LarryF

As an indication of the Freedman Group's intentions for Lectrosonics, the Human Resources Dept has been tasked with hiring more Design Engineers, as many as 7 total. See: https://lectrosonics.com/careers/ Best Regards, Larry Fisher

I ran a second test of the XTAR batteries in Lectro equipment to see if I heard any artifacts or interference from the internal power supply built into the XTAR batteries. They have to knock the 3.7 Volts of the lithium battery down to the normal 1.5 Volts of a typical AA battery. I used the IFBlue pocket receiver with two XTAR AA's and an SM transmitter in IFB mode also with an XTAR battery. The IFBlue receiver is all plastic so there was not any shielding between the two batteries and the receiver circuity. I figured if I got any weird results I could go back and do the batteries one at a time to find the culprit. Since Gordon [see post above] had found a very low level artifact, I listened for the same thing by setting the transmitter gain much too low with a very low audio input signal. The IFBlue receiver had its gain turned up to make hearing artifacts easy. There was a fair amount of hiss evident but nothing unusual. I also noted the drop out points walking the through the house. The antenna on the transmitter was a bent safety pin since Gordon hadn't brought an SMA antenna. I used a safety pin because I didn't want to damage the female SMA pin in the transmitter and a by product was that the adobe walls of the house were very effective at creating dropouts. I noticed no artifacts. Switching out the XTAR batteries for some NiMh batteries did not change any of the results; noise levels were exactly the same and the dropouts were within inches of the XTAR results. So in sum, the XTAR batteries seem like a reasonable substitute for NiMh batteries, with better life and a much better warning of needing replacement within an hour. Best Regards, Larry Fisher

Here is some info about the XTAR batteries in a test run by Gordon Moore at his church. " I put the batteries in two DHU handhelds used by singers. Gain was 22. Recorded bell choir, level deliberately low because I wanted to add significant gain in post to reveal any noise. "One transmitter had a birdie at 1.2Khz that was very low. I had to add 30dB to the signal to hear it. At nominal levels, it was not audible. Very tight, like a sine wave. A filter set to a Q of 15 at 1.2Khz knocked it out completely, no harmonics. "The software based spectrum analyzer did not even register it on the chart -80 floor. "The second handheld has nothing audible at any gain level. "Sorry didn't record the RF freqs in which they were set. "Neither unit had any audible artifacts with NiMH batteries. "At normal gain structure, I wouldn't hesitate to use these batteries. If I had to record something very weak with lots of gain across the entire signal chain...not so sure.... I should note, since the artifact was a VERY tight single freq sine wave, it was very easy to notch it out. "I'll bring the batteries and the IFB to lunch Tuesday. Gordon"

My measurements of the four XTAR batteries and the LC4 charger show 3.39 Watt-hr at a 400 mA load. All four batteries were within 1.5% of the same capacity. A Lectro SM transmitter pulls 490 mW at any Voltage from 1 to 1.5 Volts. That would be a 6.9 hour runtime, agreeing with Richard's results. There would be a little over an hour where the transmitter would continue to operate with a red or blinking red low battery indicator, plenty of time to make a battery swap, unlike NiMh batteries that simply announce "I'm out of here!". A 2 Amp discharge maintains Voltage but capacity drops by 26% to 2.51 Watt-hr. A 1 Amp discharge drops only 8% to 3.12 Watt-hr. A low 200 mAmp rate improves capacity 3% to 3.53 Watt-hr All this to say, running a single battery transmitter is in this battery's happy spot. The LC4 charges a single dead battery in 2 hours and 40 minutes. Charging four dead batteries at once requires 3 hours and 24 minutes. For capacity comparisons at the 400 mA discharge rate: XTAR = 3.4 Wh (7 hr) Eveready Ultimate Lithium = 4.39 Wh (9 hr) (30% longer) Eneloop Black = 2.46 Wh (5 hr) (28% shorter) So not as good as a premium Li-Ion but better than a high quality NiMh Next week, I'll try to get some range tests using the XTAR in receivers. No promises since things are a little in flux at Lectro, as they adjust to being part of a 50 times larger company. Best Regards, Larry Fisher

I discharged 4 XTAR batteries (one twice) with a 0.400 mA load. All the batteries had power capacities within 1.5% of each other with Voltages within 2% of 1.5 Volts. It is pleasing to see such consistency. It took 2 hours and 40 minutes to fully charge a battery from full discharge. I'll try the same thing with 4 dead batteries simultaneously in the LC4 charger. All of the batteries gave an hour or more of low battery warning, i.e., the output Voltage fell from 1.5 to 1 Volt. This was a step fall, nothing gradual about it. Lectro transmitters will soldier through this drop. I am discharging a battery at 2 Amps at the moment and will post the results along with the 4 battery charge time. So far I am impressed. I hope other users will chime in over time and let us know real world results. Thanks to Richard Patterson for the heads up. Larry Fisher

I did the first Xtar rundown at a 400 mAmp discharge. My numbers confirm Richard's experience. The total power was 3400 mWatt/hr, which is below the manufacturer's rating of 4150 mWatt/hr. They may do better under a smaller discharge current. Richard's run time of 7+ hours is right in line with my readings. The battery did give a 1+ hour warning by dropping the Voltage to 1 Volt. Lectro transmitters will typically still deliver full performance at below 0.9 Volts. So the transmitter would show green for 6 hours and then go red blinking for 1 hour. If you don't want to think Watts, the XTAR Amperage rating would be 2.43 Ahr but this is maintained at the full 1.5 Volts so the transmitter switching power supply will pull less current than from a battery whose Voltage falls as it is used. Remember that NiMh batteries are only 1.2 Volts during most of their discharge so to compare them to the XTAR battery, you have to increase the XTAR equivalent Amperage by 20% or 2.9 Ah. If you like to think in Watts, a typical good AA li-ion battery is 2.75 Watt/hr vs the XTAR 3.40 Watt/hr I am running a second battery down now. Larry F

As another opinion, RODE may be the best thing to happen to Lectro in this decade. After Covid19, various strikes, parts shortages, tariffs on certain critical parts and with sales outside the U.S. looking "unfriendly" , Lectro could use an enthusiastic owner with huge {!!!} resources. I have been with Lectro in various positions for 50 years and I think RODE is a positive thing for our brand, our employees and our customers. Larry Fisher Lectro's Previous President and sometimes Janitor

Just started the rundown about an hour ago. This week has been pretty busy. Larry F

That is interesting and good to have the warning. I might get the crew to test them in the IFBlue body pack receiver and see if there is a reduction in range. The plastic body will provide very little shielding between the battery and receiver guts. Larry F

I have ordered some from Amazon and will do run down capacity tests this weekend. Sounds interesting. Larry F

I couldn't find a schematic for the mic, even on the Shure site. Wiring 2 jumped to 4 will increase the pin 3 bias to 5 Volts equivalent, which might give you more headroom. I am kind of in the dark without a schematic. LEF

From the Lectrosonics FAQ section under Support: The Sanken CUB-01 boundary mic does not seem to have the usual FET output stage and also seems to have a large capacitor across the power supply lead (bias lead). This means that it can’t be wired as the usual three wire microphone with the SM. The wiring below seems to work well and is fully compatible with our other transmitters. Our pin 1 to Sanken shield (ground). Our pin 2 to Sanken black wire (5 Volt power). Our pin 3 to a 511 Ohm resistor and the other end to Sanken white wire (audio). This matches well to our 300 Ohm input input while providing a satisfactory 811 Ohms to the Sanken mic. Our pins 4 and 5 no connections.

Yes, the resistor is a requirement. Newer digital Lectro units have the resistor in the transmitter and switch it into circuit when DPA is menu selected. Best Regards, Larry Fisher.

You can certainly do that. The transmitter has enough gain range to handle a minor 6dB change in level. As you asked, you just need less gain in the transmitter. You won't lose 6 dB of SPL handling in the mic since the servo circuit in the transmitter will compensate for the decreased or increased current draw of the mic as you vary the resistance. Best Regards, Larry Fisher

Any value from 2K to 4K is just fine with the lower value giving 6 dB more output. 3.9k is a standard resistor value. Best Regards, Larry Fisher

It shouldn't be RF overload. Those model units were tested for overload with the transmitter and receiver antennas touching. The receiver AGC circuits were checked to make sure they had more than enough attenuation capability in the receiver to prevent any possible of RF overload. It's a good thought though, since some digital systems are not as forgiving. Best Regards, Larry Fisher

Also, cable losses at UHF would become a big factor as you stretch cable around a set. LEF

Many years ago, I setup a leaky antenna system and had poor results. As a receiver antenna, it has very low gain and depending on the placement, any weak signal picked up "leaks" out before it gets back to the receiver. As a transmitting antenna, it has very low radiation efficiency. The reason it can work in a tunnel is that it's the only practical, cheap way to get a uniform signal into a tunnel. In a tunnel setup, you can use a relatively powerful, AC powered transmitter that overpowers the poor antenna efficiency. That could work on a set if you used a booster amp (Probably not legal). Trying to use a 50 mW transmitter with a leaky antenna would give poorer results than a good medium gain antenna at the transmitter. YMMV Best Regards, Larry Fisher

The SNA600a is 2:1 only at the band edges. When defining bandwidth, the 2:1 value is a commonly accepted bandwidth definer. Inside that bandwidth, the SNA600a SWR is much lower on the order of 1.2:1. Keep in mind, a tunable bandwidth may be useful in attenuating undesired RF. "Different horses for different courses" . Best Regards, Larry Fisher

The headphone output is quiet and can be used as a line level (1 Volt) output. It is just lower impedance than most line level outputs, which is never a bad thing. I'm missing what is the reticence to use it as a line level output. (??). It's a minor point but G3/G4 receivers do not have matching equalization and compander time constants to the Lectro IFB. It certainly will work, though. Best Regards, Larry Fisher

The loss at our frequencies is on the order a quarter of a dB or less. In sum, fuggedaboutit. LEF p.s. Buying two 50 foot cables and using a coupler to make an occasional 100 foot cable is more space efficient and cheaper than buying a 50 and 100 foot cable.

Hi Derek, The EBL batteries have 95% of the Energizer runtime. For instance, if you have 6 hours of run time on the Bunny Brand, that's 360 minutes. The EBL 95% is 5% less time or .05 x 360 =18 minutes less. So you'd have 5 hours and 42 minutes compared to 6 hours. Or you can just subtract 1/20th of the run time. Regards, LEF p.s. The reason I didn't do run times is we have many transmitters at various power levels and single and dual batteries. In retirement, I'm getting to be pretty lazy.

I bought some disposable AA lithiums from Amazon and tested for power capacity. Total power was a better benchmark since average voltage and Amp hours varied by 8% or so across the three brands. Total power makes more sense due to the switching "power" supplies in Lectro transmitters, since they are like a DC transformer with power in equal to power out (less small losses). I bought Eveready as a reference, NINMA since they claimed 3500 mAh, and EBL since I recognized the brand as a larger seller of battery products. The testing rig was a computer controlled battery tester made by West Mountain Radio. The test current was a constant 400 mA similar to Lectro transmitter current drain. I also calculated cost, corrected for power capacity using prices off Amazon. Amazon has coupons and scheduled delivery discounts that will vary over time. The corrected costs are as of today, 15 Oct 2023 for 24 batteries purchased at a time. Eveready Ultimate Lithium: 4.418 Watt hour 100% (reference) $2.79 2.79 corrected EBL Lithium: 4.212 Wh 95% $1.62 1.70 corrected NINMA Lithium: 4.146 Wh 94% $1.75 1.86 corrected Conclusions: The off brand lithiums would be a cost viable choice if you don't need the last few minutes of run time. A situation where NiMh won't run long enough but an Eveready Lithium is more time than you need. The NINMA brand had the highest current capacity but the average voltage was 8% lower. That reduced its power capacity. Eveready had the highest average voltage making it the highest capacity. EBL had good current and voltage putting it in the middle. EBL was the most cost effective. YMMV Best Regards, Larry Fisher

3500 mAh is correct

The difference is in initial battery voltage. The lithium is higher voltage so the current draw is lower due to the fact that the power supply in the unit is a switching power supply. Switchers convert power in to power out. So a higher voltage can draw less current for a given power in. For instance, a switching power supply running from a 12 Volt battery could draw 5 Amps and put out 5 Volts at 12 Amps, if it were 100% efficient. 60 Watts in for 60 Watts out. The switchers we employ, are chosen for high efficiency of course. All this to say, if a unit needs 600 milliWatts to operate, that would be 500 mA at 1.2 Volts (NiMh) but only 400 mA at 1.5 Volts (lithium). And all this is complicated by the fact that the lithium starts out at 1.5 Volts and then gradually falls to 1 Volt or less before dying and the NiMh stays at 1.2 Volts until suddenly collapsing. Best Regards, Larry Fisher