[cafe zeenuts]

Before I get to tube rolling, some housekeeping for the LD MK VI.

In order to take full advantage of MK VI here are the following things that are must be done;

1.Replace stock fan to a silent Fan type eg. Noctua 80mm if they’re sounding like an Boeing 747 engine. Fan direction is blowing air up to the amp for best cooling.

2.Isolation feets to further reduce vibration cause by avtive fan. Tube/valves don’t like vibrations, so anything to help reduce any vibration is worth the money. This also raises the height level of the amp and further increase cooling. eg. Vibrapods....

3.Tube dampers: UltraSonic 50 for 5998,6AS7G and UltraSonic 30 for 6SL7.

4.Treatment with Caig Deoxit Gold G100L-2DB for all tube and XLR pins, after pre-treating with DeoxIT D100L-2DB on tube pins.

5.Gain setting on “low” for HD650/600/580, my amp came with factory gain setting on “High”. To set gain setting to low, put all switch to “on” position inside the amp.




(National Union) NU JAN VT229 6SL7GT Gray Glass and Slyvania 6080WC
I first try the NU JAN VT229 with the stock JAN Slyvania 6080WC and didn’t really notice much difference in fact I feel it’s not really a good match at all, it sounded a bit flat.

Mullards 6080 and (National Union) NU JAN VT229 6SL7GT Gray Glass
This combo is bad, small headstage lacks depth and no sense air! Rolled off highs!!!

YMMV!!!

More tubes are coming my way so stay tune for more tube rolling. This new hobby of tube rolling is very addictive and it’s costing me an arm and a leg!

Cheers

 

[razor]

Can you list where you're purchasing these items? I'm waiting to get my MK VI soon.

Thanks for posting this info!

 

[AudioJUNK]

My MK6 has not arrived yet, however I am having a few tubes on my way too.

They are quad of Tung-sol 5998, quad of RCA 6AS7. pair of Mullar ECC35, RCA button bases 6SL7

 

[cafe zeenuts]

I got most of my tubes on eBay, my current favourite power tube is the tung sol 5998. Much sweeter than the mullards 6080! I've all my british made tube arriving today, brimar black base/orange printing 6sl7, haltron EEC35, and brimar brown base cv1985.

From a quick listen they all sound very similar of each other. And all sound better than the NU VT229 much more clarity and has better depth!

 

[cafe zeenuts]

A quick note running the 5998 power tube, the amp is operating much cooler than using 6080. I'm now able to drop my fan speed from 1800 to 800rpm to futher reduce micro vibration cause by the fans. This in return gives me more focus sound coming out of the MKVI.

YMMV!!!

Cheers

 

[Pricklely Peete]

I have an idea for you nuts, pull the fans from the bottom of the case build a small frame or bracket to lift the fans off the stand and within 1 mm of the case bottom plate where the stock holes are....you get the cooling without having the fans transfer vibration to the MK VI casing....makes dust clean up far easier and you get the benefit of active cooling still but without the negative effect of vibration to the tubes. Sure it may look a little odd ......the advantages would outweigh the cosmetic difference IMO.

The fans could be mounted to the stand alone frame with rubber bushings...run them with a small fan controller pot on the side of the frame....use a thermistor in the case to set up an auto rpm control if you want to be hands free (from manual fan speed control)

One of those computer fan controllers could be built into the frame for a real fancy looking cooler setup.....you could go to 120 mm fans for even quieter high cfm operation....

Peete.

 

[cafe zeenuts]

Hey your idea is not bad but it's too much work!

I have a better idea and I'll now run the amp with the bottom plates off with no fans and use the vibrapod & cone under the amp!

Hopefully this will improve the SQ!!!

 

[cafe zeenuts]

The MK VI runs hot after a few hours with no fans using 5998 power tubes, it did have a little more air to the sound compare to when the fans are running at 800rpm!

YMMV!!!

 

[razor]

Don't have my amp yet, but guessing you need 4x of the 5998s? Do they have to be matched?

 

[cafe zeenuts]

I'm back to using active fan for the mk vi.

Yes you'll need quad 5998s, it's better to have them all matched but let me tell you this, it's a very hard task to do.

 

[Lil' Knight]

Your MK VI is from the first batch? The second one is supposed to have the new fan replacement.

 

[cafe zeenuts]

Yeah my is from the first batch! I wasn't expecting any quality OEM fans from LD anyways so I don't make a fuss out of it!

I see that as a plus not an minus, because I can change it to a quality aftermarket fan of my choice! It also add more fun to this hobby!

If I knew I what I know now I would negotiate a deal with David from LD to buy just the amp with no fans and tubes for a cheaper price! The reason is that you're going to change them anyways so why not save the money towards better tubes and fans!

 

[wudai_e]

Aren't those feet meant to only isolate external vibration sources? and since the fan is internal why would that help to damp the vibration?

 

[AudioJUNK]

I got one of the latest batch of LD MKVI after doing some research and advised by friends.

The stock fan is doing very well for me, I can't hear any noise unless i poke my head really close...

however, the 4 feet attached is a bit uneven - -, I am gonna replace them soon.

Any idea on where to get some nice tube dampers besides ebay? preferably not too expensive ones

 

[cafe zeenuts]

I like herbie tube dampers, quality stuff but they are more expensive than the eBay ones!

They work welll in my setup!!!

YMMV!!!