[coinmaster]

I think I mentioned this before when I had just installed the Ra switch, but I noticed most improvements when listening through my LCD-XC's which are only 20 ohms. That lowest setting of 77 ohm plate resistor is for use with LCD-XC's and 421A tubes. It really did wonders for the XC's. I also heard improvements with the LCD-3 (110 ohms), but not as much as with the XC's. 

You could say the same about tube mixing though.

 

[Maxx134]

I been away a few days researching other projects,
And I see Coinmaster has turned this thread to hell.

Too many wrong assumptions and suggestions I don't know where to begin..
Better to scrap the last two pages of this thread than try to fix it..

Edit not to take away from the motivation,
But design, theories and speculation is not part of the supermod thread.
Mostly this is done in PM, but a thread for this is better than to confuse/clutter the Mod thread.

 

[coinmaster]

I been away a few days researching other projects,
And I see Coinmaster has turned this thread to hell.

Sorry, it's easy to forget that this is a dictatorist thread where your vision and opinion is the only one that matters and everything must be run by you first.
 

Too many wrong assumptions and suggestions I don't know where to begin..

If you think I was wrong about that many things then you are the one who is wrong.
 
Not much of what I said was based in theory except for the v-swing of the amp and my musings behind the impedance mod.
I see where I could be wrong about my thoughts on the impedance mod though, since the top triodes should sink the combined current of the bottom triode and the incoming current through the load, requiring an unequal impedance between the two triodes to get a balance of AC level current, even if the DC currents are already balanced.
In this case the impedance mod makes sense, it would be unbalancing the load lines but balancing the AC currents.
 
In either case you should stop caring so much about what's discussed here. You are way too obsessed with your vision of the way this thread is supposed to go regardless of other peoples interests. This is a public forum, get used to people discussing what they want on it. If people want to see the mods they can go to the front page.
 
Sorry if discussing mods on a mod thread is against the dictatorship rules of the thread. Which by the way, you should put those rules on the front page if you don't want people talking about mods on a public mod thread.

 

[Bruch]

I love you all. I think that this thread is amazing and you have all done such a terrific job in deconstructing and reconstructing this amp.
 
However, for what it's worth, I do get a little lost inside Coinmaster's head. There's a lot going on in there that I have no idea about at all. It's quite fun to read his posts and I don't object to latest little flurry of incomprehensible (to me) musings but it would be a shame if that became the norm and this amazing thread lost its way in a jungle of techni-speak.
 
Don't you just love free sharing of ideas?

 

[coinmaster]

However, for what it's worth, I do get a little lost inside Coinmaster's head. There's a lot going on in there that I have no idea about at all

 

but it would be a shame if that became the norm and this amazing thread lost its way in a jungle of techni-speak.

I agree which is why I don't do it much, but when something about the mods needs or wants to be discussed it shouldn't be inhibited. 

 

[Maxx134]

Coin. Look at the Cavali papers.
Think not individual triodes or tubes.
Think the circuit design behavior.
Then think about this is balanced design.

Also, about the power.
I do not condone:

1-adding another 15vdiode
Remember this section feeds the opamp & protection PSU sections which will take the hit of voltage change and so have to also be adjusted accordingly.

2-disconnection of resistors and meters.
You essentially created a worse condition.
No matter what the PSU could possibly do, it would never be able to create that type os damage potential.

You cannot easily disconnect the PSU from the amp as the other two sections still connected.

That's just off the top of my head but basically your assumptions are incomplete.

 

[coinmaster]

1-adding another 15vdiode
Remember this section feeds the opamp & protection PSU sections which will take the hit of voltage change and so have to also be adjusted accordingly.

The opamps are fed by separate zener shunts and the increase in voltage would not put them over their rated wattage.
The protection circuitry is fed by another supply all together. The only thing the 15v diode would affect is the tubes.
 

2-disconnection of resistors and meters.
You essentially created a worse condition.

Completely wrong. You only create a worse condition when you leave the power supply connected when you know there is something wrong. Unless you like smoke.
 

No matter what the PSU could possibly do, it would never be able to create that type os damage potential.

Lol, do you have any idea how much money I've wasted on fried components because I left the power supply connected during troubleshooting? No connection = no current. No current = no smoke. If you have a problem with the amplifier it will either be caused by the power supply or it could cause problems for the power supply. 
Disconnecting the power supply before troubleshooting is the most fundamental thing to do, troubleshooting 101. You don't troubleshoot an entire system at once. You do it section by section. Not only for the safety of the components but because leaving the power supply connected with a malfunctioning system can give you unusable results during diagnosis with the meter.
 
Once you have made sure that the power supply itself is in working condition, then you move on to the remaining sections.
 
 
I've been troubleshooting the mk6 for 8 months and I've built several from scratch. Don't challenge me on this.
 
 

Coin. Look at the Cavali papers.
Think not individual triodes or tubes.
Think the circuit design behavior.
Then think about this is balanced design.

 
If you think I was talking about individual triode behavior then you didn't read what I said.
I looked at the Cavali papers. It gave a lot of mathematical equations without too much logic 
behind it, which is why I became skeptical whether it applied to our situation given the way our servoed design affects tube impedances.
 
However, like I said before I realized that the top triodes have to sink both the bottom triodes current as well as the incoming current from the load. In this situation the impedance imbalance the impedance mod creates does make sense as it would reduce the AC current into the top triode which would balance it out with the bottom one.
 

You cannot easily disconnect the PSU from the amp as the other two sections still connected.

Disconnecting the meters and the .68 ohm resistor will completely disconnect the amp from the power supply. The negative supply has nowhere to go so it will only charge the cathodes. As long as you take the opamps out there will be no issue.
The protection circuity is the only other supply and it can care less whether the main power supply is connected or not, it's completely isolated from the rest of the amp and the main power supply except for the offset detector pin on the protection IC at the output.

 

[Maxx134]

Coinmaster, remember vanity is the cause of failure.

You need admit SonicTrance 2k resistors burned because of your suggestion on disconnecting the 0.68 resistors, which as you know realize did not fully remove the PSU.

I know you think disconnecting the PSU is "troubleshooting 101",
But in this case, with this amp we don't need "textbook".
The sections are not designed to be easily separated, and there was no need to disconnect.

As you noted the opamp had its own resistor/zener regulation.
The danger was in altering the circuit the way you have done.
This is reason why your burned components.

Not gona argue about "troubleshooting101".
Be open to possibly of "troubleshooting 202" & reasons why circuits have "test points".

I don't appreciate being labeled as inhibiting discussion,
ONLY MISINFORMATION AND SPECULATION.

As stated from beginning,
We always test and verify before we push out a new mod.

The impedance/headphone matching mod is already tested and verified regardless what you believe.

The only thing is that it has been slow to push out because we have a life apart from this hobby.

 

[Maxx134]

The PSU voltage change idea can be a decent, or even a good idea,
so I will look into it.

Let us know if you have success, which is different than telling Sonic to do it.


Edit:
Still have 5o adjust the other sections of the PSU for the change.
Can't rely on the tiny zener to handle that.

The approach is having a component that can handle a safety margin higher than what is actually needed.
This is the norm especially for higher temperature ranges which this amp will produce.

Also has to be decided is a choice of the accompanying resistor change as well.

So just saying to pop in another 15v zener diode is not looking at whole picture

 

[coinmaster]

You need admit SonicTrance 2k resistors burned because of your suggestion on disconnecting the 0.68 resistors, which as you know realize did not fully remove the PSU.

I already did.
In case you forgot the same thing happened to me with my 300 ohm resistors a while back. I always remove the opamps while troubleshooting but the last time I've done any mk6 troubleshooting on the original PCB was when I helped mogos so it slipped my mind.
 

I know you think disconnecting the PSU is "troubleshooting 101",
But in this case, with this amp we don't need "textbook".

That is about as far away from truth as it can get. This amp has so many potential issues when you break it and then leave the power supply connected. It's not "textbook" it's fact.
 
 

The sections are not designed to be easily separated, and there was no need to disconnect.

Yeah well you can take the easy way or you can take the safe way. I used to be lazy and take the easy way and I ended up blowing hundreds of dollars on components because the easy way turns out to be too risky on average. Besides, desoldering a couple of components legs isn't that hard.
 

As you noted the opamp had its own resistor/zener regulation.
The danger was in altering the circuit the way you have done.

Lol, there's no danger of "altering the circuit" did you even read why I mentioned changing the regulator voltage?
The only thing adding a 15v zener would do is increase the output voltage to the tubes to 115v assuming the collector voltage was always 115v+.
If you adjust the resistors to compensate the only difference is the voltage headroom for the signal.
 

This is reason why your burned components.

Lots of assumptions coming from someone claiming that I assume everything.
I never burned any components in the MK6 from altering a circuit, it has always been from troubleshooting and leaving the power supply connected.
I have never altered the stock MK6 other than the mods from this thread.
The only other time I burn components is when I do breadboard testing for my other project.
 

Be open to possibly of "troubleshooting 202" & reasons why circuits have "test points".

Do you even know? Circuits have "test points" because when they are working properly they have a predictable operating point relative to their function. Which is one of the reasons why you don't leave the power supply connected to the amplifier so the current draw from whatever is broken does not interfere with the voltages you are testing. One of the many things I learned from 8 months of actual experience troubleshooting just about every problem the MK6 can have.
 

I don't appreciate being labeled as inhibiting discussion

Then stop complaining all the time.
 

ONLY MISINFORMATION AND SPECULATION.

dis·cus·sion dəˈskəSH(ə)n/
noun
 

• the action or process of talking about something, typically in order to reach a decision or to exchange ideas.
   
   
   
  
  
  

•  
  We always test and verify before we push out a new mod.
  
  
  

 

So what happens when somebody that's not you decides they want to contribute. They have to run everything by you? Why isn't that listed as a rule on the front page?
 

The impedance/headphone matching mod is already tested and verified regardless what you believe.

The only thing is that is has been slow to push out because we have a life apart from this hobby.

I never said I didn't believe in it. I said I was skeptical about it due to my current understanding of the cavalli paper and the way the servo interacts with the tubes as well as the sonic similarities between the impedance mod and tube mixing. All of the reasons behind my skepticism were facts, not assumptions. 
 

Let us know if you have success, which is different than telling Sonic to do it.

I wasn't telling him to do anything, I was making a suggestion that I specifically said was his decision.

 

[baronbeehive]

n

........
The only thing is that it has been slow to push out because we have a life apart from this hobby.

 Oh, lucky you 

. Wish I did, most of my year so far has been involved in the house move!
 
I also enjoy Coin's contributions, so maybe if they were preceeded by a health warning..........

I certainly am not qualified to question them and any contributions in theory should  be welcome, also now given that Coin is building real world systems. However I do value the way that the mods in this thread are subject to rigorous testing before approval.

 

[coinmaster]

I also enjoy Coin's contributions, so maybe if they were preceeded by a health warning..........

I really shouldn't say this, but I don't think you can do anything to this amplifier to make it dangerous, at least not in the "blowing up" kind of way. There's not enough power and the fuse would trip before there was. 
The health hazard lies in creating a short through your body for the current to flow, especially through your heart. Just make sure your body doesn't have a connection to ground through your other hand. A grounding bracelet would make it easy.
Even if you do get shocked it's likely to be uneventful, but obviously don't take the risk and it's easy to avoid anyway.
 
You shouldn't be scared but don't be stupid either.
 

The only thing is that it has been slow to push out because we have a life apart from this hobby

My landscaping duties have been slow lately so I have the opposite problem. 

 

[Maxx134]

I used to be lazy and take the easy way and I ended up blowing hundreds of dollars on components because the easy way turns out to be too risky on average..

OK I'll bite. .
What are the components that costs hundreds and why they broke.

So what happens when somebody that's not you decides they want to contribute. They have to run everything by you? Why isn't that listed as a rule on the front page?

This is not a sound science thread to post massive speculations without stating they are your speculations and not fact.
Read first page again.

Where is your actual contribution besides speculations.

To me, So far you have littered about 3 pages of disinformation/speculations ..

Here are but a few examples :

"So when you use the impedance mod with opamp servos you are really unbalancing the WCF."

Nonsense.

"Either the NFB of the amp is saving you or your amp is clipping. I would definitely add that 10v zener in. there."

Nonsense


I just checked and the ratio of the NFB in the MK6 is gigantic. This is indeed the only thing that is preventing your amp from blowing up your headphones

More nonsense.

You think those resistors are applying feedback in a traditional sense.
They are not.

I wasn't telling him to do anything, I was making a suggestion that I specifically said was his decision.

Why did you tell him to add diode?
Do you know why the PSU is set that way to begin with?
Your not giving tube headroom.
Only changing the parameters while diminishing the PSU headroom.

 

[Maxx134]

To be fair, I am always impressed with Coinmaster determination and injenuity and growth.
I do expect nice DIY future from him.
We just but heads from time to time.
Maybe we should open a different thread on "analysis of MK6&8 design".

 

[baronbeehive]

The bickering on this thread has a way to go before it reaches the lofty heights of other audio forums! Thank god for that.