Search found 24 matches

by ciscan.81
Fri Nov 29, 2013 3:33 pm
Forum: JLM Audio Kits
Topic: BA Input transformer ratio jumper switch
Replies: 2
Views: 11651

Re: BA Input transformer ratio jumper switch

Thanks Joe.

Very simple. :D
by ciscan.81
Fri Nov 15, 2013 4:49 pm
Forum: JLM Audio Kits
Topic: BA Input transformer ratio jumper switch
Replies: 2
Views: 11651

BA Input transformer ratio jumper switch

Hi I've got a couple of 312-Style JLM BA pres with JLM2520HV FET opamps and EA2622 from classic api. Both are working great. I am planning to mount these into a 1U chassis with 2 new 312-Style (slightly different) builds to make a nice _3124 Style pre with two slightly different flavoured pairs. I h...
by ciscan.81
Tue Aug 20, 2013 6:27 am
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Hi Joe ...I have recently upgraded to an UA Apollo 16 interface and will be needing to expand my pre collection... I've just ordered the parts for a couple of budget 312 builds for now to bring me up to 8 JLM channels, but I'll definitely be considering the 1290 x 4 later when my bank account has be...
by ciscan.81
Sat Feb 02, 2013 10:07 am
Forum: JLM Audio Kits
Topic: FIRST DIY BUILDS: JLM BAs & 1290 Complete!
Replies: 7
Views: 25800

Re: FIRST DIY BUILDS: JLM BAs & 1290 Complete!

From what I can remember, Solder them onto the two uppermost (longest) terminal legs of the 48v phantom switch...be sure to get the polarity right and make sure you leave enough length so that the LED can reach your front panel comfortably...maybe do a mock up with your PCB on the panel first to mak...
by ciscan.81
Mon Jul 16, 2012 9:48 pm
Forum: JLM Audio Kits
Topic: FIRST DIY BUILDS: JLM BAs & 1290 Complete!
Replies: 7
Views: 25800

...And a few more

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by ciscan.81
Mon Jul 16, 2012 9:45 pm
Forum: JLM Audio Kits
Topic: FIRST DIY BUILDS: JLM BAs & 1290 Complete!
Replies: 7
Views: 25800

More Pics

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by ciscan.81
Mon Jul 16, 2012 9:43 pm
Forum: JLM Audio Kits
Topic: FIRST DIY BUILDS: JLM BAs & 1290 Complete!
Replies: 7
Views: 25800

FIRST DIY BUILDS: JLM BAs & 1290 Complete!

FIRST DIY BUILDS: JLM BAs & 1290 Complete! :D IMG_0436.JPG IMG_0416.JPG IMG_0391.JPG I have finally finished my first DIY preamp builds! By way of giving thanks to those who helped me in the DIY community I'd like to share my experiences and results. Before I start I'd like to give my sincere thank...
by ciscan.81
Fri Jul 13, 2012 11:23 am
Forum: JLM Audio Kits
Topic: 1290 Build Thread
Replies: 98
Views: 305329

Re: 1290 Build Thread

Hi Joe UPDATE: ALL FIXED ! I reluctantly pulled the go-between and 1290 out of the rack case this morning to look for faults...BINGO! :) I had missed a solder pad on the input transformer, must have just been contacting intermittently. Fixed. The next problem was the middle position on the stepped g...
by ciscan.81
Fri Jul 13, 2012 12:17 am
Forum: JLM Audio Kits
Topic: 1290 Build Thread
Replies: 98
Views: 305329

Re: 1290 Build Thread

Hi again Joe I finally put my 1290 Macro together today having finished my custom rack cases... The build is standard with FET DI and a VU meter running through a buffer kit. The unit is working and sounds great when it does but is displaying some strange behaviour: The signal cuts out whenever the ...
by ciscan.81
Sun Jul 01, 2012 1:52 pm
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Yes while everything above is correct in a basic form. The transformer was designed as a 150/600 input so when wiring for 150 input the core will saturate earlier and when it does saturate it will lower the input impedance way down in the low frequencies even without a load on the secondary of the ...
by ciscan.81
Mon Jun 25, 2012 9:38 pm
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Hi again Joe...yep it's me again :wink: I've been wondering about the ratio for the EA2622 in my BA-312 style... You recommended wiring the primaries in series with the LOW ratio jumper fitted to give 1:3.5... ...it 2 primary windings so low ratio will give 600ohm input with normal 15k load which is...
by ciscan.81
Sat Jun 23, 2012 4:28 pm
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Thanks again Joe Turns out I did have the BD681 Transistor the wrong way. :oops: As search of the posts revealed: BD681 plastic face outwards is correct. I put a new one in the right way round and all voltages now are reading as expected. Thanks again for sorting me out. That is the last of the prea...
by ciscan.81
Wed Jun 20, 2012 10:42 pm
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Hi Joe Just want to check a few test voltages with you for my BA 312-style before I fit the opamp Specs: EA2622 input Transformer (with middle 'LOW' jumper fitted) SL-2520 (runs on 16V-18V) (not fitted for testing) EA2623-1 output Transformer (not fitted for testing) 1. CL = NF 2. CZ = 220pf 3. RZ =...
by ciscan.81
Sat Jun 16, 2012 10:37 am
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Brilliant! Thanks Joe, I get it now. :D

Thanks again for your patience.
by ciscan.81
Sat Jun 16, 2012 1:55 am
Forum: JLM Audio Kits
Topic: BA BA2 BA4 BAD Dual99v Build Thread
Replies: 376
Views: 868167

Re: BA BA2 BA4 BAD Dual99v Build Thread

Right, Thanks Joe, glad I got it mostly right... Take 2: So just to be painfully clear, output trim wiring pot like this for dual? Dual Gang Output trim.jpg or this for single Sinlge Output Trim Pot.jpg 0v/pot pin 2 is left unconnected so the pot acts only as a variable series resistor, thus minimis...