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Seany

The sound of a modded line magnetic LM-502CA – modded by Lansche plasma guy (LPG)

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I am writing to you, as I am still in shock at how great this dac sounds – sorry for the ramblings.

 

I was lucky enough to be invited to (Lansche plasma guy)  LPG’s place to have a listen to his modded dac – his hospitality and kindness was greatly appreciated – a damn nice guy!

 

Looking inside his DAC, he has done allot of work – this would have taken so much time and patience: changing tubes, rewiring, resistors, caps – to have a DAC with so much detail and so much timbre....I swear to god, if I was without sight, I would have thought that we were at a concert hall, a small venue, inside a studio – There was a very lifelike and natural sound and I felt pretty damn honoured to have experienced it. There was a very different experience with each song/cd we heard.

 

In 3 hours of listening – we heard most genres that I can think of: recorded live onstage, in studio, in a flat (i could hear the passing cars)  etc etc – some/most music of which I will need to get a list of so as I can buy... I’m sure we covered most genres of music.

 

What really got me was that no matter what volume LPG’s system was set at, it always sounded spot on – nothing was confused or fatiguing – just natural and just beautiful – I could hear full blown guitair solo’s with so much expression and was also able to hear what the other instruments were doing very clearly, complexity was never an issue.  In fact layers upon layers of music were handled very well by his system and details retrieved that I have never heard before on music I thought I knew very well!!

 

Can you tell I’m excited, I have a line magnetic dac also – a stock one which I have full intention of modding.

I have heard quite a few systems in my brief time here on this journey and have experience in playing in bands professionally myself - for years (without much hearing loss – I was always very careful with my ears).

 

Just sharing a great experience and I will also mention that I have no affiliation whatsoever with line magnetic, in fact, this is a shout out to Lanche Plasma Guy!  â€“ well done mate, your system is crazy and well worth all the time you have spent on it!!!

 

This line magnetic DAC was well worth the price I paid and will be well worth modding after what I heard today at LPG’s place.

 

Sean.

Edited by Sean33rpm

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Hey Sean, great story mate. I bought a Line Magnetic Tube DAC from Bill McLean a couple of months ago. Never used the stock valves. NOS valves went straight in. Wonderful sounding without mods.The board has a neat & simple layout, so I imagine that it would be relatively easy to work on. I have no technical skills myself, but I would love to hear what could be achieved.

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Do you have any idea what the mods are - apart from changing the valves and op amps?

 

The board on my DAC (bought in February) has failed and the DAC has been with McLeans for nearly two weeks.  The only response I've had from them so far was a brief phone call to confirm the problem.  They don't carry replacement boards so at this stage I don't know what they are proposing to do.  In view of the consistently good rap that McLeans get on SNA, I'd have to say that my experience with them so far has been a bit disappointing.

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Do you have any idea what the mods are - apart from changing the valves and op amps?

 

The board on my DAC (bought in February) has failed and the DAC has been with McLeans for nearly two weeks.  The only response I've had from them so far was a brief phone call to confirm the problem.  They don't carry replacement boards so at this stage I don't know what they are proposing to do.  In view of the consistently good rap that McLeans get on SNA, I'd have to say that my experience with them so far has been a bit disappointing.

That wasn't the sort of feedback I was wanting to hear. It will be sorted, I'm sure

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Do you have any idea what the mods are - apart from changing the valves and op amps?

 

The board on my DAC (bought in February) has failed and the DAC has been with McLeans for nearly two weeks.  The only response I've had from them so far was a brief phone call to confirm the problem.  They don't carry replacement boards so at this stage I don't know what they are proposing to do.  In view of the consistently good rap that McLeans get on SNA, I'd have to say that my experience with them so far has been a bit disappointing.

Some info here:

http://killerdac.com/forum/index.php?topic=2893.0

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It's interesting that he didn't mention changing the op amps.

 

Decky changed the stock 4562s for 5532s.

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Guest Muon

It's interesting that he didn't mention changing the op amps.

 

Decky changed the stock 4562s for 5532s.

Are they on the output, mate?

 

If it is switchable between SS and tube output, then those would be switched out when running tube output?

 

If so.... many of the KD crew would be running tube output exclusively :cool:

 

I wouldn't mind seeing a schematic of one of these if they are floating around the net, only for a curious look at the OP stage :)

Edited by ortofun

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Great DAC very interested in the tweaks as it is good straight up. When I first popped the top & looked at the Chinese rectifier & thought oh no cant use any of my NOS tubes. Got to love the attention to detail flick the switch & Mullard 6x4 is good to go. 

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I wouldn't mind seeing a schematic of one of these if they are floating around the net, only for a curious look at the OP stage :)

 

 

If you gave me some close up pictures of the output stage I can draw a schematic up. I've read a few reports about the output tube stage and the I/V converter being "mediocre" and can be greatly improved with a complete redesign. I would not be surprised if this is just a simple mu follower a la SRPP topology with a simple switch on the DAC to switch signal output, one to the opamp for SS OPS and the other to the valve OPS.

Edited by DefQon

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Guest Muon

If you gave me some close up pictures of the output stage I can draw a schematic up. I've read a few reports about the output tube stage and the I/V converter being "mediocre" and can be greatly improved with a complete redesign. I would not be surprised if this is just a simple mu follower a la SRPP topology with a simple switch on the DAC to switch signal output, one to the opamp for SS OPS and the other to the valve OPS.

Oh, i don't have one, or pics of one.

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When I get my camera back from the repair shop, I'll post some close ups of the innards. Am thinking of modding my stock unit too.

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Are they on the output, mate?

 

If it is switchable between SS and tube output, then those would be switched out when running tube output?

 

If so.... many of the KD crew would be running tube output exclusively :cool:

 

I wouldn't mind seeing a schematic of one of these if they are floating around the net, only for a curious look at the OP stage :)

I'll chime in here:

 

 

All three op amps are in circuit ALL the time.  Yes, even when the 12au7s are switched in, the signal still goes through all the op amps.  Bummer!

 

Standard op amps fitted to my unit are (or were) 5532s x 3.  LPG is running 3 x Burson discretes (I believe).

 

Currently I run none!!!  All op amps removed and I run one resistor (well two in  parallel actually) and a single Oscon cap.  How does it sound compared to stock?  Well much better than stock with better dimensionality.  However compared to LPGs, his is streets ahead with all his other mods.  Maybe the op amps are not that bad at all.  I had tried opa627s and a couple of others in combination with a pair of Bursons that I have had laying around from my 1541 days, but the Bursons and 5532s worked best.

 

Has anyone tried any of the DEXA discrete op amps?  And how many hours do I need on a pair of Burson discretes to run them in?

 

What I really like about LPGs unit is the absolute quality of timbre.  Just awesome!!!  My unit just does not compare....

 

The biggest peeve with this wonderful DAC though, is that it is really touchy, with ANY electrical switching in the house (ie, open the fridge door!) the link between the transport and the LM temporarily drops out.  It really craps me off!!!!!  I've heard that a simple DC blocker may help here, so I should maybe pursue that.

 

This DAC is very tweakable and for the money, a bargain.  The next mod for me shall be a pair of Mundorfs as output coupling caps when they arrive.

The quality of the cathode resistors in this circuit are quite critical apparently, but a pita job as it requires removal of the board, a mongrel job.

 

Reliability?  Mine has never had a glitch and probably done around 1000hrs.  6X4 works better than a 6Z4 in my unit. This rektumfrier is only used as a half wave in this circuit.  Reason?  Well that is beyond my level of electronics.

 

A schematic?  If anyone has one I'd love them to share it!  I'll take some pics tomorrow and attempt to post them here.

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Red, what input are you using. I'm finding that the optical input is more stable than the coax. I'm taking notes as to every one else's findings and am planning some mods myself.

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I'm using the RCA SPDIF.  I did try the AES EBU and it was clean and clear, but lacked any weight and..."togetherness" for a better word.

 

Now to find my camera.

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OK boys.  I'm a little IT challenged here...  Just how do I upload pics to this forum?

 

I have pics, I just have no clue how to get them up for all to see.

 

Can someone steer me in the right direction please.

 

Thanks, Red.

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OK boys.  I'm a little IT challenged here...  Just how do I upload pics to this forum?
 
I have pics, I just have no clue how to get them up for all to see.
 
Can someone steer me in the right direction please.
 
Thanks, Red.

 

Press on vacant box at bottom to begin then "more reply options" button at bottom right then "choose files" at bottom left then select pic on your files -> double click on it (make sure under 2mb, if over that resize/compress) then press "add to post" bottom right.

Bingo!  :D

Edited by evil c

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Many thanks evil.

 

Here is one pic, the only one under 2meg!  I have not a clue how to resize/ compress the others that are clearer here on W10.

 

Back in the old XP days all this stuff was a breeze, not anymore it seems.  I'll keep trying though, I hate it when stuff beats me!

post-140563-0-01378700-1436269960_thumb.

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I'm been trying to find close up pictures as well. Time to reverse engineer some Chinese hifi and make it better.  :cool:

 

 

Go for it @ !  It's all there and Good Luck

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