mic'ing up a jtm45 - SLP question for anyone good with mics

RobML · Post by **RobML** » Wed Aug 29, 2007 12:33 pm

hey guys

i have a quick question about the SPL the jtm45 puts out.

im using an condenser mic with a MAX SPL of 137.

can anyone tell me the max SPL a jtm45 can crank out at 10cms from the mic?

cheers
robml

toner · Post by **toner** » Wed Aug 29, 2007 2:34 pm

Sorry, I don't know the typical SPL of those amps but I seriously doubt it's anywhere near 137dB, even close-mic'ed! I would *guess* it's around 115 or 120dB max.

If you're worried about the mic, I'd suggest getting an SPL meter to be sure. Hopefully, someone else can confirm this but even so, each amp and speaker combo will be a little different.

NitroLiq · Post by **NitroLiq** » Wed Aug 29, 2007 4:36 pm

We measured a '72 100w Marshall SLP dimed at 3ft at one of our ampfests and that came out to 123db....Mark Huss' DR103 clone came in at 3db louder, if that's any help.

RobML · Post by **RobML** » Wed Aug 29, 2007 9:14 pm

thanks for those replies guys.

so i should be able to close mic with a condenser that has SPL of 137 without distortion - just need a really big pad - will let you know how i get on.

cheers
robml

7string · Post by **7string** » Wed Aug 29, 2007 11:28 pm

Rob, in addition to the close mic you should try moving the condensor back 5-10 ft. You can get a little more of the cab and room sound that way. Just keep movin it around till you find a good spot.

RobML · Post by **RobML** » Thu Aug 30, 2007 9:17 am

7string wrote:Rob, in addition to the close mic you should try moving the condensor back 5-10 ft. You can get a little more of the cab and room sound that way. Just keep movin it around till you find a good spot.

hey 7string

ive been mic'ing close with a sm57, and from 3 feet with the condenser - keeping the channels seperate left and right.. but im still having issues with phasing.. delaying one channel by several ms seems to help.. but the condensor 3 feet away does give quite a bit of room verb by itself. the sm57 by itself has quite a bit of a mid hump.

i see pics of condensers mic'd right up close on really large cabs and was wondering how they do it.. must be large mic pads and mic's with higher SPL rating than the speakers volume.

if my condenser can handle the jtm45 output volume i will make myself an adjustable mic pad (-10, -15, -20) and try it closer to the grill cloth

cheers
rob

toner · Post by **toner** » Fri Aug 31, 2007 7:30 am

Rob,
Keep in mind that even with a pad, you can still damage the mic diaphragm, especially with small condensers. Bass frequencies from proximity effect are the main concern.

Myopic Void · Post by **Myopic Void** » Fri Aug 31, 2007 2:29 pm

RobML wrote:
7string wrote:Rob, in addition to the close mic you should try moving the condensor back 5-10 ft. You can get a little more of the cab and room sound that way. Just keep movin it around till you find a good spot.
hey 7string

ive been mic'ing close with a sm57, and from 3 feet with the condenser - keeping the channels seperate left and right.. but im still having issues with phasing.. delaying one channel by several ms seems to help.. but the condensor 3 feet away does give quite a bit of room verb by itself. the sm57 by itself has quite a bit of a mid hump.

i see pics of condensers mic'd right up close on really large cabs and was wondering how they do it.. must be large mic pads and mic's with higher SPL rating than the speakers volume.

if my condenser can handle the jtm45 output volume i will make myself an adjustable mic pad (-10, -15, -20) and try it closer to the grill cloth

cheers
rob

RobML------> I am not sure what brand mic you are using....but on Neumann U87's there is a 10db pad which can put you usually where you need to be. Note: new U87's do not take as much SPL as the old ones (pre 86). Mine is a June 1970 I found and bought from Bearsville Studio's. I use my 1970 U87 right in front of my Marshall 100w SL with no attenuation. No problems at all. The Royer 121 is also a good mic for 4x12 cabs, I use them a lot. The U87 can take mid vol for rythem on the Marshalls without the pad sometimes as well.

On cheaper LDC like CAD, Audio Technica etc I have found they could not take the SPL from my Marshalls nor did they have a pad.

Cheers,

Eric

Myopic Void · Post by **Myopic Void** » Fri Aug 31, 2007 2:29 pm

RobML wrote:
7string wrote:Rob, in addition to the close mic you should try moving the condensor back 5-10 ft. You can get a little more of the cab and room sound that way. Just keep movin it around till you find a good spot.
hey 7string

ive been mic'ing close with a sm57, and from 3 feet with the condenser - keeping the channels seperate left and right.. but im still having issues with phasing.. delaying one channel by several ms seems to help.. but the condensor 3 feet away does give quite a bit of room verb by itself. the sm57 by itself has quite a bit of a mid hump.

i see pics of condensers mic'd right up close on really large cabs and was wondering how they do it.. must be large mic pads and mic's with higher SPL rating than the speakers volume.

if my condenser can handle the jtm45 output volume i will make myself an adjustable mic pad (-10, -15, -20) and try it closer to the grill cloth

cheers
rob

RobML------> I am not sure what brand mic you are using....but on Neumann U87's there is a 10db pad which can put you usually where you need to be. Note: new U87's do not take as much SPL as the old ones (pre 86). Mine is a June 1970 I found and bought from Bearsville Studio's. I use my 1970 U87 right in front of my Marshall 100w SL with no attenuation. No problems at all. The Royer 121 is also a good mic for 4x12 cabs, I use them a lot. The U87 can take mid vol for rythem on the Marshalls without the pad sometimes as well.

On cheaper LDC like CAD, Audio Technica etc I have found they could not take the SPL from my Marshalls nor did they have a pad.

Cheers,

Eric

RobML · Post by **RobML** » Tue Sep 11, 2007 9:48 am

im mic'ing up with a rode nt1a.

i ended up using a 15db pad and it turns out that thats just the right ammount to stop the mic preamp clipping.

the mic doesnt distort like i thought it was.

sounds great.

thanks guys
robml

Myopic Void · Post by **Myopic Void** » Tue Sep 11, 2007 12:36 pm

Glad it worked well...Rode is a good brand!

Cheers,

Eric

ericopp · Post by **ericopp** » Wed Sep 12, 2007 1:45 pm

First of all, make sure the cab is in the middle of the room - NOT backed up to a wall! The wall will become an extension of the cab - not what you want. Also, don't forget to take the wheels off!

Personally, I recommend the dynamic mic (SM57) right up close on the grill, point blank with the cone.

THEN, I like to have the cabinet miced with a ribbon (or condensor) on an outside back corner or back edge of the cab. When carefully blended with the stronger cone mic, you get nice woody "knock" that fills in the low-mid frequencies that the SM57 tends to miss.