[L0rdGwyn]

Bonus points if you can make it a (reasonably) cheap Chi-Fi killer. I remember watching an interview with somebody in the auto industry talking about how it was easy to make a cost-no-object luxury car, but it took serious talent to build a stand out econobox. If you can apply that to the audio realm…

Well there are certain things I won't go cheap on, the chassis and the transformers, those will be the most expensive parts, most everything else will be inexpensive. I would guesstimate parts would cost $600-800. Certainly it would cost less than $1K. I'll add that Jack's transformers are very high quality and not overpriced. I was looking into Edcor as well but they have a minimum order quantity of 25 units for custom work. So let's hope Jack is on board.

 

[bcowen]

If / when you look for guinea pigs, to try out building your kit - I am in!!

But there's soldering involved, and probably some screws and stuff to put in. Better leave it to me.

 

[Wes S]

Thanks yeah I will post here as thing take shape. Once I confirm I have a source for the transformers I'll figure out the details. Would be a dual mono power supply, CCS loaded spud circuit, parafeed output, likely Clarity Cap parafeed capacitor, LED biased. I will subjectively test several LEDs to find the best. I need to decide what direction to take the CCS (FET vs BJT vs current source IC) and make setting the current simple and low hazard. Likely the supply would not require regulation given the high PSRR of the output stage, which would simplify things considerably.

Heck yeah man, that all sounds legit! I am happy as heck with my Cayin and honestly the only other amp I would like to own would be one of your creations, so I am really pumped there might be a chance and will be following along intently.

 

[pravous]

If / when you look for guinea pigs, to try out building your kit - I am in!!

Put me down for one of the first batch as well, if and when you get there. Any ideas what tube type you are thinking of using?

 

[L0rdGwyn]

Heck yeah man, that all sounds legit! I am happy as heck with my Cayin and honestly the only other amp I would like to own would be one of your creations, so I am really pumped there might be a chance and will be following along intently.

No doubt it would be very different from the Cayin! Could complement it, we will see going to try and get it done.

Put me down for one of the first batch as well, if and when you get there. Any ideas what tube type you are thinking of using?

Cool the idea would be for me to basically provide all of the info for someone to order everything themselves, wouldn't even need to go through me - Gerber files to order PCBs, CAD files to order a chassis (although Dave at Landfall would have the files already), BOM for all of the parts and where/how to order, Excel spreadsheet denoting the part number on the PCB, then I would have to build one and take photos along the way, write instructions, etc.

The list of spud-able tubes isn't super long, have to be high transconductance types, highish gain, low plate resistance, and linear. My top choice would be a circuit that could use the 6E6P and the E810F. With their pinouts and bias points, a circuit could be made to use both. The 6E6P isn't as available as it once was before the mess in Ukraine, but still obtainable. The E810F / 7788 is still quite common and not crazy expensive.

So that's a top choice but I will review all of the options again. Since the circuit will be built onto a PCB, I could eventually post files for different tube types as well as addended instructions so they bias correctly.

 

[L0rdGwyn]

Just won these at auction, sorry if anyone else was bidding. @UntilThen told me I needed NOS tubes, so I am trying to live up to his standards.

 

[bcowen]

No doubt it would be very different from the Cayin! Could complement it, we will see going to try and get it done.



Cool the idea would be for me to basically provide all of the info for someone to order everything themselves, wouldn't even need to go through me - Gerber files to order PCBs, CAD files to order a chassis (although Dave at Landfall would have the files already), BOM for all of the parts and where/how to order, Excel spreadsheet denoting the part number on the PCB, then I would have to build one and take photos along the way, write instructions, etc.

The list of spud-able tubes isn't super long, have to be high transconductance types, highish gain, low plate resistance, and linear. My top choice would be a circuit that could use the 6E6P and the E810F. With their pinouts and bias points, a circuit could be made to use both. The 6E6P isn't as available as it once was before the mess in Ukraine, but still obtainable. The E810F / 7788 is still quite common and not crazy expensive.

So that's a top choice but I will review all of the options again. Since the circuit will be built onto a PCB, I could eventually post files for different tube types as well as addended instructions so they bias correctly.

Have you ever looked at any of AMB's stuff? I've built a couple of their components and found them to be a lot of fun. While you can buy some of the parts from them (if you want), most of the parts you have to buy yourself. Not an issue at all as they provide good links on sources. They also sell the PCB which I've been most happy to buy from them. I can buy parts all day long, but I'd be a bit leery if I had to source the board myself. Maybe that's something you'd consider stocking to sell along with the plans. Just a thought.

https://www.amb.org/audio/sigma11/

Sigma 11 LPS. I bought the board, mosfets, and (board mounted) heat sinks from them, but purchased everything else myself:

 

[L0rdGwyn]

Have you ever looked at any of AMB's stuff? I've built a couple of their components and found them to be a lot of fun. While you can buy some of the parts from them (if you want), most of the parts you have to buy yourself. Not an issue at all as they provide good links on sources. They also sell the PCB which I've been most happy to buy from them. I can buy parts all day long, but I'd be a bit leery if I had to source the board myself. Maybe that's something you'd consider stocking to sell along with the plans. Just a thought.

https://www.amb.org/audio/sigma11/

Sigma 11 LPS. I bought the board, mosfets, and (board mounted) heat sinks from them, but purchased everything else myself:

No I haven't seen their stuff! I'll check it out.

Yeah this approach is something I'm considering, if I were to buy the CCS parts myself, I could test them and then specify the correct part values for the desired current, much safer than having someone test in circuit by adjusting a trimmer for example (I do this all the time, but I've accepted the risk of being shocked if I screw up). And provide the PCB, they come in minimum quantities of 5 from most board houses, so it would be wasteful if each person had to order 5 boards when they only need one...

On the other hand, I don't really want to make a lot of work for myself, especially with international shipping. If I do this approach I will have to add some additional cost for the time and effort. But the goal here isn't to make money, just share the project. I'll consider both options.

 

[UntilThen]

Just won these at auction, sorry if anyone else was bidding. @UntilThen told me I needed NOS tubes, so I am trying to live up to his standards.

How is it? I've never tried EL37 but it ought to be good. These ones are in very good condition and rather unusual original box.

 

[cacacacaciiiiii]

I've also been scheming another project, as I said I can't help thinking about tubes on vacation...

I am considering a strictly community DIY project, a spud design. I have prototyped similar circuits and the sound is very good. However that was done with the Sowter 8665 parafeed transformers. The wait time for Sowter is very long and frankly they aren't what they once were since being sold to Carnhill. The 8665 are a little pricey too and require a somewhat complex switch to adjust the turns ratio...

So I've reached out to Jack at Electra-Print to commission a pair of headphone parafeed transformers along with my intention to create a DIY project, meaning potential future orders from others. If he can provide and my plans look good, I will look to release it on Head-Fi.

That would mean PCBs, BOM, chassis CAD files, build instructions, etc. The trick will be making it inexperienced DIYer friendly and using easily sourced parts as it will require semiconductors. TBD, we'll see what Jack says, he can be somewhat particular about his orders.

Oooo count me in!

 

[L0rdGwyn]

How is it? I've never tried EL37 but it ought to be good. These ones are in very good condition and rather unusual original box.

I'll let you know in a few days! Yes quite the interesting pair being "laboratory matched".

 

[whirlwind]

Just won these at auction, sorry if anyone else was bidding. @UntilThen told me I needed NOS tubes, so I am trying to live up to his standards.

Congrats , great looking pair of tubes. I have heard they can push 70 watts when used in a push/pull
I believe they were Mullards answer to the GEC KT66

Some of the best sounding tubes in my GEL3N amp.
Personally I like them better than KT66 and would like to own a back up pair, the only thing preventing that is the price for a nice NOS pair.

 

[Paladin79]

I've also been scheming another project, as I said I can't help thinking about tubes on vacation...

I am considering a strictly community DIY project, a spud design. I have prototyped similar circuits and the sound is very good. However that was done with the Sowter 8665 parafeed transformers. The wait time for Sowter is very long and frankly they aren't what they once were since being sold to Carnhill. The 8665 are a little pricey too and require a somewhat complex switch to adjust the turns ratio...

So I've reached out to Jack at Electra-Print to commission a pair of headphone parafeed transformers along with my intention to create a DIY project, meaning potential future orders from others. If he can provide and my plans look good, I will look to release it on Head-Fi.

That would mean PCBs, BOM, chassis CAD files, build instructions, etc. The trick will be making it inexperienced DIYer friendly and using easily sourced parts as it will require semiconductors. TBD, we'll see what Jack says, he can be somewhat particular about his orders.

Sounds like a fun project, I helped a friend with one years ago, I want to say prior to 2010. The tuber. Earliest model I can think of used television sweep tubes that were readily available at one time, not so much anymore.

 

[L0rdGwyn]

Congrats , great looking pair of tubes. I have heard they can push 70 watts when used in a push/pull
I believe they were Mullards answer to the GEC KT66

Some of the best sounding tubes in my GEL3N amp.
Personally I like them better than KT66 and would like to own a back up pair, the only thing preventing that is the price for a nice NOS pair.

Thanks Joe, that's encouraging, they weren't cheap but also not outrageous, I thought it was worth it for such a nice pair! Like the EL34, it's a true pentode, and you're right 70W in push pull. Should sound pretty good

Sounds like a fun project, I helped a friend with one years ago, I want to say prior to 2010. The tuber. Earliest model I can think of used television sweep tubes that were readily available at one time, not so much anymore.

Cool cool, I'm sure the tuber was a good amp, maybe I'll give this one a potato themed name a good spud circuit can really sound excellent. Signal path is short, and in parafeed with a CCS load and LED biasing, the only capacitor in the signal path is a high quality parafeed cap. And it will be completely dual mono, so a high degree of channel separation. Should sound pretty good! Especially for the price.

Maybe I can teach some people how to use a benchtop DC power supply to set the current on the CCS. Ideally this project would become self-sustaining so anyone could build it without my involvement.

 

[L0rdGwyn]

Greetings from the Bimini islands.