AM17 Current draw

[soundguy]

working on a pair of langevin am-17's tonight, have two units with the power bussed in series. I notice on my bench supply, that when its set for 24V output, with the two connected it drops to 16V. The unit closest to the supply sounds good, but the unit second in series is very hissy and noisy. I dont at the moment have a larger power supply to hook up, but is this typical behavior for pulling more current than what the supply can handle? Power supply works fine with other stuff, and the one unit closest to it sounds stellar. Never ran into anything like this before, what do you guys think?

dave

 

[CJ]

Something is goofy. If your supply dropped that much, something should have gotten real hot, or your supply is very limited. How big is the xfmr?

Feelaround for hot transistors in the AM17.

 

[electrog]

any further progress, soundguy? what type of psu are you using to get the required current together? would love to get some pics and details as you progress with this project. after a flurry of activity my own am17 has been put on temporary haitus until i have more free time again.

best

david

 

[soundguy]

yep, something is definitely goofy, I looked at it again yesterday and now the one unit is broken, just passes white noise. Im betting a transistor just went bad. I'll poke around tonight to see if I can figure it out. The other one sounds really good though, worth the trouble for sure.

dave

 

[wilebee]

hey dave when you remove the 2nd am17 from the power rails do you get 24vdc ? Wil

Wilebee

 

[soundguy]

yup.

Im not so sure how a bad transistor, even if shorted, could drop the power supply so much, does that send off any red flags?

learning something new everyday.

dave

 

[CJ]

The supply might have short circuit protection, or something that drops the voltage/current before the camp fire starts.

 

[JLM Audio]

The AM17 from memory draws about a continuous 1A each as they are actually fully Balanced Class A power amplifiers but with 600ohm outputs that can drive +36dBM output. I do have the full specification sheets around here somewhere.

Joe

www.jlmaudio.com

 

[soundguy]

it is in fact the most overkill mic pre out there but it does sound very very good... Im thinking just based on the weight of two its probably not smart to rack them together anyway, might put an 1108 in its place. thats not a bad box to drag around, am17, ua1108 and 2 altec 9470a's.

dave

 

[soundguy]

heres a photo so far-

http://www.glideonfade.com/images/tech/9470.jpg

the second power switch is for the am17 so I dont have to have it powered on all the time.

dave

 

[wilebee]

looking good dave

 

[jvanslem]

I just tested my two AM17 modules and I had the same hiss problem with the gain control, so I also ditched them. Using a dynamic mic I did a quick test with both and they sounded nice.
I have a power supply, now I just need to rack them!

Dave,
Seems they will just fit inside a Par Metal 10 series enclosure (it looks like that's what you're using.)
It's probably a pretty straight forward job, but do you have any tips as I go forth?

 

[soundguy]

yeah, they are really heavy so keep that weight distribution in mind when you mount them to the chasis. Other than that, I put an input attenuator on the front and it works nicely.

dave