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


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>So I would need to purchase another Burson op amp unit? I only have 2 of them now. I'm also unsure where the dual 5532 op amps are located. I'll >pop the cover open and take a closer look again. 

 

 

Well that is a little scary if you can't recognise the op amps!!!  I will post a clear pic later.  Be very careful that you insert the new ones  the correct orientation with both half moons.

 

Yes, the 502 uses three dual op amps.  If you have two, that is fine, remove the two on the left and replace both those leaving the one on the right.

 

If you want to return to the original op amps, you just reverse the operation.

 

I have 3,9uF Mundorf Gold/Silver/Oils in my unit and they are nice.  They took ages before they sounded their best though.  If I was doing this again, I would do it differently.  I would use two or three caps paralleled up to the same value.  This is inline with the BAT way of thinking and I think it has merit.   Try something different and report back your findings!  Share it here.

 

G'day Red or any other kind souls,

 

I'd like your input please. 

  • ​With reference to the LM 502 DAC. What do you mean by using 2 or 3 caps paralleled to the same value?
  • I'm looking at some 3.3uf Mundorf Silver in oil capacitors. Would these be suitable and how many capacitors would I need to get?
  • Dumb question. What are the existing stock capacitors that I need to take out of the LM 502 DAC? Is it as simple as popping out the op amps or does it require some desoldering?  

 

Cheers mate!

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Hi guys

Has anyone opened their unit and wrote down cap values for digital section (caps around chip/ receiver/OPAs) ? I've done some surgery on my previous dacs and always replaced stock ones with either Sanyo OScon or BG and always had the same sattisfying result and that is clarity and space has gone one level up. Seeing OScons cheap on PartsConnection I would like to orde these before my unit comes home. So if anyone would be kind to look inside the unit and give us the cap values that would be great. 

Also would like to know what are values of those out caps which I will replace with Mundorfs or Vcaps...basically also any cap that has any role in sound...and also puzzled by two white caps before tubes and unsure psu caps here and there are best quality...

Would love to have that for resistors too but man, haha, I know no one will bother so Ill figure that out when I receive the unit.

 

Also if there is a schematic with parts list that would be awesome

 

 

edit

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post-140563-0-31646800-1436271999.jpg

 

1> What are those 2 white caps (make and are they worth changing?)

2> They all look like low-mid grade electrolytic caps, I reckon they could be replacet with Elna Silmics II , need clarification)

3> That group of caps (gold ones) Look like Nichicon and should be if Im not mistaken power to the chip/receiver. If so BlackGates or OScons would be great here) In front of them is something black that looks like a cap but not sure :) )

4> Again some caps, no name ,make, purpose...

5>rcaOut board , golden caps, grey (mkp?)blocks ...Not sure what those are , especially grey ones or are they on par with WIMAs ...

6> PSU caps ...look like generic ones, if this PSU is unaltered then they are crying for some Panasonic FC, Elna S2...

....and also blue blocks ...same as grey ...stay or change.

Wont even start on resistors and through which signal goes ...would be golden info for me as Im crying to put some tantals in any of my units :)...

 

7> Dexa and Burson make discrete regulators that can be swapped in for some models...but you guessed it  I dont know which ones are in the unit :) ...and there is a fourth OPamp close to PSU btw ;)

8> JFC... just realised that 1pc 3.3uF V-CAP costs 700 bucks US on pcx...unpleasant surprise ...what would be close but affordable option? jesus! Only Vcap nearly affordable is this one 10x cheaper than CuTf ot TTF http://www.partsconnexion.com/capacitor_film_vcap_oimp.html

 

So ...anyone who could shed some light on make/value/worthwileness :) of upgrade of that component please chime in.

Also a sticky list of done upgrades w results would be nice too.

 

Thank you guys

Edited by STELYA
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hello everyone

i have put one burson V5 dual and 2 burson V4 instead the three ne5532 which are together with great sound !

there is another one ne5532 ( the 4 th) ; do you know if there is some interests to change him with discrete op amp ?

thanks a lot for your help

sorry for my english, i am french !

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  • 1 month later...

Here's a question thyat I have had no luck with yet - I can't get my 502 to work with Windows 10 via USB - no drivers? has anyone else had this and is there a path to redemption here?

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  • 2 weeks later...


See if it works without the opamp and that it is a real tube output stage that is just using the opamp for gain or I/V stage. Tube output stages that still employ an opamp are not true output stages, 'usually'. A true output stage takes the signal directly from the DAC (either V or Iout) chip. In this case the LM has opamps and I want to see if its taking the signal before or after the opamp from the DAC. If you get no sound with the opamp removed then you know the answer. A common cathode follower with a resistor before the tube acting as a load after the DAC is quite common in some high end DAC's that use tube outputs. Some are just very simple SRPP topologies that have low voltage fed to the tubes and sometimes a high filament to distort them on purpose and work as a half section with the opamp. Or a loaded tube I/V converter with coupling capacitors as DC blockers to the outputs.

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Fair enough.  I might have to dig out my 502 and give it a try. Won't be till next weekend though as I have a chockas week ahead.

 

Right now I have Andyr' battery phono in playin my tunes, a very nice unit, beautifully constructed with teflon boards and it works a treat!  Sorry, digital just doesn't compare to vinyl, but I am getting way off topic.

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Is there any reason to doubt that it is a separate tube output stage.

 

Much better sound if it can run without the opamp. I had a look closely at some pictures I was provided ages ago, I don't think it can, but its worth a try at your own risk.

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Hard to explain to somebody who doesn`t know about the tube topologies. I can put it in layman terms and say it is not a true tube output stage but more of a buffer circuit with tubes that purposely distort the signal it comes out from the opamps. A true valve stage taps the signal directly from the DAC chip.

Sent from my LG-D855 using Tapatalk

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Guest Muon

Deleted..

 

Oops!

 

This was established earlier in the thread. So not a good idea to remove the opamps.

Edited by Muon
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Yep I had a suspicion it was the case that it may not work without the opamps. For some heavy modifications you can put a Salas HV & LV regulator circuit disconnect the existing one. You can also rebuild the tube output stage completely and omit the opamps with its own I/V and connect it to the ESS Sabre chips.

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Yep I had a suspicion it was the case that it may not work without the opamps. For some heavy modifications you can put a Salas HV & LV regulator circuit disconnect the existing one. You can also rebuild the tube output stage completely and omit the opamps with its own I/V and connect it to the ESS Sabre chips.

That doesn't sound lite n easy?

Sent from my iPhone using Tapatalk

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