[CopperFox]

... you forgot to mention those really.. really.. really.. expensive gold plated fuses that he really ought to use... just joking!
.

I think I have those in my dac. Silver wires too.
Heard that silver plated wires were recommended for the LDmkVI. Why not pure silver? What kind of effect does the different wiring have on sound?

 

[baronbeehive]

Aaand it's done. (Got to love tme.eu and their two day delivery at no extra cost).



Had the time to burn-in for +10 hours as well. These mods - replacing the WCF coupling caps and cathode bypass caps also had a massive overall effect. This is the most detailed, lively, impactful and airy sound I've heard. Lows, mids and highs all sound awesome. It's like being a room with the music playing around and not coming from headphones - on many tracks where I haven't noticed such effect before.

(Using Shuguang 6SL7-T "Natural Sound" driver tubes and sixties RCA 6080's running from a "summit-fi" R2R dac.)

After removing the stock cathode bypass caps, I noticed that they were not Philips 220uf 50v caps but Vishay 470uf 40v instead. Well I think I'll try those +1000uf caps there then at some point.

WOW, fast work! You should notice even more effect after more burn in!

As you are using 6SL7 tubes you could also go for the anode/cathode mod which will increase liveliness and impact yet further...

Interesting about the stock caps, looks like they noticed that we had optimised those ourselves for better power performance and transit recovery, especially in bass frequencies!

Did you remove the PCB, looks like you soldered from the component side?

 

[baronbeehive]

Thanks, I made the case extension by sawing pieces from 20*40mm pine wood and drilling (or actually dremeling) holes for the bottom plate screws in them. The screw holes for the bottom plate are for standard 3M screws so I got those in 50mm length. That is actually too long for most of them as the screw holes are less deep on the sides and front than in the rear so the correct lengths would probably be something between 44 and 49 mm. (The local nuts and bolts store had nothing between 40mm and 50mm so I went with the latter. Will look into ordering the correct lengths soon.).

Also had thought that I'd use some sort of wax or varnish finish on the wood. It does look quite nice unfinished though.

Haven't replaced any resistors yet. By power resistors do you mean those near the front or something near the transformers?

The blue ones to the left and right of the cathode caps (circled), from page 1. There are 8 in all, 4 on the reverse side. 330 ohm in the MKVi.

 

[baronbeehive]

I think I have those in my dac. Silver wires too.
Heard that silver plated wires were recommended for the LDmkVI. Why not pure silver? What kind of effect does the different wiring have on sound?

That was meat to be an in joke between us... but if you feel positive about those fuses why not!!

We went for silver plated copper mostly as that was recommended by the manufacturers. But we went a stage further for the output wires coming from the power tubes to headphone sockets. Some preferred OCC copper, I decided to go for OCC silver. I felt that silver produced a slightly cleaner, sharper sound, whereas copper was smoother and warmer. I know this is controversial as the resistances of silver and copper are not that dissimilar though.

 

[Maxx134]

replaced any resistors yet. By power resistors do you mean those near the front or something near the transformers?

If your unit is new, it will take a while (months) before the stock resistors start to show burn marks from the heat they cannot handle. This will eventually change their values and alter performance.
So eventually it should be redone with wirewound resistors, but not imperative.

What kind of effect does the different wiring have on sound?

It has greatest effect on headphone cables because of the lengths and windings.

Silver "plated" usually not recommended as, in general, it excites the sound somewhat, but in low level signal (line level or less) wiring (short runs) on the circuits & boards, it is actually beneficial in my experience, as low level signal will ride the surface, so beninfit is as if it was all silver wiring.

 

[CopperFox]

That was meat to be an in joke between us... but if you feel positive about those fuses why not!!

We went for silver plated copper mostly as that was recommended by the manufacturers. But we went a stage further for the output wires coming from the power tubes to headphone sockets. Some preferred OCC copper, I decided to go for OCC silver. I felt that silver produced a slightly cleaner, sharper sound, whereas copper was smoother and warmer. I know this is controversial as the resistances of silver and copper are not that dissimilar though.

Well, I don't really know how the fuses would affect sound since those came with the dac. Read some article web-translated from Japanese that gold plated fuses would sound slightly warmer.

Also don't know what effect the different wirings would have - in internal wiring. I know that in headphone/iem cables copper is usually more warm/smooth sounding and silver more sharp and less warm. It's more difficult to compare internal wirings than iem cables

As you are using 6SL7 tubes you could also go for the anode/cathode mod which will increase liveliness and impact yet further...

Interesting about the stock caps, looks like they noticed that we had optimised those ourselves for better power performance and transit recovery, especially in bass frequencies!

Did you remove the PCB, looks like you soldered from the component side?

Removed the PCB while removing the WIMAs for the coupling caps, but didn't bother removing it while removing the WIMAs for WCF coupling caps. Which mod is the anode/cathode mod, one of those on the first page?

 

[CopperFox]

If your unit is new, it will take a while (months) before the stock resistors start to show burn marks from the heat they cannot handle. This will eventually change their values and alter performance.
So eventually it should be redone with wirewound resistors, but not imperative.



It has greatest effect on headphone cables because of the lengths and windings.

Silver "plated" usually not recommended as, in general, it excites the sound somewhat, but in low level signal (line level or less) wiring (short runs) on the circuits & boards, it is actually beneficial in my experience, as low level signal will ride the surface, so beninfit is as if it was all silver wiring.

Ahh. Think I remember seeing some brownish discoloration on one of those resistors, possibly on the other side of the PCB. Did buy the amp used from Ebay so don't know exactly how long it has been used.

 

[baronbeehive]

It's more difficult to compare internal wirings than iem cables

Yes, exactly. We only did this for the output wires to preserve the signal leaving the output tubes, because this amounts to an extension of the headphone cable, from inside to outside the amp. The rest of the internal wires are silver plated copper as Maxx said.

 

[baronbeehive]

Removed the PCB while removing the WIMAs for the coupling caps, but didn't bother removing it while removing the WIMAs for WCF coupling caps. Which mod is the anode/cathode mod, one of those on the first page?

You managed that alright obviously .

Just to sound a note of caution, the PCB is double sided and the traces are different on both sides so you could run into trouble. It would be best to check both sides of the board after any mods.

I summarized the testing of the anode/cathode mod here: https://www.head-fi.org/threads/lit...e-on-first-page.782183/page-243#post-15446810

It's well worth it! It involves changing the values of the 2 sets of resistors to optimise the operating point of the tube. This is for 6SL7's only, other tubes will have different ideal operating points.
.

Some high end amps have pure silver wire internally now.

 

[CopperFox]

You managed that alright obviously .

Just to sound a note of caution, the PCB is double sided and the traces are different on both sides so you could run into trouble. It would be best to check both sides of the board after any mods.

I summarized the testing of the anode/cathode mod here: https://www.head-fi.org/threads/lit...e-on-first-page.782183/page-243#post-15446810

It's well worth it! It involves changing the values of the 2 sets of resistors to optimise the operating point of the tube. This is for 6SL7's only, other tubes will have different ideal operating points.
.

Some high end amps have pure silver wire internally now.

Thanks, I'll have a look at it. Not sure if I'm able to figure out what to do from this data. Although I probably won't be using 6SL7's exclusively. The other mods are apparently still having a burn-in effect, as today the Shuguang Natural Sound 6SN7 sounds better than the 6SL7 version. Those two are my favorite driver tubes followed by the Tung-Sol 6SL7 reissue and some PSVane CV181 / 6SN7s. Haven't tried the original Tung Sols yet.

 

[baronbeehive]

Thanks, I'll have a look at it. Not sure if I'm able to figure out what to do from this data. Although I probably won't be using 6SL7's exclusively.

No worries! If you do decide let us know and we can tell you which are the anodes/cathodes to change.

The other mods are apparently still having a burn-in effect, as today the Shuguang Natural Sound 6SN7 sounds better than the 6SL7 version. Those two are my favorite driver tubes followed by the Tung-Sol 6SL7 reissue and some PSVane CV181 / 6SN7s. Haven't tried the original Tung Sols yet.

NOS tubes any day! I think the Chinese tubes are good nowadays, but the reissue TS's sound brittle compared to the NOS IMO.

 

[baronbeehive]

Re: the 6SL7 operating points on the graph, the new recommended is point 1 with Anode 69K, and cathode 380R. The stock position is at point 2. You can see that point 1 outputs a higher current at 1.2 mA than the stock point at 0.5mA. A further point about this is that the line where the tube operates is much closer to the bottom of the graph and you can see that the voltage lines are more curved in that region indicating less linearity. This means that the sound quality will be more distorted and therefore poorer.

The reason LD did this was probably because they chose a point that would sound as good as possible with various tube types as they didn't know what the owners would prefer to use. So tube rolling would be alright in this stock situation.

 

[CopperFox]

No worries! If you do decide let us know and we can tell you which are the anodes/cathodes to change.

NOS tubes any day! I think the Chinese tubes are good nowadays, but the reissue TS's sound brittle compared to the NOS IMO.

Okay, after a bit more burn in and considering/testing the options, I've decided it would be best to optimize the LD for 6SL7's.
I've got another desktop amp that's built for 6SN7s so those will go there. It's not balanced but has a separate power block and point to point wiring.

Next up I'll be ordering the replacement Mills 330 ohm power resistors so to get the anode/cathode resistors at the same time would make sense. Are they the small ones near the front of the board?

Also got some Wima MKP4 DC Link 500V 100uf capacitors (part nr. DCP4H161007J ) to try out as decoupling caps. Haven't used 4 pin capacitors before. What would be the correct way to connect/solder those - is it to first connect two pins on one side (as in this photo) and then add a wire from the connecting wire to the cap positions on the pcb?



(Photo taken from Klipsch community forums)

 

[baronbeehive]

Okay, after a bit more burn in and considering/testing the options, I've decided it would be best to optimize the LD for 6SL7's.
I've got another desktop amp that's built for 6SN7s so those will go there. It's not balanced but has a separate power block and point to point wiring.

Next up I'll be ordering the replacement Mills 330 ohm power resistors so to get the anode/cathode resistors at the same time would make sense. Are they the small ones near the front of the board?

Also got some Wima MKP4 DC Link 500V 100uf capacitors (part nr. DCP4H161007J ) to try out as decoupling caps. Haven't used 4 pin capacitors before. What would be the correct way to connect/solder those - is it to first connect two pins on one side (as in this photo) and then add a wire from the connecting wire to the cap positions on the pcb?



(Photo taken from Klipsch community forums)

Yes connect the pins as in the photo negative to negative, positive to positive,

then connect to the PCB as in the pic below,(caps omitted):

Cathode1.5k's circled in red, anode 220k's circled in yellow below:

 

[baronbeehive]

Okay, after a bit more burn in and considering/testing the options, I've decided it would be best to optimize the LD for 6SL7's.
I've got another desktop amp that's built for 6SN7s so those will go there. It's not balanced but has a separate power block and point to point wiring.

You can still use the amp with 6SN7's, but the tube operating point will not be ideal.

Also got some Wima MKP4 DC Link 500V 100uf capacitors (part nr. DCP4H161007J ) to try out as decoupling caps.

Interesting, those high values, they should work well. There is a trade off between high value and speed of the charge-discharge cycle, I don't know what the optimum value would be.

I didn't test the amp before and after adding the decoupling caps, so I would be interested in your observations. The point of adding them is to stabilize the PSU, and increase operating speed by adding in a reservoir of fast acting power. Anything done to aid the working of the PSU will benefit the signal carrying the sound, I don't know if the effects will be discernable in the same way that coupling caps and so on aid the sound production but a proper functioning PSU is important.