[baronbeehive]

If you have quiet background then it should be fine.
The chassis is a good shield too.

What sort of shielding did those input wires have?

Also I was wondering about the diode bridge mod, did anyone try this?

There was a diode mod for the APPJ amp which reportedly had a positive effect. Maybe having fast recovery diodes would impact positively on sound, and speed of recovery.

 

[Maxx134]

What sort of shielding did those input wires have?

Also I was wondering about the diode bridge mod, did anyone try this?

There was a diode mod for the APPJ amp which reportedly had a positive effect. Maybe having fast recovery diodes would impact positively on sound, and speed of recovery.

The 4 wires was in one with aluminum coax type braided shielding..


Haven't heard of diode mod so if possible post link.

 

[baronbeehive]

The 4 wires was in one with aluminum coax type braided shielding..


Haven't heard of diode mod so if possible post link.

I never noticed that shielding when I took out the input wires, don't know if the MK8 is different.

You mean this:

Diode Bridge : (Optional)

IXYS FRED Rectifier Bridge FBE22-06N1 ( High performance 600v/22amp rectifier bridge with fast recovery diodes). Sonic improvements were not verified at time of installation.
http://www.mouser.com/ds/2/205/FBE22-06N1-6885.pdf

on page 1 this thread?

I mentioned the diode mod for the APPJ as both you and I have this amp and I had heard about this mod that was offered on the APPJ by an APPJ distributer way back when it first came out some years ago. I haven't been able to find out any details about it despite a full search. So I assume it involved fast recovery diodes, and was wondering if this was likely to be sufficient to cause sonic improvements for the LD, as it was said to do for the APPJ when I first heard about it.

 

[Maxx134]

and I had heard about this mod that was offered on the APPJ by an APPJ distributer way back when it first came out

Can you tell me if that is the same thing we already mentioned in first page?

If so, and you want to try it... it mostly benefits the power supply caps.
I could not compare to verify differences and so would have to go off memory.
And My memory tells me I don't know, ha

 

[Maxx134]

Little dot amp design was based on a heavily buffered capacitance PSU.

In contrast, the appj is very small lean switching PSU so probably heavily reliant on specific parts...
So unless you actually seen another one successfully using that bridge in place of stock parts, I would not mess with it's PSU, as those parts are pretty specific.

 

[baronbeehive]

Little dot amp design was based on a heavily buffered capacitance PSU.

In contrast, the appj is very small lean switching PSU so probably heavily reliant on specific parts...
So unless you actually seen another one successfully using that bridge in place of stock parts, I would not mess with it's PSU, as those parts are pretty specific.

Yes.

That SMPS has held up well over the years, I wasn't sure about it at the time, I've heard of them going up in smoke, but seems to be a good design solution.

I can't say whether the diode mod for it is the same as mentioned in the first page for the LD as I haven't been able to find out anything about it annoyingly. Whenever anyone has mentioned it it is always along the lines of "people have said it is a noticeable improvement" but the trail goes dead from there when it comes to what the mod actually is... I'm beginning to wonder if it actually existed! In any case people at the time also said that putting in silver fuses was an improvement which we know is pure unadulterated snake oil... which is why I only put in a cheapo silver fuse LOL!

I was thinking that a faster acting diode would be good for the LD. Not so sure about the APPJ as the SET design is already very fast and open sounding, and I have no issues with it. Can't see the diode making much difference though.

As I said the 2 amps are performing comparably now post mods... but there are slight differences not surprisingly, such as speed and attack but frequency response is very similar. The LD is slightly warmer and fuller sounding with more bass heft, the APPJ is a tad leaner.

 

[baronbeehive]

Can't see if the wires are shielded here:

 

[SonicTrance]

Can't see if the wires are shielded here:

My mk6 used shielded wire on the input but the shield was not connected, so effectively useless. You suppose to ground one end of the shield. Anyway, it's not needed in the mk6 as I replaced the input wire with non-shielded wire and had no noise issues.

 

[baronbeehive]

My mk6 used shielded wire on the input but the shield was not connected, so effectively useless. You suppose to ground one end of the shield. Anyway, it's not needed in the mk6 as I replaced the input wire with non-shielded wire and had no noise issues.

Right! I thought so, I remember seeing yours. Anyway we bunched up the wires into 2 groups and tied up each group together so if there were any issues that would have showed up.

 

[Maxx134]

1- I plan to upgrade the cathode caps to to Nichion KZ / Muse at larger size so meters won't dip at high volume with planars (remember I have the lesser current MK8)

2- Then the caps WCF caps to jupiter (expensive) or actually the "Clarity Cap CMR

I finally got around to ordering replacement caps.
** Nichion KZ (1000uf)f replacement of my small cathodes.
I like the balance and extension of this specific electrolytic.
It doesn't need any help with any bypass cap.

** Audyn true silver for my WCF position caps.
I feel for this area of the circuit, we need a lively cap that is bright, fast, immediate and detailed and is least thick or harmonic, so no copper or mix caps.

The WCF position is coupling and in between the triodes which react with each other, so a pronounced speed and clarity type of cap would be best.

I noted in the past that normal caps sounded thicker & duller here, so it is more critical to get a brighter and lean cap( least harmonics added sounding) cap.

This is the weakness of old school designs.
That you must know about the parts you put in, to a specific area, which is like choosing ingredients to a chef.

An experience designer in this type area (where parts are critical to sound) would know which brand caps or other parts to use.

 

[baronbeehive]

Really interested in hearing how you get on... if you can manage to fight your way past those sphagetti wires lol!
.

 

[Maxx134]

if you can manage to fight your way past those sphagetti wires lol!

Haha yeah I'm a bit sloppy but the mess doesn't phase me...
The caps finally came in:

I had initially planned on buying from US & Canada vendors, and I checked three, but they didn't have all the caps I wanted.
Only this site had everything I needed in one place.
Indeed they have the most complete selection of caps and I now prefer them over any other supplier for name brand stuff..
I needed caps for three different amps.

 

[baronbeehive]

The caps finally came in:

Maybe you could warm up on the APPJ before getting up to speed for the LD.

When you've finished you can use the monster caps as doorstops, or an occasional stool!

So far so good...
.

 

[baronbeehive]

Guys, I've looked again at the tube operating point I recommended back a while ago.

This graph shows the operating points Sonic and Maxx chose, with the stock operating point show also.

The graph below shows the point I chose, "my operating point", together with another point which I have now called "new operating point."

The reason I chose "my operating point" was that the voltage swing area is evenly spaced on either side, with the same slope on the grid curves. However this only results in a voltage swing of 40V which I was resigned to having. However you can see that if the operating point was at point 9 on the graph then the swing would be 110V, considerably more.

Therefore if we are to get maximum transparency and liveliness this could be a better operating point. The only problem stopping me from choosing that before was the problem area indicated which is where the curves become nonlinear.

In light of the discussion on the Oblivion review thread I now know a bit more about tube operation.

Therefore I was wondering about seeing if there would be a different tube that would be better in this problem region that would enable us to get more anode voltage swing for a more lively sound. I rather doubt it because the problem area is much the same in different tubes, and since we can't draw a horizontal load line we might be stuck with it.

Having said that I was pleased with my choice, but was wondering if there could be an even better solution.

 

[Maxx134]

Therefore if we are to get maximum transparency and liveliness this could be a better operating point.

Some of the main differences I noted in various bias points, when listening, were more of image distance and liveliness, rather than distortion.

Sometimes a livelier tube bias settling, was also a more forward sound, so selecting bias points always needed listening observations.

Therefore I was wondering about seeing if there would be a different tube

What tubes are you using now?
I tried so many, I lost count.
Not only the 6pin varieties, but also of the 12pin variety..
My tube of choice was also limited to the fact I did not use CCS.

Anyways, my pick ended up being the 6SL7 variety, not the 6SN7.
My fav being the "coke bottle" version, with top anode(6C8G):

I also preferred the 6pin types overall, over the 12pin that came stock on my MK8 version.