Author Topic: Really stupid question: F-1X vs. F-2B...What's the difference? (Read 972 times)

kmh364 · « **Reply #15 on:** December 05, 2005, 07:08:15 AM »

Dave: Try cleaning the pots and switches with plastic-safe electronic spray cleaner with lube a la Cailube MCL or equivalent.

I look forward to your take on the both of 'em.

I wouldn't mind hearing about the SF-2 as well...BKBASS (Barry Kravitz)) has been after me to get one since he heard I took the Alembic plunge last year, LOL!

Cheers,

Kevin

gblick · « **Reply #16 on:** December 05, 2005, 07:21:59 AM »

One thing to keep in mind when comparing the F-1X and F-2B is that differences in tubes can be a large factor. To really make an accurate comparison, I believe you should have the same tubes in both units.

kmh364 · « **Reply #17 on:** December 05, 2005, 07:31:40 AM »

That would be ideal...just remember, no tubes are exactly the same, even matched pairs.

FWIW, there was an earlier thread here about what tubes to use in an F-1X/F-2B, which sparked a debate similar to which strings are best. It's all about personal preferrence...even the same tube will interact differently with the different circuit architectures of the two Alembic pre-amps is what I got out of that discussion.

David Houck · « **Reply #18 on:** December 05, 2005, 07:43:37 AM »

Kevin; Alembic uses sealed pots, so spraying them with a cleaner wouldn't do anything.

Gus; yes, the thought did cross my mind that some portion of the difference may be attributable to differing tubes. Perhaps someday when I'm really ambitious I'll open them both up and switch tubes.

kmh364 · « **Reply #19 on:** December 05, 2005, 07:55:21 AM »

I didn't realize Alembic used Mil-spec pots. If they're noisy or intermittent, exercising is the only remedy, short of replacement.

A little DeoxIT contact cleaner on the jacks may help.

David Houck · « **Reply #20 on:** December 05, 2005, 07:55:48 AM »

While I'm thinking about it, if I were to get an A/B foot switch to switch between preamps, what would I do about the outputs from the preamps? Do they need to be switched as well, or can they be joined with a Y connector before going on to my reverb unit?

kmh364 · « **Reply #21 on:** December 05, 2005, 07:57:44 AM »

You'd probably need an A/B for the outputs as well...probably not a good idea to sum the outputs with a Y cable.

David Houck · « **Reply #22 on:** December 05, 2005, 08:11:21 AM »

Thanks Kevin! That's kind of what I thought; makes the idea a bit more complex than is practical.

dfung60 · « **Reply #23 on:** December 05, 2005, 07:27:05 PM »

Actually, the setup doesn't have to be that complicated - you split the input signal and feed both preamps all the time, then use the A/B switch between the preamp outputs.

You don't want to run a tube *power amp* with nothing connected to the output, but this won't hurt a tube preamp.

One thing that you do need to be careful about however is that you *really* don't want to have any switching pulses being fed into the power amp as they will lead to loud, speaker killing thumps (that's actually the way my pitiful attempts at slapping have been described).

The dead channel in the F-2B might be a bad tube. I can't even remember what the inside of mine looks like, but there are multiple tubes and a failure of one of them may knock out one channel with no effect on the other.

David Fung

kmh364 · « **Reply #24 on:** December 06, 2005, 06:46:15 AM »

Good point, David. They have buffered A/B amp switches (usually ABY's) that won't kill the amp or speakers when you switch.

It didn't occur to me to Y the pre-amp input as it would probably unecessarily load passive instrument electronics, but probably wouldn't be an issue with Alembic's active stuff.

David Houck · « **Reply #25 on:** December 06, 2005, 07:25:52 AM »

Thanks David and Kevin! I'll keep it in mind. There are some relatively inexpensive A/B and A/B/Y switches on Ebay. Would these have the required buffering? Also, are these switches going to add appreciable noise to the signal chain?

And thinks for the tip on the tube. If cleaning the jack doesn't help, I'll open it up and check the tubes.

David Houck · « **Reply #26 on:** December 06, 2005, 07:29:43 AM »

Kevin; one other thing I've been noticing is that the F-2B seems to have more low end warmth.

kmh364 · « **Reply #27 on:** December 06, 2005, 07:44:52 AM »

They should be good if they're similar to this one by Peter Frampton...switching transients will destroy drivers and amps! As with anything additional in the circuit, there can be artifacts added and/or signal subtracted. This particualar switch is actively buffered to avoid munging-up the sound, but it could add some noise.

kmh364 · « **Reply #28 on:** December 06, 2005, 07:45:31 AM »

http://www.frampton.com/switcher.html

Sorry, forgot the link

kmh364 · « **Reply #29 on:** December 06, 2005, 07:48:16 AM »

or this, by the King of The Realm, Pete Cornish:

http://petecornish.co.uk/abcbox.html