Quickie hum

[aragorn723]

Hi,

So i'm sure a bunch of other people have asked this before, but I have a hum in my Quickie that won't go away.  A few minutes ago I ran a piece of 22 gauge solid core copper wire from one of the ground shells to the chassis of my amp, but there is still a hum.  What could be wrong?  Thanks,

Dave

[Paul Birkeland]

Hello Dave,

Is it one or both channels?

Is it the same level regardless of volume control position?

You may need to try touching the wire to the ground of your source as well.

-PB

[aragorn723]

Hi Paul,

The hum is only in one channel, and is the same regardless of volume control position.  I tried switching tubes from left to right, and the hum moved to the other side.  Right now my source is a laptop playing itunes, should I try another source?  Thanks,

Dave

[Doc B.]

If the hum moves with the tube, the tube is the source of the hum. Try letting it run in for while. If that doesn't improve things we can send another tube.

[Paul Joppa]

Also try inserting and removing the bad tube  few times, to clean the pins. A bad connection to the grid could easily cause such symptoms.

[aragorn723]

Paul,

Is there a way to clean the pins besides inserting and re-inserting?  I did that a couple of times, and had some improvement.  Maybe using some light sandpaper like 300 or 600 grit, then rubbing alcohol?  I ran the Quickie about 10 hours today to break it in, do you think the tube might need more time than that to break in?  Out of curiosity, do you know of any new stock 3S4 tubes?  I see mostly NOS on the web, but wondered if China or Russia has any suitable tubes (maybe under a different name?)  Can other tubes run in the Quickie circuit without modification?  I had a Cary 6SN7 preamp years ago, and liked the sound of the Chinese tube in there, so maybe there is something like that for the Quickie?

Thanks,

Dave

[Paul Joppa]

I chose the 3S4 because as far as I know it's the only tube of this type that has specifications for performance when triode-wired, and it's surprisingly linear that way. I presume the 1S4 would work the same if you re-wire the filaments. The ancient Type 31 could be made to work, though it might really want more high voltage, and it's designed for a single lead-acid cell filament - also it has a reputation for horrible microphonics!

When transistors became available, the first thing the replaced was portable radios. The advantages were huge ao it happened immediately; the market for these tubes disappeared immediately. There are still tons of old ones very cheap, so there's no incentive to make any new ones.

[aragorn723]

Doc B,

Thanks for the offer, looks like i'll have to take you up on a new tube.  The hum doesn't go away after cleaning or switching around RCAs.  Do you need my shipping info?  Thanks,

Dave

[Doc B.]

We're more than happy to send a replacement. Unfortunately the ease at which customers can contact me via a huge number of routes - several forums, PMs through those forums, three or four email addresses, a couple of phone numbers, text messaging, Facebook, etc. combined with my inability often to place a forum moniker with a real name and the fact that I am not always around the office these days means that it is very easy for me to misplace or just plain miss such a part request.

I don't actually handle these requests, that is the bailiwick of Eileen and Josh. So you are gambling a bit in asking me to remember to relay the message. My apologies in advance, that may not seem like the best customer service. But I think being honest about the best way to get what you need is part of that service too. Best bet is to use the replacementparts at bottlehead dot com email address to request a new part. That is monitored on the weekdays by the folks who will actually get the part to you.  Or as always, calling us at 206-451-4275 M-F 10-5 will work too. I promise to try to remember to ask the kids to watch for your message.

[aragorn723]

No worries Doc, i'll send Eileen an email.. I'm a new customer, so wasn't sure about how Bottlehead does these type of things.  I'm very happy with Bottlehead- about 13 years ago I seriously considered building a foreplay, but just built a Quickie.  It easily beats the $600 Cary that used to drive my amp..  Altogether its been a really good experience.  Can't wait to try some mods.  Thanks!

Dave