A LM518ia followed me home today.

[RH67]

For anyone looking or interested,... I have a 518ia I picked up about 2 weeks ago. It replaced a Decware SE34i.3 which I loved. After seeing pics of and reading about the 518ia, there was no turning back, I had to try it. I am driving some Zu Omens that have a few internal mod's. My particular 518ia is dead quite, no transx hum. Even with the volume wide open, on ~98db speakers there is very little tube rush and no hum and only heard with my ear physically at the speaker,... (the input tubes I mention below (5751) are an order quieter than the stock ones). The mains transformer does get very hot, the 2 output tranx's not so much. I do use a PS Audio Power plant for line regulation,....

I found the stock 12ax7's to be very 'glassy' in my setup. A pair of JAN Sylvania's helped this a bit. I am currently using some GE- JG5751 triple mica-blackplate ('57). These tubes are literally in another class,... so smooth, excellent extension! Could not be happier and doubt I will ever look for other expensive 12ax7's. Most will read that the 5751 has 30% less gain than a 12ax7 and while that is true is does not necessarily mean that your amp will operate at ~30% less volume. Actually I can not tell that they decreased the volume level for a given volume knob setting much if any at all. Regardless they are a fantastic tube for the input section of the amp. I also found that I preferred 6L6gt's to the stock 6P3P's and to EL34's. I have some 6V6's on the way to try. I have used a 5R4GYS rectifier and felt it was a little soft/spongy due to the greater voltage drop compared to a 5AR4, but it is compatable and did not alter the bias of the 845's. I'm tempted to try a 5U4G I have on hand but they draw ~1amp more current from the transx tap and I'm not sure as to the transx spec's,... I emailed LM and have received no answer (not to surprising). My gut feeling is that it'd be ok, but that transx is already supper hot and the extra current would certainly add to that, so I will hold off and wait for a definitive answer.

I did 'pop the hood' and look at the guts, although quickly. I can tell you that the 12ax7 closest to the volume knob (V7 I believe) is the true input tube, with the sections being the Left & Right channel input. I didn't have time to follow the wires and determine exactly how the second tube is being used,.. ie, Mu follower, SRPP, etc,.. I am also curious as to whether the rectifier (5AR4) is only used for the input and driver tubes B+ while the 845's B+ are utilizing the 2 diode bridges I saw. I will ultimately reverse engineer and draw a schematic of this thing but it is not a top priority. Soldering is top notch! The main coupling caps between the driver and 845's are (if I remember correctly) MKP's or metalized polypropylene in construction. Yes the are German N-Caps (no name), what ever that means,... marketing in my opinion.. I do personally believe that a nicer cap could be easily replaced there for a nice improvement.

For now though, I'm just gonna sit back and enjoy the sweet music this thing puts out. It really does sing!

Congrats on the 518. I really enjoy mine, it makes me feel that i`m part of the system and not a bystander. Enjoy!!

 

[seikosha]

Thanks

Hi jslateiv,

Thanks for taking the time to share your thoughts on that comparison. I very much appreciate it! Enjoy the new amp!!!

 

[jslateiv]

I received an email back from James at Line Magnetic as to my question of how much current can the transformer tap for the Rectifier handle. The answer is 2.5 amps. So this means no 5u4G, GZ33,a and others that draw more than 2.5a from the 5v heater tap.. however a 83V (with octal to 4pin converter) is a possibility along with a 5v4 (which is an octal 83V) and some others.

I replied back to James asking a few more questions as well. Hopefully he will reply with the Plate voltage used on the 845, Plate voltage and set bias for the Driver and whether or not the Tube rectifier is used in the 845 circuit. I don't believe that it is, which would widen the possibility of other tube rectifiers as the output current draw on the rectifier plates would be significantly less.

I will report back when I hear from James again,....

 

[Spektre]

This is an old thread I know but I dropped some coins on one of these based on reviews and my experience with their LM215 CD player, I've also never heard a valve amplifier so its going to be interesting.

I haven't heard anything solid state to replace my Destiny 2 other than perhaps the LFD NCSE but they have similar sonic signatures so it seemed more like a sideways move than a revolution.

 

[opnly bafld]

Hope you like your new amp.
I have looked at the LM 215 CD player; not sure I want to spend the money.

 

[Spektre]

Whilst the LM 215 doesn't come close to vinyl in my set-up, it does manage to make a case for itself.