Author Topic: Advice on Lowpass Frequencies (Read 1553 times)

edwardofhuncote · « **on:** October 26, 2015, 11:59:20 AM »

After I made a hash out of someone else's thread, thought I'd start a new one on something I've been trying.

So I finally built a pre-amp/power-amp rig for bass, around an Alembic F-1X and a Crown XLS 2000. I came into a (lightly used) mirrored pair of these: http://avatarspeakers.com/product/sb126/ but with optional 8 ohm speakers capable of handling 500w, and also optional 1.6 KHz crossovers.

I ran them daisy-chained them on channel 1, with the amp bridged in mono, per the manual's (and Joey's) instructions. It's just fantastic... I hear stuff out of my basses I never heard before. Wow! And the F-1X controls, so easy-peasy to find what you're looking for there. I grinned for twenty minutes after the first time I flipped that Deep switch... you guys know what I'm talking about.

So after spending some more time reading the manual, I begin to realize the potential here... the Crown DriveCore series amps come with a built-in crossover, you can access through a simple cascading menu. Hmmm, cool. Then I get a gleam in the eye and decide to go bigger. Ordered a matching 115 cab from Avatar with this speaker: http://www.eminence.com/speakers/speaker-detail/?model=Kappalite_3015LF_4 expressly for the purpose of sending only low frequencies to. (as an aside, Dave at Avatar - super-nice guy. I ordered that cab on a Thursday, eight days later it's on my porch)

Following the instructions, I connected the full-range output of the F-1X to channel 1 input, and set the Crown up in Y crossover mode, connecting the 115 LF cab to channel 1, and the pair of SB126's to channel 2. The Crown has a standard default crossover setpoint of 125 Hz, which is adjustable in 1/12 octave(?) increments, the next lowest being 118 Hz, 111 Hz, 105 Hz, and so on.

So my question is, what's a good recommendation for that setpoint? I will say this - it sounds just unreal with the crossover set at either 99-105 Hz, with all frequencies above that going to channel 2.

Am I missing something, or is it possible I'm finally home?

(Message edited by edwardofhuncote on October 26, 2015)

keith_h · « **Reply #1 on:** October 26, 2015, 12:37:20 PM »

I cross subs around 98 Hz as that is what works best with my PA subs and mains frequency response curves. My Bag End subs are factory set at 98 Hz as well. If you look around in the sound reinforcement area this is a common place to crossover as it keeps the subs and higher frequency cabinets from receiving frequencies towards the ends of their response curves.

Keith

edwardofhuncote · « **Reply #2 on:** October 26, 2015, 12:55:33 PM »

A-ha... so my ears were right. =) I will play around with 99 Hz some more.

mtjam · « **Reply #3 on:** October 26, 2015, 05:09:03 PM »

Looks like a mighty rig! Hope you're having fun with it!

edwardofhuncote · « **Reply #4 on:** October 26, 2015, 05:35:49 PM »

Thanks Rob - You are partly responsible for it. =)

Seriously, I followed your thread to the logical conclusion... this is exactly the result I was hoping for, and honestly, after the Mesa rig sells it'll almost be revenue neutral. Except for the one new cab, all the components are used. (well, to be fair, the amp was an open-box deal) The heaviest part is still lighter than the Walkabout/Scout 15 combo, by nearly a third.

I've only used it for two gigs so far, but in addition to being super high quality sound, it's just *obscenely* powerful. I have a series of Christmas concerts coming up I plan to use it on with my Persuader 5-string, and eventually there'll be a fretless Alembic being played through it too. =)

edwin · « **Reply #5 on:** October 26, 2015, 08:07:33 PM »

Just curious, have you ever heard a fEARful? It's got the same woofer. Very nice sounding design.

bigredbass · « **Reply #6 on:** October 26, 2015, 11:11:10 PM »

Power amp-based rigs are just different. Provided you're happy with the preamp
(F1x, no problem!) and you've got your levels right thru the signal chain, it just gets louder. You REALLY have to push it to get to distortion, generally far beyond your typical stage level.

This is just different than most over-the-counter bass amps, and it's almost strange at first. But soon enough you realize what you're missing (distortion), and it's liberating. You'll hear timbres in your instruments that weren't there before (or in the case of Alembics, different timbers?). Between your Alembic instruments and this sort of amp rig, you really begin to approach a totally different way of hearing, and thus playing bass, as now almost like an acoustic instrument, (the amp straining has been taken out of the equation) you simply hear what's plugged into the end of your guitar cable.

Back in the day, I constructed a JBL/CS800/IVP preamp (remember those?) for a hero of mine that played in big horn/R+B bands, and he'd played his ancient Precision thru an SVT for years. Tried it for one night, and he was so freaked out at what he was hearing, he passed on buying it. He said he was hearing too much, and went back to the SVT, like old jeans. This happens.

It's generally not understood by a lot of players, the difference in guitar and bass amps and effects and the sound reinforcement world and the components that are typical. There's a huge gulf between guitar`bass amps and commercial power amps and studio/touring effects tone-wise, and that utter cleanliness is fine for bass and electric/acoustic instruments or keys, not so much for some electric guitar styles.

Over time, you will find you're using less and less EQ. Sometime, try the crossover in the F1x and use that HiPass gain: You can accomplish a lot of tone control (without using the tone controls . . . ) simply by varying the amount of high end over the low end.

Congrats. You might try standing the two twelves vertically (as a line array) and see if you hear a difference. And since this is essentially now a full range system, with a little reverb inserted inline, this will work well with upright or other acoustic/electric instruments. That rig would SMOKE with a Steinberger upright.

Joey

edwardofhuncote · « **Reply #7 on:** October 27, 2015, 06:50:07 AM »

Edwin, regarding fEARful, I know they are highly regarded, but I have not played through one. When I contacted Avatar, the idea was just to see if it was possible to build a dedicated low frequency cabinet that would match the two mirrored baffle SB126's I had gotten second-hand, but still be within what I was willing to put into it. The guy I talked to there, (Dave) was quite helpful, and actually recommended exactly that speaker based on what equipment I had, and I wanted to do with it. He allows that thing can more accurately reproduce the low B from my 5-string basses, and then lower still.

Joey, I will eventually try the F-1X crossover outputs too... I need to read a little more about how to set the amp up for two inputs first. I already have another 1/4 TRS to XLR cable for it. As for the cabs, yes all three are stackable, but I haven't tried the 126's vertically yet. I did put both of them on top of the 115 though... that's a heck of an imposing stack of cabs. =) It does put the mids right at your ears though. (more perceived volume) I'll try a few combinations.

I totally agree on the less-is-best eq'ing... if you remember, that's how I started down this way in the first place - I like the way my basses sound, but by the time the combo amp/cab I'd been using got through with the signal, it was somewhat skewed. (that probably isn't the right descriptive word) Anyway, this was *definitely* where I wanted to get, but I can see where other players might be freaked by the stark honesty of it. After reading up on how the circuit in the F-1X works, I'm doing very little with it's controls. Basically this - volume between 7-8, bass, mid, and treble all start at 5, deep switch engaged, bright switch disengaged, then I tweak the treble to taste. It really is a great piece of gear. Don't know how I got by without it for so long.

*I do need to experiment with the upright too... generally I have to do a lot more take-away eq'ing with that thing to get higher volume out.

sonicus · « **Reply #8 on:** October 27, 2015, 07:19:56 AM »

Gregory ,
I have done business with Dave at Avatar . I purchased eight Faital 10R300 sixteen ohm 10 inch speakers from him. I installed them in my SWR Goliath JR. cabs. I am very pleased with the sonic results and the process of the transaction.

Wolf

StephenR · « **Reply #9 on:** October 27, 2015, 04:46:47 PM »

Gregory

Congratulations on the new rig. I got my first preamp/power amp rig around 1982 and never looked back. I just like the way a preamp/power amp respond to my playing. Pretty much every amp head I have played through seems to have very little dynamic range compared to a dedicated pre running through a good power amp.

Agree that you should check out the crossover in the F-1X and especially agree that you should try stacking your cabinets. Beyond the fact that it will be easier to hear at stage volume the cabinets will couple and give you a few extra dBs on the low end. Rig should sound fuller and project into the room better.

Joey...

I remember the IVP preamp. Sorry to say this but I though it was the worst sounding preamp I ever owned. I was very happy when I got the opportunity to trade it for a Bag End cabinet.

The IVP is the only preamp I didn't keep. Still have my 70s era F-2B, an Eden Navigator and a SWR Studio 220 head that I only use the preamp section of. I had gone to buy a Groove Tube pre back when SWR was making them for Groove Tube and the SWR had the same pre plus a power amp for only a bit more money. Never much liked the sound of the head on its own but it came in handy occasionally for jams and gigs where it was impractical to bring my whole rig. Sounds great, though, pumped through a power amp.

bigredbass · « **Reply #10 on:** October 27, 2015, 10:57:04 PM »

Stephen, I'd have to agree, but back in the 70's it was one of few choices. We had sold some of the Furman pre's, and strangely I thought the solid-state Yamaha PB-1 sounded best (it was utterly solid state). I have a feeling we were swimming in IVP's after a late night with their rep at NAMM with our owner . . . we A/B'd an IVP/CS800 and a PB-1/P2200, and the Yamaha rig won the day.

I completely agree that the sense of dynamic range with a pre/power amp rig is different than any over-the-counter bass amp I can think of: The dynamic range, slew rate, etc., all the 'fine print' specs are in a different level than typical dedicated bass amps, by multipled factors.
It's like the difference between a bingo-calling 'box' PA head and a Midas board, two different worlds.

I've never seen anyone bring this up, but how fast an amp responds is like the difference in steering feel on an M3 and a 60's Buick. Get the signal chain right, and you feel a connection to the sound thru your fingers. Get it wrong and you just feel present, but somehow and somewhat removed from that instant feel, that connection thru the rig, from your fingers to your ears. As if you were standing directly on axis in front of the speakers vs. trying to time yourself off the bounce from the room. Admittedly, this is a very ephemeral phenomenon that I've sensed, but I've felt both ways over my time.

Joey

sonicus · « **Reply #11 on:** October 27, 2015, 11:24:07 PM »

I pay attention to the damping factor of a power amp. I have found that I prefer a higher damping factor then lower.

Wolf

jazzyvee · « **Reply #12 on:** October 28, 2015, 12:14:18 AM »

Joey I have exprerienced exact what you mention in your last paragraph. I was at a rehearsal with a band I was depping in and their Class D Ampeg head with Gallien Krueger cab sounded less immediate than my own Mesa boogie or F1-x/QSC rig. I thought It was in my head until I mentioned it to the drummer who is also a successful record producer and he assured me that what I was experiencing is real.

StephenR · « **Reply #13 on:** October 28, 2015, 01:14:35 PM »

Hey Joey

Excellent post. Last paragraph nails something I have never quite been able to articulate to anyone properly.

I firmly believe that the majority of your tone comes from your fingers and technique. I like both basses and amps that get out of the way as much as possible and let you focus on your playing and drawing out the character of the sound you want to hear. Not a big knob twiddler, if I have to use lots of eq and play around with the settings too much to get a reasonable sound, or in some cases still not get close, I would prefer to use another amp.

I was at a party/jam session last week and plugged into someone else's rig. I generally try not to change people's settings if possible but after playing one tune the amp just wasn't allowing me to bring out the notes the way I like to hear them played. I turned off things like contour and tweaked a few other things and when we started to play again I realized that, while not perfect, I could finally hear enough of what I needed to hear to play my bass without getting hung up on what the amp was doing to the sound.

On the other hand occasionally I will be at a jam where the amp sound is so far from what I normally use that I find it fun to just play differently than I normally would and exploit the sound of the amp for what it is. But, I would never want to play a gig under those circumstances.

edwardofhuncote · « **Reply #14 on:** October 28, 2015, 01:43:51 PM »

With every post on this subject, I have become more certain this was *exactly* the right move. I just never knew how to express what I was looking for.

Thanks (again) Alembic Club!