[cats4cans]

You're welcome. Those two books are great, top recommendation for me for people wanting to get into tube DIY.

I’m working my way through some of the same reading as well, but had a philosophical question. What’s the proper etiquette in “borrowing” designs? I know sometimes there’s only one practical way to do things and it’s the obvious solution that everyone uses. It remains to be seen how many of my harebrained ideas actually coalesce into real projects. But if I were to heavily modify a project, maybe even using your PCBs as a starting place, would you want to know? I imagine you’d want to be very hands off. But what if someone else then wanted to buy parts or know details from what could be considered a collaboration or mod to your project, even if you had no involvement. Or would you want to talk me out of damn fool ideas first. I don’t like stepping on toes. I get the impression imitation is considered flattery in the DIY community, just acknowledge your sources. I’ll be sure to crawl first.

 

[g0ldl10n]

I frequently use CCS loads or gyrators to load triodes which are essentially a hybrid mu follower where the bottom triode is loaded by a transistor as opposed to another triode. Surprisingly not many commercial amplifiers utilize these circuits and load tubes with resistors, which is bonkers because it's not that much more expensive and infinitely better.

Was actually just talking to someone about this possibility which would reduce the overall amount of triodes needed.

Infinitely better.. it is fantastic!

I will say though that using a true mu follower is definitely cooler than using a transistor, even if it isn't as high performing. Kinda like tube rectification

A pair of twin triodes make it not as painful, but I will definitely explore the SS solution to the CCS for this sort of loading.

Another thing you could try with a dual triode that accomplishes similar goals to a mu follower is an SRPP stage.

I did notice earlier that these two designs are very similar indeed.. may have to explore it as well!

 

[L0rdGwyn]

I’m working my way through some of the same reading as well, but had a philosophical question. What’s the proper etiquette in “borrowing” designs? I know sometimes there’s only one practical way to do things and it’s the obvious solution that everyone uses. It remains to be seen how many of my harebrained ideas actually coalesce into real projects. But if I were to heavily modify a project, maybe even using your PCBs as a starting place, would you want to know? I imagine you’d want to be very hands off. But what if someone else then wanted to buy parts or know details from what could be considered a collaboration or mod to your project, even if you had no involvement. Or would you want to talk me out of damn fool ideas first. I don’t like stepping on toes. I get the impression imitation is considered flattery in the DIY community, just acknowledge your sources. I’ll be sure to crawl first.

I think most people in the DIY world would agree that as long as you are not selling whatever it is you make using other people's circuitry or ideas, then that's totally fine. But once it turns into a business venture it's frowned upon.

 

[AnyDave]

I think most people in the DIY world would agree that as long as you are not selling whatever it is you make using other people's circuitry or ideas, then that's totally fine. But once it turns into a business venture it's frowned upon.

I agree with this, but will add one general caveat: I think an element of time is involved as well.

A lot of commercial designs (not just tube amps) are based on previously patented work, but the patents have now expired. At that point, it's fine to use them commercially as that is precisely how the patent system is supposed to work. Original designs were never intended to have exclusivity in perpetuity.

It's a lot different to commercialize a version of something that's been on the market for 40 years and in the public domain than to take something that has just been released (patented or not). I've seen this from both sides of the fence. It's always a bummer when you've worked on a patented design that is now public domain, but that's by design.

 

[L0rdGwyn]

I agree with this, but will add one general caveat: I think an element of time is involved as well.

A lot of commercial designs (not just tube amps) are based on previously patented work, but the patents have now expired. At that point, it's fine to use them commercially as that is precisely how the patent system is supposed to work. Original designs were never intended to have exclusivity in perpetuity.

It's a lot different to commercialize a version of something that's been on the market for 40 years and in the public domain than to take something that has just been released (patented or not). I've seen this from both sides of the fence. It's always a bummer when you've worked on a patented design that is now public domain, but that's by design.

Yeah I agree. I mean, 99% of tube headphone amplifiers out on the market right now are using the same single-ended triode circuit that's been around for 100 years.

When asked this question, I'm specifically thinking of DIY designs seen on diyAudio and the like, ancillary circuitry like power supply regulators. Many of these circuits are new, but are not patented. If someone were to turn around sell something using them without some sort of licensing agreement with the designer, that would be pretty low IMO. For example, there are power supply regulators I use in some of my personal and one off designs that a friend designed. I would never put them in a commercial circuit.

 

[AnyDave]

Yeah I agree. I mean, 99% of tube headphone amplifiers out on the market right now are using the same single-ended triode circuit that's been around for 100 years.

When asked this question, I'm specifically thinking of DIY designs seen on diyAudio and the like, ancillary circuitry like power supply regulators. Many of these circuits are new, but are not patented. If someone were to turn around sell something using them without some sort of licensing agreement with the designer, that would be pretty low IMO. For example, there are power supply regulators I use in some of my personal and one off designs that a friend designed. I would never put them in a commercial circuit.

Yeah, I would agree with all of that.

 

[g0ldl10n]

I will say though that using a true mu follower is definitely cooler than using a transistor, even if it isn't as high performing. Kinda like tube rectification

Got a question about this for you pertaining to the mu-follower - can you think of any major drawbacks by using a triode that is typically used in lower mu higher current positions (such as outputs tubes) for the "upper" triode in the mu-follower which acts as the 'CCS' for the "lower" triode.

It seems like it would be performing such light duty compared to what it would typically be asked to do that it would keep the CCS about as stable/consistent as it could get with this sort of valve solution for CCS. Maybe I am thinking of this wrong, but it was an idea that struck me a couple days ago and have been meaning to ask you.

BTW, I have this sort of setup running in my prototype circuit right now using a dissimilar triode (power section for the CCS triode and higher mu triode for the lower amplifying triode) .. ofc, some resistors within the mu-follower needed adjusted quite a bit to drop proper voltages across each, but right now the power triode which typically would expect to see 50mA of plate current is currently "handling" 1.3mA of plate current .. now, I can say it sounds quite good.. but, I am unsure if there is an obvious reason why one wouldn't do this.

 

[L0rdGwyn]

Got a question about this for you pertaining to the mu-follower - can you think of any major drawbacks by using a triode that is typically used in lower mu higher current positions (such as outputs tubes) for the "upper" triode in the mu-follower which acts as the 'CCS' for the "lower" triode.

It seems like it would be performing such light duty compared to what it would typically be asked to do that it would keep the CCS about as stable/consistent as it could get with this sort of valve solution for CCS. Maybe I am thinking of this wrong, but it was an idea that struck me a couple days ago and have been meaning to ask you.

BTW, I have this sort of setup running in my prototype circuit right now using a dissimilar triode (power section for the CCS triode and higher mu triode for the lower amplifying triode) .. ofc, some resistors within the mu-follower needed adjusted quite a bit to drop proper voltages across each, but right now the power triode which typically would expect to see 50mA of plate current is currently "handling" 1.3mA of plate current .. now, I can say it sounds quite good.. but, I am unsure if there is an obvious reason why one wouldn't do this.

There's nothing necessarily wrong with using a power triode as the load / cathode follower in the mu follower. Transconductance / gain will determine the AC impedance to the bottom triode as well as the output impedance of the stage. Check the formulas in Blencowe's book, I'm sure he goes over it. It's on his webpage as well:

https://www.valvewizard.co.uk/mufollower.html

New top plate for my PCM63 DAC is arriving today. I'll finally be able to add my Finemet line output transformers!

 

[L0rdGwyn]

Got the Finemet traffos in my PCM63 DAC.

Changed the top plate color to a clay texture, came out really well I think.



Closed up.



In the rack, listening with Aegis. Wow, sounds really good! Better clarity, imaging and more body relative to the Sowter traffos. Those are good ones, but I thought we could do better. Happy with the change.

 

[g0ldl10n]

Got the Finemet traffos in my PCM63 DAC.

Changed the top plate color to a clay texture, came out really well I think.



Closed up.



In the rack, listening with Aegis. Wow, sounds really good! Better clarity, imaging and more body relative to the Sowter traffos. Those are good ones, but I thought we could do better. Happy with the change.

Damn, that DAC is huge! You probably already have shared somewhere in this thread, but do you have any pictures of the internals of it you mind sharing again?

Any book recommendations on tube DAC DIY?

 

[L0rdGwyn]

Damn, that DAC is huge! You probably already have shared somewhere in this thread, but do you have any pictures of the internals of it you mind sharing again?

Any book recommendations on tube DAC DIY?

Yeah here's the inside before I closed it up.



I don't really have any book recommendations on DIY DAC building, sorry! Probably isn't much out there that is DIY focused, it's definitely a more advanced thing to work on.

 

[Wes S]

Yeah here's the inside before I closed it up.



I don't really have any book recommendations on DIY DAC building, sorry! Probably isn't much out there that is DIY focused, it's definitely a more advanced thing to work on.

Damn man! That looks clean, and I love the look and color of the top plate too.

 

[L0rdGwyn]

Damn man! That looks clean, and I love the look and color of the top plate too.

Thanks! Had to change the top plate since Dave at Landfall says the original matte black powder I used seems to be having some issues lately. Figured I'd go two tone and wanted something that matched the amber LED.

 

[miketlse]

Thanks! Had to change the top plate since Dave at Landfall says the original matte black powder I used seems to be having some issues lately. Figured I'd go two tone and wanted something that matched the amber LED.

The colour contrast does feel a good match.

 

[g0ldl10n]

Yeah here's the inside before I closed it up.



I don't really have any book recommendations on DIY DAC building, sorry! Probably isn't much out there that is DIY focused, it's definitely a more advanced thing to work on.

My favorite part(s) of the entire build! There is just something about using batteries within these types of devices .. when I first used batteries to hear what fixed bias sounded like compared to cathode bias in my amps circuit, firstly the sound quality amazed me but IMHO there is elegance in its simplicity, especially when it does such a good job.