JLM Baby Animal

[mattmoogus]

Ok so the power supply or your wiring is not delivering 48V to the BA PCB. So unplug the PSU and measure its output voltage, if its 48V recheck your wiring until you find the break.


M@

 

[Schmilsson]

Thanks!

The psu was 48,7.
As I suspected I screwed up the powerled wiring.

 

[Schmilsson]

Bypassed the led and resistor and NOW WE'RE TALKING! :grin: :grin: :grin:
I'll sort that out later, cause now I have to record, this sucker sounds like a millions bucks! :thumb:

 

[bluezplaya]

Also check the transformer wiring (if its a 1:4) and that there isnt extra solder thats run down the legs (if its an OEP) and shorted anything out.

Matt, I fixed the problem. There was a bad solder connection. However, one of my 10k reverse pot's doesn't seem to work. I get a constant signal at the lowest volume (as if the pot is not hooked up). But everything is wired the right way. I am certain of this. It is just like the 4 channel I just finished (sweet!). I guess my question is can 10k reverse pots go bad?

Adam
:sam:

 

[mattmoogus]

They can, its possible that the pot was a dud and you can also damage them by applying too much heat or soldering to the wrong place on the tabs. The way to check is to remove it from the circuit and measure the resistance between the middle pin and either outside pin. At one extreme it should measure 0ohms and at the other it should measure 10k. In the middle it should be roughly 9k or 900ohms depending on which side you measure. If that all looks right then Id say the pot is ok and its some other problem.



M@

 

[wiz1der]

Hey Matt or Joe,

Is the case included with the front panel? I usually order cases from par-metal here in the states, and all the cases i order seem to have the holes in front for the front panel to be bolted on. I do not see these bolts/screws on your fully assembled unit from front panel to case.

Where would I get this type of case in the states to work with your front panel? Do you also sell cases?

 

[bluezplaya]

They can, its possible that the pot was a dud and you can also damage them by applying too much heat or soldering to the wrong place on the tabs. The way to check is to remove it from the circuit and measure the resistance between the middle pin and either outside pin.

Yes, Matt, the 10k is a dud.

Adam
:sam:

 

[mattmoogus]

Last weekend (to celebrate my quater century) I finally built myself a Baby Animal pre, DIY style in one of the black alum cases we had lying around. Actually, it was just to prove that I can actually build these things aswell as just giving advice about them :razz:

It worked first time (as it bloody should have!) and has so far reinforced my view that the 1:4+99V+1:1:1 is the best all round combo. I went for the arty shot cause Im sure youve seen enough inards in this thread already :green:

M@

 

[bluezplaya]

You mean to tell me all this time the advice about Baby Animal pre's I was getting was from some amateur?!!! :shock:

J/K. Nice work. Hey Matt, how does the sound of the 1:4 + 99v change by adding a 1:1:1 to it. What characteristics I mean?

Adam
:sam:

 

[mattmoogus]

Hey Adam,

The 1:1:1 doesnt make a big change, just a little smoother than without. Its very transperant as far as transformers go, however I like the small amount that it does, aswell as the extra 6db of gain which is the main reason for using it.


M@

 

[bluezplaya]

My 4 channel Baby Animal mic pre. Channels 1 and 2 use the DI kits. Channels 1 and 3 use the 99v opamps and channels 2 and 4 use the Hybrid opamps.

A couple more pics with my 4 channel Green Pre.

Adam
:sam:

 

[JLM Audio]

How do I wire it up with a 10k resistor and a power led?

I've got a firebox, same as whoever it was having problems with that combo earlier in this thread. The firebox is balanced, perhaps not set to +4? Who knows, I'll send them a mail.
I've tried it in other setups too(balanced +4) but it's pretty much the same, distorts way too easy. DI's bass for instance distorts with the pad in and the gain at zero. I mean, should you even get a signal?

When using a Firebox for pro level input and to eliminate the built in mic pre section in your firebox you need to plug into the line in 3 & 4 TRS on the rear panel and make sure the Input level boast for Line in 3 & 4 in the software screen is off. The TS in the middle of the XLR's on the front are unbalanced DI inputs and should not be used.

anything special about the green resistors thought i read somewhere they were carbon instead of metal film. any reason i can't replace with metal film

Metal Film can go open circuit on power up surge with no external sign or actual fault. 1/4w or 1/2w Carbon will have no trouble with the power up surge and will char if there is a fault.

I'm a huge fan of the JLM stuff since I built the dual 99v. Amazing. Now I'm thinking about putting together a few of these and I have a question about the Hybrid opamp. It seems to me that it would be useful to add a switch on the front panel wired to the two pads which change the opamp from class A to class A/B. Is there anything about this idea which would not work? Would it be bad to switch the opamp while the unit is powered up?

:grin: No that is fine but keep the wires twisted together and as short as possible.

yea, well, uhmm, it seems i didn't get rl installed [27k or 100k]
could that be the problem sounds so nice now, should it even be able to work without it

Yes it will work without it but the frequency response will be way brighter and the pre will probably oscillate at high gain.

There was a bad solder connection. However, one of my 10k reverse pot's doesn't seem to work. I get a constant signal at the lowest volume (as if the pot is not hooked up). But everything is wired the right way. I am certain of this. It is just like the 4 channel I just finished (sweet!). I guess my question is can 10k reverse pots go bad?

Only faulty pots we have seen so far is ones where the wires are soldered to the leg to carbon track rivet holes which should never be done as flux can get into the pressure joint and insulate it making it permanently open circuit. Only ever solder to the leg. But there could always be a faulty one out of the 1000's we have made. Sent you a free 10k rev log pot in today Air mail to get you going. Your email bounces my replies I have been trying to send you.

Is the case included with the front panel? I usually order cases from par-metal here in the states, and all the cases I order seem to have the holes in front for the front panel to be bolted on. I do not see these bolts/screws on your fully assembled unit from front panel to case.

Where would I get this type of case in the states to work with your front panel? Do you also sell cases?

The undrilled JLM front panels do not have the 4 holes in the corner as universal cases have these holes in slightly different places. To drill our front panels tape over the front of the panel with 50mm (2") white paper tape like painters use as the centre punch markers can still be seen through the tape. Lay the blank front panel on top of the JLM one and mark the 4 mounting holes on the tape. Centre punch all hole centres including the 4 mounting holes and drill all centre punches out with a 2.5mm pilot hole before drilling with the final holes size drill. Finish holes on the front and back of the front panel with a deburring tool or large drill bit. Then peel the tape off and the panel should be perfect and ready to go.

We do sell full cases with the great strong extruded front panels that do not need front panel holes but they are heavy to ship as most of the case is steel. So for most overseas customers we recommend just buying the front panels as they can be sent in a postal tube with a few kits for not much extra cost. The full case with lasered front panel text with all holes milled out on the front and back panel is $130AUD but postage is about $100AUD but lots of kits can be sent inside the case basically free.

how does the sound of the 1:4 + 99v change by adding a 1:1:1 to it. What characteristics I mean?

The JLM111DC is adds very little tone difference but can give you an extra 6dB of gain when wired 1:2.

Some nice looking finished BA's starting to show up :grin:
Anybody still having any problems let me know as I am almost caught up with my emails since bubs arrived early a couple of weeks ago.

 

[matta]

Okay,

Since everyone else is sharing... here a couple not so great shots of my unit. This is number 2, first was built with JLM panel and about to complete unit 3, which will have 1 channel of JLM 1:4 with JLM99V and one with OEP and OPA IC, hope to get some sound test done to compare them, along with putting the pres up against some entry level stuff, and maybe some other High end.

Cheers

Matt

 

[Greg]

C'mon Matt... you can do better work than that... geez !!! :shock:

As always, nice work ! You're cranking 'em out now.

 

[skipwave]

[quote author="JLM Audio"]

how does the sound of the 1:4 + 99v change by adding a 1:1:1 to it. What characteristics I mean?

The JLM111DC is adds very little tone difference but can give you an extra 6dB of gain when wired 1:2.[/quote]

Do you omit the output coupling cap, since the 1:1:1 is gapped? I'd really like to use it that way in a BabyAnimal and maybe my Hampton-design JFet pres.

Thanks,

Brian

 

[matta]

[quote author="Greg"]C'mon Matt... you can do better work than that... geez !!! :shock:

As always, nice work ! You're cranking 'em out now.[/quote]

What little ole me? Hah hah. Yeah, I guess having a background in design is kind of helping a little with the front panels, it takes a long time to get it all right, sources the parts, designs etc, but when I see the end result I'm mighty proud.

Hoping to build another GSSL soon with a bit of a difference.

Thanks for the compliments

Cheers

Matt

 

[JLM Audio]

Do you omit the output coupling cap, since the 1:1:1 is gapped? I'd really like to use it that way in a BabyAnimal and maybe my Hampton-design JFet pres.

No. The Baby Animal has the opamps output sitting at half of the single 48v power rail so the output cap can never be left out. Otherwise the low DC resistance of the transformer would short the opamps output to the 0v and fry the output protection 51R resistor. This basically goes for all one power rail designs including the Hampton Jfet if it is the one I am thinking it is.

But when using a output transformer the primary is connected to +out and 0v (not -out) on the Baby Animal.

In a opamp design that had split +/- power rails with very little DC offset on the output a gapped or not gapped output transformer would work fine with no cap.

To use a gapped transformer properly have a look at the 1073 class A biased single transistor output stage and be prepared to waste a lot of current.

 

[mfdu]

ok. so i have a couple of OEP mic input trannies floating around (left over from a fabio opto compressor build)

i plan two build two (high gain) units to start with, one of each type of opamp.
what is your opinion of OEP/OPA2604 versus the OEP/99v? (where was that review someone did?)
is the Hybrid opamp the OPA2604, or is it a different opamp altogether?

(i have six of fabios 2520 descrete opamps - i'll have to try them, when i do the build - i presume they share pinouts)

another question - will i be able to achieve variable impedence with the OEP trannie? that would be nice to play with . . .

chris.

finally - i see everyone using the pre-made power supply, and placing it externally. leaves a hell of a lot of spare room in the rack case.
couldn't we mount the PSU inside the case?
after all, it is already boxed and presumable shielded . . . should be cleaner than a handbuilt PSU?

 

[Schmilsson]

[quote author="JLM Audio"]
But when using a output transformer the primary is connected to +out and 0v (not -out) on the Baby Animal.[/quote]

Really? I totally missed out on that and wired it to + and -

 

[mattmoogus]

Hi mfdu,

All of the opamps you mention sound good. The 99V is my all time fave (as you may have read here several thousand times) but the Hybrid and OPA2604 will make you a great mic pre too. Theyre generally faster and 'cleaner' sounding and probably better if youre trying to capture an already overly warm sound just the way it is. This thread is full of descriptions of the differences between the opamps and transformers so have a read. Of course the only way to know for sure is to listen and try them yourself.

Yes you can have variable Z with the OEPs, weve tried a 100k log pot with 12k in series, but Ive forgotten what value we used for CL (maybe nothing?). This gave quite a good tonal variance that I think will be useful in the studio.

I think Joe is answering aswell so Ill leave the rest to him.




M@