2. amps-preamps
  3. 140029-80294

Does anyone care to ask an amplifier designer a technical question? My door is open.

I closed the cable and fuse thread because the trolls were making a mess of things. I hope they dont find me here.

I design Tube and Solid State power amps and preamps for Music Reference. I have a degree in Electrical Engineering, have trained my ears keenly to hear frequency response differences, distortion and pretty good at guessing SPL. Ive spent 40 years doing that as a tech, store owner, and designer.
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Perhaps someone would like to ask a question about how one designs a successfull amplifier? What determines damping factor and what damping factor does besides damping the woofer. There is an entirely different, I feel better way to look at damping and call it Regulation , which is 1/damping.

I like to tell true stories of my experience with others in this industry.

I have started a school which you can visit at http://berkeleyhifischool.com/ There you can see some of my presentations.

On YouTube go to the Music Reference channel to see how to design and build your own tube linestage. The series has over 200,000 views. You have to hit the video tab to see all.

I am not here to advertise for MR. Soon I will be making and posting more videos on YouTube. I don’t make any money off the videos, I just want to share knowledge and I hope others will share knowledge. Asking a good question is actually a display of your knowledge because you know enough to formulate a decent question.

Starting in January I plan to make these videos and post them on the HiFi school site and hosted on a new YouTube channel belonging to the school.


128x128ramtubes
ramtubes's avatar
ramtubes OP
460 posts
 
Power is equal to volts times amps and is also equal (thru Ohm's Law) to current (squared) times Ohms.
In this case, to make 100 watts into 8 ohms, you divide 100 by 8 and take the square root, which is about 3.4 amps. That's all thats needed to make 100 watts if the load is 8 ohms and it makes no difference what kind of amplifier it is. So what is the 29 amps??


HI, I was involved in that discussion about the Benchmark amp. Some of us were trying, without much luck, to advise the owner not to bridge the amps into his speakers. Then we got into current. Then the whole thing fell apart and I left. 

To answer your question. 100 watts at 8 ohms is 40 volts peak. If you have an electrostatic or other speaker that goes down to an ohm or two you will need a lot of current to play trumpet music at full level. You may need 40 amps to get your 40 volts at 90 degree phase and most amps will be very unhappy. The Beveridge ESL required 1500 VA to play Miles. There was no way to get that through a reasonable transformer so we made Direct Drive 3000 volt amplifiers that provided 1/2 amp of current. 
ramtubes's avatar
ramtubes OP
460 posts
 
@oldtecg05
 Whose thread is this?


I thought it was mine. I dont mind a bit of controversy as long as its Gentlemanly and with some sense of humor. Its the sense humor that I find lacking.


ramtubes's avatar
ramtubes OP
460 posts
 
Here is a great example of what I consider the proper use of 6SN7 and 6SL7. Note all the preamp and phase inverter are SLs. Interestingly the SN is used as a push pull output tube... So cool. Its worth reading some of the thread.

https://music-electronics-forum.com/showthread.php?t=16661
fsonicsmith's avatar
fsonicsmith
963 posts
 
This is a golden nugget of wisdom;
(In their book "Control Design And Simulation", Jack Golten and Andy Verwer discuss (in chapter two) with regard to applying mathematical models to the real world: "...mathematical models invariably involve simplification. Assumptions concerning operation are made, small effects are neglected and idealized relationships are assumed." 

Ralph-you should never have entered this thread. You tried to kill the OP with kindness and camaraderie, and he spit on you every chance he got. I think most of us reading through this thread can see the OP for what he is; entrenched in the remote past and bitter. His hubris is out of bounds. I have been around long enough to suspect that there must be something else going on in the OP’s life that is causing him to behave so poorly.
krelldreams
128 posts
 
What causes a designer to choose a certain tube type for an audio circuit? Is the circuit designed around a specific tube, or is the best tube type found for the circuit that’s been/being designed? I know there are different electrical properties (I’m not an EE, so that is my untrained understanding), but does one choose the tube primarily for its electrical ability, sound, reliability, or some combination?
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