JLM 99v

[quote author="adrianh"]...who needs servos messing with my bass?[/quote]I'm glad you brought that up, Adrian, as I've heard much about the servo hurting the low-end more than it helps the highs. I've not compared a servo'd circuit to a cap'ed one yet (I will soon, though) but a few folks I respect have sure caused me to have doubts about the servo method.

When using an output transformer, I don't see why you can't just use a diode/dc offset circuit on the input aka the Jensen/990 method, and let that be the end of it. Of course, if the J99's offset is too high, that may throw things off-kilter and cause asymmetrical clipping, or something.

The JLM99s is a 10 transistor Class A fully symmetrical circuit opamp with no DC offset that runs on +/-24v only and is designed for Pure High Current Buss Summing Amps and Pure Classical recording Mic Pres. It is not meant to replace the 99v at all. But to be used where the 99v cannot be easily used due to its offset. Like the 99v which is like no other 99 pin compatible type opamp the 99s will be the first 99 pin compatible type that I know of running in a full symmetrical circuit configuration. Basically extremely low noise floor & THD & IMD with high current drive. It will also be more $ than the 99v due to all the extreme transistor matching that is needed. Will not be available until early 2005 most likely.

Joe

I'm sure this is a dumb question for all kinds of reasons, but how about using two different opamp designs in a dual circuit? It just occurred to me to ask.

Bear

Great work Joe, looking forward to seeing the JLM99s.

Just a question to those that have built this. What did you use for a power transformer? I'm wondering what rating I should be looking for. Assuming I'm running the pair at +/- 34V. Thanks.

> What did you use for a power transformer? Assuming I'm running the pair at +/- 34V.

Use 34+34VAC or 68VAC CT. A 30+30VAC will probably work OK.

Is +/-34V even legal for that amp? Is there any point in feeding it more juice than any line input can swallow?

Is +/-34V even legal for that amp?

Click to expand...

According to Joe that's the voltage it's optimized for.

Basically the JLM99v will run on +/-15v to +/-34v but is best on +/-28v to +/-34v. So the simple answer is to use a 25vac - 0v -25vac transformer or one 24vac plug pack and adjust the +/- rails to be about 5volts under the unregulated voltage whcih will give you somewhere between +/-28v to +/-34v. Also you do not want the unregulated voltage to go over 40v or you may damage the regulator IC's. The 48v rail regulator on the JLM AC/DC & New Power station PCB is protected by a 36v or 39v 1watt Zener Diode. So if the pump charge voltage goes above 80v the zener will start to conduct and over ride the regulator so the 48v rail cannot be adjusted down to 48v.

Below is from the JLM Web site http://www.jlmaudio.com/JLM Power Supply.htm

What Power Transformer secondary volts do I need?

The transformer secondary AC volts needed depends on the +/- dc regulated voltage rails wanted. If you want +/-34vdc regulated for 99v you will need 37v to 40v unregulated which would need one or two 26vac to 28vac transformer secondary windings. This might sound like a odd voltage value but in reality when you take the fully loaded voltage and add the regulation percentage specified by the transformer manufacture to get the no load voltage it all works out. So if the voltage output of a transformer is stated as 25vac at full load by adding the 10 to 20% regulation amount you will end up with 27.5vac to 30vac unloaded with is perfect. Also if you use one 25vac winding then the refresh rate to the large storage capacitors will be 50 or 60Hz depending on the country you are in. If you use two 25vac windings or a 50vac centre tapped winding the refresh rate will be 100Hz or 120Hz which will almost half the amount of ripple on the large storage caps. Also the dual 25vac has symmetrical ripple.

Joe

www.jlmaudio.com

Joe (JLM)
Did you get my e mail about ordering the pcb's to the uk?
Vikki(uk) :grin:

alo
just to say i am recording my new record,and all the guitars were done with 99v i got from joe.wish i had more.
think i am giving a call to joe in the near future.
best regards
pedro
.

Thanks for the kind words on the 99v Pedro :grin:

Vikki sorry for the delay. I had a couple of days off from the email which has been topping 50+ a day. Have almost got it down to 2 pages now.

Joe

www.jlmaudio.com

:thumb:

I wanted to bump this because I bought a pair of 99v preamps from Joe about two months ago and they've been living on my overheads. We just finished tracking the new organissimo record (my trio) and I used the 99v preamps with some ATM450 mics as overheads on the kit.

Wow.

Big step up from the Topaz preamps (duh) and even from my Quad Eights, which sound great on individual drums, but not so great for cymbals. The 99v's are beautiful sounding. No harshness in the cymbals, no muddiness in the low-end. Just beautiful sound.

I also used a channel with my Shure 330 ribbon (re-ribboned by our very own Marik, who did a fantastic job) on acoustic harmonica. You know how harmonica can easily sound sort of grating and piercing? Not with the 99v and the Shure. I didn't even have to use any EQ and it just sits perfectly in the mix, right on top, without any harshness. Amazing.

I will be adding another pair to my arsenal when funds allow.

Great job, Joe!

I used Joe's output transformers and Lundahl 1538XL input transformers, btw.

I love mine more by the day. These with a pair of Trakkers are about all I could ever ask for. Size AND articulation. I just can't say enough about them, so I'll stop. :green:

Gosh darn it. All I can think of these days is getting my pair of Dual 99v's and then I see this right at the top of the lab forum. Very frustrating.

[quote author="b3groover"]they've been living on my overheads. We just finished tracking the new organissimo record (my trio) and I used the 99v preamps with some ATM450 mics as overheads on the kit.

Wow.

Big step up from the Topaz preamps (duh) and even from my Quad Eights, which sound great on individual drums, but not so great for cymbals. The 99v's are beautiful sounding. No harshness in the cymbals, no muddiness in the low-end. Just beautiful sound.[/quote]My dual 99v also beat out other preamps including some Q8s for overheads. I used a pair of AT4050's and I also thought Wow.

I'm using a 1538 and no tranno out. Very, very nice

The AT4050s are on my short-list of mics. I'd love to get a pair. Audio Technica makes some really nice stuff.

I'm proud of the tracking we did, all in my little basement room, no headphones. Lots of energy, good vibe, and the sonics are pretty damn good if I do say so myself. Plus I got a Moog Voyager halfway through the sessions and started using it in wacky places! Too much fun!



Hey Miko, you still have those MAPs? I'm finally re-racking mine and swapping out the 5004 chip for some of Scott Lieber's SL-2520's. Gotta get my PSU stable, though. It's acting weird.