DIY Audio Projects Forum

nice amp koogar.

I am using the same tube, same heatsink as yours but your build is much neater; I used a vero/stripboard, you etched your own board?
what are the capacitors you use?

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but here I want to ask everyone... does changing the tube changes the sound characteristics? the tube is the preamp right? and each brand of tubes have a sound signature right? I believe so?...

Hey Guys

Thanks for the kind comments regarding my amp i am sort of torn between leaving it open or making a chassis but since i want to stick an single analogue VU meter in the front i will probably make one as i have some aluminium sheet from my other builds.I also need to order a new Pot as the one thats in is passed its sell by date ,So i will know doubt make a board for the right hand side to take care of inputs the VU buffer and the pot .


I etched the board Santik on a single sided 160 x 100 mm copper clad using Sodium Persulphate i may have a go at double sided next time i buy some board as this would cut down on alot of dead end problems i had when routing 3 parts into 1 board.

I am not the best when it comes to routing i would probably include a ground plane also to cut down on tracks but since i used the toner transfer method this may be problematic as its alot to transfer to the copper.
I get great results though with Laser OHP acetate transparency sheets and a laminator as long as you pass it through the laser printer twice to get plenty of toner on it just peels off the sheet like a transfer . takes about 4 passes through the laminator

The PSU Caps are Panasonic 1000uf/50v and the amp caps are (C2)Nichicon Fine gold 100uf/63v and (C3)Nichicon 470uf/63v Muse , although i changed the input caps (C1) to 4.7uf/25v Elna Silmic II as i did'nt have any Muse in that value i also bypassed the output caps with some 0.1uf/63v Wima MKS to help the top end but only time will tell.

out of interest i also included outputs from the switched side of the headphone socket to a header so when the headphones were disconnected this header become an ouput this is then sent to the other set of phono sockets as an adhock preamp .As long as your easy with the volume it works rather well .

The header at the side of the relay was intended for a mute option incase of thump off i also thought of using a rotary switched pot and tieing it to the mute header rather than having another switch you could just turn the volume knob till it just switched the relay off before removing the headphones

I was all set to make this out off salvage but since i was ordering some caps for my GainClone amp it was silly not to buy some for this project as they were so cheap.

In the spirit of community anyone is welcome to the Eagle files if they want them or the etch/component layout pdf's

Koogar

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Homebuilthifi Projects
runawaybrainz.blogspot
Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp

so, how is it? the amp?

warm or bright? what is the sound characteristics.

after that Power Capacitor, does your amp still produce hissing?

I used Panasonic FM 1000uf 16V C3 and Panasonic FM 220uf 25V C2, Illinois Capacitor 2.2uf 250V MKP for the input caps.

bass is punchy, aggressive sounding and bright sounding, there is also some warmth.

Here I have a question, there is a vacuum tube as a preamp. Does the sound produced from this amp has changed to analog sound?

Its a little early to form a stong opinion regarding the amps sonics yet as im still tweeking it and its still burning in but today i had a little time to to a A to B comparison with my AUNE DAC headamp i listen to both through the DAC of the AUNE and i have to say i was pretty impressed on the whole although my Pot is junk i have a new one on the way .It does not drive the lower end of my HD580 Jubilees (320 x2 Ohms) as well as the AUNE but at normal listening levels its good yet my test headphone HD500's (32 x2 ohms) it drives them very well as expected.

Regarding hiss i do not have any at all nor has it ever.

i should really get round to building a dummy load for burn ins


and yes apparently just like OP-AMPs valves have there own signature i just wish i had some more to try .

i would also like to try some Polypropylene input caps but they seem rather rare mind you its hard to get anything in the UK you Americans have all the good stuff lying around

Koogar

_________________
Homebuilthifi Projects
runawaybrainz.blogspot
Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp

Let me preface this post by saying that I am _NOT_ a "true audiophile." I like good sounding audio, I just don't have any gear better than my Sennheiser HD555s that I just picked up from Amazon on GoldBox deal for US$75, and my Sennheiser SD280s before that. To be honest, I'm not sure why I got the bug to build a tube amp, but I did, and this design looked like a good place to start.

Boy, was I not wrong. I've been collecting parts over the last few months waiting for a free evening to put stuff together, which happened to be tonight. I don't have an etched board yet, but even on a breadboard, this thing sounds pretty sweet.



Of course, given that I've historically plugged my (better than ear-buds) headphones directly into my iPhone and thought that was sounding pretty good, what do I know, right?

My plan for this circuit: Eventually, I'd like to put a mixer on the front end with several inputs (probably 4: one for each of my two computers at work, one for the iPhone and one for the desk phone), and a master volume, then feed it into this amp and drive my HD555s with it. I'd love to do the mixing completely passively, but passive mixing is tricky to do right, so I'll probably stick a TI (formerly Burr Brown) OPA2227 in the mixer so I can do current summing correctly, then feed that to the tube.

I confess I haven't read all 46 pages of this thread (46 pages!!), but I have seen a few people talking about running the tubes at higher voltage. I figure, if I've got an 18v supply from an old laptop, is there any reason I shouldn't just regulate 12.6v for the heater elements and run the plates at the full 18v? It's not a LOT more than 12v, but it's some...

I'm pretty proud of this, my first tube amp. Thanks everyone.

-Mark, @SmittyHalibut

SmittyHalibut, what tube you used in this project? I just wanted to know.

what you use to power your amp?

I have made a power filter... capacitors in parallel.

1000uf, 1uf, 1000uf, 1000uf, 1000uf and 0.1uf.

that's is more than 4000uf. I have removed most of the hissing from the power supply but there is some light hum, very light that need attention to be able to listen to it. Is there any way to remove it? add more capacitors? how much capacitance do I need, I wonder.

I got a 12AU7A from my local Tube Guy (really, just the guy at the local electronics frea market (De Anza for anyone from the San Jose, CA, US area)).

I found a 12v 1.25A switching wall-wart in my junk pile. My listening environment was loud enough (my computer with it's fans were right there and my wife was watching TV in the next room) that I couldn't tell how noisy it was. I didn't HEAR any buzzing or humming, but it was hard to tell.

Anyone have any G-Code files to mill a PCB for this beast? This is my first time trying to make a PCB on my mill, but it looks like it should be relatively simple with http://pcbgcode.org/. I'm going to give that a shot.