L-Pads. Speakers Awful Without Them, New Ones Ordered
I just found Bob Crites web site https://critesspeakers.com/electro-voice-crossovers.html email: bobcrites@gmail.com I wrote and asked for prices for new diaphragms for 62 year old horns; new x336 three way crossovers; new AT37 L-Pads |
Erik, Scoundrel Thou Art. The other thread was about my 16 ohm speakers, my amp having 16 ohm taps, and sadly it’s bias adjustments only with the bottom off. Maintenance, I found the wires of the original L-Pads fried when I blew the tweeters blasting In-A-Gadda-Da-Vida. Replaced them, 16 ohm L-Pads were easy to find those days. lewm made me remove them. As long as they are out, sounded terrible, thought I would find better ones to re-insert. 16 ohm no longer easy to find. Hooray for Crites, they seem to be high quality, Lewm, Did I forget the punch line: I’m lazy. Seriously, I try to think long: For me, I prefer the ability to tame the tweeters now, and easily achieve progressive boost, speck by speck, as my ability to hear highs diminishes. I die, Donna, who loves them, might move in with her twin sister, then give them to my son Chris. Who knows who and where they will be in the future. That’s the beauty of Balance Controls of any kind. ................................................... Making new speaker cables has led to a full ’long’ look at these speakers, what should I overhaul? Spares?. To keep going for the next generation, people who know nothing except they sound great. Woofers: just replaced one 15W with dried out paper cone (near the hot-air wall vent) with my re-coned spare; bought a recently re-coned 15W; bought a cone kit for my dried out one, will have a spare pair. Horn Mid: Original, 62 years old still sounding great, 1 spare downstairs Horn Tweeters: T350’s, 16 ohms at least 50 years old, pair of spares downstairs. (not sure if 16 or 8 ohm versions). And, a spare pair of the original tweeters from 1956: smaller T35b’s, 16 ohm (early smaller magnet than later T35’s) They were re-coned by E-V many years ago after Iron Butterfly blew them. That’s when I put the T350’s in (and cut their +3db higher efficiency/output with you know what). How can the diaphragms of these 62 year old horns still sound great? E-V said: "virtually indestructible phenolic-impregnated linen". I asked Bob Crite’s son, he said, yes, if working leave them alone, they can last forever. Crossover: Original x336, tar filled can. Crites says leave them alone. I can easily revisit that later. Given that I am leaving the crossover, horns, re-coned woofers, I don’t think lewm or many of you would qualify any part of these ’best’, and in context, I think real 16 ohm L-Pads fit right in with the other decisions. yap yap yap, even I’m getting tired of this |
while searching, an E-V Mode Control https://www.ebay.com/itm/ELECTROVOICE-STEREO-CONTROL-MODEL-505-NOS/124521379996?hash=item1cfe0d789c:... |
atmasphere 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. Like pots in receivers, The original Electrovoice AT37’s were attenuators: 0 being no attenuation (just a solder joint), 1-9 progressive cut of signal strength. IOW, no boost, no center position, simply cut the signal. Unless you design the system with 5 as normal. My original Fisher’s AT37’s, the system seems to be based on a center position of the attenuator, say 5, then it’s + or - was toward zero or toward 9 (more attenuation/less signal; less attenuation/more signal. After the crossover, not altering the response of the driver in any way, just it’s volume, which is why they are not as bad as purists make them out to be. ?. |
lewm I value and learn from your knowledge and advice, (even if I don’t take it). Sometimes I can anticipate your reaction, which is why I specifically said no to resistors in original post which you caught the second time. Another thing you missed, I AM currently using the treble control, of the Chase RLC-1. It is last in the chain, gives me remote control of everything. It goes directly to the Cayin amp.. As always, I can tweak any track, now using it’s treble. 1st time I ever used it’s tone controls. For fun I will mess with it’s bass control today, Not 1812, but some Ray Brown with Stan Getz I was listening to yesterday after I tamed the shrill beasts. Chase treble is doing a very good job, surprising to me, I thought it would take too wide a band and the sound would go dull. Happily it has returned the sound to pretty darn good. Did you read the seller’s description of vintage, currently common, and his pot design? It is interesting, he does seem to know what he is doing. Before buying I clicked on the right ’see other items’, it’s extensive. |
These risers tilt the speakers back to aim the tweeters at seated ear level https://critesspeakers.com/heresy-slant-risers.html |
intactaudio I looked up L-Pad, I see what you mean about 2 stages to maintain impedance shown to the crossover (or amp). https://en.wikipedia.org/wiki/L_pad The original electro-voice AT37 Attenuator was indeed an L-Pad, maintaining a 16 ohm load to the crossover. (AT38 was the 8 ohm version) I remember it having the dual 'stacked' design. https://products.electrovoice.com/binary/AT37%20and%20AT38%20EDS.pdf I replaced them years ago with 16 ohm L-Pads, (also dual stacked design) the ones I just removed, I still have them. The speakers sound awful without them. When I wanted to put level controls back in, why not new? I searched and found the ones I ordered, not understanding about constant impedance shown to the crossover. They do seem to be a single resistance design, thus they would vary the impedance shown to the crossover, thus affecting the crossover frequency. Their screw terminations mean I can avoid solder, try em, keep or return them. |
intactaudio This is a new separate discussion, but it came up in an earlier discussion, I removed them based on advice in that thread. So, this was an answer to everyone: I tried, it sucked, I need em. If you scroll down the E V Six link, the wiring diagram at the end shows 5 selectable resistances for the tweeter and midrange together. It has to be a rotary control with 5 specific positions. I posted a find of an E V Six, local pickup only in CA, great price. If I lived there, I would be over there in a heartbeat. Posted here, some response. Posted on the Speaker Forum, not a single response. I am not known there. I have friends here that help me with everything I do. You have been helpful here also. I like it here! |
I just spoke to Bob Crites’ son, (I think he said Mark, my memory sucks, I should have asked) They are still doing business. Two boards, a pair of real 16 ohm L-pads each, $100. + tax/ship. https://critesspeakers.com/electro-voice-crossovers.html I am going to return the ones I ordered (they already shipped), and buy these. |
atmasphere "What you’re looking for is the driver to blend with the other drivers, resulting in flat frequency response". 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. I say: speakers in generally advisable position and toe in first. Tilt/aim tweeter at seated ear height; then L-Pads for listening spot; then if nodes, problems, sound treatments. Move them to another space: L-Pads to the rescue! Too many people, without L-Pads, have to resort to, perhaps need to over-do room treatments!locations. That’s what I mean by Functionality/Flexibility may be better than perfection offered by a single resistor. Even better: Advanced L-Pads by Electrovoice, for their 4 way systems like this E V Six https://products.electrovoice.com/binary/E-V%20Six%20EDS.pdf had L-pads with 4 or 5 switchable positions, each a specific resistor, that controlled the tweeter and mid range together. Separate Low Bass and Upper Bass drivers with no level controls. Of course, a specific resistor requires no maintenance, whereas L-pads and their contacts require maintenance. |
oldhvymec I agree, before I hook up a vintage piece, I take off the bottoms, tops, sides, anything removable, especially the face plates in my shop, You need face plates off for real access to the pots and rotating contacts. Then hose the pots and controls of tape recorders, tuners, receivers, amps, preamps with contact cleaner/lubricant, blow dry with compressed air, repeat. Then, frequently, while in the system, I swish em full spin back and forth, keep the contacts clean, re-check balance after doing this just in case. I also tend to leave my preamp volume set, zero noise, and use more modern equipment's volume control up/dn from there. Surprisingly, all my tube stuff is and has been dead quiet, My McIntosh SS C28 preamp, noise started at 11 o'clock, that's another reason I like my Remote Line Controller. Another reason to have efficient speakers, to keep the volume/work of the components in a lower state. |
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. .................................. 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. ………………………. 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? ……………………….. 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 .................................. 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. ……………………………………… 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. ............................................. 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 |
lewm, Yes, it occurred to me I could make a 5 ’step-type’ resistor type as you would surely prefer. Would have to, but could find the ’exact’ resistors for my specific driver’s (not the SIX). Figure out the mechanics for changing individual selection. It would not be inexpensive. Or, stick with a simple progressive level of adjustment via proper high quality L-Pads. After 46 years designing Corporate Offices, each plan, decision, budget, schedule, light fixture (I designed my own frequently), hvac system decision (I hired my own engineers), each item selection the ’best’ choice I can find/make for clients: when I retired I decided to leave the constant search for perfection behind. These things worked well then and now, you know I like vintage, not to mention I have two 1-3/4" diameter holes in each speaker’s rosewood back panel. High in the rear corners where I can reach them without moving the speaker out of position. I will transfer what I buy from Crites into my original face plates. Fisher’s Recessed Cup and push on knob, both Bronze. They fit these 4 holes and recess into the 3/4" back panel. I will position them, not like EV AT37’s were, 0 to 9, but as Fisher did: up is center attenuation, then up or down from there. These drivers/this 3 way system was originally designed to perform ’normally’ in the center of the attenuation range. That’s why they are so screechy without attenuation. |
OH YEAH! New 16 Ohm L-Pads installed, back to wonderful (more wonderful?). .................................. the whole story 1. Ruin a good thing: L-Pads removed as advised. Actually, they were 8 ohm pots, I didn’t know better way back when I replaced the original 16 ohm L-Pads. The Pots worked as needed, but altered the resistance shown to crossover, whereas the original L-Pads maintained 16 ohms shown to the crossover. Speakers without controls were very screechy, horrible. Used RLC-1 to cut treble, at least sounded listenable while looking for a solution. 2. Research: The Fisher President II I inherited used all Electro-Voice drivers, L-Pads, Crossover. They are in my new enclosures. The Vintage Fisher consoles, and Electro-voice speakers were designed with L-Pads: AT37 (16 ohm) or AT38 (8 ohm). Two way had 1; Three way had 2 (Brilliance and Presence, like mine). Adjust from Normal for room and personal taste. NORMAL Room: Center position: Half attenuated. LIVE, BRIGHT Room: add attenuation progressively DULL, DEAD Room, reduce attenuation progressively EARS AGE: reduce tweeter attenuation as ability to hear highs progressively reduces. Model EV-SIX had a unique 5 position step-type attenuation control using resistors. As they were not progressive, 5 frequency graphs were shown in the engineering bulletin. 3. Re-install new L-Pads: Ordered High Quality Pots, thinking they were L-Pads, returned them. Ordered 16 ohm L-Pads. Installed L-PADS yesterday. RLC-1 tone control back to neutral. OH YEAH! |
Recently, for fun in another thread I went to hifishark, searched: Vintage Speakers, sorted price high to low. I found MANY vintage speakers that provided adjustment, L-Pads, rotating or sliding switches, changeable connections to resistor boards, MANY, IMO, it is wrong not to provide a means to adjust 2/3/4 way speakers in their listening space. Mine are quite difficult, but precise stepped resistor networks ought to be easy enough. |
fiesta, did you read this whole thing, or just respond to my recent post? Ideally resistors are 'better', but in practice, I'll settle on quality L-Pads for their flexibility. modern makers are not offering any methods to adapt to the unknown space their speakers TRY to be perfect in. Maybe they all own stock in room treatment companies! I found the resistor network Electro-Voice created for the E-V Model Six, higher up in this thread. 5 specific switchable response curves! L-Pads are infinitely adjustable, notched L-Pads would be nice because they are hard to match L to R. Anyone can twirl a dial, make a decision that's right for them, they cannot make a resistor network for themselves, and then not adaptable as we age and out hearing shifts. |
fiesta75, please don't refrain from commenting, that would be a loss. I certainly did not mean to be negative, I just wondered, because it's old and long, and your comment is succinct. I'm glad you commented, I just wanted you to see some of the vintage info I found earlier in the thread, and add that very many other designs had built-in frequency modification capability. i just caught you said fixed resistors 'on switches', which is exactly what the E-V Model Six uniquely had, 5 precise resistor based switch positions. I want that! It took me a month to make final (did I say final) positioning of my L-Pads. The speakers sounded HORRIBLE without them, because the crossover and frequency response was designed with 50% attenuation of the AT37 controls as normal, leave it, boost or cut as needed. Without them (as some advised) the mid horn and tweeter horns were full out over the unchanged woofer. HORRIBLE. My current contention is to resurrect the past. You said "With older speaker designs L-pads were needed to make the speakers more versatile." I contend we need modern better options to adjust new speaker designs, making them more versatile. |
