BA BA2 BA4 BAD Dual99v Build Thread

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timos
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by timos »

Hi all,

First time poster. Wondering what the jumpers in the DI socket on the PCB are actually for? I dont have a DI running on either of my channels and Im getting no signal out of them. Im thinking these jumpers missing would be the cause of the problem. Being so small I lost them, and I can find any in the shops anywhere, but if they are essential (as you would think, they wouldnt be there for nothing) , Ill find them somewhere. Thanks.

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

timos wrote:Hi all,

First time poster. Wondering what the jumpers in the DI socket on the PCB are actually for? I dont have a DI running on either of my channels and Im getting no signal out of them. Im thinking these jumpers missing would be the cause of the problem. Being so small I lost them, and I can find any in the shops anywhere, but if they are essential (as you would think, they wouldnt be there for nothing) , Ill find them somewhere. Thanks.
Yes the 2 jumpers in the DI header are to link the audio to the input when no DI is fitted. Fit the 2 jumpers where shown and it will complete the input path. You Can just solder the 2 pairs of pins together under the PCB if you do not have the jumpers.
Joe :-)
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sonicwarrior
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by sonicwarrior »


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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

sonicwarrior wrote:The PDF http://www.jlmaudio.com/Baby%20Animal%2 ... PA2604.pdf is password protected. :?
Please read the first thread on the forum at the link below
PDF Problems on JLM Site Please Read
Joe :-)
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Eric Beam
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Eric Beam »

Well just ordered a BA4, look forward to it. Going to be building it with a few Jensen in/out transformers & some 990c's.

I have a few areas I'm unsure about.

1. What would the optimum Jumper, RL & CL values be for a Jensen JT-11K8-APC 150:1.8k input with a JH990c?
2. What would the optimum Jumper, RL & CL values be for a Jensen JT-MB-CPCA 150:150 input with a JH990c?
3. What would the optimum 68R RGain value for use with the 990c
4. Would using a JT-OLI-3 be beneficial? Where would they live? Would they eliminate anything else otherwise needed in the path?
"Any experiment of interest in life will be carried out at your own expense." [url]http://rhythminmind.net[/url] - [url]http://signaltonoize.com[/url] - [url]http://popsound.com[/url]

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Eric Beam wrote:Well just ordered a BA4, look forward to it. Going to be building it with a few Jensen in/out transformers & some 990c's.
OK I see the order in the system 8) :D
I have a few areas I'm unsure about.
ok
1. What would the optimum Jumper, RL & CL values be for a Jensen JT-11K8-APC 150:1.8k input with a JH990c?
From the Jensen Datasheet Rload = 15k. Cload , CZobel or RZobel not needed or fitted.
2. What would the optimum Jumper, RL & CL values be for a Jensen JT-MB-CPCA 150:150 input with a JH990c?

From the Jensen Datasheet Rload = 3k. Cload , CZobel or RZobel not needed or fitted.
3. What would the optimum 68R RGain value for use with the 990c
Since the 990c is a high gain opamp you should be able to get down to 10R for RGain giving heaps of extra gain.
4. Would using a JT-OLI-3 be beneficial? Where would they live? Would they eliminate anything else otherwise needed in the path?
No not needed the the BA has all you need on there for isolating the output already.
Joe :-)
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Eric Beam
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Eric Beam »

Thanks for the info.
If I wanted to use the impedance knob, How do you come up with the variable Z values?

Out of curiosity, I already have the JT-OLI-3 output isolators. Would they eliminate the need for the 51R & 470uF if I used them before output pins 2 & 3? Or maybe just the 51R? Not sure what the DC situation is coming out of the 990.
"Any experiment of interest in life will be carried out at your own expense." [url]http://rhythminmind.net[/url] - [url]http://signaltonoize.com[/url] - [url]http://popsound.com[/url]

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Eric Beam wrote:Thanks for the info.
If I wanted to use the impedance knob, How do you come up with the variable Z values?
Try changing 15k to be 50k log pot in series with 1k8 resistor. Change 3k to be 10k log pot in series 150R. Centre Z position will be rough 1k input impedance for both.
Out of curiosity, I already have the JT-OLI-3 output isolators. Would they eliminate the need for the 51R & 470uF if I used them before output pins 2 & 3? Or maybe just the 51R? Not sure what the DC situation is coming out of the 990.
The 51R can be replace the JT-OLI-3 but you canNOT remove the 470uF cap or you will fry the output transformer with +24vdc. Connect the output transformer between +out and 0v on the primary. If the pre is sounding to harsh it is usually the ringing in the output transformer caused by no output resistance. If to harsh go back to a series resistor of 10R to 51R instead of the JT-OL1-3.
Joe :-)
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Eric Beam
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Eric Beam »

Thanks again.
I'll experiment with the isolator & check ringing with a scope.
"Any experiment of interest in life will be carried out at your own expense." [url]http://rhythminmind.net[/url] - [url]http://signaltonoize.com[/url] - [url]http://popsound.com[/url]

Sylvain
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sylvain »

Hi Joe,

A while back I build a BAD (with a pair of JH99C and Lundahl 1538) that has worked great until recently.

When I power it up it goes into a cycle of "power LED lights up and slowly ramps down" (sawtooth like)at a frequency of about once a second. If I pull the +48v feed off the BA and re-insert it, then it behaves correctly.
N.B. this BAD is in a BA4 case with three BAs powered by a JLM 48v/380ma supply and they are all working properly if the BAD is left un-powered. Any thoughts...? :?

Sylvain

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Sylvain wrote:Hi Joe,

A while back I build a BAD (with a pair of JH99C and Lundahl 1538) that has worked great until recently.

When I power it up it goes into a cycle of "power LED lights up and slowly ramps down" (sawtooth like)at a frequency of about once a second. If I pull the +48v feed off the BA and re-insert it, then it behaves correctly.
N.B. this BAD is in a BA4 case with three BAs powered by a JLM 48v/380ma supply and they are all working properly if the BAD is left un-powered. Any thoughts...? :?

Sylvain
Switchmode is in 120% overload hiccup protection mode which will cycle it on and off like you explain. Does the power supply run the BAD by itself with no other BA kits ok? If not there is a fault on the BAD kit?
Joe :-)
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Sylvain
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sylvain »

Joe Malone wrote:
Sylvain wrote:Hi Joe,

A while back I build a BAD (with a pair of JH99C and Lundahl 1538) that has worked great until recently.

When I power it up it goes into a cycle of "power LED lights up and slowly ramps down" (sawtooth like)at a frequency of about once a second. If I pull the +48v feed off the BA and re-insert it, then it behaves correctly.
N.B. this BAD is in a BA4 case with three BAs powered by a JLM 48v/380ma supply and they are all working properly if the BAD is left un-powered. Any thoughts...? :?

Sylvain
Switchmode is in 120% overload hiccup protection mode which will cycle it on and off like you explain. Does the power supply run the BAD by itself with no other BA kits ok? If not there is a fault on the BAD kit?
Aha!

It looks like it's the power supply.

Your mention of "120% overload" put a bug in my ear about current draw.

Any three BA and/or BAD combination will work together. But not all four.
This is a "GS25A48-P1J" supply.( s/n R090507455)...(I think this supply gave me a similar problem about a year ago with a "BA2 everything" kit.)

I tried another supply: an "ES18A48-480" and it works fine.

Ironically the supply that works is rated at a lower current(0.375A) and the supply that is choking is rated at 0.5A. :?

FYI, the rack contains 1 BA w/99V, 1 BA /JLM Hybrid, 1 BAN w/2x 2604 and 1 BAD w/2xJH990c. I did'nt do the math, but I assume that the GS25A48-P1J should be able to handle this combined load...

I guess I'll need a new supply.

Sylvain

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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

There is nothing wrong with the supply except that it is MEPS Green low standby version. Please read the info below from the first post in this Build Thread.

My advice would be to use the 48v 380mA NON MEPS supply with this BA4 and the 48v 520mA MEPS one with the BA2. Or look into the below options.

Notes & Errata
Note 1. The New 48v 520mA 25w MEPS SMPS external & 48v 315mA 15w internal SMPS power supplies under high capacitive and dc current power up surge can go into hiccup protection mode (power light will flick on and off) more easily than the old non MEPS ones so the below soft start mod is recommended for all new BA BAD BAN builds.

1. Do the soft start mod shown below. This leaves all parts fitted as normal but one track is cut and wire link added with #BD681 and #10k fitted. This gives 5 second soft start with no direct capacitance across the 48v SMPS and allows for the maximum possible BA BAD BAN combinations on one SMPS power supply. (#Zener is only needed as usual if opamp needs lower than 48v (+/-24v) rail.)
2. As always test each BA BAD BAN module on the 48v power one at a time without opamp fitted and test voltages and then with opamp fitted and test voltages to make sure the module is working properly. If one BA BAD BAN module puts the supply into hiccup mode there is a real fault.
3. While testing measure the voltage across the 10R resistor to see what current the BA BAD BAN module is drawing at idle (mA = V/10). Add up the total mA to check it is less than about 2/3rds of the specified current of the SMPS you are using to leave some headroom fro driving 600ohm loads.
4. Once all BA BAD BAN modules are tested to work correctly turn off and connect all the modules and power supply should powerup smoothly. If you are having problems email me with your exact configuration and which power supply you are using.

(Without mod each BA has 470uF and BAD abd BAN have 1000uF capacitance direct across the 48v rail which causes a short circuit for to long for the new MEPS SMPS)

BA MEPS SMPS Soft start mod
Image

BAD MEPS SMPS Soft start mod
Image

BAN MEPS SMPS Soft start mod
Image
Joe :-)
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Sylvain
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Sylvain »

OK :roll: :lol:

That explains it all.

I had'nt seen the "Notes & Errata" about this since I build these BAs(&BAD) before this issue showed-up on the forum. They had all behaved correctly until I inadvertantly swithched the supplies...

I'll perform the mod to all my BAs. I think the "soft start" option is probably healthyer for the electronics in the long run...

Thanks for pointing this out Joe.

Sylvain

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Joe Malone
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Re: BA BA2 BA4 BAD Dual99v Build Thread

Post by Joe Malone »

Just swap the power supplies back to the way it used to be and no need to do any mods if they work that way. The caps are fine either way.
Joe :-)
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