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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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ramtubes's avatar
ramtubes OP
451 posts
 
@ffzz My speakers are 93db sensitive (1w/1m) with 8 ohm impedance (7ohm min).With a listening distance of 8 feet, it seems 15w will be more than enough to produce 100db or so loudness that Symphonic music peaks into from time to time.Assuming 100db is my max need, will there be any advantage of using, say, a 30w amp rather than a 15w amp? What if the amp is class AB rather than A?


I think thats a little light on power. 8 feet is more than double a meter so 9db loss there but 3 gain for stereo so lets make it minus  6 dB on your sensitivity. You are going to get 87 db per watt. 10 watts will get you 97 and 20 watts will get you 100. If that is peak, not average then 30 watts is barely ok. If your room is absortive then more power is needed. 

100 db is a high level, have you checked with an SPL meter.  I listen no louder than 90 peak. A 30 watt amp is fine for me and most people but they dont listen at 100 dB

The class of amp will make no difference. 
ramtubes's avatar
ramtubes OP
451 posts
 
@oem  This thread is going way to fast for me.. Way back, power cables was mentioned.. For those that said that they don't make a difference, does speaker cables and interconnects make a difference ? I felt that if the latter two makes a difference then the power cables do to.. I swear when installed Audioquest's Hurricanes it improved the sound.. Maybe its just me thinking that ??.. I need one more to complete the full loom (4pcs).. I'll try 4 $100 cables after the complete loom and see..


We can slow down, no problem. 

Audio cables make a difference no doubt. However after $100 I think there is little to gain. Cables have measureable and predictable effects of capacitance, inductance etc. 

Just because they make a difference it does not follow that a power cord does. In power cables there is not much to measure and a lot of other wire to consider. 
ramtubes's avatar
ramtubes OP
451 posts
 
In my experience, it is not a myth and it does incrementally improve the sound quality. My understanding of the technical reason is it reduces the negative affects of the crossover by (almost) directly connecting the amplifier to the drivers.

The best crossover is no crossover. When are we going to stop piddling around with tiny effects when we can bi amp and do someting that really makes a difference.

Many of these cables and little tweaky things cost more than a good electronic crossover and a second amp.
ramtubes's avatar
ramtubes OP
451 posts
 
@tinear   Richard... I am enjoying the heck out of this forum and am learning quite a lot.  I am interested in your thoughts and insight into Bob Carver’s latest tube amps


I heard the amps were very light weight, had tiny transformers in those big cans. He has to be cutting corners somewhere at those prices. Check the weight of the 275. Wheres the measurement?

Roger
ieales's avatar
ieales
297 posts
 
My understanding of the technical reason is it reduces the negative affects of the crossover by (almost) directly connecting the amplifier to the drivers.
Bi-Wiring has no effect on the crossover. In an electronic circuit, when current flows through a resistance, voltage is developed. In a Mono-Wire system the tweeter connection is modulated by the woofer current. By providing a direct path to the low impedance amplifier output, the tweeter is not modulated by the woofer circuit current. On some program material, it is quite evident, not so much on others. YMMV.

The best crossover is no crossover. When are we going to stop piddling around with tiny effects when we can bi amp and do something that really makes a difference.
As mentioned earlier, the devil is in the details. Some speaker crossovers are more complex in their action than a symmetric electronic one. My dbx223 sits in the cupboard because the dual 4th order did not sound as well as the 4th/2nd passive on the mains or the electronic 3rd / passive 1st for the sub.

Digital may have promise, but at this stage, new hardware elicits no interest.
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