Tube headphone amp kit for $25!? - Page 4

just pulled the trigger on one too...first project, will update as I go.
Anyone used it as a preamp, too?

Agreed....input side.

Peete.

Nice pics to share. I am even interested to try, especially its low cost with a great loud sound generated.

I have no experience of building anything like this but i had to buy a solder iron the other day to try and change the fuses on a nintendo ds so this kit appeals to my wetted apetite to tinker with lecky bits and bobs

Ouch!!

Haha. your bits and bobs are safe, hopefully I wont blow mine off.

I just ordered one today... how long do they take to get into the US?

Yeah I was wondering that too,what has the shipping time been for folks in the States?

I think it took two or three weeks for me. I don't remember exactly when I ordered but it was sometime at the beginning of November and I received it by Thanksgiving.

Okay guys, so I just got the kit in the mail today. For the people wondering how long it takes to get to US, I placed the order about 2.5 weeks ago, and it shipped 9 days ago.

This is the first real electronics project I've done [although, I'm proficient with a soldering iron], so bear with me while I ask some *probably* silly questions in the future.


squid+, how would I go about doing this?

Also, I see that your amp has a big variable resistance knob on it {that's what it is, right?}. I didn't see one in my kit {although, I haven't really opened it up and sorted through the parts}. I have a few 9V battery clips laying around, but are there any other parts I should buy before I go ahead and start building this kit {electronic parts is not super close, so I'd like to make one trip if possible}.

Finally, the silliest question: would it be possible to have the capacity to power it through wall power, as well as run it off battery power? I imagine that having the wall power charge the batteries would require some advanced/extra circuitry, but if possible, it'd be neat to have the option to take out the batteries and run it off the wall power, no?

It's kind of related. The knob is a potentiometer , which is essentially a variable resistance control as far as I know. Actually, it's two parts though. It's the potentiometer itself then a knob that goes over the pot shaft. In any case, the kit doesn't come with so you'll need to get one if you want to do volume control on the amp.
On that note, you'll have to set up something to receive audio input, whether it's a pair of RCA jacks, a 3.5mm jack, etc. From that jack, you would wire it to the potentiometer then to the board itself. As in the pot will be between the input and the actual amp stage.

Regarding parts you'll need, sounds like you'll want to get the potentiometer and a fitting knob. You'll also need either the RCA or whatever kind of jacks you want to use for input, a headphone jack for output, and a power switch if you'd like to have one. I'm guessing you have some wire and solder already. You'll probably also want some grommets to fit onto the tubes, as they're really microphonic without anything. I have two small ones on mine and it helps a lot, but I think I'm going to add another one on each. They carry these at stores like Home Depot and Lowes, but maybe some electronics shops do too.

I'm looking to change my amp so that I can use a wall outlet vs batteries, but keep the option to use batteries. To keep it simple, I'm guessing that you could wire them both up and remove the battery when you're using it at home, then put the battery in if you plan to bring it somewhere without power outlet. That's the simplest way to do it as far as I can figure and I think it'll work.
The only thing I don't know is what kind of amperage I would want on the power supply. I've found many that are 9V, but they vary widely on the other values so I'm not sure what is safe to use or not. Maybe someone else can chime in?

Well, that's a bit long winded, but I hope it helps.

I'll ask this question again at the bottom though, for anyone who didn't read it
The only thing I don't know is what kind of amperage I would want on the power supply. I've found many that are 9V, but they vary widely on the other values so I'm not sure what is safe to use or not. Maybe someone else can chime in? I'm guessing a 9V 500mA would be approximate to a standard Duracell 9V battery, hm?

Thanks!

Thanks so much squid+!

One quick question however. How is having the volume control on the input side different from changing the volume on the DAP itself? I read your initial post a few times, but I feel like I'm missing something. If it's something really trivial, you could even PM me.

Not to distract from your own question, for anyone who passes by here:

Well for instance, if you are using a LOD from an iPod, it would be a line level signal and you can't change the volume using the iPod. Same case if you have a DAC sending a line level signal.

Quick update: all of you guys who got one of these recently is getting a different circuit board with your purchase. The documentation says that it's the same exact circuit board, but with an extra space for two AA batteries, to be used in conjunction with the 9V.



I'm having some trouble though... I'm only getting sound in one channel {right}. Is it possible that I blew out something, like a tube? I bought a spare, but have no idea whether or not that's the problem.

Question about the two blue things with white knobs on them (a type of pot?): should they be sitting on the board, or a little raised? I ask because they seem to be the most finicky component. I accidentally bumped into one, and the volume on the only channel dropped down significantly. After hitting it a few times, it came back to the regular volume.

Okay, my budget-fi radar alarm went off a while ago while I was looking for a project to play with while I debug my Mini^3 project (U5 desolder starts this weekend...). I found this thread and I'm buying a kit in a few minutes...