years of listening and then making amps to learn what you lay out above. You are so correct. Would anyone believe that my NAD M22 amp provides less believable bass than my 300b or my Primaluna push pull? It tests with virtually no distortion too. There’s no meat on the bones compared to these others than measure poorly in comparison. |
For people with poor matching speakers who still want some of the 300b set magic, there's also the possibility of adding a "booster amp" such as the first watt F4. As outlined in the below 6moons review, you can drive this amp directly from the speaker outputs of your set. The set provides all voltage gain and the F4 provides the full current necessary to respond to difficult loads. Depending on setup, the set can simply see a perfect 8 or 16 ohm load and thus can be run with minimal distortion. Or, as I will probably do with my Coincident PRE's, if you've got bi-amp compatible speakers, you can use the f4 to take the bass load off your primary amp. Because it has zero gain and is being driven directly by the set, you do not get the normal coherence issues that come with bi-amping. It's no longer available from new from FW/Pass, but thanks to the generosity of Nelson Pass et al. you can build one yourself for under $1k... https://www.diyaudio.com/forums/pass-labs/234355-guide-building-pass-f4-amplifier.html https://6moons.com/audioreviews/firstwatt6/f4_3.html |
@cal3713 , This is very intriguing. I tried making sense of how to hook up the F4 and got a bit confused by the diagrams. I get that I'm running speaker wire from the SET output to the high level inputs on my loudspeakers. Am I running a duplicate speaker wire to the F4 and what am I hooking it up to on the F4? |
@jbhiller You’ve got to use some homebrew cables that are speaker level (spades, bare wire, or whatever) at one end and RCA at the other... use a multi-meter to check whether black or red is tied to ground at your SET output. That will then connect to the outer jacket of the RCA plug. The other wire will be your signal wire going to the RCA pin. If you’re driving only the F4 with your SET, you’ll also need to add a resistor across the SET’s outputs... probably somewhere between 8 and 16 ohms. When driving only the F4, your SET will essentially be unloaded, so you need to add some resistance to prevent damage to your tubes and transformers. Ideal resistance is whatever the SET was optimally designed to drive... and it should be easy to experiment to see if you get a cleaner signal when it’s seeing a particular load. If you’re using the F4 in a bi-amping setup, then you don’t need to worry about this aspect (as the SET will still be loaded by the midrange & tweeters). Note that Mark at RenoHiFi used to make these cables for customers, so perhaps you could pitch him to buy a pair if you don’t feel comfortable building your own. Also, I had some trouble decoding this from the writing, but all the quotes you see in the 6moons article are directly from Nelson Pass. I think he’d probably provide a bit of input too if you wanted to get it directly from the source. Unfortunately I haven’t yet implemented any of this, so it’s all still theoretical on my end. |
