Alembic F-2B knobs Log Out | Topics | Search
Moderators | Register | Edit Profile

Alembic Club » Owning an Alembic » Troubleshooting » Archive through December 03, 2005 » Alembic F-2B knobs « Previous Next »

Author Message
lowfreq
New
Username: lowfreq

Post Number: 2
Registered: 11-2005
Posted on Thursday, November 03, 2005 - 11:07 pm:   Edit Post

I bought serial number 4318 off ebay not too long ago, and the unit sounds great. The tubes needed to me changed but I guess that's a good thing in Tube Land.
Anyhow, the EQ knobs seem to be mislabeled/missoldered. The Bass knob on both channels affects mids, and the Mid knob affects bass. Also, the B channel is about equal in volume to the number 2 input of the A channel. Is it supposed to be voiced that way? Can anyone help with information or troubleshooting tips?
Thanks,
Justin
mica
Moderator
Username: mica

Post Number: 2745
Registered: 6-2000
Posted on Friday, November 04, 2005 - 11:07 am:   Edit Post

The controls are interactive, and so changing the bass setting will change the mids and treble. There is always the influence to get a nice EQ "smile" just like the tradifiton Fender circuits the F-2B is based on. Start out at 2-10-2 (bass-middle-treble) as the closest thing to flat. These numbers describe the labels on the dial, not on a clockface.

The channels are identical. If the settings are the same on each channel, using input 2 on either should be the same volume.

As for the tubes, what sound are you noticing that indicates the tubes need changing? There's a couple of entries in the FAQ for the F-2B that you might find useful as well.
lowfreq
New
Username: lowfreq

Post Number: 3
Registered: 11-2005
Posted on Friday, November 04, 2005 - 4:22 pm:   Edit Post

The tubes that came with it were sovtec. I replaced them with telefunken, groove tube, and tesla tubes. This was just a matter of taste.
On mine, both channels are not identical. We just tested them with matched Telefunken tubes, and channel B is noticeably quieter.
What I meant about the EQ is, when sweeping the bass knob, mostly mids are changed: when sweeping the mid knob, basses are the mostly changed. This happens on both channels.
As far as age, this has the teal/black casing with the aluminum knobs mentioned in the FAQ, and Santa Rosa, CA is the city on the back.
mica
Moderator
Username: mica

Post Number: 2773
Registered: 6-2000
Posted on Thursday, November 10, 2005 - 6:53 pm:   Edit Post

Taking great care to only touch the capacitors, wiggle the 6 orange capacitors on the circuit board and see if it changes. Strangely, we just repaired an F-2B where Tony had the same observation - the bass control seems like the mid control. We found these caps were clipped short before soldering, and therefore did not make a good connection.

If you find they are loose and want to resolder them, unplug the F-2B and wait 5 minutes before working on it.

If you feel uncomfortable about testing this (I can understand - high voltage is dangerous), we'll be happy to test it for you no charge.
mica
Moderator
Username: mica

Post Number: 2807
Registered: 6-2000
Posted on Thursday, November 17, 2005 - 4:23 pm:   Edit Post

Hi Justin,

Have you tried this to see if there is something funky with your preamp?
lowfreq
New
Username: lowfreq

Post Number: 5
Registered: 11-2005
Posted on Saturday, November 19, 2005 - 2:39 am:   Edit Post

No I haven't had time to look at it yet. I can get it to work and the sound is suitable, but I would like to take a better look at it soon and ask for more details regarding what I'll need to resolder/fix

Topics | Last Day | Last Week | Tree View | Search | Help/Instructions | Program Credits Administration