I am all for lush.  I'm far from an orthodox audiophile.  The whole notion of what the artist intended strikes me a mythological and unobtainable unless you have the same equipment and room as the artist, as well as the artist in house to explain whether or not the final cut was how they wanted it.  That's a whole lot of variables making such a thing impossible.

I have no issue with EQ's and love the ZRock2.

That said, I do wonder how an EQ setting being hardwired into an amp will be received by the greater audiophile community.  A community that has long condemned EQ's.  Even though the 1:15 setting has the gain and EQ below what can be heard, it still must be doing something to contribute to the lushness otherwise Steve would not be characterizing it as such.  Calling it a ZRock2 built in certainly characterizes it as an EQ.

I'm personally all for it.  I want things to sound good to me and honestly don't give a hoot what the artist intended.  But perhaps to satisfy the overwhelmingly prevailing audiophile orthodoxy, a bypass switch for the embedded ZR2 might be a good idea.  If nothing else, it will clearly demonstrate how much better it sounds with than without.  But also gives the prevailing ideology of "no EQ's" an option to satisfy their dogma to keep it "pure".

Lon, well, I certainly don't need them!  But if I were an amp company, I'd certainly take their concerns to heart as they represent the vast majority of audiophiles.

I'm not technically knowledge enough to know the difference between an EQ and a driver stage with gain.  But I do know my ABC's and my figures enough to know that Steve called it a ZRock2 built in, only without the ability to adjust.  And a ZRock2 is an EQ.  

The ZRock2 itself seems to take this into account with the presence of a bypass switch.  Just thinking, in my folksy fresh off the turnip truck way, that maybe a bypass switch on the 300B might not be a bad idea....

Switches degrade sound.

Ok. Sorry I posted. I'll let Steve answer.

I too have switched my Torii MK5 order to a Sarah 300b.

I'd like to say this is what convinced me this new amp was for me:

"Just to be clear, if you don't like to tube roll, want the best, want to get it done with a single component you will have the sound of a ZROCK2 with anniversary mods feeding a CSP325 and the fully anniversary modded SE84UFO series amplifiers but with 4 watts instead of 2 and with 3 times less distortion at 2 watts and up to 8 watts at 10% distortion not to mention seldom if ever having to replace the output tubes since they are likely to outlast many of us."

But to be honest, he had me at "Sarah"....

Thanks for the clarification Steve!  You are a brave man, audiophile orthodoxy be damned, let them eat cake... not only are we going to put in the heretical EQ, we're going to preset that EQ and you can't change it.... I love it!

Lon wrote:

Quote:


Well, that seems to be a misinterpretation of my interaction.  I don't recall telling Steve what to do.  I merely raised a concern (in effect seeking clarification) and making a good natured design suggestion that is found in the ZRock2 itself, namely a bypass switch for the EQ part.  A core principle of any successful company is to listen to and welcome customer concerns.

In this Decware bubble it's easy to forget how horribly most audiophiles think of EQ's.  And every audiophile amp that I know of who has bravely added an EQ, always has a bypass switch.  Always.

But hey, Steve is going all gangsta, totally fine by me.....

As for your repeated decree of me over thinking, the main point is to feel free to disagree with my points, but there's no need to degrade my competence or intelligence, or discernment for making those points.  The term "over thinking" implies a dog chasing its own tail rather than doing anything productive.

I've seen this sort of thing in internet forums before.  People stray from good natured debate and instead, usually when they've run out of good points, drift into a personal undermining of their dance partners act of making their point in the first place.  And that enters shady ground.  And it's from that space that I'm encouraging you to take a different approach.  Feel free to show the error of my opinions, but do so without seeking to undermine my place to make those opinions in the first place.

Lon, I have always greatly appreciated your endless wisdom on the forums, and continue to do so.  

Kind Regards,
John

Found this A/B comparison of a MC275 and a 300B SET amp.  I thought the AB switch setup was pretty cool and test parameters fair.  I resisted the temptation to skip to the end for the reveal.  I can't say that I could detect when switching occurred via my Bose Bluetooth headphones and the music sounded great.  I think that says a lot about 300B SET.  :D

https://www.youtube.com/watch?v=LtWqgdw4E44

Steve, I appreciate your thoughts.  But I find them confusing.

If you're taking the magic part of the ZRocks2, which is an EQ, and you are taking that part between noon and 1:15, then you are taking something that contributes to the lushness you have described, which is an EQ type of behavior.

That noon to 1:15 is still an EQ of some sort.  Perhaps not as pronounced as the EQ actions of the adjustable ZR2, but it's some level of equalization.

As mentioned, totally fine by me.  But it's likely to cause a number of orthodox audiophiles to spontaneously combust.

And in fairness, it seems to me wisest to be straight about what you're doing in your marketing.  If you're adding the magic parts of your tube EQ, then shouldn't that be clearly conveyed to the customer rather than somewhat hidden?

To my sight, the only way to please all comers, and certainly that vast majority of audiophiles, is to provide a means to bypass the ZRock2 magic bit.

Buy hey, it's your pony.  And I'm sure it's going to sound great.  But I don't think hiding the presence of the ZRock2 in the 300B is the best way to go.....

You did write:

Quote:


Which seems to be the truth.  A 3 in 1 solution of which one part is the ZRock, which is an EQ.  

Please don't shoot the messenger.  I don't make the weather, rather just report on it.


2 rupees...

That's it, I just emailed Sarah about her namesake. I'm changing the Torii to the Sarah; I'm all in.

Additionally, I'm keeping the CSP325, the ZROCK2, the ZP3 and the ZLC on my order. If the 300b sounds good without a pre, I'm banking on it sounding just as good, and just a bit more so, with it! This will be my first foray into SET, and I can't think of a better project to kick me off!

I've found if you want to ask the real experts, talk to the radio guys.

Hum balance explained- https://www.antiqueradios.com/forums/viewtopic.php?t=63462

I have what many consider one of the most transparent, harmonically correct, yet ballsy 300b set amps every produced (coincident technology Frankenstein mark 3 monoblocks).

I have multiple speakers, but one pair is the newest Li Audio reference speakers (tall version).

On the right music, this combination is absolutely stunning, with dynamics and speed that are unparalleled.

But… I bought a used zrock2 for the not so perfect level of recordings and it serves a very useful purpose.

The beauty of it is the weight it adds. I do adjust the zrock2 stepped volume control, but not often.

The idea of a more transparent version of this without the extra cabling to me has merit for Steve’s product vision.

It is what it is, and if it can be bypassed gives the user choice and avoids the issues being discussed here (is this flat or eq’d).

In a perfect world this wouldn’t be a binary switch, instead adjustable, but we all know audio is is filled with trade offs.  

Interested to watch your experiment Steve, thanks for sharing.

It's pretty cool that Steve encourages, and even appreciates feedback. A lot of builders would clutch their pearls at the mere notion of peasants daring to question.

 




Ten different NOS 12AU7's.  The best of the best and one of my all time favorite sounding low mu tubes.  Average cost on eBay $20. each -- even today.  It's the best deal in audio as far as I am concerned. I have started with the black plate RCA on the far right. My only thought is that there is no way I am going to try the other nine. It sounds that good. For all we know it could be the worse sounding one of the ten.

This is the main input stage for the amp, and it does both channels so a single tube change will give you a new signature -- one that is exactly matched between the channels.

The two driver tubes can be 6N6P, 6N5P, 6N1P, 6922 and all the variants there of. So far you would think the 6N6P would win, but I am using the Cryotone 6922's and so far they have been impossible to beat.  

Speaking of Cryotone, as many of you know they make a 300B.  I will be trying some soon.  Some of you might be thinking hey... why not send Don at Wathen Audiophile who makes Cryotone a pair of 300B and have him cryo them?

I knew better than to ask, but here is what Don sent me today:

Quote:
 

There is a reasonable chance these will sound better, and be several hundred dollars savings over the WE300B's so this is going to be a real option for those who either want to roll output tubes, or save a bit of money without compromising the sound.

Anyway, back to the input tube.  With the Cryotone's driving the output tubes, pretty much all the voicing from tube rolling on this particular amplifier will happen with a single $20 tube.

-Steve

UPDATE

Tonight/Today I cleaned things up, got it down to one switch.  Rolled tubes, playing some great music, changed the value of the main coupling caps again and I am really happy with it. I finally have that feeling that it's 100% right. I can't really hear the amplifier anymore. The music is alive. It's just right.  

I can tell you a secret about amplifier design... if it didn't really hurt, and take a really long time to explore all the possibilities, by ear, not by spice, then you can be sure no mater what one might come up with , it's not right. Not this kind of right. Trust me, when you hear it, you'll know.  This is probably on the level of the UFO25 now, and that's amazing considering...

Steve

Steve,
Have you tried the Cryotone 12AU7-WCL long plate tube in the 300B amp yet?

I just received a Decware email advising that Kevin Deal at Upscale Audio is a good source for NOS tubes.  IMO his selection is not that great.

In my experience Brent Jesse has a much broader selection at fair prices.  A google search will quickly turn up his contact info.  No affiliation whatsoever except as a satisfied customer.

Well "Uncle Kevvy", as he likes to call himself, is a salesman first. He over-hypes everything he sells as the answer, the greatest, blah blah blah. Over-hype gets real boring, real quick.

That aside, the internet seems to tell the tale of a man who isn't always a stand-up man. Many stories of what Doug explains as his as well.

I never bought anything from him and never will. I find his personality and salesmanship to be a total turn-off.

Brad

Hey Steve,

Two quick questions:

1. You earlier described the 300b as “I believe what is actually happening is that the SEWE300B is like HD or even 2K resolution at 60 fps and the SE84UFO25 is like 4K at 30 fps”.  Do you still think this comparison is accurate? I very much love the “lit from within” SET magic midrange, and very well may grab one of these.

2. If you had to estimate from your listening, at what wattage-ish do you start to hear non-pleasing distortion?  I know this 300b is optimized for 4 watts but perhaps we can squeeze a pleasant sound from 6 watts, as example.  

P.S.  I love your approach to design. Science coupled with trusting your ears. I’d take trusting your ears over anything else. It shares some similarities to the lean startup model adopted by most SaaS tech companies these days. Create the basic version and release it to the wild (your listening room). Then get feedback quickly from users (your ears in this scenario) and then continue to tweak and release iterations fast and often until it’s as “right” as possible.  (The updates, new features, and changes continue forever in software these days, and are just pushed automatically thanks to the internet. In SaaS there is never a finished product.)

Big fan! Great stuff Steve.

I’ve only had great experiences with Brent!

Quote:


I usually avoid absolutes, but I’m confident there is absolutely no "right" answer for that question. Some people are going to like it with no preamp at all, and others will prefer what their favorite preamp adds to their system, and some will no doubt add a zrock with or without a preamp. One well know poster on this site would probably use 2 preamps... It depends on your taste, your system, your room and probably a bunch of other stuff that only you can answer. Or put another way, its up to you to optimize your system so it sounds best to you, regardless of the circuit.

My 2 cents.

CAJames, 2 preamps? Lulz.

Ahh, I understand. I thought he was just joshing around. Hey, man, as they say, trust your ears and nothing else! Ya gotta do what works for you and keep on keeping on.

In fact, I just hooked up a nicer (on paper), more expensive set of speakers that I just recapped tonight, only to decide that my old speakers were indeed better. So guess what? We swapped them back out. Kind of a bummer, but my wife and I agreed that the old ones were better!

I love the powder coating color. The silk screen should be darker than the powder coating to be more readable.  I could suggest a couple of colors but I won't. I had a better idea. Sarah...the amps namesake... should pick the color of the silkscreen. It would be her personal touch. It could be her favorite color or whatever she thought would make it "pop".

I listened to Tool's Fear Inoculum on my system last night. It sounded glorious.  I can only imagine what it must sound like on this new Decware 300b.  I'm thinking, it can't sound any better, but can it?  How much better can something get?  There has to be a point where there is no more improvement.  I mean, besides being there while the actual music is getting recorded.

 
UPDATE 5/12/22

Now that the amp is pretty much done I thought it would be a good idea to start seeing how it measures compared to other 300B SET amplifiers. There are so many I decided I would just look at John Atkinson’s measurements of various 300B amps reviewed in Stereophile.

One thing I noticed in several popular 300B amplifiers is that if you want the best performance you need to use 8 ohm speakers.  When the amps were measured into 4 ohms or less, the high frequency response began to roll.  I saw several that actually rolled off at 10K as the impedance dropped.  Correction, resistance dropped, as during measurements the amp is connected to a dummy load.  The name comes from people who think this is how an amplifier measures on speakers - which have impedance instead of resistance relative to frequency.

In any case it is a good standard by which to evaluate one amp against another and or against itself during development.  



(click to enlarge)


Tonight I am doing measurements all evening. Getting high resolution plots in the low bass area is time consuming. Also, never trust test equipment with your life.  So I have two completely separate but similar stations for doing distortion analysis and frequency response measurements and measure the amplifier many times on both. If they both agree, I know it’s right.

The Audio Gods are here to watch. Specifically to here to watch me realize that I am seeing their signature. The signature is the response.  

So instead of being rolled off on both ends this amp is so far measuring flat within less than 2 dB from 20 to 20kHz at all impedances from 2 ohms to 16 ohms. And instead of rolling at the ends it is slightly lifted. This beautifully compliments the general signature of the 300B tubes.

I was very surprised to see that the amplifier didn’t roll off in the treble at 2 ohms. If it is true that some of these big name 300B amplifiers can have the frequency response roll off at 10kHZ just because the load dropped to 4 ohms or less then it is no wonder why people think this tube is dark and romantic sounding.

Frankly I’m not comfortable with that, as our amps have always had unwavering frequency response at any impedance, and most will drive nearly a dead short. Having the frequency response follow the impedance of the loudspeaker would certainly have some interesting effects but frankly would be pure fantasy with respect to fidelity. Yea it might sound cool, but be wildly different from one speaker to the next and have nothing to do with accuracy.

Also I noticed that many amps are claiming 8 watts or even more, but at those levels have pretty high low order harmonic distortion. The most interesting thing to me as I looked at all the measurements of these reviewed amplifiers was the distortion ramp and how it changes in slope angle from amp to amp and its general shape. It really reminds me of horsepower curves on a dyno.

Since the audiophile world is well triggered by specifications and measurements I do need to make sure that this subtle but mind melting tug at the midrange frequencies still measures legally flat and it does so not only at 8 ohms but between 2 and 16 ohms. Well happily it is and actually doing it on only one of the two taps offered by the UFO output transformers. You know when you can get this range of performance from a single tap something is going really well.

I fully expected at this part of the show, the measurements, to have some regrets about not using a higher primary impedance on the output transformers… but the 3.5K ish primary seems to be the magic bullet. I thought it would be higher.

The way I designed the UFO transformers was with reflected impedances in mind. For example; If you have a primary of say 5K and an 8 ohm secondary but hook that secondary tap to a 16 ohm load, the primary is actually going to rise to nearly 10K. The opposite is also true, a 8 ohm speaker could drop it to as low as 2.5K. So let’s say just for fun we wanted the tube to see a 2.5K impedance and we knew we were going to use a 4 ohm speaker. We could wind a transformer with a 2.5K primary and a 4 ohm tap, or wind one with a 5K primary and an 8 ohm tap hooked to the 4 ohm speaker. Get it ? : ). UFO transformers are set up with secondary taps that are set at 6 and 12 ohms knowing that connected speakers will range from 2 to 16 ohms and using the reflected impedance to actually set the impedance that the plate of the output tube sees.

Anyway this approach in combination with the way I voiced the frequency response seems to really work and I can’t take all the credit for it, as usual, because I’m not that smart. In fact I didn’t have any idea that so many 300B amps couldn’t handle a low impedance and actually rolled the response under those conditions! I actually just found that out tonight.

Audio Gods.

With respect to distortion, that is very tube dependent. But the way I have it currently configured with the WE300B and the Cryotone driver tubes and NOS RCA input is consistent with my first statement. At 1 watt it has around 0.5% THD At 8 watts it’s approaching 10% THD. But when comparing this to other 300B amps that might do 8 watts at 4% or less, pay attention to the frequency response and power output into low impedances. Remember an 8 ohm speaker will often have dips in the response that get dangerously close to 4 ohms. And 4 ohm speakers will have impedances that dip well below 3 ohms.

This means that the distortion of the amplifier will be different at different frequencies as well the high frequency response will also be changing with impedance. This is what drives serious audiophiles insane and keeps other audiophiles from getting serious.

So far at every possible impedance this amplifier has not rolled off at the ends, it actually rolls UP.  Just he exact opposite of virtually every other amp I saw measured. This and the fact that it takes so far over 3 hours to take meaningful measurements though all the combinations would probably short Mr. Atkinson out because it doesn’t make any sense relative to the norm.

Right now I am in the process of measuring everything on the other output transformer tap  and am presently doing the hardest of all the measurements with a 2 ohm impedance. I have special transformer loads that work more realistically than a ‘dummy load’ resistor.

FINISHED

63 measurements the last one being the most brutal test, a 2 ohm impedance on the wrong tap. Worse case scenario and it measured within 1.57dB I think, and was rolled UP at each end not down.  Full response from  20 to 20kHz. To measure higher than this I have to switch frequency generators and do the sweep manually. My guess is that this goes well beyond 20kHz. I used very high grid resistors in every stage of this amplifier. This would tend to drop excitement in the high frequencies but in this case you don’t hear any roll off and we measure the opposite, roll up at the extremes.



(click to enlarge)


Basically this response is legally flat because it is within 2dB from 20 to 20kHz in both of my settings.  In this shot, I did one channel in setting A and the other channel in setting B to save time, and there isn’t enough difference between the two to make any sense of why the sound is so different.  So what you see here is the worse case scenario, a 2 ohm speaker on the amplifier set on the wrong tap with the power output at 1 watt.