[baronbeehive]

Well... it was announced by the FIA some days ago that this will be on the WRC calendar this year... so there is at least some use for cars. Trying to figure out how to apply to be a marshal there.

Then there is reindeer dodging as well!

Haha!

So you're in Finland.. in the arctic! One of the guys on the forum lives in Sweden.

I'm a huge fan of WRC, always watch it on TV. Elfin Evans narrowly missed out on world champion when he slid off in Monza leaving Seb Ogier champion.. again!! There is usually a rally in UK, in Wales but cancelled this year, I really must go and see it when it comes back. I'm interested if you get to be a marshall, PM me if you have any interesting pics to share .

I have a Mini Cooper S, so driving is a bit of an addiction!

 

[baronbeehive]

I've spent some time with this amp now and all I can say is "the veil has been lifted", "the window has been polished clean".. and any other metaphors you can think of. The "finished".. .. amp is transparent to the music after the sum total of mods done. I didn't really think it would be possible with the design of this amp to push it to such limits.. but no.. it was!

The beauty of it is you can alter the sound to suit your preferences, I like transparency so long as it has euphony also. If you wanted a different sound then vary the wiring, tubes, caps and tube operating point to get clarity or lush sound, dynamics or softness. With the CCS and filter I have achieved extreme clean sound, and the soundstage with the silver wires is very defined, violins, for example screech with the bowing of the gut strings.. in a good way..! Another advantage of the CCS is I no longer have to worry about achieving balanced operation, the current is kept constant by the CCS. If you wanted to try to achieve fast transients and sharp bass you could try using those huge MKP film decoupling or cathode caps that some here have done. I wanted to keep everything in the chassis so that wasn't possible, maybe I was too sensible to try!

 

[coinmaster]

Add water and it will sound more liquid. Trust me.

 

[baronbeehive]

Add water and it will sound more liquid. Trust me.

Hey coin, and a Happy New Year to you too!! Always there with the helpful suggestions .

Really this amp is great, the SQ is fine for me. How's progress over there? I shudder to think what new designs you've come up with over the past few weeks!

 

[CopperFox]

Next I'll be trying those +2000uf Nichicon caps for the cathode bypass position.

Ok, now I've tried four different +2000uf Nichicon caps there and I found one of them, which would be the 2200uf 100V KW series, to be an improvement over the 1000uf 50V KZ series.

The ones that I tried were the 2200uf and 3300uf options from both the FW and KW series, all with the 100V rating.

The 3300uf caps from both series just did not work and had a strange hollow sound that didn't improve over time. So I'd think the capacitance value was too large.

I didn't like the FW series sound. It had some emphasis on midbass, lowed mids and low treble and was relatively dark. This would match what I've read about the FG series which has the same gold-black colour scheme as the FW series. I haven't actually heard the FG series myself though.

The KW series is also similar to the KZ series both in name and their black-gold colour scheme. The overrall sound presentation of the KWs is also very similar to that of the KZs.

I'd say to my ears the improvements with the 2200uf 100V KW over the 1000uf 50V KZ are not small. Bass is more controlled and detailed and there is more detail and better transients overall. With the KZ series there was some slightly unnatural metallic edge to stringed instruments (smearing from overly fast attack?). It was reduced when moving from 470uf to 1000uf though. But with the 2200uf 100V KW it's not there anymore.

Having the 2200uf 100V KW once again changes how the output tubes sound. I had been looking at the various chinese tubes with the KZs but now it's the RCAs that are sounding the best. For some reason the Svetlanas now have a mad bass sound which they never did before.

With the right output tubes these don't need the 0.1uf Rifa bypasses. If you want to try the KWs, it's a good idea to get the 100V version ( part number UKW2A222MRD ) even though the voltage in itself isn't needed, as that one has better specs otherwise as well than the lower voltage versions.

 

[coinmaster]

Hey coin, and a Happy New Year to you too!! Always there with the helpful suggestions .

Really this amp is great, the SQ is fine for me. How's progress over there? I shudder to think what new designs you've come up with over the past few weeks!

Mainly just a waiting game for me. Despite having objectively better stuff than anyone else I am still not in a position to sell anything due to lack of connections and funds.
Funding the finalization of my projects is taking a really long time and coronavirus came along right when I was supposed to get my prototypes professionally tested and reviewed so that really screwed me.
I haven't worked on amps in quit a long time though because its a problem that is completely solved for me. I can demonstrably make cheap amps as good, or better than the best amps no problem. However the airlines destroyed my only high power prototype of my best design so...yeah.

I'm currently finishing my headphone design, should hopefully have a finalized prototype next month (knock on wood). It takes forever because of the cost and lead-times of custom parts. However the headphones are so far above any other headphones it is laughable, so as long as I can get these done it will be easy to finally get investment since all someone has to do is place it on their head unlike the amp where I need to spend a zillion dollars for the privilege of getting a third party lab to officially measure it before I can bring it to investors.

Also if you want to make the LD MK amp much better just delete the output stage and replace it with a simple DC servo controlled source follower. The output tubes are nothing but a detriment to the SQ regardless of how you arrange them. Although like most mods that 'solve' the issues of this amp there isn't really a clean way to do it.

 

[baronbeehive]

Yeah, this coronavirus business has knocked us all for six, as I hear you have in the States, the best that can be said, most of us are all still here.. at least as I write this. We are in the middle of a vaccination programme here. Maybe now that you have someone moderately sane as President (IMO) you might make some progress!!

I still feel you might have trouble getting patents for what amounts to changing the components around into new configurations, but I don't know where you are at atm.

Those ribbon headphones you mentioned a while back sounded ahead of their time and exciting, and with the headphone market constantly changing it could be a winner for your prototypes. I reckon people are clammering for anything new, and that won't stop. Any forum like here would spread the word fast and a review or two, even if you don't go into details of your designs would help massively.. and a website too?

I haven't worked on my amp for ages until the last week or so I decided to finish it for once and for all. Before that I was just massively relieved it worked at all lol! Yes I thought about source followers but quite honestly the changes I have done have got the SQ just right for me and I don't really want to mess with it anymore.

Look forward to hearing from you when you next demo at Maxx's again.
.

 

[baronbeehive]

Ok, now I've tried four different +2000uf Nichicon caps there and I found one of them, which would be the 2200uf 100V KW series, to be an improvement over the 1000uf 50V KZ series.

The ones that I tried were the 2200uf and 3300uf options from both the FW and KW series, all with the 100V rating.

The 3300uf caps from both series just did not work and had a strange hollow sound that didn't improve over time. So I'd think the capacitance value was too large.

I didn't like the FW series sound. It had some emphasis on midbass, lowed mids and low treble and was relatively dark. This would match what I've read about the FG series which has the same gold-black colour scheme as the FW series. I haven't actually heard the FG series myself though.

Yeah, you could be getting some sort of oscillation. The whole business of choosing caps is massively complicated, I just happened to get the right type of improvements from previous recommendations. But it depends on what the caps are used for, and the rest of the system configuration, and really you need to know some of the theory as well.

I'd say to my ears the improvements with the 2200uf 100V KW over the 1000uf 50V KZ are not small. Bass is more controlled and detailed and there is more detail and better transients overall. With the KZ series there was some slightly unnatural metallic edge to stringed instruments (smearing from overly fast attack?). It was reduced when moving from 470uf to 1000uf though. But with the 2200uf 100V KW it's not there anymore.

Again, different people say different things so it's difficult to say, the best you can say is that you think it's better "in your setup." For example I know the Miflexes you use are more forward sounding than the Jupiters I use and that the Jupiters are more natural sounding so that I don't believe I have the problem of metallic sounding strings, guitars really ring out beautifully, even acoustic guitars with just the right level of attack to bring out the soundstage nicely.

Having the 2200uf 100V KW once again changes how the output tubes sound. I had been looking at the various chinese tubes with the KZs but now it's the RCAs that are sounding the best. For some reason the Svetlanas now have a mad bass sound which they never did before.

Those RCA's are great! People dismiss them but they would give most tubes a run for their money. I think the natural sound and balance of these tubes would make them a good match for anything. And what you say about the Svetlanas is what has been putting me off trying them as I've heard that the bass can sound unnatural with them.

With the right output tubes these don't need the 0.1uf Rifa bypasses. If you want to try the KWs, it's a good idea to get the 100V version ( part number UKW2A222MRD ) even though the voltage in itself isn't needed, as that one has better specs otherwise as well than the lower voltage versions.

Thanks for this information. This has got to be very useful for anyone wanting to try this out.

I've most likely finished modding now on the LD, it sounds the way I like and it's not worth screwing me up anymore wondering if all the wires are still there in the back of the amp when I've put the board back again LOL


Have you finished the operating point tests?

How are you finding the amp sounding now after all that great work?

Edit: I'm interested in how you would describe the sound to see if it tallies with what we have found here.

 

[coinmaster]

I still feel you might have trouble getting patents for what amounts to changing the components around into new configurations

The problem with patents is the expense of purchasing one and defending it if it is infringed upon.
Despite the original design I'm no longer concerned with patents because it is effectively pointless since china or powerful companies in the US can steal whatever they want anyway.

but I don't know where you are at atm.

That entirely depends on the context of what you mean.

Those ribbon headphones you mentioned a while back sounded ahead of their time and exciting, and with the headphone market constantly changing it could be a winner for your prototypes. I reckon people are clammering for anything new, and that won't stop. Any forum like here would spread the word fast and a review or two, even if you don't go into details of your designs would help massively.. and a website too?

They aren't really ribbons per se. But yeah, if people knew what I've created, it would be a big deal. I'm not exaggerating when I say that they make all other headphones sound like a toy in comparison. (which makes it all the more frustrating), but my first prototype weighed 15 LBs and was fragile..(made of wood blocks and steel lol) I barely managed to get it safety to NY once to show Maxx and compare against a bunch of other top-enders.
My latest version is of normal weight in a finished design but the parts are all custom and expensive to purchase in low volume. So essentially when I finish this version of the prototype it will be the first time I've made something that can be moved around and used and reviewed like normal.

But I'm moving to Japan for a couple years starting in April because I'm sick of constant R&D that just eats up my time and money without financial return so I'm getting some "fresh air" for a change. With my typical luck I could cure death and not be able to monetize it so I'm going with the mindset of "if it happens it happens" at this point.
Maxx and I are formulating some sort of a coordinated effort to begin making and selling the headphones on different fronts within our respective regions, but there are some things to be done before that point.
Eventually if I get the headphone business off the ground I will be able to fund the selling of my amps as well.

 

[baronbeehive]

.. but my first prototype weighed 15 LBs and was fragile..(made of wood blocks and steel lol) I barely managed to get it safety to NY once to show Maxx and compare against a bunch of other top-enders.

Really surprised you were worried about that, when the HiFiMan HEK's came out it looked like you were carrying around miniature speakers on your head, very silly..

But I'm moving to Japan for a couple years starting in April because I'm sick of constant R&D that just eats up my time and money without financial return so I'm getting some "fresh air" for a change. With my typical luck I could cure death and not be able to monetize it so I'm going with the mindset of "if it happens it happens" at this point.
Maxx and I are formulating some sort of a coordinated effort to begin making and selling the headphones on different fronts within our respective regions, but there are some things to be done before that point.

Curing death.. now you are talking.. a good idea for once!

Anyway stay in touch, hope the move goes well, that is one of my life's ambitions to go to Japan, especially when the Cherrys are in blossom.

 

[coinmaster]

Really surprised you were worried about that, when the HiFiMan HEK's came out it looked like you were carrying around miniature speakers on your head, very silly..

It was more of the fact that the driver is a complex structure and they were super fragile and a pain to transport. They needed to be hung from some sort of apparatus because they were too heavy to put on your head for long and the headband was just a bunch of wood blocks lol.

 

[CopperFox]

I have a Mini Cooper S, so driving is a bit of an addiction!

I assume that would be the 2000s new Mini I remember wanting one of those in British racing green when they came out. Now I decided to go electric though and got a new Renault Zoe GT R135... in blueberry purple.

Again, different people say different things so it's difficult to say, the best you can say is that you think it's better "in your setup."

I've most likely finished modding now on the LD, it sounds the way I like and it's not worth screwing me up anymore wondering if all the wires are still there in the back of the amp when I've put the board back again LOL


Have you finished the operating point tests?

Yes, we all do have some varying components in the amp and also different sources and headphones. Knowing when to stop is admirable and knowledge many people in hifi do not possess. And as you wrote before, these LDs can be modded to various preferences. Even if it would be difficult to settle on one specific kind of sound, it would be possible to add some adjustability with switches. It would be interesting to have switches for the decoupling caps and 2-3 different cathode bypass caps. And even then, it could be hard to enjoy music without thinking if it would sound better with the switches in another position I don' t really feel that I have enough knowledge and/or experience from electronics though to build those switches.

Looks like headphone modding is more straightforward than amplifier modding. Less variables and more clearly defined targets.

What are the operating point tests?

I might still be trying the Audio Note Kaisei for WCF caps. They are available in 680uf which the others aren't.

 

[baronbeehive]

I assume that would be the 2000s new Mini I remember wanting one of those in British racing green when they came out. Now I decided to go electric though and got a new Renault Zoe GT R135... in blueberry purple.

Yep, that's the one, I will PM you a pic!

Yes, we all do have some varying components in the amp and also different sources and headphones. Knowing when to stop is admirable and knowledge many people in hifi do not possess. And as you wrote before, these LDs can be modded to various preferences. Even if it would be difficult to settle on one specific kind of sound, it would be possible to add some adjustability with switches. It would be interesting to have switches for the decoupling caps and 2-3 different cathode bypass caps. And even then, it could be hard to enjoy music without thinking if it would sound better with the switches in another position I don' t really feel that I have enough knowledge and/or experience from electronics though to build those switches.

You wouldn't believe how many amps some of the guys have on other threads! I stopped for several reasons, the main one being I am happy with the sound signature, also I know that the modding has pushed the amp to end game, so the only reason to change would be that you want some other kind of sound, not that another amp would be better necessarily.

The amp now is really transparent sounding, yet has the tube euphonics still, a perfect combination for me. The mods have brought out all the good points like soundstage and resolution to the highest level. The frequency band is in balance and extended and all the instruments sound real, emphasised by the mods we have done now. And the dynamics are good, whereas before it was a bit on the polite side. If I was to change anything it might ruin what has been achieved!

Yes decoupling caps especially would be interesting to vary. A switch would be easy.. if you're in doubt check out sonic's 5998 bias switch mod on page 1. Basically all you do is connect the switch in parallel to the existing circuit with the added on bit comprising an alternative part of the circuit. You could always get back to us on this if you decide to give it a go.

You've done a great job with testing the cathode caps and so on, I would have tried those you liked but as I have the compact version there wouldn't be any more space inside for bigger caps!

What are the operating point tests?

I might still be trying the Audio Note Kaisei for WCF caps. They are available in 680uf which the others aren't.

The operating point tests are what you've been doing experimenting with different anode/cathodes for the driver tubes.

Kaiseis are excellent caps, I have them in my other amp, the APPJ Miniwatt speaker amp, however I stuck with the Nichicons for the LD because I believe they tightened up the bass sound a lot, whereas the bass on the APPJ was already tighter.

 

[CopperFox]

Yep, that's the one, I will PM you a pic!



You wouldn't believe how many amps some of the guys have on other threads! I stopped for several reasons, the main one being I am happy with the sound signature, also I know that the modding has pushed the amp to end game, so the only reason to change would be that you want some other kind of sound, not that another amp would be better necessarily.

The amp now is really transparent sounding, yet has the tube euphonics still, a perfect combination for me. The mods have brought out all the good points like soundstage and resolution to the highest level. The frequency band is in balance and extended and all the instruments sound real, emphasised by the mods we have done now. And the dynamics are good, whereas before it was a bit on the polite side. If I was to change anything it might ruin what has been achieved!

Yes decoupling caps especially would be interesting to vary. A switch would be easy.. if you're in doubt check out sonic's 5998 bias switch mod on page 1. Basically all you do is connect the switch in parallel to the existing circuit with the added on bit comprising an alternative part of the circuit. You could always get back to us on this if you decide to give it a go.

You've done a great job with testing the cathode caps and so on, I would have tried those you liked but as I have the compact version there wouldn't be any more space inside for bigger caps!




The operating point tests are what you've been doing experimenting with different anode/cathodes for the driver tubes.

Kaiseis are excellent caps, I have them in my other amp, the APPJ Miniwatt speaker amp, however I stuck with the Nichicons for the LD because I believe they tightened up the bass sound a lot, whereas the bass on the APPJ was already tighter.

I see. As I'm not done with the mods I'm not sure if I will still try different cathode resistor values. Still leaning towards the 470R as it had more prominent mids than lower values.

But for the anode resistor I remember you recommended 69K and I have 68K. What resistor brand do you have there? It seems most brands have 68K available but not 69K.

Today I started wondering what would happen with more than one cathode bypass cap in parallel... for example both a Nichicon KZ and an Elna Silmic.

 

[baronbeehive]

I see. As I'm not done with the mods I'm not sure if I will still try different cathode resistor values. Still leaning towards the 470R as it had more prominent mids than lower values.

I don't know what anode you are using, but if you are using 68k then I agree that 470R, or thereabouts, had the liveliest sound.

But for the anode resistor I remember you recommended 69K and I have 68K. What resistor brand do you have there? It seems most brands have 68K available but not 69K.

Don't get too hung up on that difference. The reason is that it will not have much, if any effect because the operating point will not move with that much of a difference in values. Also other factors will come into play, your amp will most probably have a slightly different B+, depending on the components you have put in, making the calculation different as well.

I didn't fully document my mods so I can't remember if 69k was what I arrived at in doing the calculation or if it was a specific value that had been used. I suspect that the 69k value was calculated from the load line and I then found the nearest resistor to that value to put in. Also I kept the stock 220K anode resistors in place and added another resistor in parallel to arrive at the 69k value. I think I added a 10k to get the final value of 69, or 68k or whatever was nearest.

For the anode plate load it is usual to load it many times its plate resistance which is done for the stock amp. This is good because the resulting operating point allows 6SL7 and 6SN7 tubes to be used, neither being at the optimum point though. Also the output current is low. So we tried different anode resistor values to boost the current and change the operating point to arrive at the optimum value for the operating point. I think that's why the 69/68k anode works best because it doesn't go as low as the 33k that I tried which was too low a plate load.

There's still scope to try different values to vary the operating point still though if you want different sounds as I suggested. The lower the point on the graph the more distortion the sound will have which may or not be pleasant to try giving a more tubey sound. I prefer a more transparent sound with just a touch of tubes in there.

I used TKD resistors.

Today I started wondering what would happen with more than one cathode bypass cap in parallel... for example both a Nichicon KZ and an Elna Silmic.

You can add as many bypasses as you like but we don't recommend it. The main purpose of the cathode caps is to help transient recovery which will affect bass frequencies. The fastest cap you can have will be best to do this and avoid clipping as much as possible. Apart from this it won't have that much effect on overall sound signature, that is where the coupling and WCF caps come in, they will have greatest effect on sound.

If you imagine several batteries of different types all connected then the electrical signal coming out will be mashed up because of the differing discharge rates. This won't matter ordinarily but for the music signal it needs to be as pure as possible so smearing will inevitably occur as the signal is affected by the differences in the charge/discharge cycle. The signal at one point in the chain will be trying to move on but at another part it will be waiting for another cap to finish it's part of the cycle.

Your findings on the different cathode cap values was very useful and proved that going even larger in capacitance than we did had a beneficial effect on bass responsiveness! I suspect that going even larger than that would have negative returns possibly.

The whole point of much of the mods is to get as stable PSU as possible. The large fast capacitance MKP decoupling caps you put in will help as does the fact that the amp is balanced in the first place. Also we uprated the PSU caps to be as beefy as possible to provide a good reservoir of power on tap. Apart from that we can't do much with the PS without completely rebuilding it which would involve adding on an extra stage to the amp as it is now.

Where we did go for a bypass to the cathode cap was because we swopped the stock caps for higher capacitance, musical grade caps, which meant that we needed to add some very small bypasses to complement the lytic cathode cap techno. So we added some small fast film caps to restore the high frequencies that were lost.

So I would suggest if you want different sounds to try different coupling and WCF caps. Due to their position in the push/pull cycle the WCF caps we feel need to be the fastest and responsive to the high frequencies as you can go for, I have Mundorf SIO which I feel complement the more natural sounding Jupiters in the coupling position.

The switch you mentioned before would be easiest to implement for the different anode/cathodes by adding a supplementary circuit with other anode/cathode resistors in parallel. With a switch for different coupling caps that would be more complicated to implement though.