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
Thank you for posting this.  I have a question specific to a tube tester I own and use.  It is a Weston 981 Type 3;  it incorporates a line check adjustment where the line voltage is adjusted to a mark on the meter.  When I test 6550 or KT88 tubes with the tester is in Gm test mode and the line check is done the voltage drops.  The voltage holds steady when testing less powerful output tubes.  Should I compensate by readjusting the line voltage or use the reading with the lower line voltage?  Or do I have a problem with the tube tester?

Hello Roger,

I'd like to come back to tube testers.  I'm not sure I understand correctly about your recommendation for a simpler device, to measure emissions.  Is this for the basic purpose of monitoring for tube failure?  Would I need a tester with more capacity in order to check prospectively for tube matching?

Thanks,

Mark

I would like to know the capacitance of the panel itself, the electrode spacing and the polarizing voltage.

Direct Drive is the best way to go. I have found many cases where half the power goes into the step up transformer and other EQ components. How does he EQ the speaker these days? I just started reading the
speaker description. Sounds like its an entire system.
I wish I could tell you more on the specs of the speaker but there's little info. Roger Sanders does use a dbx Venue360 DSP unit he modifies (there are no crossovers or transformers in the speakers that I'm aware of). 
When you say "direct drive" amps since I'm non-technical what are you referring too? Can you send links to your own direct drive amps?
Much appreciated.

If a system is not broken and has serious deficiencies cables will likely not correct the problem. How can they?
I'm not suggesting cables can cure a serious deficiencies. However, since cables interact with the amplifier and the loudspeaker, they can ameliorate slight deficiencies be it amplifier, loudspeaker or environment.

Some amplifiers are nearly immune to cables, but loudspeakers are not.
Dennis Had (alive and well in Apex or Cary or someplace) hand built the best sounding amp I’ve owned over many decades of owning things. The amp’s 2nd birthday happened recently (he signs and dates these things), and I rewarded it by giving it a new tube. Although mine is one of the extremely high powered versions of his "Firebottle HO" (it’s a HO...says so right there) SEP at a massive12 watts pc (hide the children, batten down the hatches), his stuff, other than the well regarded headphone amps he makes for Moon, is subject to his whim of making one a week maybe and only selling ’em on Ebay. He currently seems to be making only a 2 to 4 watt SE version (8 watts with KT150s?), but I hear he might make something else if you ask nicely. There are no specs published by him for the Ebay stuff, and he’s nothing if not enthusiastic. I am consequently tied to highly efficient speakers, but the bondage works for me.

On another note, neither of my current fave tube guitar amps has a "standby" switch as they’re relatively low powered (18 and 15 watts respectively), so the question is: When can I get my beer? Another question I’ve asked elsewhere is how do Premium Fuses work? What do they do and why? Thanks in advance for the answer (or answers).