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83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 1
Registered: 6-2014
Posted on Friday, June 20, 2014 - 4:05 pm:   Edit Post

Just got a used F2-B --- s/n 77X.
Need help on how to set up w my bass, power amp and cab.

I am using a Yamaha BB1200s active bass, Crown DC300a amp (bridged for mono), and Mesa 15" 8 ohm cab.

Questions:

If I use channel A input, where do I connect my 1/4 inch cable from the bass --- input 1 or 2?

For output on rear of F2B, do I use 'A' or 'M'?

Anything else I need to be aware of?

Thanks!
davehouck
Moderator
Username: davehouck

Post Number: 11370
Registered: 5-2002
Posted on Friday, June 20, 2014 - 4:31 pm:   Edit Post

Hi Jon; welcome to the club, and congrats on getting an F-2B.

Input 2 has a 6 db pad on it; so if you think your bass is sending too much signal, you might want to use that one. I use input 1 with my Alembic bass, but I don't turn the gain on the F-2B past 5.

Since you're just using channel A, then using output A is probably fine.

Our FAQ section for the F-2B is here.

Enjoy!
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 2
Registered: 6-2014
Posted on Friday, June 20, 2014 - 4:55 pm:   Edit Post

Thanks for replying Dave, much appreciated!!!

I Tried it again. Bass to crown to mesa --- clean sound. Next, tried only alembic to crown to mesa --- no bass. When I turn on alembic it is still OK, but once I start turning the vol knob slowly from zero ---superbuzzz. Like a bad/incorrect connection. Same for either a/b/m outputs.

Based on this , w/o any input into the F2B, it looks like somthing is not right from F2B output into the Crown amp. What do you think Dave?
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 3
Registered: 6-2014
Posted on Friday, June 20, 2014 - 4:59 pm:   Edit Post

BTW Dave --- any way visually inspect the innards of F2B and determine if there are bad tubes or circuits?

Also --- thanks for the welcome!
davehouck
Moderator
Username: davehouck

Post Number: 11372
Registered: 5-2002
Posted on Friday, June 20, 2014 - 5:07 pm:   Edit Post

Is the superbuzz happening on channel B too?
davehouck
Moderator
Username: davehouck

Post Number: 11373
Registered: 5-2002
Posted on Friday, June 20, 2014 - 5:13 pm:   Edit Post

Alembic uses sealed, mil-spec, self-cleaning pots. If the pots haven't been turned in a while, they may need cleaning. To clean a pot, turn the knob back and forth through it's complete travel about thirty times.
davehouck
Moderator
Username: davehouck

Post Number: 11374
Registered: 5-2002
Posted on Friday, June 20, 2014 - 5:15 pm:   Edit Post

You might also check the jack-cleaning instructions here.
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 4
Registered: 6-2014
Posted on Friday, June 20, 2014 - 5:16 pm:   Edit Post

Yea, superbuzz on A B M outputs
davehouck
Moderator
Username: davehouck

Post Number: 11375
Registered: 5-2002
Posted on Friday, June 20, 2014 - 5:32 pm:   Edit Post

(Note: I am not an electronics tech; you may want to have someone else here in the club, or a real tech, confirm the following suggestions.)

After you've cleaned the pots and jacks, you may want to open it up and check the interior. Please unplug it and be very careful. If you don't feel comfortable doing this, have an audio tech do it.

There is a nice picture of the interior here.

The two large metal sleeves house the tubes. You can visually inspect the tubes by plugging the unit back in and watching them glow.

I think it can also help to reseat the tubes. Unplug the unit, remove the sleeves, then carefully pull the tube out and then put it back in.

Also in the picture, note the four big blue capacitors. They are supported by a piece of felt. If your F-2B is fairly old, that felt may need to be replaced to properly support the caps. Visually note the connections. If the felt is gone, the weight of the caps may loosen the connections. I'm guessing you don't want to touch these if you don't know what you're doing.
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 5
Registered: 6-2014
Posted on Friday, June 20, 2014 - 6:58 pm:   Edit Post

Dave --- Thanks again. I opened her up and saw a piece of foam was just lying around --- not under the 4 blue caps. I tried to p/u the foam and put under the cap, but the foam was old and brittle and disintegrated/crumbled.

Further CAREFUL inspection of the 4 blue caps, I saw that only the one furthest to the left (channel B side) was actually attached/soldered to the 'vertical plane' circuit board. The other three were not attached. That, I believe is the problem.

I will contact the seller and see about getting a remedy to get it fixed, or refunded. You've been a great help. I will report back what I learn a bit later.

Cheers!
mica
Moderator
Username: mica

Post Number: 8196
Registered: 6-2000
Posted on Friday, June 20, 2014 - 7:10 pm:   Edit Post

That is the problem - the foam degrades over enough time (and your F-2B is around 40 years old) and the caps can vibrate off their leads. Sending the F-2B here for recapping is currently about a $65 job.

Please note that there is HIGH VOLTAGE on the top trace of the circuit board, so if you are poking around an F-2B, give it a good 15 minutes to dissipate the capacitance.

If you want to send the unit in for repair, please email me and I'll help make the arrangements.
mica
Moderator
Username: mica

Post Number: 8197
Registered: 6-2000
Posted on Friday, June 20, 2014 - 7:19 pm:   Edit Post

You might also want to familiarize yourself with the F-2B FAQ.
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 6
Registered: 6-2014
Posted on Friday, June 20, 2014 - 7:33 pm:   Edit Post

DAVE --- I think we're get'n somewhere now. It would be good to get a quote from Alembic so that I can present to the seller to help me settle the matter. But, I like the idea of sending it in to Alembic to get it repaired/tuned-up!

Also --- I just noticed that the blue round 'dial looking thing with a top slot for a flat screw driver' is loose. In the photo link you provided, it is that blue piece where the blue/white wires terminate. What is that for and is it a problem that it is loose?
davehouck
Moderator
Username: davehouck

Post Number: 11376
Registered: 5-2002
Posted on Friday, June 20, 2014 - 7:57 pm:   Edit Post

If you need a printed quote, you should probably call the shop. However, I'm guessing you could probably just tell the seller that you've corresponded with Alembic, maybe even link to this thread, and that they're estimating $65 for recapping. You'll want to add shipping both ways when you discuss with the seller.

When they are inside an Alembic instrument, those blue things with the dial are for adjusting the gain output of the preamp. However, I don't know what it's function is inside the F-2B. If you send it to Mica, you might want to include a note about it appearing loose.

Personally, I highly recommend sending it to Alembic. I have the highest regard for the people there and the quality of craftsmanship.
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 7
Registered: 6-2014
Posted on Friday, June 20, 2014 - 8:33 pm:   Edit Post

Cheers Dave! And, you've highly impressed me with your help. I will follow your tips/advice and ultimately send to Alembic --- once I get the terms sorted out with the seller.

JC
smuprof
Advanced Member
Username: smuprof

Post Number: 236
Registered: 12-2003
Posted on Saturday, June 21, 2014 - 6:30 am:   Edit Post

Jon -

Welcome to the club, and congratulations on your F2-B. I too bought a second-hand unit long distance, and had a slightly different problem. Mine was largely functional but I had a local amp tech go through and tweak it, i.e. replace a couple of components and touch up the solder. Now it works beautifully.

I think you're on the right track. The blue caps are filter caps that help turn the AC voltage out of the transformer into DC voltage. If they're not in the circuit, the "DC" is not very smooth, i.e. noisy, and that shows up in in audio circuits.

I'm not sure what the blue pot is for. Looking at the schematic, the only pot that is not on the front (gain, tone) appears to be associated with the LED, so it shouldn't be part of your noise problem - but you'll need someone with more expertise than me to confirm.

Do heed Mica's caution - the tube voltage is about 300v I recall and you don't want to get into that.

One more note: I believe the way the design is done if all of the tone knobs are turned all the way down (left) you'll get no signal out. If I get a chance I'll confirm later today (or someone else can confirm).

Good Luck!

JFT
hieronymous
Senior Member
Username: hieronymous

Post Number: 1383
Registered: 1-2005
Posted on Sunday, June 22, 2014 - 8:53 am:   Edit Post

Not sure if you get no signal with all tone knobs turned down, but very important to remember that "flat" is bass 2 mid 10 treble 2!

Hope you get it up and running! I consider the F-2B my secret weapon! I use it 99% of the time when recording.
terryc
Senior Member
Username: terryc

Post Number: 2223
Registered: 11-2004
Posted on Monday, June 23, 2014 - 8:05 am:   Edit Post

Having read this with interest..sending it to Alembic is the only way.That way you will get top quality service and parts with most probably a guarantee as well..No brainer really!
83_silberpfeil
New
Username: 83_silberpfeil

Post Number: 8
Registered: 6-2014
Posted on Monday, June 23, 2014 - 5:18 pm:   Edit Post

Sent inquiry to: orders@alembic.com
Asked for quote and "ship to" address. Is that correct email address? Or should I send it to a specific person?

Thanks!

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