JTM45 headroom issues

kimbo5150 · Post by **kimbo5150** » Wed Feb 22, 2006 8:00 am

Hi All,

Absolutely loving my JTM45!
However I am finding I dont have enough headroom using my Les Paul through her.
I am running stock Metro specs, and was wondering if anyone has any suggestions on how I might be able to reduce the gain, and up my headroom.

Thanks!

Kimbo

Post by **VelvetGeorge** » Wed Feb 22, 2006 3:55 pm

Try a 12AT7 in the phase invertor. That can add headroom.

Overall, with 400V B+, tube rectifier and an 8K primary on the OT, you won't have a huge amount of headroom.

George

Broken · Post by **Broken** » Wed Feb 22, 2006 6:17 pm

Could you change the amount of clean headroom by running the amp at 16ohms but with a load of 8ohms.

That would reduce your primary impedance to 4k wouldn't it? Or would this be to much for the OT?

johnny b · Post by **johnny b** » Mon Mar 06, 2006 11:35 pm

Just posted a threads about speakers and cabs with a similar thought about 16ohm into 8ohm

I have a Germino 45, just fyi. Nice head as well. This one is hardwired 16ohm only. Asked Greg Germino about feeding a Sequis Motherload DI which has a load at 8 ohm. He assured me the 45 would be fine, told me the original Bluesbreakers combos were 16ohm into 8ohm, gave them that richer, juicier mid quality.

But just to be safe, think you should check with George. I've been running my G45 like this for direct recording--sounds amazing.

Paul humbuckers will overdrive an amp quick. Maybe a split coil swithc? Either that, or pick up a Strat on the downlow to keep for cleaner stuff.

But who needs cleans in rock'n'roll anyways? My Paul's clean enough for my tastes.

Broken · Post by **Broken** » Tue Mar 07, 2006 5:06 pm

Also have a look at the volume your runing your LP at.

To get a good clean out of a LP on the neck pickup, you would never want your volume past 3.

rockstah · Post by **rockstah** » Tue Mar 07, 2006 5:13 pm

my understanding is its never ok to give the amp less resistence than its wanting to see. unless you want to fry an OT
so if its set to 16ohm it better see a 16ohm load.

Broken · Post by **Broken** » Sat Mar 11, 2006 12:49 am

rockstah wrote:my understanding is its never ok to give the amp less resistence than its wanting to see. unless you want to fry an OT
so if its set to 16ohm it better see a 16ohm load.

I can't see how, unless it was a very poor quality transformer. When you think about the job the OT performs all the impedance switch does is change the primary load for the output tubes when connected to a mismatched load.

Running an amp without a load will definately blow something if you run it long enough.