Discussion in 'DIY' started by Redboy, May 28, 2014.
You destroy the sound, the moment you parallel Finals, or for that matter, use a 300B instead of a GOOD 2A3 monoplate, or...maybe...just maybe till I do more A-Bing, a Type 46 !
Theory and calculation is very important for SS amp design, why is it different for tubes? As long as you are matching the impedance of the primary to the plate resistance, you will get the divider effect and ripple will go to the speaker. 5mV is a lot at the speaker and you will hear it.
I don't mean I don't trust you, but if you have been it this for 30 years, you got to work on the theories, why don't you share some insight backing up with theory.
What is the reason you cannot parallel tubes with SE amp? People parallel tubes in push pull, we parallel transistors in SS amp. In fact, the more you parallel, the better it sound. My design has 9 pairs of output transistors and it is sweet. AND there is theory behind why the more the better, not just "it is".
35 years. Please see page 6 in this Thread, post #108, where the poster explains, a " normal " SET is 1 to 3 Watts.
Have you looked-up and "digested - internalized" the Isamu Asano and Nobu Shishido Loftin-White type 2A3 DC amp circuits yet ??
WHY are we having this conversation, when you do not disclose how sensitive your speakers are? I have mentioned two or three times, you need 98 dB or higher to play this game properly, otherwise you are making too many compromises.
If you don't have 98 dB, I suggest to own an ALTEC, two way, 15 inch woofer, compression driver, vintage, as the best compromise..
The basic reason why myself and others do not parallel, in Push Pull or in SE, is because no two active devices play exactly like the other. On a high efficiency speaker, you will easily hear this in a A-B. Also, with TUBES in particular, they WEAR differently , one from the other, when in use. A SET can be made so pure and transparent sounding, that you will hear, with paralleled tubes, what is called a " CHOIR " effect, .... you HEAR the two devices, not being in synch with each other.
I grant you, some people build and sell SEP amps, called Single Ended Parallel ( Parallel Finals stages ) , but this is ONLY done for marketing reasons, for the manufacturer to make a dollar from the dummies who don't know that efficient speakers, very often horn loaded, rule. ALL those SEP amps are " marketed " to the novice audio people, with money, who are not smart enough to own 98 dB and higher speakers.
Another compromise, besides " having" to parallel tubes on speakers below 98 dB, is the common use of bigger Finals tubes ( 300Bs, 845s, etc ) . Guess what, those larger tubes, on an real efficient speaker , NEVER sound as good, or can outperform a smaller triode, like a single JJ 2A3-40.or smaller.
Also, Alan,. the " bigger " the power possibility is in the Finals ( to play the "wrong type of speaker ") the more demanding it is of the preceding circuitry, to DRIVE the Finals, and the more compromised the amp becomes, in terms of tube currents, and the number of stages needed to drive the Finals.
The " magic" number in a SET design, an ultimate SET design, is always going to be TWO stages, with a high-mu driver, operating at high impedances.. Its never THREE stages in the amp, which is easily beaten by a proper TWO stage implementation. KISS and "less is more", when done well....rules in the ultimate performing SE tube amp !!
My guess is, you will need to move into more efficient speakers. If not, the best possible amplification will be solid state. The answer there is to buy a California-made SPECTRAL DMA 200, about $18,000 new, less used. You won't beat that today, on less efficient speakers.
Take away conclusion.........there is NOTHING as good as a two stage amp, done well, in the 1 to 3 Watt output range., if you are talking about the BEST possible sound to be had with a SET amp. This amp, by definition, will be always directly coupled, one stage to the other.
I've already told you, the total " L" series resistances to the Finals will be low. I had to go, by my ear, below 20 Ohms total on my recent 46 build, to get it sonically acceptable in 2017, on my VOTT ALTECS..
Thanks for at least explain a little more, whether I agree or not, at least I know where you come from.
I design my own amp, I read a little about the Spectral DMA200, I stop when I read the spec. My amp is so much lower THD than what they are boasting. They claimed 0.015% THD into 4ohm. My amp is 0.0035% at 20KHz at 112W output into 4ohm. That amp is faster, but I don't know what it's for!!!! Mine already do 30V/uS slew rate, 1.5uS rise time and about 300KHz BW. What more do you want for an AUDIO amp that never see anything over 20KHz!!!! I am very happy with my SS amp, it beats the Nakamichi Stasis PA-7 designed by Nelson Pass that is almost the same as his famous Threshold S300. With more detail, sound stage and separation. That PA-7 or S300 already a $4000 amp quality. You should look at my thread on "My Amplifier" that I have blow by blow posting the construction and final FFT plot on the THD at 1, 5, 10, 12, 15 and 20KHz. Below 10KHz, it's less than 0.002% THD. At 12W, the THD dips down to 0.0009% at some frequency. This is my first even amp designed, from theory to final amp. My open loop damping factor ( not negative feedback) is over 200, with closed loop, it must be way over 600 to 1000 theoretically.
My speaker is JM Lab Spectral 913.1, I don't know the exact sensitivity, I remember it's in the low 90 db. So it's not going to be sensitive enough for SET with 1 to 3W. I spent $3000 on this pair of speaker and I really like it already. I am not going to spend $10000 on another pair to beat this pair. More importantly, I don't like horn speaker. No offense, I hate Klipsh horn speakers type. Even if I buy another pair, it's going to be either JM Lab Utopia, Sonus Faber or Martin Logan that is even less sensitive.
Enough for these talk. Big Red already not happy we hijack the thread already.
Big Red , I think, or hope, is OK, this is a good conversation, carried on a high level. .
It will help other people who read it. Thanks for your post. I see, you are just a specs person, inexperienced, very smart, but not a Listener !!
LOL, minimal THD is NOT much important, NOR is it the reason...... why one amp will sound better than another!!!
That is hilarious.. Especially if you use ANY NFB to get a good spec.
Q: What is the feedback in the Spectral DMA 200, versus what you use?
I HATE to listen to feedback in any amps.
I know, from what you have said, two things
( 1 ) if you A-Bed your amp with a Spectral, you will learn something truly valuable !! ( 2 ) You are totally lost in audio, just as I was ( but in a different way ) when I was your age. .
Thats OK, I went through about 35 years in audio, lost , before I re-discovered ALTEC and heard a GOOD SET amp to play them. I bought MANY high end audio systems Alan, much much money and time, wasted by me. Now, finally, at age 72, I HAVE it figured out.
The reason why you don't like a Klipsch , or horns, is usually because of the mediocre tube amp that is almost always driving it. 99.9% of them FAIL. And also, I never suggested a three way Klipsch with its cheap drivers. ALTEC Vintage, two way, 15 inch driver, can be had for a fraction of what you suggest.
None of my words were meant to be offensive, or said with malice, please understand.
Have FUN in audio, I do. Thanks Big Red !
I used to think THD is not important until I research into speaker cables. THD is everything. I think people that claim THD is not important likely to have inferior speaker cable. I have a long thread on speaker cable and distortion. Speaker cable is everything. 10ft of Monster cable raise the THD from 0.006% to 0.14%. If you don't have a good cable, you'll never get the benefit of an ultra low distortion amp.
I might be new in audiophile, But I have been a senior engineer and manager of engineering for 30 years designing with transistors, IC design and all different things. I also designed tube guitar amps with channel switching, power scaling. So please don't talk to me as if I am a green horn. I owned two US patents solely under my name and I published papers in America Institute of Physics Review of Scientific Instruments.
There is a lot more to electronics than just by try and experience. You can have 30 years of experience OR you can have 3 years experience repeating 10 times. Theory is everything, you have to have solid grounds to stand on. No GNFB is ONLY your opinion, there are plenty of people disagree with you. All I know is My amp has better clarity, more separation and better sound stage than the Famous Stasis amp designed by Nelson Pass that has no GNFB. AND it is a quite expensive amp. I am not going to say I know it all as I don't. But I did accomplish a big mile stone on my very first design.....based on theory and surprisingly, proofed with listening. My amp comes alive.
Years of experience in ultra low noise, microwave and HV design taught me to conclude that those who think it's black magic is very likely they don't know enough to explain it. You work long enough with so many PhDs like me, you'll see the other side.....that EVERYTHING can be explained IF you know enough. I designed RF circuits of multi GHz from paper and simulation to real circuit ONE TIME THROUGH with performance, Smith Chart plot almost identical to my simulation. It's the knowledge that matter. If you cannot explain it out, you just don't know enough.
Back to the speaker cable, I have a long thread on testing, comparing and building speaker cable and the difference in sound due to speaker cable.http://audiokarma.org/forums/index.php?threads/effect-of-speaker-cable-on-thd.764633/
The different in changing the speaker cable is staggering. With the old multiple monster 12 gauge cable, I could not tell the difference between the Stasis amp and my amp. BUT with the new cables I made, the difference came out clearly. It's all scientific, and then proof by listening.
The PASS Threshold Stasis amp is a VERY old design is it not? Not good enough to compare to.
I gave you the name and model number of the best USA solid state amp, go LISTEN to it, bring your amp along !!
The other question is, should one be comparing any amp design against a PASS design. I think not !!! Even his First Watt attempts, while voiced nicely, cant compare to a 1 Watt tube amp " I " may do, at home, as a totally amateur DIYer !! The PASS amp will sound UNinvolving by comparison, and far less dynamic..
If you went to San Francisco with your amp, and asked Spectral people to A-B yours and theirs, you will learn a LOT.
Regards, best wishes, lets please totally end this now. Thank you.
My email is firstname.lastname@example.org. Leave this thread alone.
Regards, best wishes, lets please totally end this now. Thank you.
This has taken a strange turn.
Red, I've got some new altecs in. I've been run into 2a3s lately, but I'm going to have to sub back in 45s just to see how things sound. Your amp are a good reminder of what a simple circuit and simple tube can do.
Sorry about all that.
Are you done with your projects so you can make me a SP-210 PS?
In post #117 of this thread on your 46 amp, You asked me to tell you more about my own 46 amp..." in another thread.
I wasn't planning on doing another thread, but I wanted to share with you, as a avid DIYer, a reliable URL, for you to view, ..... perhaps consider. Maybe it will encourage you to do your very own Direct Coupled Type 46 SE amp.
Please use the above-referred URL, to see a post of mine. which is #2 in that thread. It includes a background history of the DC approach, and folks can review the Marzio and Jelasi Sound Practices 1994 article, .... IF anyone wants to build this.
I highly recommend DIYers make the changes - specifically suggested in the above-post, to the magazine article's schematic.
Since I have already just adapted this circuit, for a Type 46, ( half a 12AX7, DCed to the Type 46 ) I would be happy to personally help with my OP POINTS on the two stages, or answer any other questions, ie, try to be helpful in a general way.
My email address has been given right in this thread, in the last post to Alan,.#129.
Regards and best wishes to you - Happy Listening !!...
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