JLM AUDIO

Hi there!

I have a Baby Animal with 1:4 input trafo, 99V opamp and 1:1:1 output trafo.
What bothers me a little is that there is no smooth transition from clean to distorted sound when I set the gain too high.
It's just clean and sounds really good and then when I turn the gain up a bit too much a loud spike and distortion (very transistory clipping type) comes in. Ofcourse, when I increase the gain the distortion further increases, but it goes like 0-spike-80-100.

Is this a normal behavior of this preamp or is there something wrong in mine?

Thank you all for comments.

RMD

Hey mate I have not noticed this at all. I find a better tone in most instances when I get the pre up a bit and working past the 2 o'clockish mark but only have clipping issues if the source is too hot and then I'll tend to go for the pad if I can't get it manageable (at the source).

Not sure if this helps and your description certainly sounds wrong so unless your source has an issue, I'm thinking the JLM gurus will steer onto a path of audio correctness.

Cheers.

Thanx Mully!

This is making me a bit worried, though. It seems that my BabyAnimal doesn't have all the gain it should. If I use SM57 I mostly use it with gain at 4 or 5 o'clock. Most of the gain on mine is from 2 o'clock onward.
With condensers that isn't a problem, but with dynamics it can be. I recorded a voicever a few days ago with MD421 and had to set the gain to the max to get a workable volume!

Any idea what might be wrong (it there is something wrong)? But note that soundwise the sound is superb if we ignore the clipping at high input levels.

Thanx!

RMD wrote:This is making me a bit worried, though. It seems that my BabyAnimal doesn't have all the gain it should. If I use SM57 I mostly use it with gain at 4 or 5 o'clock.

I was in exactly the same position when I was judging gain levels on the basis of my DAW's input meters. I really struggled to get what I thought was a decent signal level. Then it dawned on me that the DAW meter was in dbFS (ie 0db = loudest signal possible for AD converter without clipping). What I needed to do was set a more realistic gain target using different metering (either hardware, such as the JLM VU PCB and a meter, or in software (channel strip plugins are available).

I've now set my meters so that 0db on the VU meter = -14dbFS (= about +4dbu), and I target 0dbVU for my recording level. The BA's deliver this in spades. You can then drive them harder if you want while still leaving loads of headroom and no distortion.

You then turn up the volume on your monitors, rather than than relying on a hot signal. Since recording at these much lower levels, I'm finding I get better mixes and dynamics as well.

This may or may not be the solution to your problem, but your description of the symptoms immediately brought it to my mind, having been there and done that.

Hi Chrisp!

I see what you mean, but my problem is more about the curve of the gain pot. I'd like it to be more anti-logarithmic, so that from 2 o'clock onwards there is more of a fine tunning than now. Now most of the change in gain is from 2 o'clock on. Before 2 o'clock changes in gain are not so drastic. I've simulated the circuit digitally and the graph confirmed what I hear. Although the pote used is anti-logarithmic the curve is stil logarithmic. It's not even linear.
Maybe I should use a resistor to change the curve of the pot. Any suggestions?

Thank you.
RMD

The gain pot wiper tab is hot wired to the CW lug, which is connected to ground yes? And the CCW lug has the GAIN output from the PCB?