* The DIY Audio Thread *

adamau5 · 5 Apr 2009 at 18:46

almost, You just have to check the heater voltage - there are jumpers on the board. Some valves are 6.3v heaters in series, others are 12.6v in parallel. the Valves it comes with are 12.6v and so are the 8416.

And other than that, its just a case of swapping them. the tirode stage is all Constant current source driven, so it doesnt really care which valve (out of a specific family) it has, it just passes 2ma through it. Normally you have to play around with resistors, but the designer has been very clever with this.

basically, you can try any 12au7 / 6dj8 / 8416 / 6922 or equivalent. For cheap and cheerful i would look at the 12au7's. You wont be dissapointed with the stock valve, they still impart that valve midrange. My preferance would be to go for some 8416, but they cost a bit.

chet84 · 5 Apr 2009 at 18:59

Adam W said:
almost, You just have to check the heater voltage - there are jumpers on the board. Some valves are 6.3v heaters in series, others are 12.6v in parallel. the Valves it comes with are 12.6v and so are the 8416.

And other than that, its just a case of swapping them. the tirode stage is all Constant current source driven, so it doesnt really care which valve (out of a specific family) it has, it just passes 2ma through it. Normally you have to play around with resistors, but the designer has been very clever with this.

basically, you can try any 12au7 / 6dj8 / 8416 / 6922 or equivalent. For cheap and cheerful i would look at the 12au7's. You wont be dissapointed with the stock valve, they still impart that valve midrange. My preferance would be to go for some 8416, but they cost a bit.

Great stuff... I think i'll get used to the stock ones before playing with it - I want to appreciate it for what it is...

Founder_film · 6 Apr 2009 at 14:54

Hello, does anyone know where I can get a UV bulb from for PCB etching? I am thinking that the "Black light" bulbs won't work (the bulbs that have been painted deep purple).

adamau5 · 6 Apr 2009 at 17:47

http://uk.farnell.com/mega/34-0707/tube-starter-kit-8w/dp/1201819

I think these are what you're after

Founder_film · 6 Apr 2009 at 18:30

Excellent thanks. I am going to try the iron on method of ironing on toner from a laser printer first I think. Any body here ever etched their own boards?

p4radox · 6 Apr 2009 at 18:59

Founder_film said:
Excellent thanks. I am going to try the iron on method of ironing on toner from a laser printer first I think. Any body here ever etched their own boards?

Yes, a few years ago. I used a home-made black light box and an acetate sheet and it worked fine. It wasn't a particularly intricate layout though.

Yaka · 7 Apr 2009 at 18:43

update on the case work on my starving student. need to make the tube sockets striaght and flush as they are a tad wonkey :rolleyes:

adamau5 · 8 Apr 2009 at 08:08

looks good yaka.

I would reduce the gauage out the output wire (the heavy braid, is it output or intput?).

i think you would see more improvement from a shorter path than the heavy gauage.

Having sold a load of amps recently and being left with just the bijou, i am now building a Cavalli Compact Tube hybrid.

I'll report back when its done.

Yaka · 8 Apr 2009 at 23:54

aye thats one of things im gonna do had some kynar braided cable left over from a wii case mod i did so used that

p4radox · 9 Apr 2009 at 11:36

Does wire quality/gauge make a real difference in these DIY builds?

Also, I was looking at the DIY cable/interconnect thread on HeadFi, and was stunned at the amount some people spend on them. Is it really warranted for sound quality, or is it more of an aesthetic/ruggedness thing?

J1234 · 9 Apr 2009 at 11:39

It's the people that spend loads more on the 99.9999999% silver wire than settling for just the 99.999% silver wire.

J1234 · 9 Apr 2009 at 18:59

Hmm, I want to upgrade from my Starving Student to another tube amp.

Adam, what's the Bijou like to build?

adamau5 · 9 Apr 2009 at 20:26

not too bad, dare i say easier than the soha II. The only difference being, if you get it wrong it can kill you. even when off, the output caps hold a horrible amount of voltage.

the case work is the hardish part. mine worked fantastically off the bat, has been modified to sound even better. Its a really really superb amp. and if it goes **** up, i will happily help.

I have not heard a better amp. period. Thats not to say better amps arent out there.....
Glassjaraudio has kits, you'll just need to buy a transformer + case + bits and bobs.

photoshop · 9 Apr 2009 at 21:13

How does one commission such an amp and how much do they cost on average?

adamau5 · 9 Apr 2009 at 21:21

depends on the amp. A bijou would be £400+, but its one of the best in class.

A sohaII (hybrid) is maybe $160 in parts, plus case which can be anything from $24 to £100 with custom engraved front panels from FPE like this:

then you need to pay a builder. With all the case work, i would expect to pay someone £15 an hour. My guess is 6 hours for a build. Again, the bijou would be more.

A chinese amp like the darkvoice would come it at a similar price, but it would be built with inferior components and you would have to spend a pretty penny on valves to get it up to scratch.

As for a builder... people on headfi do it.... I do it..... depends on what you want.

J1234 · 9 Apr 2009 at 21:22

Adam W said:
not too bad, dare i say easier than the soha II. The only difference being, if you get it wrong it can kill you. even when off, the output caps hold a horrible amount of voltage.

the case work is the hardish part. mine worked fantastically off the bat, has been modified to sound even better. Its a really really superb amp. and if it goes **** up, i will happily help.

I have not heard a better amp. period. Thats not to say better amps arent out there.....
Glassjaraudio has kits, you'll just need to buy a transformer + case + bits and bobs.

Excellent, thanks.

The kit isn't too expensive either. My next amp was going to be a Little Dot (II or III) but I'm reconsidering the DIY approach again, however I don't like the idea of killing myself.

Edit ^ Hmm, maybe the Soha II would be best as it is significantly cheaper.

adamau5 · 9 Apr 2009 at 21:27

its a good amp... just ask chet84.

the soha II is vastly cheaper when you consider the standard hammod case, the fact it only needs two valves... only needs a 15-0-15 v transformer.

it still have enough volts in it to really hurt you (it uses a cap muliplier to hit 120v on the plates). Cracking amp to play with, because once you have set it up, tube rolling is doable without any further work.

Its a step up from the starving student. Although i maintain that the starving student + grados is a frighteningly good setup, synergy is amazing.

starving student + senns = not so good.

J1234 · 9 Apr 2009 at 21:30

It looks to me to be slightly more straight forward than the point to point work on my Starving Student, that got really messy and irritating.

Where are you getting those cases from? The silver ones.

adamau5 · 9 Apr 2009 at 21:31

modushop.biz

Buy yourself a couple as you know you will use them.

excuse the blurry pic, but this gives you an idea of how neat a sohaII can be compared to a point to point student. .

Vs point to point (my speaker amp, the baby huey)

J1234 · 9 Apr 2009 at 21:39

Wow, that looks fantastic.

I don't know if it's just my starving student, but it gives me a lot of distortion at higher volumes when there is a lot of bass. I've had to fiddle with the equalizer in iTunes to get it right. Some songs still sound a bit weird though.

It's probably due to the huge mess inside the amp. That's another reason I was considering the Little Dots or similar as I wouldn't have to worry about messing up the insides and it giving me a rubbishy sound.

*** The DIY Audio Thread ***

* The DIY Audio Thread *