Home OTL Asylum

OTL, Output Transformerless Amplifier User Group.

Negative speaker lead goes to "ground"

in any single-ended amplifier, as a convention. (You could also connect the positive speaker post to amplifier ground, which simply inverts the phase of the music signal, as long as you do the same in both channels.) But in our balanced output amplifiers, the amplifier outputs are created equal.

My point was that the output from the bridge MUST connect to ground somehow somewhere, otherwise the PS won't work at all. And the fact that your schematic shows the negative node of the bridge rectifier, which to create a positive voltage is the node that must connect to ground, going through the negative sides of the two capacitors, suggests to me that the negative poles on the capacitors are internally connected to each other, i.e., the negative side is like straight wire connection. Which I think is why Caucasian Backplate asked you to measure resistance across the negative posts (input to output). It should be near zero. If it's near zero, what is gained by having those extra connections in circuit? Perhaps to reduce noise, but I really don't know.

Bottom line: Don't invest in these 4-pole capacitors, IMO. You might do a search on Tweaker's Asylum to see what those guys say. They are like "Mikey" in the commercial; they will eat anything.

After writing the above, I did some searching on Tweakers myself. Here is one post that hints at a benefit:

"The whole point of the capacitor is that the negatives don't go to the same point in the circuit.

Forget about ground. Think about current flow in the circuit. The current in both directions flows THROUGH the capacitor and thus, according to the theory, additional filtering is achieved and better isolation between the supply and load results.

Is it better? In some cases I have noticed an improvement, while in other cases it didn't seem to make much difference. I guess, as with most components, it depends on the circuit."

True, the current flows "through" the capacitor, but why this would improve filtering and isolation, I do not fathom, because of what I wrote above; there has to be continuity between the negative node of the bridge rectifier and ground. I would love to do what Caucasian Backplate suggests, to check my hypothesis.

As to your question about "two bridges in the MA1", I would say no, you are not safe to assume they are in parallel. But I know nothing about your MA1; I've never owned an MA1. My guess is that there is only one bridge for the HV supply, as in my amplifiers. The LV supplies for the output stage do require two separate bridge rectifiers, but those are not in parallel either. Here's where I say "ask Ralph".



Edits: 03/27/14 03/27/14

This post is made possible by the generous support of people like you and our sponsors:
  Parts Connexion  


Follow Ups Full Thread
Follow Ups
  • Negative speaker lead goes to "ground" - Lew 06:48:56 03/27/14 (0)

FAQ

Post a Message!

Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.