@ramtubes with Class D switching freq over 450/500 KHz these days do you still think output filtering is an issue?. How do I educate more about this ?. If the issue of filtering not a function of switching freq please correct me. Thanks again.
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.
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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@terry9 In case you are wondering, the 25V rails are to accommodate Quad ESL's. With 75:1 step up transformers (Plitron), the amps can only punch the panels to 3750V, exactly half the level which engages the protection circuit. So I can bypass the protection circuit with impunity, and get a remarably refined ESL sound. You have my ear. Tell me more about what you are doing. Which QUADS? I am guessing 63s. |
@enobenetto I own your RM-10mkii, which is a mysteriously addictive amp. How did you approach low-frequency response? I ask because the bass the amp produces is punchier than any 100-watt solid state I've owned. I am pleased how many people love the bass of that amp. I think I just lucked out. I designed and prototyped all the transformers myself. The application is unique. Very high voltage, perhaps its that. I gave a talk about it at Burning Amp2018 that outlines the application and compared it to the typical applications http://berkeleyhifischool.com/having-fun-at-burning-amp-2018/ I stock several brands and vintages of EL84s. I do not stock JJ so I can't say much. Im glad you like them. |
@geek101 @ramtubes with Class D switching freq over 450/500 KHz these days do you still think output filtering is an issue?. How do I educate more about this ?. If the issue of filtering not a function of switching freq please correct me. Thanks again. One would want to see the measurements John Atkinson style. There is no other way to know but measure it. If these things interest you Stereophile is your best bet and its a good deal at $14 or so. The filtering is easier the higher the frequency. That does not mean its done right. JA recently reviewed a D amp that had what I assume is pre EQ to make up for the drop. I think it was NAD. Of course there are flaws in that idea because it EQ's for a resistive load. At least one can play with it and choose by ear. |
@terry9 Thanks for the nod ... I guess the takeaway is, "Don't be so lazy. Match HFE at operating temperature and current." Thanks! Have you measured the idle current of each transistor at operating temp in the amplifier? You of course know just to measure the Emitter drop divided by R. How well is it distributed? Then you could put a scope on them at full power and see how equal those are. Dont spread the emitter resistors too much because they might not track and share over full swing. I would make all the emitter resistors the same and do good transistor matching. You might make them a little higher like 0.22 ohm. You won't loose much output. The concept of varied emitter resistors is a thought I have not had. :) |
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