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1/2 Rack preamps with parametric EQ

Discussion in 'Amps, Mics & Pickups [DB]' started by Chris Fitzgerald, Jul 20, 2004.

  1. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Geez, I feel like I live in this forum these days... :help:

    I borrowed a friend's preamp to try with my PUB - it's a Presonus Digi Tube with 3-band semi parametric EQ and a bass rolloff. It sounds ****ing great, and gives me a lot more clean volume than the Raven Labs unit, and with the bass rolloff feature, I'm not making the 8" driver of the PUB get all "poofy" at higher volumes. I'm just curious what other 1/2 rack pres (don't want to carry anything bigger) are out there that I might try before deciding which one to buy. The bass rolloff is a must, and multiple parametric bands is on the wishlist, although is not a must. What other units are worth looking at within these guidelines?
  2. scott reed

    scott reed Supporting Member

    Nov 4, 2002
    Try the Presonus Acousti-Q preamp. Two channels so you
    can blend a mic or a second pickup with the FC. You also
    get a notch filter along with a semi-parametric mid eq.
    Also a footswitchable master volume so you can get a
    solo boost above your normal level if you want it. Lists
    at $299.95, street at $250 or so, AC adapter extra.
    For a really handy small parametric look for an old TC
    Electronic Dual Parametric Equalizer. Great box - solved
    a lot of problems through the years and it's the size of
    a slim stomp box.
    Good playing on tonight's gig.
  3. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    I've looked at the Acousti-Q, and like some of what I saw, but two things worry me about it:

    1) There is no "Hi Pass" filter, so you have to give up your "notch" filter to cutting lows, thereby cutting back on EQ options;

    2) Both channels have the same EQ applied to them, which could be OK and could be dicey, depending on what the "mic-like" part of the mix demands.

    The DigiTube did a real nice job last night, but had one minor flaw - it doesn't have a phase reverse switch, and the Full Circle seems to sound best (on this bass, anyway) with the phase reverse engaged. I wonder if there's any other way to get around that?
  4. Tim__x


    Aug 13, 2002
    Alberta, Canada
    I'm stopping in from the BG forums so I'm not familier with that pickup, but if it has a balanced out (XLR/TRS) then you can make a cable with the #2 and #3 pins switched on one end.
  5. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Thanks for the info! The Full Circle ends in a 1/4" out, so I guess that's not really an option.

    Anyway, I decided to order a preamp that has phase reversal as a built in feature - the TubePre, and I also ordered the EQ3B for tone shaping. I'll check back in when I've had a chance to check it out.
  6. So, you're using the TubePre with the EQ3B thru the Pub. Is there a huge difference between that and the Raven? What's the signal chain then?
  7. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    The TubePre arrived DOA, so I sent it back and have yet to get the new one. The EQ3B works great, though. For now the signal chain is FC into the PMB; unbalanced out into the EQ3B, then balanced out into the PUB. When the TubePre arrives, it will simply replace the PMB unless I decide to mix in a mic signal.
  8. Uncletoad


    May 6, 2003
    Columbus Ohio
    Proprietor Fifth Avenue Fret Shop. Technical Editor Bass Gear Magazine
    I've been using the Raven Labs True Blue EQ in the effects loop of the Raven PMBII turned up all the way to interrupt the input signal. It is outstanding. Unity gain regardless of where you put the knobs. Very transparent. Freindly EQ points. Unity gain structure is weird for those used to traditional EQ. A bit of a learning curve but it is worthy of an audition.

    They live in a little nylon portable cooler thing surrounded by road case foam. Sits next to me on stage with a long cable reaching to the amp as far away from me as I can get it.

    Rig is Plywood German Bass, Full Circle, Raven PMBII, Raven True Blue EQ into Euphonic iAmp 800 and Euphonic CX-310. I play bloody loud too.

    Caveat: I am a Raven Dealer.
  9. Marcus Johnson

    Marcus Johnson

    Nov 28, 2001
    Caveat not needed. RavenLabs is great stuff. I'm awfully glad to have my PMB II nearby when I need to tweak my sound on the fly.
  10. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Got the replacement TubePre, and it's got amazing headroom, just like the DigiTube. I don't know if I care for the "toob" gain, but if I need a steroidal sound, I can get it from that...but it sounds better for most stuff with just the solid state pre. However, there is a drawback: the phase reverse switch is only set to work with the XLR in - it doesn't apply to the unbalanced 1/4" input. :spit: Oh, well...looks like I should have listened to Scott.

    Anyway, on my Raven Labs PMB-I, the phase switch works with the 1/4" input, so I was wondering if reversing the phase of the signal is really as easy as just swapping the leads out on one end of the patch cable that goes from the pickup to the pre? If so, I could just make a "reversed" cable or two, since the Full Circle seems to sound best with the phase reversed. Any gearhead/techie types out there who can clear this question up for me before I go cutting into a perfectly good cable?
  11. Hey Chris, what are you using as a power amp with the EQ? Different power amps have different input sensitivity and so need a hotter signal than some musician oriented (as opposed to pro sound reinforcement) equipment will provide. Sounds like the Presonus is sending a hotter signal to your amp than the Raven Labs unit.

    I was having this problem with a Fishman Bass Pro EQ (it didn't provide enough signal on the unbalanced out). I stuck an ART Tube Mic pre after the Fish and got plenty of gain to fully drive the power amp (downside was the tube coloration, works fine for my blues gig, too warm for jazz).

    If you like the Presonus tube preamp (when you get a workable one), you might try it inline after the Raven PMB. It should boost the signal enough that the Raven will be able to drive your amp as well as the Presonus EQ.

    BTW, ART used to make a half rack Tube Pre and parametric EQ. You can still find them used on EBAy. Has tube and master gain, low shelving, 2 sweepable mids, high shelving, and bypass. Sounds pretty good (doesn't color the sound) and I've used it on gigs along with a half rack Stewart amp. As with other inexpensive equipment, it's a roll of the dice whether or not you will get a good unit. I've had good luck with ART, but others have reported problem.

    EDIT Just realized from your last post that you have a PMB 1. I'm pretty sure that Raven offers a free upgrade to that unit so that it will put out a hotter signal.

    Attached Files:

  12. About phase-reversal: Did you mean that when you change the phase, the FC sounds better from where you (the player) are standing, or in general (i.e. away from the bass, out in the room)? I've found that changing the position of the amplifier alters things. I would do some experiments with the phase switch and the position of the amp. The bass will sound different out in the middle of the room…

    Just a thought…

    - Wil

    BTW - my PMB-1 has a phase switch on each input…
  13. Jonas has just brought D-TAR to our attention. They make an "audiophile quality" 3 band parametric with two notches. And it can be used as a stand-alone preamp or in conjunction with a separate preamp. Cost is around $259. I'd like to try one. Also if you download the manual there is a handy glossary of amplification terms, as well as a history of equalization fo yo edification.

    There is no remedy for G.A.S..
  14. Is there an advantage to running it this way as oppopsed to putting the EQ in the effects loop?
  15. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY

    Right now I'm running into a Schertler PUB 280, which is an amazing little powered single 8" cab. The problem with it is twofold:

    1) It has plenty of power IF your preamp has lots of clean headroom, but if not, it can come up short in some situations.

    2) It can put out an amazing amount of csound for a single 8" cab, but the low 60hz and below frequencies start to get "poofy" on the speaker at higher volumes. A high pass filter (which the Raven unit doesn't have) is needed for these situations to get the most clean headroom out of the cab.

    You hit the nail on the head with your description. I've thought of this, but I'm looking to avoid carrying two preamps if I can. If I have to, then oh well... If only the RL unit had a high pass filter and a hotter signal, or if only the TubePre has a 1/4" phase switch. Doh!

    EDIT Just realized from your last post that you have a PMB 1. I'm pretty sure that Raven offers a free upgrade to that unit so that it will put out a hotter signal.[/QUOTE]

    I've not heard about this, but would be very interested to find out how to follow up on this, since it would solve half of my problem with the Raven Labs unit. I may contact the local studio guy here in town who designs amps and preamps and see what it would take to flip that signal coming out of the pickup anyway, but if the PMB-I can be modified to have more clean headroom, that would be great. Thanks for the tip!
  16. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    In my experience, the effects loop is best used for effects which are meant to be blended with the original dry signal, like Reverb or Delay. With EQ, since you are trying to get rid of unwanted resonant frequencies, it doesn't make a lot of sense to keep any of the unaltered original signal mixed in when you could be affecting the whole signal. I could be wrong, but this has been my experience both with recording and with live sound.
  17. So even if the effects level (on the preamp) is all the way up, you still get some of the dry signal mixed in?
  18. I get this "flitting" at higher volumes also, usually just on the lowest 3 or 4 notes. It seems to be coming from the pickup signal, which is carrying most of the low end (not the mic). So with the EQ3B, does the high pass filter eliminate the problem, or just reduce it? Does it take away any of the fatness or warmth of the sound? Do you find that having the low cut starting at a fixed frequency is a drawback? Did you find any other units that had the high pass, or better yet shelving type filters with adjustable frequencies? And and and and is this too many questions for a $129 piece of gear? (rhetorical) :bag:
  19. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    Last things first: The fixed frequency for the rolloff can be a drawback, especially at low volumes. On the both the TubePre and the EQ3B, the bass rolloff is set at 80hz. At low volumes, I find that this setting steals more lows than I would like, although it definitely cure the "poofiness" problem. Fortunately, the first band of parametric on the EQ3B can be set for adjustable low shelving, so at lower to medium volumes I use it to roll off everything under about 40-60hz. Once the volume gets to a certain level, it's cool to rollll off at 80 hz, since it's the lows that get artificially heightened at higher volumes anyway, and also because at higher volumes, you're going to lose some of that "natural" sound quality anyway. O, and you'll probably want to use that rolloff with your mic anyway, since those lows on a mic are deadly for feedback. It's likely that your mic pre is already doing that. Refresh my memory about what your pickup/mic/pre setup is at the moment?

    Too many questions? Nah. As (All Hail) GOLLIHUR'S CAKEWALK is fond of saying, "Life is too short for bad tone". Besides, it's not like you have to walk around worrying about this **** for the rest of your life - once you find the sound you can live with, it becomes more of a "set and forget" thing. Presonus makes a blender called the "Acousti-Q", which has three semi-parametric shelving filters, which runs about $250. I almost bought one, but didn't because with that unit both signals share the same EQ settings. I'm sure there are other units out there, but I don't yet know what they are. BTW, the street price of the Presonus units is about $99. :)
  20. flatback

    flatback Supporting Member

    May 6, 2004
    I am really interested in the Solstice from Dtar...Seems like the raven only with xlr inputs and maybe a little higher quality...although I have played thru a raven and I really like it. I like the choices on the dtar and would really be interested to know if it has as much gain as the raven pmbII. Like Chris I am running a preamp into a powered speaker and despite the ample amplification of the amp (say that 3x fast) you really need lots of headroom in the preamp...or so it seems...