Dave,
thanks for the clarification, I yap about an issue but have often been ignorant/wrong when it get’s technical. I wouldn’t recognize an ohm if it crawled out of my boot.
I always referred to these as Rheostats, Then some say Potentiometers, L-Pads, learning about changing/not changing what is shown to the crossover is specifically helpful here, thanks.
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BALANCE CONTROLS TO THE RESCUE
E-V SIX is very illustrative of this discussion and my decision to put mine back.
It is a 4 way system with a 5 ‘STEP-TYPE’ Balance Control (5 selectable/specific resistor settings) 18" Woofer, how about that!
https://products.electrovoice.com/binary/E-V%20Six%20EDS.pdf
Back to E-V SIX
Page 2: ADJUSTMENT OF BALANCE CONTROL “precise adjustment of the system to room acoustics AND personal tastes”.
Bottom of Page 2 is the wiring diagram, showing that the Balance Control alters both the Treble (upper mids) and Tweeter together, Bass and Upper Bass unchanged.
Position #3 ‘Standard’ rooms; #2 and #1 are ‘CUTS’ for ‘hard/live’ rooms; # 4 and 5 are ‘BOOSTS’ for soft/dead rooms.
Page 1, Figure 1, shows 5 frequency lines, each selector position and it’s resulting frequency graph.
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IMO, PERSONAL TASTE should also be understood as ‘a specific listener’s hearing ability: ‘live or soft’.
FMC: The Fletcher-Munson Curve shows that our hearing ability, effecting personal tastes, changes as we age.
CHANGE: the rooms furnishings may/probably will change, or the speakers may be moved to another room, more dead or alive.
AVERAGE is FAR FROM EVERYBODY; can be SOME, NOT MOST. FMC, like shoe size or desk/chair height, or hearing ability, is an average. I just had a hearing test. My lows are ‘un-characteristically’ still flat, mid to low highs ‘normally’ flat, upper highs decline progressively, ‘normally’. Thus I’m ‘near average’ What about you, or him or her?
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EARLY E-V systems: 2 way have 1 Balance Control; 3 way like mine, have two Balance Controls: ‘BRILLIANCE’ (only effects the Tweeter) and ‘PRESENCE’ (only effects the midrange). Quite often highly efficient horn systems.
E-V literature of AT37’s and AT38’s describe them as true L-Pads, maintaining 16 or 8 ohms shown to the crossover.
https://products.electrovoice.com/binary/AT37%20and%20AT38%20EDS.pdf
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IMO they are an asset, not a detriment. I ordered simple coil type which affects the crossover. Thanks to input from Dave and others I will return them and order true L-Pads with constant 16 ohm shown to the crossover.
https://critesspeakers.com/electro-voice-crossovers.html
I spoke to Bob’s son yesterday, they are still in business.
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Using Balance Controls was easy in the MONO era, but for a STEREO PAIR, matching L to R is far from easy. I have often said, I value/need my McIntosh MODE Control to achieve matching frequency performance L to R; Volume Balance; Room Balance. Then remotely adjust volume and occasionally refine a specific track’s balance via my Remote Line Control. Now using RLC-1’s Treble control while waiting for my new L-Pads to arrive.
And, MONO or STEREO, they need maintenance perhaps replacement over time.
Aside from costs, I think it became hard for manufacturers to trust their use and maintenance to the general public. Hard to trust that in an given user’s space, unknown acoustics, unknown adjustments, that they would sound ’proper’ to any/everyone who might decide to buy/not buy them.
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Oh yeah, the listening position diagram, 30-40 degree angle, is quite interesting. Mine is similar, but with toe-in, which I adjust for wider center for pretty decent imaging 2 listeners.
Elliott
