Vfet / SIT Amplifiers

@sonetduo I love the idea of a SIT-based preamp! The problem here is the Yamaha is far too complex. When you're dealing with purist amps and speakers (and let's be clear here- people these days that insist on crossover-less single-driver speaker tend to be on the purist side of things) the least circuitry you can get away with (without making it **too** simple) usually the better. That Yamaha has its heart in the right place, but it has a lot of encumbrance. It would be really interesting to find out how it sounds with no tone controls or tone control switching, just done in a simple no-nonsense approach. 


Now as a designer, the idea that an amplifier needs to hit a certain power level to 'come alive' is disturbing. I have a VFET amp that was designed by Nelson Pass and it certainly does not behave that way. This makes me think that its the Yamaha that is why you are saying what you are. In looking at the preamp and its signal flow, apparently its equipped with a loudness control in addition to a volume control. Your description matches that of the loudness being improperly set. If this was my preamp I'd be cutting all that extraneous stuff out of it. Since that would ruin whatever collector value it has, it seems prudent to me to just go to the type of circuit that the SITs behave as anyway- triodes.

I love the idea of signal-level SITs; I wish they were commonly available.

@atmasphere 
I see some assumptions on your part which could probably come from a misunderstanding.

First off, I love the SIT-3 amp. Low volume, high volume, I love the amp all the way. What C-1 does, it allows SIT-3 to play louder (if and when needed), but SIT-3 does extremely well at even the lower levels. 
In short: at no point I voiced any dissatisfaction with SIT-3, but emphasized the synergy between the vfet pre and vfet amp.

About C-1: my unit is fully restored and with SIT-3 I use it with all tone controls defeated (including loudness). If you have not heard the line stage of a C-1, I wish you have the opportunity to do one day. I am also thinking that if you like tube preamps, you will be in for a pleasant surprise listening to a vfet preamp :) 
Tone controls in the C-1 come in handy with certain amplifiers, or to tune in the room. I did not find it necessary to use any of the tome controls with SIT-3.

About the simplicity of design: The simplicity of design can be argued back and forth. Designers have learned since the 70s and are able to simplify modern designs. Also, certain components are built better today then were built in the 70'. All that is true but also many things done in the 70' have been forgotten. 
In the case of Yamaha, most of the complexity comes in the form of circuit protection of sorts...quite crazy in the case of the B-1 for example, or tons of features in the C-1 pre, which at first glance is the anthesis of "wire-with'-gain".  Some features of the 70's amplifiers are probably there just because the marketing department wanted them to be there. Some of these features can be defeated or carefully bypassed. Additionally, after 40+ years of use, some of the original ancillary components are at the end of their functional life and can be substituted for better components built today, and one can use the 70's vfet amps the proper way ;) and ensure that it would ran for many more years to come.

Making a side note here: complex or not, these 70's amps run for 40+ years already. I giggle when I hear some manufacturers marketing claims related to 20 years warranty as if that would be of any relevance....yet you see many consumers basing their opinion of brand preference based on such irrelevance.

What is important in the end is what the amp sounds like and will the amp be around long enough for the owner to enjoy it. That is simply the ultimate test, right?

One could argue for instance, that SIT-3 has relatively high THD, right?
But if most of the harmonics are of the even kind and if overall the amp sound as good as it does, how important are the technicalities?
Same goes for the Yamaha or Sony amps...yes more stages, NFB, etc...but if the amp sounds good, why do technicalities matter?

As far as I know, there is no scientific proof or empirical evidence that just for being simple, it must also sound best. Since we are talking about Yamaha, one of their other statement pieces, the MX-10000, is one of the most revered amps of all times. Yet, it is one of the most complex designs I am aware of, has stupid low THD, but in the end, it sounds phenomenal and can pretty much drive any load speaker. 

I hope I was able to clear any misunderstanding. I am a fan of anything that sounds good to my ears, agnostic of how complex or simple it was built, in technical terms :) 





 

I hope I was able to clear any misunderstanding.

@sonetduo  You did- I realized reading this that I had conflated some of your comments with that of another poster. I was addressing his comments, not yours, but with the idea that he was running the Yamaha. In a nutshell, I blew it. Sorry about that.

That explains it!  I was confused.  It seemed like @atmasphere might be talking to me, but I wasn't sure.  I was jealous of the answer @sonetduo was getting!

No worries at all.
I am happy to see there is still so much interest in SIT/vfet amps.