JLM Baby Animal

[TornadoTed]

I finally got some time to wire up my Baby Animals this week and tested them this morning.

All 4 of the Cinemag, API 2520, JLM111DC appear to be fine although I have included the voltages I am getting at the 6 pins.

7 of the JLM14, JLM99v, JLM111DC appear to be fine, again I have included the voltages I am getting.

The 8th however is giving me 11v on 2 of the pins instead of 0v which can't be right, any suggestions?

I have run a mic (dynamic & 48v condenser) into the 11 working channels and all seems to be spot on. I haven't tried with the opamap or run a mic into the channel I am getting 11v on 2 of the pins.

 

[TornadoTed]

Many apologies, the problem is fixed I think.

When I tested it again the 11v dropped down to 6.5v later on it was 2.5v. I changed the 2 big capacitors next at the top near the gain terminal block which both measured the same as the pins and all is now well.

So do you reckon it was a faulty capacitor or could something of damaged it?

 

[sonicwarrior]

[quote author="JLM Audio"]
If it fits the 5.5mm hole but will not push in you will have a 2.5mm centre pin socket.[/quote]

Now that you say it I recognized that I indeed tried to use a 2.5 mm jack.
Thanks for answering. Will order a 2.1 mm jack then.

 

[JLM Audio]

When I tested it again the 11v dropped down to 6.5v later on it was 2.5v. I changed the 2 big capacitors next at the top near the gain terminal block which both measured the same as the pins and all is now well.

So do you reckon it was a faulty capacitor or could something of damaged it?

Was actually probably just some charge in that cap. If you get a reading like that you can try to discharge it with a 10k resistor to 0v with the BA turned off and try measuring again. If it is still there it is most likely a soldering short between to close solder pads.

The main thing to make sure of so you don't blow an opamp is to check that there is no 0ohm or 51R short on the opamp output socket to 0v. This can be checked before ever powering up a BA with an ohmmeter.

 

[dufo]

Is ordinary masking tape ok to use on the front panel for protection during drilling? I think I read somewhere it wasnt ok, but I cant imagine why...

 

[JLM Audio]

Is ordinary masking tape ok to use on the front panel for protection during drilling? I think I read somewhere it wasnt ok, but I cant imagine why

We use white (creamy) paper tape like painters and panel beaters use. It is thin enough to see the laser text and centre punch marks through it and it stops scratches perfectly even on the CNC milling machine. Only put it on when you are about to drill and remove it straight away when finished especially if the panel gets hot and it will come of easy but if you leave it a day or two it can be hard to remove.

 

[dufo]

thanks Joe.

I know masking can be hard to get off, but its what I have right now and it will be coming off quickly.

I just wanted to make sure that masking cant harm the decals, that was my main concern, getting it off im bit of a expert at :0)

 

[dufo]

back again.

Where can one find some of those black multi pin connectors that are used on the ribbon cable? I have dropped and stepped on one!

 

[Osse]

How much gain will I get with the jlm14+Hybrid+111DC

Compared to BAD kit with jlm14+2x99v?

Will I be able to get the impedance down to 150 with variable if I choose hybrid+111DC?

I want to be able to record quiet sources with ribbon + proper impedance loading AND hybrid op amp, is there any way to achieve this?

 

[JLM Audio]

I just wanted to make sure that masking cant harm the decals, that was my main concern, getting it off im bit of a expert at :0)

If it is one of our lasered text front panels you will be fine. You would have grind off the black anodising to remove the text.

Where can one find some of those black multi pin connectors that are used on the ribbon cable? I have dropped and stepped on one!

You can get them from most electronic stores like Jaycar etc. You want a 10pin IDC Line Socket.

How much gain will I get with the jlm14+Hybrid+111DC

60dB.

Compared to BAD kit with jlm14+2x99v?

75dB and can be increased to 80dB if needed.

Will I be able to get the impedance down to 150 with variable if I choose hybrid+111DC?

The variable impedance has to do the input transformer not the output one. We usually set our pres to 300 to about 6k by using 5.1k in series with a 100k log pot. If you change the 5.1k to 2.7k it would go from 150ohm to about 5k range but 150ohm is really only for 50ohm mics and if you were using a real 50ohm mic I would change the green wire from the JLM14 to the black one as this will give you 6dB more transformer gain to make up the low level out of the 50ohm mic.

I want to be able to record quiet sources with ribbon + proper impedance loading AND hybrid op amp, is there any way to achieve this?

Most ribbons want the higher 5k impedance if you want all the high frequency content. The BAD is made to get the high gain needed for quiet ribbon recordings. But with the Hybrid in a BA you may be able to get more stable gain so you can try a smaller Rg value. 33R would give you 6dB more gain and 15R would give you 12dB extra gain. Just need to listen for oscillation and watch for smoke :grin:

 

[patilon]

next to 2x jlm14/99v/jlm111dc i think of one lundahl 1578
and one cinemag channel.

how does the cinemag sound in comparison to jlm14 and lundahl ?
never heard an original api.
better take a stereo lundahl instead of 1x mono lundahl and 1x mono cinemag ?
i know.. there is no objective answer, but.. if recording stereo sometimes..
don´t know, if the jlm14 is always the right one for cello/guitar/piano or
is the jlm14 just good enough for these signals ?
does anyone combine different channels while recording in stereo ?

do cinemag+hybrid and lundahl 1578+99v have enough gain ?
i plan not to add a jlm111dc to these two channels.

thanks!

 

[herrmann]

Hello
I've just builded a pair of BA (JLM14 and hybrid), all is working fine and well sounding, but I have some buzz problems. At full gain, a big 100Hz noise at -40dBFS.
I've tried to make a star ground, with no result. No better idea. :?
Maybe the problem came from the psu? I'm using the small psu from Joe.

 

[Schmilsson]

One of my BA died on me, the other one's acting a bit strange too.

My measurements are in red/black. Any ideas?

 

[JLM Audio]

Hello
I've just builded a pair of BA (JLM14 and hybrid), all is working fine and well sounding, but I have some buzz problems. At full gain, a big 100Hz noise at -40dBFS.
I've tried to make a star ground, with no result. No better idea.
Maybe the problem came from the psu? I'm using the small psu from Joe.

Some people are getting hum/rf problems with the latest BA PCB dated 09/07. This is the PCB with no CL position. See fix in jpg below.

One of my BA died on me, the other one's acting a bit strange too.

My measurements are in red/black. Any ideas?

The 10R resistor is open circuit. Remove the opamp replace the 10R and test the voltages. If the voltages look good put the opamp back in and see if the voltages stay good. If the 10R blows again then it may be faulty opamp or dead short on the output of the BA. Make sure you use a 1/4 to 1/2watt Carbon 10R.

NEW STUFF

Also for all those who have been emailing me about the transformerless BAN. The final PCB passed testing with all the different input combinations (2 x BC550C, LM394, MAT02, 2 x 2SK389. It has 20k input impedance and can be made variable input impedance easily as well. The BAN is for those looking for wire with gain and no colour at all. It is based on Graeme Cohen design used in Amek / SSL etc mic pres but made to run on one 48v power rail like all BA* PCB's. So these are perfect when what you’re recording is so fat sounding that you do not want to add any more warmth to it. I would only use the BAN pre in large warm rooms recording classical music or drums at a distance etc. The only Rock music use I would us it on sometimes would be with large ribbon mics that are warm and lacking top end. But if it is close micing or rock or blues then the BA and BAD are the always the way to go.

BAN with LM394 + OPA2604 + 99v output stage

BAN with LM394 + OPA2604 + OPA2604 output stage

BAN with LM394 fitted (Can also take DIP8 type LM394)

BAN with 2 x 2SK389 fitted (As suggested by Fred Forssell in a schematic on his site)

BAN kits will be up on the web site as soon as we finish packing the first batch of BAN kits next week.

 

[herrmann]

Some people are getting hum/rf problems with the latest BA PCB dated 09/07. This is the PCB with no CL position. See fix in jpg below.

Ok, so I have to put the 220pF cap in parallel of the CL.
Do I have to solder another 0.1uF ? It does'nt appear in your schematic http://jlmaudio.com/Baby Animal Mic Pre with JLM14 with JLM99v or Hybrid on 48v.pdf
Thank you

 

[JLM Audio]

Ok, so I have to put the 220pF cap in parallel of the CL.
Do I have to solder another 0.1uF ? It does'nt appear in your schematic http://jlmaudio.com/Baby%20Animal%20Mic%20Pre%20with%20JLM14%20with%20JLM99v%20or%20Hybrid%20on%2048v.pdf

Yes 220pF CL goes under the PCB in parallel with RL.

You can also put CL into CZ and put a wire link over RZ if these are not being used.

The 0.1uF is not needed where CL used to be on the top of PCB but is also ok if one is fitted there.

 

[herrmann]

Ok, all mods are done. Still have some noise floor and hum, but it's gone to about -65dBFS at full gain. :grin:
Now time to play some music !

 

[herrmann]

I think a need a little more gain, I'm looking for an output transformer. Maybe it will be benefit against ground buzz?

 

[JLM Audio]

Ok, all mods are done. Still have some noise floor and hum, but it's gone to about -65dBFS at full gain.
Now time to play some music !

That is correct as you will have about 54 to 60dB of gain. So noise floor at minimum gain will be below -100dBFS or close to the noise floor of your A/D converter (which should be set to work at it highest professional input level usually +18dBM to +22dBM)

I think a need a little more gain, I'm looking for an output transformer. Maybe it will be benefit against ground buzz?

A JLM111DC wired 1:2 will add 6dB of extra gain and give you a fully floating balanced out. But the quasi balanced output without the transformer is still very good at rejecting hum and buzz as long as its BA output is going into a balanced input.

 

[Schmilsson]

[quote author="JLM Audio"]The 10R resistor is open circuit. Remove the opamp replace the 10R and test the voltages. If the voltages look good put the opamp back in and see if the voltages stay good. If the 10R blows again then it may be faulty opamp or dead short on the output of the BA. Make sure you use a 1/4 to 1/2watt Carbon 10R.[/quote]

Thanks!

That did it, the voltages are good and it sounds brilliant again.
The 10R was nuked on both channels. I wonder how I managed to do that?
I have them stacked pretty much all the times and I might've accidently switched the phantom power on some time. Could that be it?