Hello all, this is my first post here. I am interested in getting into DIY hifi with a raspberry Pi and a hifi HAT or add on card to produce decent sound from such a small PC. I have the pi and experience with DIY projects (electronic and otherwise), but no experience with setting up tube amplifiers.
Basically, I'm needing to know if the amplifier kits sold on ebay and a few other places are decent, or if for the $300-500 pricepoint, it is better to do point to point wiring and source all the components myself. I already own a temp controlled soldering iron and I am used to soldering PC components, so I can handle the point to point method, with some help on circuit design.
Basically, I'm needing to know if the amplifier kits sold on ebay and a few other places are decent, or if for the $300-500 pricepoint, it is better to do point to point wiring and source all the components myself. I already own a temp controlled soldering iron and I am used to soldering PC components, so I can handle the point to point method, with some help on circuit design.
You need to decide what exactly your requirements are, how much power, single ended or push-pull. Will this be a "desk-top" amp for the computer, or will it be used in a larger setting?
jeff
jeff
Not very much power at all this will be driving probably a pair of desktop/bookshelf speakers integrated into the box.
I want to use a single ended set up.
I want to use a single ended set up.
Take a look at the Bottlehead SEX amp. The assembly instructions are very easy to follow. Fun to build and sounds great.
Dynavox VR-70E is a decent starter as assembled amp everybody says here and easy to mod. I'm thinking of buying one, and mod it if it's needed. They are for sale from 600€ on in Europe (where are you located?)...
https://www.elektronicatekoop.nl/dynavox-vr-70e-2-stereo-buizenversterker
I hear the bottlehead is a good kit, just like the ones from Oddwatt and a few others. Some of their models fit your pricerange more or less.
https://www.elektronicatekoop.nl/dynavox-vr-70e-2-stereo-buizenversterker
I hear the bottlehead is a good kit, just like the ones from Oddwatt and a few others. Some of their models fit your pricerange more or less.
waxx, I appreciate the info but I prefer a DIY solution. I want to get my hands dirty! lol
Nikon, that looks great, but pretty pricey (I realize it's cheap by comparison to a lot of the kits around) by my standards. I don't need something amazing, and would be willing to settle a bit on quality as long as it is decent for my first buy in this new hobby. but if that's where the "decent" kits start, I'll just have to wait a bit.
I picked up one of the 6j1 DIY kits off ebay, and based on reviews from a few other sources got a pair of GE 5654s for it. I can use this to play with, since I have the Pi-hat and the Pi as well as an old Astrosonic hutch with inputs for RCAs. THis is just to familiarize myself with the theory and the equipment on these tubes. Does anyone here have any experience with these kits?
Thanks to everyone for your replies so far.
Nikon, that looks great, but pretty pricey (I realize it's cheap by comparison to a lot of the kits around) by my standards. I don't need something amazing, and would be willing to settle a bit on quality as long as it is decent for my first buy in this new hobby. but if that's where the "decent" kits start, I'll just have to wait a bit.
I picked up one of the 6j1 DIY kits off ebay, and based on reviews from a few other sources got a pair of GE 5654s for it. I can use this to play with, since I have the Pi-hat and the Pi as well as an old Astrosonic hutch with inputs for RCAs. THis is just to familiarize myself with the theory and the equipment on these tubes. Does anyone here have any experience with these kits?
Thanks to everyone for your replies so far.
If you can manage point-to-point, that's usually the better way to go with tube stuff, for a number of reasons. For one, it's much easier to re-work than PCB stuff. And with PCBs, damage, wear & tear tends to accrue over time - with p2p, you can simply replace terminal strips, wires, etc. as needed to fix things as they fall apart.
With the PCB, you're pretty much stuck with what you're given, unless you want to do a bunch of cut & jump - in which case, p2p would have been the better option. And it's also much simpler to change circuit topology / physical layout and wire gauge / type with p2p work.
IMO, the best of setups use a combination of chassis-mount sockets & terminal strips, plus the occasional tag / turret-board. I keep a small stock of NOS / used turret boards for this kind of thing. They're almost impervious to rework, vs. a plated PCB. If you need a small chunk of turret, let me know..
With the PCB, you're pretty much stuck with what you're given, unless you want to do a bunch of cut & jump - in which case, p2p would have been the better option. And it's also much simpler to change circuit topology / physical layout and wire gauge / type with p2p work.
IMO, the best of setups use a combination of chassis-mount sockets & terminal strips, plus the occasional tag / turret-board. I keep a small stock of NOS / used turret boards for this kind of thing. They're almost impervious to rework, vs. a plated PCB. If you need a small chunk of turret, let me know..
Legendre, I will definitely need a piece once I start ordering things for this. Thanks for the offer and I will be sending you a PM soon.
As far as designs go, is the tube lab simple SE when built on the "frugal" side around $300 worth having?
As far as designs go, is the tube lab simple SE when built on the "frugal" side around $300 worth having?
http://www.diyaudio.com/forums/swap...fitted-raspberry-pi-dac-upgraded-speaker.html
To give you guys an idea, the audio feed will be coming from a similar set up to this. but with a better quality DAC from hifiberry
To give you guys an idea, the audio feed will be coming from a similar set up to this. but with a better quality DAC from hifiberry
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for desktop / low output consider an ecl86-based item. Super-simple, but quite low output in SE. Power supply requirements are undemanding which helps keep cost low
The Piccolo is a example of the genre.
The Piccolo is a example of the genre.
An externally hosted image should be here but it was not working when we last tested it.
@aardvarkash10
There seems to be an error in the way the UL / Triode mode switch is drawn in your diagram..
Assuming the RH terminal is the common, which is how it's drawn, it's pretty obvious where the problem lies. The lower LH term should be common, if the design makes sense. Else, you have an open g2 circuit in one position.
There seems to be an error in the way the UL / Triode mode switch is drawn in your diagram..
Assuming the RH terminal is the common, which is how it's drawn, it's pretty obvious where the problem lies. The lower LH term should be common, if the design makes sense. Else, you have an open g2 circuit in one position.
Very possible - I didn't look. Its not my schematic, I did build it but redrew the schematic and recalc-ed the values to both learn and be sure. It was a long time ago...
Here's a detail of the schematic:
If the switch is set to the "tri" position, you'll get a triode mode, though I'm not sure how (un)desirable the 330R resistor is, in series between g2 and plate. But in "u/l" position, a section (15%?) of the opt secondary is just shorted-out, while g2 simply floats off.. and that just ain't gonna work at all.
For proper operation the point marked "tri" should be the +common+, with the un-marked terminal being "tri" mode, while the the "u/l" terminal remains the same. It's really a simple error, but an error it is.
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Cheap stuff: use PA (aka "line") iron for your PP OPT (or 12V lighting transformers for SE) and back-to-back some power transformers to generate your HT. You can use SS rectifiers with a little series resistance (to quiet them down a bit) to save a bit more (v.s. choke input supply with valve rectification)
If you're in the US Hammond's stuff is cheap for "proper" iron.
If you abandon global feedback then it's all pretty straight forward: A standard triode gain stage followed by a cathodyne driving a cathode biased PP output is simplicity itself. Triode strap some 5 to 10W pentodes/tetrodes and use medium or low mu triodes and it'll just about work out all by itself.
After that you start "improving" and the fun starts.
Yup - it's back to front: common should be attached to screen and A/B options to plate or U/L tap. Given the foibles of the mechanical switch there should be a largish resistor to B+ (i.e. pentode mode) for the moments when the switch is not connected to anything.
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Making SE is easy, just few items to put together. Having working points right is more important.
If you are from eu, toroidy.pl is ok for the price. It´s little complicated, but fet follower on driver tube gives detailed sound than anode resistor.
If you are from eu, toroidy.pl is ok for the price. It´s little complicated, but fet follower on driver tube gives detailed sound than anode resistor.
Why would it matter if g2 briefly went open-circuit during the transition? Other than shutting down the Ip, I don't see how it might be a problem.
But if the concern is real, then your approach using a large-value R just to keep things sane is fine. A make-before-break style switch would also be ok, though, that's a bit esoteric. You can also specify that the mode only be switched when cold, but that's hardly idiot-proof.. especially with the robust quality of latter-day idiots. ;-)
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It's a gate: if it's not connected to a virtual ground Murphy says it will find a signal. AM radio or IF oscillator, anyone?😀
I think the circuit diagram hooman posted here is not a simple amplifier to build by a "first timer" builder if I have understand this thread starter correctly. Lot of chances for instability/oscillations here if you do not have much building experience.
Also I do not quite understand how the lower triode gets its DC bias. Expecting a resistor connected to earth here, but I may be wrong.
Also I do not quite understand how the lower triode gets its DC bias. Expecting a resistor connected to earth here, but I may be wrong.
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