How are we wiring our Mono systems?


Hello.

I'm building a mono system* out of stuff I have laying around:

CJ PV-1 (or H H Scott LK-72 if I can't get the CJ pots unstuck)

Bryston 2B

Harbeth HL Monitors

Thorens TD-165

I see mono cartridges that have 2 pins out and 4 pins out; the 4 pin people (Grado) say just use one pair but shouldn't a single generator moving in just one direction need only two pins? I'm confused...

Ok, after that it's a single RCA cable to the preamp and a single RCA cable to the amp and single speaker cable to the (single) speaker, correct?

Where should I set the Stereo/Mono and Balance knobs? I guess that will depend a bit on the particular  preamp in question of course. Try and see is always a good way to go. Depending on how the preamp is wired it might be possible to use two speakers but isn't that not mono? 1950 hi-fi magazines say as much...

If you enjoy a mono system please share how yours is set up, or was set up if you've taken it apart.

 

*Please don't come here to poop on mono, or throw your weight around about how smart you are and how dumb everyone else is, it's childish and frankly, boring.

I'm interested in a positive discussion.

128x128tzed

lewm,

I believe the dealer had it between the linestage and the amplifier.  He had a very young tech who built the comparator box and would also make the mono adapters for customers (put them in various vintage component cases with RCA jacks).  I don't recall what specific transformers were used, but some were current production and others were vintage; the most expensive being Western Electric transformers.   Based on recommendations he found on the internet, he built one such mono adaptors using two transformers (both Western Electric transformers) and that was the best sounding, but a bit pricey. 

I have no idea why transformers with zero gain sound better than a Y connector, although I sort of have a theory.  I suspect that the transformers introduce some phase shifting that actually improves the sound.  

The impedances (input and output) seen by the two devices would be very different in transformer connected mode vs Y connector mode.  That also would affect SQ of course.  I am actually trying to figure out how you would do it with transformers interposed between linestage and amplifier.  When you say "zero gain", I presume you mean 1:1 turns ratio, so the transformer is in essence isolating one device from the other. One problem with using an external Y connector, either between linestage and amplifier or as is done more commonly, between the stereo leads from a tonearm into a single pair of inputs on a phono stage, is just that, impedance gets messed up, because the driven device sees the output Zs of the two driving devices in parallel.  And in the latter case, each channel of the cartridge sees the internal R of the other channel (in the cartridge) in parallel with the input Z of the phono stage.  A good linestage with a mono switch incorporates resistors to mitigate that issue, in mono mode.

You know a lot more than I do about this stuff; I just sat there and listened while someone flipped the switch on the comparator box.  There were two transformers that were very good and quite close in sound--one was the somewhat expensive Western Electric transformer, the other a much cheaper modern transformer--which made the cheaper transformer a "bargain."  I am not a mono system person myself, but I do see how it is more practical in certain situations where someone cannot sit in the ideal spot for stereo listening but wants good sound.  One of the buyers of the conversion box has a crazy nice mono setup built into his kitchen where a lot of time is spent.  He has a three way system with a field coil woofer, a Western Electric 713b midrange compression driver (my personal favorite compression midrange driver), Western Electric 32a horn, and an RP302 tweeter.  

I’m a "one ear" since the age of eight. I don’t hear stereo and have no directional hearing except by trying to discern the direction of the loudest sound. I do, however strive to make my hi-fi sound the way music does in the concert hall or opera house. A forlorn struggle, but there’s no reason not to try. So I’m good at analysing the quality of sound, if not the solidity of the stereo image.

Having some mono LPs, not so much deliberately collected as just acquired along the way. They go from 1951 Furtwangler up to mono releases of the Beatles and Moody Blues in the late 60’s. Having discovered for myself that proper record cleaning is the biggest upgrade of all, I was intrigued to learn that a mono cartridge sensitive to lateral movement only could reduce surface noise dramatically, and be more dynamic. I had to find out, and I believe it is true. True enough that having bought one decent mono cartridge I’m now getting an old favourite stereo cartridge rebuilt as a true mono pickup just to see if it will be better still.

All this is entertaining and fun, but if I weren’t mostly an analog guy I don’t think I’d bother. I have some mono CDs, but when I had a mono switch (I don’t now) I couldn’t tell the difference when playing them. I do use Y-connectors rather imaginatively to make my headphone amp feed both signals into both ears, otherwise I’d hear only one channel and that’s no good.