Search found 2067 matches
- Wed Mar 06, 2024 11:37 am
- Forum: JLM Audio Kits
- Topic: NV500 Mic pre BUILD THREAD
- Replies: 0
- Views: 423
NV500 Mic pre BUILD THREAD
UNDER CONSTRUCTION NOTES & ERRATA R30 is marked on pcb as 100k but is 10k for current orange HPF led to be correct brightness. The 2 x BA283AV SMD plug-in modules have been pre-biased so are plug-and-play and swapable. You can check if bias is correct by measuring the voltage across the 12R 1W resi...
- Mon Mar 04, 2024 11:36 am
- Forum: JLM Audio Kits
- Topic: KRAFTWERK Power Supply BUILD THREAD
- Replies: 33
- Views: 107337
Re: KRAFTWERK Power Supply BUILD THREAD
Thanks, Joe, that's super. Can I just double check one more thing: from my 51X racks, I should wire the rack 'chassis' ground directly to the star point in the PSU case, is that correct, rather than the PCB audio 0v starpoint? Just wire your mains ground to the power supply chassis and onto the 51X...
- Sun Mar 03, 2024 12:35 pm
- Forum: JLM Audio Kits
- Topic: KRAFTWERK Power Supply BUILD THREAD
- Replies: 33
- Views: 107337
Re: KRAFTWERK Power Supply BUILD THREAD
hi Joe - a quick question about Kraftwerk grounding, I'm just trying to make sure I understand why there are two 0V points on those Phoenix output connectors. Audio ground is connected to chassis ground via 10ohm resistor in series with 0.1uF cap, right?, and I thought that's the only way that audi...
- Tue Feb 27, 2024 2:34 pm
- Forum: JLM Audio Kits
- Topic: MAC Rack kit Build Thread from October 2023 with slow attack led
- Replies: 39
- Views: 26507
Re: MAC Rack kit Build Thread from October 2023 with slow attack led
Ok 98.8k in parallel with 831k = 88.3k. So you can try a 1Meg pot. Since pots are +/20% it will not guarantee the pots will be at the same point in the turn of the pot due to the log curve mismatch but can help. Once you balance the ac volts at these 2 points you will need to redo the makeup balanc...
- Mon Feb 26, 2024 6:39 pm
- Forum: JLM Audio Kits
- Topic: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
- Replies: 108
- Views: 186366
- Mon Feb 26, 2024 6:36 pm
- Forum: JLM Audio Kits
- Topic: MAC Rack kit Build Thread from October 2023 with slow attack led
- Replies: 39
- Views: 26507
Re: MAC Rack kit Build Thread from October 2023 with slow attack led
Ok here are the measurements CH A had .316 vac and 98.8k ohms with pcb cables unplugged. Ch B had .307 vac and 88.3k ohms with pcb cables unplugged. Settings are, y cable with 1.23vac at inputs. 1.3 ratio, VU, and flat. Ok 98.8k in parallel with 831k = 88.3k. So you can try a 1Meg pot. Since pots a...
- Mon Feb 26, 2024 12:10 pm
- Forum: JLM Audio Kits
- Topic: Scorpion Tube power Supply Build Thread
- Replies: 34
- Views: 32743
Re: Scorpion Tube power Supply Build Thread
There is no filament connected with those previous voltage measurements. The filament is set to 6V right now. These are the original tubes to the preamp. The 48V seems fine. Haven’t put a load on it though The schematic for the mic pre you put up showed 12v filament as the 2 tubes are wired in seri...
- Mon Feb 26, 2024 11:59 am
- Forum: JLM Audio Kits
- Topic: MAC Rack kit Build Thread from October 2023 with slow attack led
- Replies: 39
- Views: 26507
Re: MAC Rack kit Build Thread from October 2023 with slow attack led
Cool. With Y cable and thresholds CCW measure the voltage across the outside threshold pot tags again. If one is higher voltage a resistor can be added to bring it down to match the lower voltage side and then the makeup trim will need to be redone. This can sometimes balance the threshold pot mid ...
- Mon Feb 26, 2024 11:50 am
- Forum: JLM Audio Kits
- Topic: BA BA2 BA4 BAD Dual99v Build Thread
- Replies: 376
- Views: 881540
Re: BA BA2 BA4 BAD Dual99v Build Thread
My voltage was running a bit high. 47.5 volts in and 24.75 out or so on all 4 pres', So I dialed the volts back to about 46.5 in and around 24.33 out and that was enough to get the power supply out of hiccup mode. now all 4 preamps are running smoothly and sounding great! I was going to use them on...
- Mon Feb 26, 2024 9:43 am
- Forum: JLM Audio Kits
- Topic: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
- Replies: 108
- Views: 186366
Re: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
Hi Again Joe, apologies for all my bungling! So I decided to put the compressor back together after soldering the dip 8 pins I had missed on the side chain board. Good news is the meter appears to be working well now. the Sidechain NE5322A pin voltages all match the NE5322A on BIO500 board now as i...
- Fri Feb 23, 2024 5:53 pm
- Forum: JLM Audio Kits
- Topic: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
- Replies: 108
- Views: 186366
Re: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
You have to measure the 1.23v between pin 2 and pin 3 of the output XLR as that is the balanced out. Otherwise the output transformer is floating and you will just get random meausrements OK as stated previously closest to 1.23vac I can get is 1.224vac. I send this 1Khz sine to FC500A input. In VU ...
- Fri Feb 23, 2024 10:55 am
- Forum: JLM Audio Kits
- Topic: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
- Replies: 108
- Views: 186366
Re: LA500A opto comp MAY 2021 BUILD THREAD 500/51X
OK main thing below is to test if the meter coil is intact. See below I had another good go at all the toggle switch points with the solder iron. Cool Input to JLM Eleven rack measured the 1Khz sine wave at 1.228 volts With rack power off or on and 500A connected via edge connector I measure 1.224 ...
- Thu Feb 22, 2024 10:29 am
- Forum: JLM Audio Kits
- Topic: Scorpion Tube power Supply Build Thread
- Replies: 34
- Views: 32743
Re: Scorpion Tube power Supply Build Thread
I only have one preamp connected. With nothing connected to the PSU I have 306VDC unregulated and the regulated supply jumps up to 296VDC. Both HV1 and HV2 have the same issue, when the Filament is connected they won't go higher than ~256VDC Ok that is a bit low. Does it go to 320v with no filament...
- Thu Feb 22, 2024 10:15 am
- Forum: JLM Audio Kits
- Topic: MAC Rack kit Build Thread from October 2023 with slow attack led
- Replies: 39
- Views: 26507
Re: MAC Rack kit Build Thread from October 2023 with slow attack led
I found the culprit, not sure how this got checked on or if it is set this way by default in REW but I went back to not using the Y cable and then I unchecked this and the link switch works perfectly. Such a stupid waste of time trying to troubleshoot a problem that really wasn’t there. IMG_6982.jp...
- Tue Feb 20, 2024 3:07 pm
- Forum: JLM Audio Kits
- Topic: Scorpion Tube power Supply Build Thread
- Replies: 34
- Views: 32743
Re: Scorpion Tube power Supply Build Thread
I’ve got the scorpion up and running now with it bolted to a 1/4” bar of aluminum. The heater voltage seems solid, but I’ve got HV2 cranked as high as it will go, and under load it stops at 256V. I’ve got 266V unregulated at the power resistor and 116VAC at the outlet (USA). Does this seem correct ...