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

Showing 3 responses by ct0517

ct0517's avatar
ct0517
2,041 posts
 
Roger
this is related to a question you raised in past post on subs and remote controls.

ramtubes - The amp is any old SS 100+ watt amplifier. Currently a nothing special Denon. The woofer level control is on the crossover.

This solves a lot of problems with powered subs. Unless they have a remote (do they now?) it is difficult to adjust the level for different CDs,


Firstly I Agree, especially if someones subs are setup in typical fashion across the room with the main speakers.

My solution
I am using for the last two years, two Dynaudio BM12s studio subs in Room B with my Wayne Picquet restored Quad 57's. They (BM12s) are one example of a solution with a credit card sized remote control that handles db and crossover levels, phase, and allows you to save 4 settings. Classical is typically a higher DB setting then compressed popular music.
The BM12s are handling 60 hz and down and the RM10 has full control of the 57's. The subs come with their own Class A/B amps and on the boxes are heat sinks. Mine are now positioned on either side of the listening couch. This allows for the db levels to be set the lowest, phase 180. The sub amps heat sinks don't even get warm. Very little vibration from the boxes.

************

We last conversed about a year ago when I inquired about slope cards for an RM3 that I own. I was thinking about a project to bi-amp my Matrix 800's at the time.

btw - A nice surprise coming back here for winter conversations to find you have the most popular thread on Audiogon. 8^)

Cheers Chris

ct0517's avatar
ct0517
2,041 posts
 
Clio09
I am curious how you settled on the 60 Hz cutoff and what other levels you may have experimented with.


Clio09
atter much experimentation I found the 57's positioned the way they are in my space to be the most room filling and linear top to bottom - down to about 50-55 hz. Still, to get the bottom octave and bass impact (it's a large room) I needed to add subs. I used to have a big HSU set up in nearfield next to me. It was fine as long as you were sitting in one spot. But if one uses the room - walks around, and sits in different spots around the room;  multiple subs are the answer to eliminate the bass nodes. Adding the two 12" Dynaudio subs improved on the single large HSU. Keeping the HSU as a slave would have been interesting, but my son took it. 8^0
The lowest crossover point on the Dynaudio BM12s is 60 hz. So that is where they are set. I have tried higher settings in the past with other subs and felt it interfered with the 57's bass too much. 


ct0517's avatar
ct0517
2,041 posts
 
Clio09
@ct0517 - thanks for the response. With the subs in place are you still running the Quads full range, the using the sub fior 60 Hz and under, or are the Quads completely cutoff at 60 Hz?

Hi Clio09
The 57's are full out on the RM10 and in parallel to the subs. The preamp I am using in that room has two direct outputs. One output set going to the L and R 57, the other set going to the L & R sub. The subs are on each side of the listening couch, the opposite room side to the 57's. The Quads are seven feet from the front wall. So they are about a third of the way into the room. 
   
I realize that the way I have set up the Quads (see virtual system pics) and the subs is, well, unorthodox. But that is just one of the aspects of a dedicated room, that allows you to manipulate speaker placement, and affect the way the speaker output and the room gel. The hell with aesthetics. Hey, anyone with Quad 57's isn't into aesthetics anyway - 8^0.  

Room A is my main room, it pressurizes easily due to its shape and the speakers used in there; but Room B is a better room for entertaining due to its size. It's been a lot of fun when people visit and if any are interested in audio, watching them get a grasp that the Quad 57 is actually a speaker. Equally entertaining is when I tell them there are two subs in the room and to tell me where they are as music with a lot of bass plays. They start looking over at the 57's across the room, looking in the corners nearby. When I tell them they are on each side of the couch they are sitting on, one right next to them on the left - they are in disbelief.
Cheers

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