Author Topic: Help Me Decide on a Power Amp For My F-1X (Read 518 times)

David Houck · « **Reply #15 on:** November 15, 2004, 08:59:55 AM »

First test the F-1X. Plug the bass into input one. From the full range output, plug into the power amp input of the Peavey. This should tell you if there is a problem with the F-1X.

Next test the PLX. Plug the bass into the Peavey. From the preamp output, plug into channel one of the PLX. Set all of the DIP switches ON except for number seven which should be OFF. This should tell you if there is a problem with the PLX.

davekoch · « **Reply #16 on:** November 17, 2004, 05:52:17 AM »

Thanks to all of you - bless your hearts!!!

Mica was right about the Effects Loop jack - it was actually bad and needed to be replaced. It was barely getting a very, very weak signal. Jeff Krumm at Savage Audio, who designs and builds the Savage tube guitar amps, did the repair. He is a very competent audio guy, I trust him, and a great guy to boot. He did work for The Who when they were last in town. BTW, Jeff mentioned he's very impressed with the F-1X design, sound, and construction. He's worked on them before.

So, he verified both the preamp and power amp, so all the gear is up and running. I feel good about it. However, the guy that sold me the F-1X maintains that it worked before he shipped it to me. Hmmmmm.

Anyway, it works like a champ now, and I already love it. The sound of this rig is so very, very clean and warm. The response is just great.

I've noticed posts about the Bass/Mid/Treble knobs affecting one another. Is there a guide or some recommendations on how they affect each other, or is it just trial and error? Any other information about using the F-1X that would be helpful?

As for the out-of-phase issue, is this a big deal? In Stereo mode and using Full Range and High Pass output jacks, what actually happens? Can it cause damage to the gear? What's the fix - reversing the polarity on a cord, etc.? If I use Parallel mode, it wouldn't be relevant, right (as I'd be just using the Full Range output jack, sending the same signal to both channels of the power amp)? Does Stereo mode sound different than Parallel mode?

To all who held my hand through this ordeal, thanks for all your help and concern. I've always heard great things about Alembic Support, and now I'm a believer. But the knowledge and concern on this forum is simply amazing. WOW - you guys are real pros, very smart, and perhaps even more importantly, nice people!

I've wanted this preamp for many, many years. I don't play out as often anymore, as my wife's health is failing. I'm a caregiver now (severe diabetes, kidney transplant, and many, many other issues). But now I'm so excited about this gear.

Thank you!!

Dave

effclef · « **Reply #17 on:** November 17, 2004, 06:09:25 AM »

Dave, out-of-phase won't damage anything except your tone. ;-) When two speakers are out of phase, the sounds will cancel at the listener's ear. This is especially pronounced at bass frequencies! Thus the warning - I'd modify a cable or reverse the spade lugs as was suggested.

I'm sorry to hear about your wife. But remember, music can be therapy for you, too, to keep you positive through the tough times.

EffClef

David Houck · « **Reply #18 on:** November 17, 2004, 08:13:01 AM »

>> I've noticed posts about the Bass/Mid/Treble knobs affecting one another. Is there a guide or some recommendations on how they affect each other, or is it just trial and error? Any other information about using the F-1X that would be helpful?
_________

The following is taken from an article by Mark Gavin.
_________

Fender-style controls are used by many amp manufacturers because most guitarists prefer treble and bass boost (which is to say they prefer midrange cut). The Fender-style tone stack CANNOT provide treble or bass cut (in other words, no true mid boost). One way to regard boost circuits is that all frequencies are
attenuated--then that attenuation is cancelled for a range of frequencies. The amount of broad-band attenuation is called insertion loss, and is a necessary evil of any circuit that provides a boost. The standard Fender midrange control does not really boost just the midrange--it boosts ALL frequencies. In other words, it decreases the insertion loss. This is why the value of the
midrange pot cannot be increased much past 10k or so: it will render the treble and bass controls ineffective. This is perceived as mid-boost because it does cancel some of the midrange cut, but it cannot be a true boost because there is no way for the mid control to elevate midrange levels any higher than bass or treble levels. In fact, increasing mid control will actually boost the bass and treble a bit.
___________

To visually see how the tone controls interact with each other, go here and download the Tone Stack Calculator:
http://www.duncanamps.com/tsc/index.html

Choose the Fender tab. The values should be as follows; double click on any value to change it. (I believe these are the correct values for the F-1X; if not, please correct.)

Zsrc = 38k
R1 = 100k
C1 = 250p
C2 = 47n
C3 = 100n
R2 = 250k
R3 = 250k
R4 = 10k
R5 = 1M

(Initial post was incorrect, I had the wrong file open!)

(Message edited by davehouck on November 17, 2004)

davekoch · « **Reply #19 on:** November 17, 2004, 08:35:26 AM »

EffClef, thanks for the kind words. I totally love her so I'm happy to care for her. Yes, playing music is therapy to me too - it is amazing in that respect. She's been a little better this past year, so maybe I can play out a little more. I'm hoping....

As for modifying a cable, it's only relevent in Stereo mode when I use two poweramp-to-cabinet cables, thus using both the Full Range AND the High Pass jacks, right? So there's no out-of-phase issue with Parallel mode, right? A pretty tech-savy guy told me that using Parallel mode would be just fine because even my Eden 2x10T cab can handle lows quite well and it matches up nicely with my Eden 4x10T - the coupling thing, I guess.

Exactly what do I tell the guitar tech to do to modify a cable? My preamp-to-poweramp cords have 1/4 plugs on both ends. Both my poweramp-to-cabinet cords have one banana plug and one 1/4 plug. In Bridge mode, I connect the banana plug into the poweramp (straddling the 2 channels) and the 1/4 plug into the one cabinet. In Stereo mode, I would connect the banana plugs into each channel of the poweramp and connect the 1/4 plugs into each cabinet. Perhaps to have a backup cord, I should get a new cord made? Or would you suggestion I modify one of my existing speaker cables? Suggestions?

Is Stereo mode preferred over Parallel mode by most players? Sound different? Would Stereo mode necessitate I use the Crossover with the High Pass output. If so, I'd connect High Pass output to the Eden 2x10T to reduce some of low frequencies, as it doesn't handle the lows like the Eden 4x10T. If the Crossover is required, what frequency would you set it at?

David Houck · « **Reply #20 on:** November 17, 2004, 09:01:24 AM »

>> As for modifying a cable, it's only relevent in Stereo mode when I use two poweramp-to-cabinet cables, thus using both the Full Range AND the High Pass jacks, right?

Right.

>> So there's no out-of-phase issue with Parallel mode, right?

If you are running just one cable from the full range output of the preamp, no cable from either the High or Low Pass outputs, then right, there is no out of phase issue.

>> A pretty tech-savy guy told me that using Parallel mode would be just fine because even my Eden 2x10T cab can handle lows quite well and it matches up nicely with my Eden 4x10T

That seems reasonable.

>> my poweramp-to-cabinet cords have one banana plug and one 1/4 plug

You don't need to modify the cable. Simply reverse one of the banana plugs when you plug it in so that the tab side is inserted in the wrong binding post.

>> Is Stereo mode preferred over Parallel mode by most players?

I use parallel mode. I run one cable from the F-1X full range output to the PLX; and thus, in parallel mode, run both cabs full range. I think this a more efficient use of the cabs. Since your cabs probably do not have a significant difference in low or high end tone, then as far as tone is concerned there is probably no advantage to using both the full range output and the high pass output and running the amp in stereo mode.

>> I'd connect High Pass output to the Eden 2x10T to reduce some of low frequencies, as it doesn't handle the lows like the Eden 4x10T.

In this case, don't forget to reverse the tab on the banana plug when you plug it in.

>> If the Crossover is required, what frequency would you set it at?

You may find that you will vary the crossover frequency depending on the room. The accoustics of the room and the type of floor significantly effect the low end coming from the cabs. So you can view the crossover frequency as another tone control.

davekoch · « **Reply #21 on:** November 17, 2004, 10:35:05 AM »

You don't need to modify the cable. Simply reverse one of the banana plugs when you plug it in so that the tab side is inserted in the wrong binding post.

So that's all it is? Cool, I think I can even handle that....

Dave, thanks so much for clearing all this up. I am truly grateful.