Tubes amp

[huangyong 0]

if you guys want to make PCB, pls use protel format. i will try to persuade digi01 to make for us at cheap price.

Edited January 8, 2006 by huangyong

[squalle 0]

I was thinking making the PCB, DIY way

I dont wan to make the cost increase

getting factory produced will make the price go up and not to say digi01 sure wnana earn some

 

[kross 0]

squalle, your vol pot looks quite well built. how much you bought it for?

anyway, i have tried removing my vol pot and fixing a fixed 100k instead but the buzz is still there, which really puzzles me. now i dunno whether it is the vol pot fault or whether the soldering is at fault.

[Kippei 0]

Is the 337 facing left or right.... If the correct orientation is face right, while i following the perfboard diagram. I think i soldered vout to R 11k

[squalle 0]

hahaha

 

LM 337, looking at its labeling, it's A I O

I did this SOHA till I remember that pin-outs

[squalle 0]

kross: check all ur AC line.

dont let them get near, and also did u somehow put ur switch and it's wiring passing thru the signal part?

and also chk for cold joint or cold connection. last time I've got the hum due to that

 

is that hum or buzz?

if more like buzzing, then more like there's a strong EM source nearby, i.e. the trafo

[kross 0]

haha...i also find it hard to find the problem. i have remove the hum from the psu by not using a too high voltage, around 24V. but the buzz from the vol pot is there, slight irritating sound by i turn the vol pot too small, ie, in the range of 10k and above to 100k. if it is only a few k then there is no buzz. hmm, maybe when i have the time i'll redo the soldering again

 

[squalle 0]

do u have other pot? might be the pot somehow

 

and at the same time, recheck ur connection

if u suspect something's loose, then you can try to pull it see if it comes off.

good luck

getting the hum off aint that easy even the culprit is simple things

happened to myself before

[squalle 0]

kippei : for the DC blocker (that guy calls it Da Blok), you have to tape out the caps. at the top of the caps where the metal part is exposed, can cause short. haha. happened to me as I did not tape out properly and caused my house circuit breaker cut off

[Kippei 0]

[Kippei 0]

How come the 560R can be taken off.. The 2k pot provide enough trim?

[squalle 0]

yup definitely

 

I tried one side with 2*300R and one side just the 2k trimpot

both can reach 40V.

[Kippei 0]

Darn... till the last moment i am short of a 2134...

[squalle 0]

how can you miss that?

 

do you have other op-amps?

see this config: http://home.swbell.net/acavalli/images/Cav...llower_1.00.gif

if u're going to use 2227, gotta do that kinda config.

a little change of where the signal is tapped from.

putting 100k for the input resistance will lower the DC offset at the output

DC offset will be problematic if you're using 2227 or NE5532 or some other op-amps with input bias current higher than 10pA

 

btw, you do use jfets for CCS rite?

[Kippei 0]

yep... i found 2132.... now the tube lights up.... plate voltage... in mV range dc offset 12 volt...