233 replies to this topic

[ironbut]

for the past 2 days ive noticed this really high pitched whiny noise coming out of the right channel. audible without music. with music i just know its there because the music doesnt have any notes that high. if i unplug the headphones and plug them back in, it goes away for like a minute but then comes back again. using 421a and amperex 12au7 (bugle boy). any thoughts?

Try switching tubes, cables, channels on your source to isolate the problem.
Also, take your set up into a distant room and try it there. It could be airborne digital or something that's leaking into your grounds on that household circuit( a different house would be definitive).

[crappyjones123]

changed the bugle boy to a mullard. changed channels but whiny noise remains even with the cables switched and unplugged. problem is either with power or within the amp itself. i dearly pray it isnt the 421a. all else is cheap and easily replaceable.

[Tyll Hertsens]

Hi guys,

Got a Crack coming in as my first DIY build to write an article on. I'll do the basic build first, then the Speedball upgrade.

Then I'll no doubt re-read this thread and start making a friggen $1000 amp out of it with all the good ideas here.

Thanks for the great thread! No noise Head-Case FTMFW.

[Beefy]

Cool beans. Would really be interested to see how the articles turn out!

[crappyjones123]

Hi guys,

Got a Crack coming in as my first DIY build to write an article on. I'll do the basic build first, then the Speedball upgrade.

Then I'll no doubt re-read this thread and start making a friggen $1000 amp out of it with all the good ideas here.

Thanks for the great thread! No noise Head-Case FTMFW.

lol you need we 421a's first. and some bugle boys. and mullards. and hytrons. and rca's. and 5998s. and 6080s. and 6as7g's. and moar 421a's. thats like $1000 right there

post pix dood. it is quite good for a cheap(ish) amp.

ps. completely forgot about using motor run caps throughout the amp.

Edited by crappyjones123, 19 February 2011 - 12:22 PM.

[bhjazz]

Hi guys,

Got a Crack coming in as my first DIY build to write an article on. I'll do the basic build first, then the Speedball upgrade.

Then I'll no doubt re-read this thread and start making a friggen $1000 amp out of it with all the good ideas here.

Thanks for the great thread! No noise Head-Case FTMFW.

Not a Crack, just crack. Bottlehead is what got me completely in to DIY and tube audio, God bless 'em. Enjoy the ride, Tyll.

[digger945]

Gotta listen to a ModWright Transporter > crack/speedball > HD650 combo yesterday. Never heard the 650s sound that good.

[ironbut]

Hi guys,

Got a Crack coming in as my first DIY build to write an article on. I'll do the basic build first, then the Speedball upgrade.

Then I'll no doubt re-read this thread and start making a friggen $1000 amp out of it with all the good ideas here.

Thanks for the great thread! No noise Head-Case FTMFW.

Hey Tyll,

don't forget about the Bottlehead forum. Tons of great info there too!

http://www.bottlehead.com/smf/index.php

[sbelyo]

another +1 on this amp.... It's really good for the money and very easy to put together. The steps are layed out and explained very well. So well in fact that I lett my 11 yo son solder a few joints and this has now peaked his interest in the DIY arts.

It sounds really good with my 250 ohm darth beyers. The sound quality was the same as some amp designs that I've thrown hundreds of dollars of caps at let alone the full cost of building them. I cant wait to try the speedball upgrade

[Lone Midranger]

I heard this amp driving HD800s which is a can I don't really like but this combination sounded very good. It's a heckuva amp for $219 in kit form.

[crappyjones123]

after a year or so with this amp, my cbs/hytron 5814a seems to have stopped wanting to play clean noise. too much static and warbly noises continuously. Reseating the tube would help for a minute but once the tube warmed up, the noise would come back. I don't want anything too expensive as I already have a slew of tubes for the amp but I loved the sound of the hytron. is there anything similar to the tube anyone can suggest? i will probably get one of the hytrons as they aren't too costly but something new/similar to try out would be reasonable.

[ironbut]

If it sounds like static and isn't the bubbly, popping sound (which is usually a tube gone gassy), it could just be the pins have corroded a bit.
One sure cure for that is to clean the pins with metal polish. I use my Dremel tool and Mother's Aluminum and Mag Polish (at any decent auto store). If you have a Dremel, cut a Q-Tip in half and insert it into the small mandrill chuck, dab a bit of Mother's on it and polish each pin for a few seconds. Clean the residue with a clean swab, put your favorite contact enhancer on (I use Pro Gold) and call it done.
In low noise applications (phono pre etc) you'll often get a few dB less noise and any contact related noise is histo'.
It's kind of a "poor man's" gold pin.

Oops,.. forgot to say to give a Mullard/Amperex 12au7 a try. Since you just need a single, you can get some pretty decent prices on them. A real smoothy.

Edited by ironbut, 29 December 2011 - 08:16 PM.

[crappyjones123]

I have both of the suggested ones. The bugle boy and the black plate mullard set me back a fair bit but the 421a and the 5814a seemed to sound the best - probably why they stayed in as a combo for over a year. I have the bugle boy in right now and its a very very clean sound. I don't want to call it clinical but it is colder than the hytron. Don't have a dremel tool but do have a drill. I'll see if I can hack up something from it. Or perhaps ask around my neighbors.

Might throw in some 5998 or a 6AS7 for a different flavor tonight since I changed the input tube too.

Needless to say a much cleaner sounding amp with the input tube replacement.

[bhjazz]

If you have a Dremel, cut a Q-Tip in half and insert it into the small mandrill chuck, dab a bit of Mother's on it and polish each pin for a few seconds. Clean the residue with a clean swab, put your favorite contact enhancer on (I use Pro Gold) and call it done.

Good stuff. I tried to find a way to do this without the Dremel, no dice. This is a "why didn't I think of that" technique. Excellent!