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I have two SM transmitters that I bought two months apart and they seem to have different gains. Why does the newer one have 10 dB more gain?


On the side of the newer units, on the blue metal strip, you should see a +10 dB marking indicating that these units have an increased gain compared to your older units. Here's what we said on RAMPS (What is RAMPS). Though a little long it explains our rational to making the change and what some users were seeing as far as typical gain settings on the SM transmitter. We didn't make this change lightly because we knew it would cause some confusion. Below is the slightly edited version of the RAMPS thread. The actual thread is at Link to RAMPS thread. We kept the display at 0 to 44 due to memory limitations.

Larry Fisher Sep 6 2006
To the Group: 
After some 6 months or so of field experience with the SM transmitter, we are strongly considering increasing the overall gain of the SM and SM series transmitters by 10 dB. This would increase all input configurations including line level input. The display would now show 10 to 54 dB of gain rather than the current 0 to 44 dB. The same displayed numbers for gain would represent the same gain on either version, i.e., a setting of 30 dB would be the same on either version. Equivalent input noise, response, limiting and so forth would not change. 

From what I've read on RAMPS and various emails, indicates we are a little light on gain. Also, I think some users don't like running the gain at maximum levels even if that is the best setting in a given case. Any and all feedback from the real world would be appreciated. Best Regards, 
Larry Fisher 

Scott Farr Sep 6 2006, 9:27 am 
I run my SM transmitters at 38 on the gain setting never any higher and I am using TRAM TR50's 

Larry Fisher Sep 6 2006, 10:13 am 
Thanks Scott, 
You are within 6 dB of full current gain (44). You would still set the transmitter to 38. What is the lowest you remember setting the transmitter? 

Scott Farr Sep 6 2006, 11:10 am 
I think around 32

wyatt Sep 6 2006, 12:05 pm 
I am using 8 SM transmitters on my current production. I am using an assortment of lavs, and my gain settings varry accordingly. The lowest gain I have used to date would be 24 using a cos-11, outdoor scene, times square. the highest would be 44, indoors, using either a b6 (grey band) or a TR-50 (i dont quite recall which at the moment). My normal operating gain for a cos-11 has been between 29 and 31. I think a gain increase would a beneficial improvement, especially considering that you can get most of the lavs that we, as soud mixers, employ daily with attenuated output levels. I have yet go below 24db on my transmitter gain.
Wyatt Tuzo

Larry Fisher Sep 6 2006, 2:29 pm 
Thanks Wyatt, 
More good info. 

Scott Smiith Sep 6 2006, 8:20 pm 
This is something I have noticed as well (although the output of the mike used definitely plays into the equation). I would say at least 6 db would be helpful, and there is certainly nothing wrong with 10 db, as long as it doesn't risk overloading the front end preamp. Scott D. Smith C.A.S.

Larry Fisher Sep 7 2006, 12:13 pm 
Hi Scott, 
When the gain is set to minimum, even with the additional gain, the SM will still require 250 uA of peak current from the mic before the limiter even begins to engage. This would require a lavaliere that pulled 500uA of bias. This is higher than any pro mics we have measured. Another way of saying this is that at minimum gain, any known lavalliere will run out of bias (clip) before the limiter starts to limit let alone overdrive the preamp. Further, even at minimum gain there is still more than 30 dB of limiting before the limiter gives up and allows the preamp to overload. As I said earlier, I think we were being way too conservative on gain. Field experience seems to be bearing this out. 
Best Regards, 

LaFayette Sep 8 2006, 3:20 am 
Greetings Larry,
Would this be an upgrade mod on existing units or only for new versions? 

I've set mine from 30 w/ Sankens outdoors to 38 w/ Sonotrims indoors. It has been suggested to go w/ red dot Sankens since the regular ones tend to be hot w/ SM's. Although, I also hear that the Sankens wired specifically for the SM sound better anyway, more low end. Should I save my money on new Sankens and just buy the upgrade on the SM? Cheers, S.L.

Larry Fisher Sep 8 2006, 4:42 am 
There is no downside to running the current SM at maximum gain or close to it. Performance of the current units at 44dB gain (wide open) will be exactly the same as the new units at 44 dB gain (10 dB left). So if you have sufficient gain now to handle the mics you have, then it is not necessary to change the units. This is not a necessary "upgrade" and won't be automatically done to units in for other repairs unless the customer requests it, unlike mandatory upgrades that we always make to repairs. Mandatory upgrades are due to a mistake we made and are done at no charge. 

Older units can be changed to the new gain structure and corresponding firmware. There will be a $70 charge to open, test and reseal the unit. This is the same as for the RM addition mentioned earlier on RAMPS. On the other hand, you can get both done at once for the same charge. Depending on the age of the SM you may also pickup a new emulation also.There is no charge for the firmware and new value resistor themselves; just the work involved in opening, closing, sealing and testing the unit. If we are already inside a unit for other reasons, there will be no additional charge for the gain change. As I said above, the customer must request the change since if they are happy with the current gain structure, we are very satisfied to leave it alone. 
Best Regards, 

morantzsound (Steve Morantz, C.A.S.) Sep 9 2006, 11:35 pm 
I was told when I bought my SM's anywhere form 24 to 30 was average. I usually stay around 27 or 28 and make adjustments at the board or Deva. It has worked pretty well for me, but will start experimenting with higher outputs. 
Steve Morantz C.A.S.

Posted 1 year agoby LectroAdmin