Thanks! Yeah I would've been super disappointed if I couldn't get the switch in, so in the end I'm not all that mad, curious if they will give me any kind of refund, not cheap as far as switches go.
L0rdGwyn's DIY Audio
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Thanks! Yeah I would've been super disappointed if I couldn't get the switch in, so in the end I'm not all that mad, curious if they will give me any kind of refund, not cheap as far as switches go.
I've gotten serious about winding my own inductors over the past 24 hours. It's something I've planned to do eventually, I have a few texts already, just wasn't sure when. The time is now!!! I spent the whole flight home reading RDH4. It's going to take some time and lots of planning. For now, all books, then once I feel comfortable enough to design a transformer, I'll source components, a hand crank winder most likely to start, and give it a go. Lots of learning to do and no doubt it will be a lot of trial and error, but I think I can do it. I like to learn by doing, in the near term I need a parafeed transformer, as I mentioned, and I'm interested in some line output step-down transformers for my PCM63 DAC, so likely those would be the focus of my early efforts.
whirlwind
Headphoneus Supremus
^ Great idea! You go Keenan ^
Thanks! It should be fun, I am excited, when I get the bug for something I tend to go all in, there is no middle ground lol so I think that should help speed things along. Was doing more reading / learning this morning. None of my other projects are urgent (e.g, PCM63 DAC, LCR phono stage) and winding transformers could potentially help those projects along. So it's a good time to do it, but it will take time and it will be an iterative process of improvement.
In the mean time, I took some low impedance measurements of the pentode headamp, looks good. Mostly I wanted to see the frequency response with a 32ohm load, down 0.8dB at the frequency extremes which is good. Just gotta figure out the packing situation. Unlikely I'll get the Brimar CV1985 and Mullard EL37 before it hits the road, so I'll have to look forward to hearing them at a later date.
The only planar magnetic headphone I have in house is the Oppo PM-3. 26ohm impedance, 102dB/mW, so not a hard-to-drive planar. That being said, I haven't really cared for them in the past, but this is the best I have heard them, they sound great! And virtually hum free with volume at max without music playing, very quiet.
Maybe a good sign for other planars?
we'll see. With GZ34 and EL34, this is a 2W amplifier, so it has the juice to handle power hungry headphones, and a relatively low output impedance for a single-ended tube headamp at around 4-5ohms.
whirlwind
Headphoneus Supremus
Winding your own transformers will be a huge convenience for you and save loads of cash, not to mention the learning experience.
I was going to mention this awhile back but did not think you would want to mess with it as it is bringing on quite a lot more work and time.
I was going to mention this awhile back but did not think you would want to mess with it as it is bringing on quite a lot more work and time.
In a year from now, winding transformers will be a piece of cake to you. You will be able to do it in your sleep, saving both time and money 
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Yeah it really would, of course it is a big investment, but if I can manage to do a decent job of it, it would be extremely convenient. One tricky aspect however is sourcing parts, most companies that can provide laminations have minimum order quantities that exceed DIY needs. I am only just touching on that topic though, just a cursory look at where to source laminations so far. Edcor can supply M6 lams at good prices which is a great option, especially for high power output and mains transformers. For higher permeability core materials, like 50% nickel (permalloy) and 80% nickel (mumetal), sourcing it is typically from Asia with minimum order quantities of 5-10kg. That's a few hundred bucks and a lot of material, so I'd have to feel pretty confident in what I'm doing to go for it.
Anyway, just the tip of the iceberg, I'm simultaneously reading about how to design / build and looking at the market in terms of laminations, bobbins, wire, etc. Got a long, long way to go!
In a year from now, winding transformers will be a piece of cake to you. You will be able to do it in your sleep, saving both time and money
I sure hope so, time will tell
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Well... if you wind the transformers for your DIY amp design - it will be a huge win-win!!
Xcalibur255
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Are they wound by hand or with some kind of rig with a stepper motor? I've read that tolerance consistency is important to the performance of OPTs.
You can do either, wind by hand with a crank winder, or some sort of motorized setup. Some people use a modified metal lathe. You can get a pretty high quality CNC winder for around $600-700.
You can make one yourself of course. Why not?
Xcalibur255
Headphoneus Supremus
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Before we can DIY this project we have to DIY our tools so we can DIY our parts? 
You can make one yourself of course. Why not?
Lol maybe I would, if I didn't have a job. Some things are worth buying
Pentode headamp is on its way to @zach915m along with a nice selection of NOS tubes. I'll be interested to see what he and other people think of it. Due to its "old school" design, it is a warmer / more euphonic sound relative to other circuits I've recently made, but maintains impressive technical performance. I would still call it a prototype, subject to change based on the feedback I receive. I've started looking into what a "new school" aka with transistors version of this circuit would look like as it would save on cost at the expense of increased complexity. A good alternative option depending on where this project goes.
OTL monster is back in action.
OTL monster is back in action.
jgwtriode
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Oh yeah!
jgwtriode
jgwtriode
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