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L-Pads. Speakers Awful Without Them, New Ones Ordered

I removed the L-Pads, the tweeters are way too bright, screechy above mids. Disturbing. Played my best source: R2R, Sgt. Peppers. Normally magnificent. Unlistenable!

Using my Chase Remote Control to cut Treble temporarily, until new L-Pads arrive.

I ordered these 16 ohm pads:

https://www.ebay.com/itm/153892668925

mine don’t have the issues he discusses, my insulation is modern, crossovers are tar filled metal cans, not much heat in 6.3 cu ft; these and originals were large ceramic body.

Will put the tweeter ’Brilliance’ ones in first, listen. Then add ’Presence’, listen, decide: leave in, or out. IN more than likely. They (orig and 1 set of replacements) have been IN for 62 years.

My original bronze ones came from original Fisher console, they were a custom version, still labeled ’Brilliance’ and ’Presence’.
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Many of these old Electro-Voice designs had L-Pads (16 ohm used AT37 Attenuators; 8 ohm used AT38). 2 way have one. 3 way designs have two: ’Brilliance’ and ’Presence’.

You can balance the drivers to each other, and to each space, and as you age, ability to hear highs diminishes, you can creep the tweeters up speck by speck. Imbalance due to irregular spacing: adjust each individually

I’m not going to measure and install a fixed resistor, I want future adjustability.

’L-Pads: Terrible Idea’. Bullshite, everyone who ever heard them loves them!

And, let’s not forget, the originals, with L-Pads, first one mono speaker, later two for stereo, are the designs that made these companies successful.






elliottbnewcombjr

Showing 3 responses by atmasphere

atmasphere's avatar
atmasphere
11,574 posts
 
I qualify flat frequency: IN THE ROOM, at the LISTENING POSITION.

That’s one of the benefits of L-Pads, you buy from company specs, auditions in showrooms, get them home, they start out sounding different.
@elliotbnewcombjr   This is where I side with @lewm ; a tone control would be more appropriate for adjusting the system to the room rather than the driver level controls (although I do understand the temptation).


Proper room treatment works better and as you've stated, proper speaker placement too. Keep in mind that with only two woofers its likely that the bass won't be right, and if the bass isn't right the mids and highs won't be either. So it might be advantageous to add a couple of subs like a pair of Swarm subwoofers, placed asymmetrically in the room so as to break up standing waves that are likely to otherwise be present.
atmasphere's avatar
atmasphere
11,574 posts
 
You mentioned this before, L-Pads are for the amp, not the drivers.

I don’t understand.

Right or Wrong?

L-Pads, like any pot in a receiver, volume, balance, bass, treble determine how much juice, more or less, i.e. each one a signal strength control, modifying the amount of the signal it will pass to the amps (L/R).

To boost or cut bass or treble, they must be designed with a center amount of juice as normal, then pass more or less.

L-Pads like these are after the amp, in fact after the crossover. Aren’t they also just controlling how much juice, more or less, (after amplification, after basic crossover band filtering) i.e. modifying the output of individual drivers, thus how their volume blends with other drivers volumes.

What you're looking for is the driver to blend with the other drivers, resulting in flat frequency response. Generally there is no control for the woofer; usually the midrange and tweeter are more efficient (and are often different from each other in that regard).


The midrange might be 8 ohms while the tweeter might be 16 ohms. Or vice versa. If the amplifier has a high output impedance (which was common in the 1950s and before) then it will put out different power levels into 8 ohms and 16 ohms. So the level controls are there to allow you to equalize the levels to get flat response.





atmasphere's avatar
atmasphere
11,574 posts
 
If you have a treble control on your preamplifier, which I might guess you do have on the Mac MX110, then you can achieve much the same effect as with an L-pad.
@lewm This isn't correct. The preamp treble control won't control the tweeter output. Its a bit different. The reason the control is there is the same as on your Sound Labs (prior to your modifications); the voltage response of the amplifier is an unknown so the tweeter level (or midrange level) control is there to allow the speaker to accommodate the amplifier.


This idea took a while to go away- from the late 1950s till the early 1970s, by which time the idea of 'voltage driven' loudspeakers had taken over.


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