16 ohm speakers: any amp sounds better with more resolution. speaker cables less critical.
boothroyd Yes, I will be watching Steve, then do it myself after that. I dug out my Multimeter, took apart, cleaned it up with contact cleaner .. fresh batteries, and realized, I have no idea how to use it. Tandy, Micronta, 1990, I found the manual in my fat 'instructions' folder. You know I like Vintage stuff. What holes do I plug the cables in? What big center wheel setting? What adjust little pot to? I'm bringing it with me to Steve's. |
Elliott - The multimeter will be set to Volts DC. Things are really well laid out internally and easy to see with the bottom cover removed. The speakers should be connected (fairly certain 16 ohm taps are fine) and unit powered up while resting on its side which is quite easily supported by the structure. The multimeter’s ground lead is attached to the (-) negative speaker post of either channel to check the 2 respective output tubes (one of which has an Orange wire and the other with a Blue wire) associated with that channel. The reason I mention the Orange & Blue wire associated with each power tube socket is because that is where the multimeter’s positive lead will be attached for checking bias. Adjacent to each pair of output tubes is a small bias board with an evident blue plastic insulated bias pot for each power tube. As I recall, Steve said ~ 40millivolts is the optimal adjustment. Final adjustments are done once the unit has been powered up for at least 30 minutes for things to stabilize. The more we know and understand our equipment, the more we enjoy it! |
boothroyd thanks I was going to hook up my shop speakers, they are small 8 ohm, does it matter? is any load good enough? or, I avoid carrying the 55lb beast, just disconnect inputs, flip it on it's back, have at it. I've seen inside, took the cover off the hour I received it. Very impressive, and very spacious, easy to reach the contact points and adjusters. plangco here posted: 1. set his multi to 20V (as a preliminary setting, just to be in that range?; says spec is .4, he uses .35 to get longer tube life and slightly warmer sound. .4 what? how is .4 equal to 40 millivolts? is he saying start at 20, then increase to 20.4 or 20.35? I need brain surgery as previously discussed! |
@clio09 , Hi clio, I wanted better dispersion so that everyone seated on the sofa (watching movies) would have the same frequency balance. I am sure the Sound Labs will suit that purpose. ESLs are very simple devices. I suspect if there is going to be any change in sound quality it will be in the design of the interface which in the case of the Sound Labs has been upgraded on several occasions. Like any ESL they need the right amp to sing and I know I have a pair that suit wonderfully. We shall see. |
L Pads are Staying! Full on mid and full on tweet ((similar to removing them) was not good! I messed about with them for quite a while. It is again clear to me that these speakers were designed with the control of mid to woofer and tweeter to mid in mind. The center position is their designed default, then carefully adjust. Then, as I have said, getting L and R matched is not easy, but I have my methods and experience with them in different spaces/locations for 43 years, especially using McIntosh Mode control to move stereo/mono/l/r this way and that. Next: Cassandra Wilson; Annie Lennox; Friday Night in San Fran 3 guitarists; Andreas Vollenweider; War of the Worlds. Rare Earth, Mickey Hart, Oscar Peterson. The advantages are clear, they have sounded fabulous all these years, using the controls in the listening space is an asset, and as I age, as my/our high frequency hearing naturally diminishes, I will be able to boost the tweeter year by year. |
I messed about with them for quite a while. It is again clear to me that these speakers were designed with the control of mid to woofer and tweeter to mid in mind.@eliottnewcombjr A little trick you can do is mark the correct position with a bit of tape. Then about once a month or so work the Lpads back and forth to clear corrosion, and reset them to the original level you marked. BTW I'd be careful about using an analog mulitmeter when setting the bias on a newer amplifier (a vintage amp's bias procedure might expect that you are using a multimeter). A multimeter has a lower resistance than a DVM or VTVM (Vacuum Tube Volt Meter) and that can affect your reading a bit, how much depends on how high the voltage is (the higher the voltage, the more accurate they become) and the impedance of the circuit. Multimeters a nice to look at in a post-industrial world so to speak, but DVMs are actually easier to use and more accurate unless you get a junky one. If you want to use vintage stuff to do this task, get a VTVM and have it serviced out and calibrated. |
Ralph, I am not sure what you are saying, because the terms "multimeter" and "DVM" are so often conflated with one another. VTVM is a clear acronym, because you are talking about a vacuum tube voltmeter. But let's take my Fluke 87 meter. It is a "multimeter" in the sense it can read DC and AC voltage, capacitance, DC and AC current, and it includes a diode checker. But it is also a DVM in the sense it is digital and solid state. On voltage settings, it offers 20Megohm resistance across the leads. So, what is a "multimeter" and how do you distinguish it from a DVM? Or, why isn't my Fluke a multimeter? Folks like Elliot might benefit from this clarification even more than I. For sure, any respectable voltmeter can measure the -10V to -50V range of the grid bias voltage that is typically seen for most tube amplifier output tubes. |
A 16 ohm speaker was designed for high efficiency and damping when the amps did not have high damping factors because of high output impedance so they made the speakers that way to control the sound themselves and not rely on an amp to do it for them. the main benefit of that is that the speakers respond very quickly to the input from an amplifier in the micro dynamic sense because of this, they have a tendency to make the music come to life and breathe the air in the room turning your room into the studio where the recording was made. the key is to find the best recordings to play on them and when you do you will know it because the sensitivity of the mic that was used will match the sensitivity on playback and you will hear what you have been missing. |
Ralph, I am not sure what you are saying, because the terms "multimeter" and "DVM" are so often conflated with one another. VTVM is a clear acronym, because you are talking about a vacuum tube voltmeter. But let's take my Fluke 87 meter.If it has a digital display its a DVM and should have a similarly high impedance like a VTVM does. A multimeter is an older analog device with an analog meter. Its impedance is much lower and so its voltage measurements in sensitive circuits will be lower than actual (Ohm's Law after all...). I agree that 'multimeter' and 'DVM' are often conflated. |
speakermaster, There issome truth to your claim that 16-ohm speakers were more often the norm in the early days of hi-fi audio than they are now. And maybe the rationale did have something to do with the high-ish output impedance of the then prevalent tube amplifiers. However, I look at it the other way around: The current and rather longstanding trend toward 4-ohm speakers is the product of speaker designers insisting upon multi-way, multi-driver speakers, which inevitably requires complex crossover networks that typically will present a net low impedance load, because one is paralleling several different drivers that individually are likely to be high-ish in impedance, and because the networks per se tend to reduce net impedance. In other words, "speaker wars" (3 or many more than 3 cheap drivers in a box so one can claim a wide bandwidth of response) led to 4-ohm speakers. I admit that I hate the sound of such concoctions and wouldn't have any of them in my house. |
Nearly ALL brand new Zu Audio speakers are 12 - 16 Ohm ! Wonderful high efficient speakers, my favorite is Druid. Made in Utah, USA |
Dear friends: in other thread with main subject: all tube phono stage and audiophile named Wavestreams unit that by coincidence years ago ( along other audio friends. ) when I was traveling in California ( La Joya. ) I had the opportunity to listen it in a very good audio system at the home of the gentleman that hosted me and not only listened but we had a direct comparisons against two top SS phonolinepreamps ( one of them Dartzeel. ). Looking to google I found out a lot information on WSK and the designer and found out an interview with him where almost 70% of that inteview was centered to feedback what was for me an unexpected point and due that here the feedback subject was touched maybe for some of you could be interesting to read that interview: https://positive-feedback.com/Issue1/InterviewScottFrankland.htm Regards and enjoy the MUSIC NOT DISTORTIONS, R. |
I removed the L-Pads. I inspected the Woofers: Electrovoice 15W’s, 16 ohm from 1958. They have been re-coned twice so far, once a pro, 2nd time I did it! We have forced hot/cool air system. I suspected the left side woofer (near the heating vent) would be dried out, and it was. No holes, but paper was brittle. Other side surprisingly looked/felt an hour old. I put my re-coned spare in the left. I covered the heating vent temporarily, that will solve both heat and dust, I will buy a new register that opens/closes well, this one is from 1951, seals shot, hinge nasty. I'll have to see if it stays warm enough, and more importantly for me, cool enough in the summer. Of course opening it for cool air won't dry out the paper. now looking for a rebuild kit for Electro-voice 15W 16 ohm. Anyone know a source? thanks, Elliott |
