SSMH build

TwsT

TwsT

TwsT

Soldato
Joined
7 Feb 2011
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Right I'm going to build a starving student hybrid tube amp

Already ordered the PCB from fred on headfi

just wondering about aquiring the 19J6 Tubes anywhere in the UK that can be used or is it braving the depths of importing/ebay
 
yeah

it's a hand full of resistors added on the L and R channel inputs and come caps on the other side.

I've bought the pcb from fred on head fi so i'll hav e to have alook wouldn't be too had to put them in
 
lol edited your post instead of quoting it i'm a genius

freds pcb is 12AU7 lol stupid brain :)
 
So the boards arrived

bCBnNeVh.jpg.png
fdutLyhh.jpg.png


sadly can't afford to do it till the end of the month but still should be fun.

I do have spares if anyone would like one i'll put it on the MM
 
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well to build all 5 boards

I'd be looking at around £50 for all the parts excluding tubes mosfet coolers and a case, as for the tubes finding RCA clear tops in the UK seems a bit hard so mullard NOS have been recomended

most ofthe resistors come in packs of 100 and teh caps seem mainly available in packs of 5



Anyway it should be fun, once it's built i'm going to look at acrylic, wood and metal housing i'd like to use a guitar pedal case if I can.
 
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Shame those Nichicons muses are really only available from mouser in the UK AFAIK - I've had to do a few big orders of them (different uf values to that BOM) so I don't keep spending £15 on shipping for small quantities.

EDIT: (Ignore - misread schematic)
 
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well fred who designed the pcb just suggested generic

lzxo3JG.jpg.png


for £5 i can buy the resistors potentiometer 510 and 640 mosfets for one build from http://www.bitsbox.co.uk/

the tube sockets are availible in packs of 5 for £5 on ebay

but the caps are hit and miss i can't find any one place to buy them all from

i can't really decide on a heatsink till i pick a case either.
 
I actually mis-read the schematic (trying to do too many things at once) looks like the 470s are actually output capacitors so different rules apply completely :S

Most stuff can be bought from Farnell - if you already have an account they have some discounts at the moment for existing customers - but they are much more limited for audio grade capacitors.

C3a/C5a you really want polypropylene film capacitors as they are in the signal path, like wise C3/5 which are the 470s I was talking about are in the signal path but for that design you need that size capacitor for the full audio frequency range so can't realistically swap them out for anything better than aluminium electrolytics so the Nichicon KW or other audio grade are a good choice.

C2/4 aren't so critical but as they are the same value as C3a/5a might as well use the same ones.

Definitely use 1% metal film resistors as this will noticeable reduce the noise floor over carbon resistors.
 
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thanks for the info

63V polyprops seem hard to find, will pick up some wima polyetser ones anyway, main reason i bought more than one board was to play around with caps and mosfets
 
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While it kind of defeats the original purpose of the design (simple and cost effective) - can see all kinds of potentially interesting tweaks looking at the schematic - wondering if sticking a LM317HVT filter stage and doubling up on the 680ufs on the input would have a noticeable effect on supply filtering or whether the tube design has robust enough power supply noise rejection to not make it worth it.
 
TwsT said:
thanks for the info

63V polyprops seem hard to find, will pick up some wima polyetser ones anyway, main reason i bought more than one board was to play around with caps and mosfets
Click to expand...

http://uk.farnell.com/wima/mkp1f032204d00jssd/cap-film-pp-220nf-250v-rad/dp/1890234

Think those are functionally the same as the ones linked in one of the builds for the 0.22uf - not the cheapest mind for what they are.

EDIT: What is the lead spacing for the 0.22uf caps on the board? hard to see from the picture but looks like 10mm rather than 15mm as on some builds. (The caps in the link are 15mm spacing).

EDIT2: When I mentioned voltage earlier I was mistaking where the 470ufs were used - for the output ac coupling capacitors the designer recommends 50v or higher, for the power supply 63V or higher.
 
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they are 10 mm (less than tbh) more like 8/9

so essentially as long as they meet the minimum it doesn't matter if i go beyond it. Good to know.
 
Ah they will be spaced for 10mm film caps then, the 15mm potted ones like I linked wouldn't fit elegantly. There is like 3 different variants of the design one of them uses 15mm hence my confusion.

With film caps higher voltage has no disadvantages aside from taking up more room physically and can sometimes be of higher quality, with aluminium electrolytics there is this whole thing about "linearity" (frequency response) with some people claiming different voltage ratings of different caps are more linear than others if there is anything to it usually the 35v ones of a model that are claimed to be the more linear followed by 63v then anything else (no idea if there is anything to it - I've not noticed anything sonically between voltage ratings or with a basic oscilloscope - though I don't really know to much about using it).
 
Right well finally got off my ass and bought some parts should all be here today

These arrived on saturday
me0nACCh.jpg.png


Sadly the sockets for the tubes had to be ebay'd from china so it could be 2 weeks or 5
 
Did you get proper measurements for the caps I was referencing above btw? I thought at some point after posting it might have been 7.5mm as that is one quite popular spacing :S
 
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