Zaubertuba
100+ Head-Fier
- Joined
- Feb 3, 2009
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LOL - Now that *is* funny.
Originally Posted by amb /img/forum/go_quote.gif Whether summing with a transformer or summing via a summing amplifier (or some other means), the effect would be the same. The sum of two signals is what it is. You cannot simply connect the L- and R- outputs together, though. The two amplifier's outputs would "see" each other and fight. One or both of them would most likely be damaged as a result. |
Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif No, it's not the same. If you common the L- and R- outputs of a pair of bridged amplifier channels as would be the case with a four board B22 or similarly configured amplifier, the two channels see each others' outputs as an effective short circuit and output current from one channel will flow through the output of the other and vice versa. If you common the bottom secondary windings of a pair of output transformers, neither secondary sees the other and there is no current flowing from one channel's secondary into the other channel's secondary. |
Originally Posted by amb /img/forum/go_quote.gif You would be creating a "ground" that's swinging an out-of-phase version of the MONO signal. Think about the implications -- I don't think you'd really want to do this. |
Originally Posted by Zaubertuba /img/forum/go_quote.gif But, I'm not well versed enough to understand if you common transformer secondaries, why is that not a short? |
Originally Posted by Zaubertuba /img/forum/go_quote.gif I'm kind of starting to bark up the wrong tree, methinks. Two discrete headphone outs is still a major criteria for this design. |
So, barring summing outputs are there other benefits inherent in using transformers in the output stage? |
Do they effect output impedance with respect to high- or lo-impedance headphones, for example? |
Originally Posted by cobaltmute /img/forum/go_quote.gif Unbalanced to balanced? The Dynalo shows a way of going from un-balanced to balanced (see how Figure 2 ties into the main schematic to create the negative output) |
Originally Posted by Zaubertuba /img/forum/go_quote.gif Or...I found this: EDCOR - PCW600/600 Certainly not a Cinemag or Jensen, but freq. response looks allright, and it's probably more in line with the rest of the build. |
Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif Yeah. Though don't know what the winding resistance is on those, which will be something worth considering if you're going to use it on the output. |
Originally Posted by Zaubertuba /img/forum/go_quote.gif Also, how do I go about calculating the values for the resistors across the secondaries and the (I assume) shunt resistors? |
Originally Posted by Zaubertuba /img/forum/go_quote.gif Well, for now they'll just be for the input--so I suppose I'm O.K. It's a 1:1, but is the 600 Ohm input and output resistance appropriate for an input stage? |
Also, how do I go about calculating the values for the resistors across the secondaries and the (I assume) shunt resistors? |
I found this, but with the shunt in series with the primary and what (I again assume) appears to to be a load resistor across the secondary this appears to be an output stage and not exactly applicable. |
Since these transformers are not really high-end, I'm also wondering if I'm better off using them exclusively for just the unbalanced inputs (my unbalanced sources are relatively lo-fi, anyway). I don't want to *degrade* the signal coming from my 1212m. |
Although, I've read having a well-matched receiver complement can be important to the performance of a balanced cable. Yes, that's the sound of me waffling again. |