JLM Baby Animal

[skipwave]

[quote author="3nity"]First 2 channels use OEP, Hybrid and Cinemag output. very very nice on it's own.[/quote]

Did you bias the Hybrids ClassA or A/B?

I've got some boards on the way, and I can't wait to compare the two biasing schemes.

Thanks,

Brian

 

[Lowfreq]

[quote author="JimiH"]What's going on? Has everyone become bored with their baby animals?? I wanna see some BA bragging and more show off photos! [/quote]Maybe after discovering how they sound, everybody's too busy using them. :grin:

Mine sound awesome!! :thumb: :thumb:
Magic on drums!!!

Inexpensive, but sound like I've spent a lot of $$$$

I can't brag enough!!!

 

[JimiH]

[quote author="Lowfreq"]I can't brag enough!!![/quote]
No no!!! Keep bragging!! I'll be here to listen (well, read...) and pat you on the back. I LOOOOOVE my baby animals on drums too. My only problem is that I want more channels. MORE!!!

 

[MegaMutt]

Hi All,

Can anyone clarify the correct way to wire up a Sowter 9825 (API 2503) output transformer with the Baby Animal?

 

[gevermil]

[quote author="Lowfreq"][quote author="JimiH"]What's going on? Has everyone become bored with their baby animals?? I wanna see some BA bragging and more show off photos! [/quote]Maybe after discovering how they sound, everybody's too busy using them. :grin:

[/quote]

Ive been recording with them
nice preamp , lots of low end !
:thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb: :thumb:

 

[Godders]

Yup, still very happy with mine. :thumb:

Cheers

Nick

 

[3nity]

Megamutt....
http://www.jlmaudio.com/BabyAnimalWiringOverlay.gif

From your transformer primary: red to +out. brown to 0V, -Out not connected.

Secondary, Yellow and green together (soldered) and orange to + at the XLR and blue to the - at the xlr.

Enjoy it.

 

[MegaMutt]

3nity,

Thanks. That's exactly what I needed.

Just to be 100% clear on this (I know this is a stupid question, but bear with me I'm new to all of this)

Yellow and green soldered together, but NOT connected to the + XLR, correct?

Only the orange and blue are connected to + and - XLR respectively?

Also, what about the violet and grey wires? are they connected in any way?

Thanks!

-rich

 

[3nity]

yellow and green soldered together but not soldered to nowhere.
other wires not connected.

 

[MegaMutt]

Thanks. That's exactly what I thought.

-rich

 

[Hammond]

Ok guys here is my baby: oep+99v+di
Sounds awesome!! Thanks to Joe Matt & Purusha for his wonderful cases.
The only problem i got is that the impendance pots are not perfectly matched so one is 84k and one is 89k, so with the impendance control fully clockwise i get one channel a few db louder than the other.Any suggestion about where to get two matched pots?

 

[Hammond]

Ok the pots works fine, it was a cable......

 

[3nity]

Did anyone here used the baby animals in a Active summing buss?
Using a double rev 10K????
Any sugestions??

 

[skipwave]

[quote author="3nity"]Did anyone here used the baby animals in a Active summing buss?
Using a double rev 10K????
Any sugestions??[/quote]

The pots from JLM have detents, so you can set them at the same gain easily. Dual pots don't tend to track that accurately. I learned that trying to use a dual pot to attenuate the feed to my monitors, the stereo image shifted as the pot was adjusted.

 

[MegaMutt]

Hey All,

I finally got the first 2 BA's wired up and they sound great!

My only question so far, is that when I crank up the gain to about 3/4, I'm getting major distortion on the output. It starts out sounding like I'm cranking my fender amp, but then goes into a rumbling mess.

I'm recording a stereo track of acoustic gtr with 2 pencil type condensers.

Any thoughts as to what is causing this?

 

[indigom]

I meant to post this in the JLM Baby Animal build thread, but the button made a new topic instead. So now I post it here for you BA masters to help me solve:

Hi Guys, I could use a little help. Here's the scenereo:

Supply volage=49V via JLM's ig supply. The ground pin of it is grounded to the chassis.
I injected a Sine wave around 440H into the input jack.
off BA ine level Cinemag transformers feeding unbalanced int BA board check ok on the scope. The Cinemag are grounded to the chassis
All voltages check on BA prior to plugging in a discrete opamp (DOP), +48, +24, 0V.
The signal makes it to the BA, but then I plug in Joe's Hybrid OPAMP:
http://jlmaudio.com/JLM%20Hybrid%20opamp.htm
using the used the charts from:
http://www.jlmaudio.com/Baby_Animal_Mic_Pre.htm
zener=NF 10k=NF bd681=NF 63V=NF NF NF

RG=68K, CL=NF, RPAD=NF RL=10K (onboard the transformer PCB)
inputs to transformer PCB +/- = 470

Gain pot=10K rev log.

I when I check pins of the 2604 I see 48V there, should it be halfed to 24volt? Also the LED doesn't light even though the class A/B pad is not soldered.
The output signal is short bursts of square wave, no sine on the scope.
I get the same replacing this with a Milenimum opamp.
I inject the transformer signal at the top of the CL pad. CL is not fitted.
THe transformers secondary is gorunded, not tied to 1/2 like in the schematics.

Anyone have suggestions what to do next? I hope that I have not burned out the BA's that I built, they are not hot and do not show signs of damage. Or the DOA Milenimum OPAMP.

Voltages measured:
With no audio/sig gen signal applied I measured this:
from 0v to pin V+ of the DOA without the DOA fitted= 48v
from 0v to pine V- of the DOA without the DOA fitted=24volts
from 0v to pine 0v of the DOA without the DOA fitted=0v
out=no voltage
in+=no voltage
in-=no voltage

with JLM hybrid opamp fitted=
opa2604chip measured from 0v to chip pins
1=932mv
2=433mv
3=6mv
4=0v V-
5=678mv
6=19.27mv
7=870mv
8=47.99V V+


pin 8 is still 47.99volts when voltage is taken from the -IN on pin 4 to pin 8.


think that i trashed these opamps with too much voltage? I see no RED LED even though it's supposed to be in class A mode.
Here are the closeup pics:
http://img.indigom.net/ts_ba/

thanks guys for any help you might send my way!
-Jay

 

[keefaz]

I remember I asked a question about power voltage of 5532 opamp in G1176 input balanced circuit.
http://www.groupdiy.com/index.php?topic=229848&highlight=#229848

On the G1176 circuit, the 5532 is fed with 0V at power pin - and 30V at power pin+. Jackob answered to me that it is the same as connect -15V/+15V

So in your case, the voltages on opamp power pins seem good (0V/48V is equivalent to -24V/+24V)

 

[skipwave]

[quote author="keefaz"]So in your case, the voltages on opamp power pins seem good (0V/48V is equivalent to -24V/+24V)[/quote]

Trouble is the 24V bias on the input is gone when the opamp is plugged in. That has to be there in order to idle the opamp midway between the full supply rail of 48V and ground. As I mentioned in the other thread I think that is the issue. The OPA2604 might be bad, you could plug it into a simple test circuit to find out. If you don't have a dual power supply handy, just use two 9V batteries. That should be fine for a simple test; Click here for a diagram, if needed.

 

[rattleyour]

Hey Joe or Matt,

Can your BA front panel work with go betweens kits instead-- is the spacing equivalent?

Sorry if this has been asked before, I tried searching to no avail.

Thx.

Liam

 

[JLM Audio]

I when I check pins of the 2604 I see 48V there, should it be halved to 24volt?

Keefaz is correct (0v/48v = -24v/+24v) so this is fine.

The transformers secondary is grounded, not tied to 1/2 like in the schematics.

Skipwave is right about the 24v bias is missing.
And this is your problem as you have the input transformer secondary tied to 0v instead of +24v half rail
which is used to bias the +in on the opamp to half volts
which then holds the output of the opamp at half volts so it will all work.

Also the LED doesn't light even though the class A/B pad is not soldered.

This will be because you have the opamp input sitting at 0v so there is no voltage for the LED until you fix the bias problem above.
All you will need to do is move the secondary wire from 0v to the half rail point and it should all start to work.

Can your BA front panel work with go betweens kits instead-- is the spacing equivalent?

Yep GO Betweens and all BA type PCB's have the same 3 x 11.7mm switch spacing and 6.5mm hole size.
So will the New Go Between Plus that will be here in about 2 weeks. :wink: