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.


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d2girls's avatar
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d2girls
1,029 posts
 
Is it harder to design a amp or preamp?
ieales's avatar
ieales
1,201 posts
 
I would like to hear how each of you figured out how much power you needed to buy in watts?
Never bought by power. Always purchased by sound.
Currently have 100 and 150w SS and 40w tube

84db 1w / 1m. min 3.2Ω, max 16Ω, mean 7Ω

Loud level is 90db C weighted slow measured with REW at seating pos 13ft from LS. Don't have low level. Each selection is listened at optimum for type. Sonic wallpaper is MP3 over internet in MONO, MP3 is intolerable in stereo.

SS amps not rated @ 4Ω

mapman's avatar
mapman
22,198 posts
 
Never bought by power. Always purchased by sound.

On several occasions with lackluster sound at higher SPLS, I ended up purchasing more power elsewhere and that has worked.


HI, Roger here with a question.

I would like to hear how each of you figured out how much power you needed to buy in watts?

I would appreciate the following information in your response.

Your listening level LOUD SPL (preferably measured at 1 meter from the speaker with a REAL SPL meter. Your low listening level. If you are using a cell phone app then you have confirmed it?

Your speaker sensitivity?

Listening Distance from speakers?

How many watts at your load is the amp is rated to supply?

I figured it out by listening and trial and error over time and based essentially on those parameters as a guide. However specifications alone seldom tell the whole story. The devil is always in the details much of which is never specified. Detailed measurements like those in Stereophile help a lot but I have found there may still be surprises playing real music even with very comprehensive test measurements at ones finger tips, though if done correctly, measurements certainly help with the decision making process of what to try next or not.







ramtubes's avatar
ramtubes OP
460 posts
 
@d2girls

 Is it harder to design a amp or preamp?


Thanks for a lovely simple question. Preamps are much easier and to me not so interesting as power amps. In my career I have designed two major preamps, the RM-1 a very high performance preamp that was not at all easy and then the RM-5 which was quite easy. 

With power amps I could go on forever. They are challenging because one has to consider the wide variety of loads they will encounter, there is a lot of energy so if things go *BANG* lots of stuff can be destroyed. I have designed dozens of power amps and only produced the ones I feel will perform well in a variety of systems.
fsonicsmith's avatar
fsonicsmith
957 posts
 
 Preamps are much easier and to me not so interesting as power amps.
From the heart, I don't want to tease you out and set you up for some type of audio sparring, a form of website f-erism I despise. I respect you and am willing to do my best to listen/read with an open mind. But that said, you can't possibly mean that preamps are easier in general and I am unaware of any accolades for your preamps (whereas you are lauded for your amps). Obviously you mean that for your tastes and purposes, preamps are easier than amps. Few would argue that the audio world is full of great amps and that there are a dearth of great preamps. I have an opinion that is not subject to proof-that the easier a loudspeaker is to drive (in terms of both impedance curve and sensitivity) the more a great preamp's sonic attributes are appreciated. A great preamp does more than attenuate a signal. It breathes life into music. A great preamp is quietly powerful, while a great amp simply provides grunt. Once again, purely resorting to engineering and lab measurements is a sure way to fail when it comes to preamps. A great preamp needs a great PSU section, preferably outboard. Lab measurements don't explain why a great PSU is so important to the performance of a preamp. 
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