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Crate powerblock Ohmage question

Discussion in 'Amps and Cabs [BG]' started by ::::BASSIST::::, Apr 20, 2009.


  1. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Probably should know this but...

    The manual says 75w at 4 ohms per side or 150w at 8 ohms bridged.

    How many watts would it be putting out if I used two 8 ohm cabs?

    Gotta be more than 75w right?
     
  2. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    You can't hook up the cabs in parallel, because that would be 2 Ohms, so you have to connect each cab to its own side of the power amp. Each amp would receive half of 75 W, so the total would be 75.

    In other words, it's a :meh: for running multiple cabs.
     
  3. Thundar

    Thundar Living in sin at the Holiday Inn

    Bassist, are you using this to push a bass cab? reason I ask is cause I was laying down some tracks with my band in a lil' local studio, and they told me not to bring an amp cause the studio had their own bass amp...so I show up, and the engineer dude shows me the amp/cab...it was a Crate Powerblock pushing a Hartke 115XL...I kinda chuckled but to my complete surprise it sounded pretty good.
     
  4. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Yeah, I was thinking of using it as a poweramp with my PJB Bass Buddy as preamp.

    Mainly for rehearsals and such.

    However, if I cant use it with two 8 ohm cabs its probably not going to happen.
     
  5. Bumping this because I have been talking to my amp tech about it.
    I wanted to power a 4 ohm cab with the powerblock at 150w.
    No can do.
    If you try to hit the bridge mono button with a 4 ohm cabinet, it will over load the amp and it will probably shut down.
    So i guess a good 8 ohm cab with a powerful 12" or 15" speaker would be a great match for the powerblock?
    Anyway, heres the note he wrote me. Figured someone else might find it interesting:

    "Hi Steve,
    You already know that you can run the amp at 4 ohms per side; you absolutely CAN NOT run it bridged mono into one 4 ohm cabinet, since the amp reconfigures itself when you set it to ‘Mono’ and you would effectively be running each channel into 2 ohms, which would overload the amp. Bridged mode is strictly 8 ohms. What I haven’t been able to find out is whether it’s OK to run the amp with only one cabinet and leave the other channel with no load; the manual doesn’t say, and I’ve only hit dead ends trying to get a straight answer. I’ll keep looking, I think that company has changed hands a few times recently "

    So any adds to this or recommendations of a cabinet?
    Was really hoping I could hear my VX215 cabinet run at the full 150 even though the 75 actually sounds great.
    thanks
     
  6. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    until i got my micro vr, i was using a power block and vt deluxe into a b-15 cab for my micro needs. hell of a good little amp if you bypass its guitar oriented pre. you can run only one side of the amp. i used to do it all the time.
     
  7. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    If you use the CD input (via a cobbled together cable) you don't get the low cut of the built in cab sim, you might not notice it, depending on the sort of cab you use, it is in the signal path diagram. They are quite well protected in that if you bridge into 4ohm, it just shuts itself off.
     
  8. seamonkey

    seamonkey

    Aug 6, 2004
    It's 75w per side at 10% THD
    A normal SS "Bass" amp would be rated at 1% THD - you'd hope.
    So this this is probably only around 45w a channel.
    Use two 8 ohm cabinets - and if they're the same cabinet type you'll get more acoustic output than one bridged at 8 ohms.
     
  9. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    seamonkey is actually right about the distortion in the power block. even at low levels bypassing the preamp, there is always a tiny little undercurrent of audible distortion. in a band situation it's completely unnoticeable, though.
     
  10. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    THD does not quite work like that for a Class-D amp...... you'd be right for a tube amp. :)D)

    The spec does not mean it HAS 10% THD, it's pretty much for "wiggle room", and a little on top for clipping. But Class-D doesn't typically "like" clipping that much, so not a lot. The PB is based on a Philips class-D power amp chip, one meant for hifi audio, so the spec isn't really as you assume.

    Too bad Loud nixed the bass version that was being developed.

    Actually Loud didn't "nix" it, they totally ignored it, they didn't ask for even ONE Crate product for more than a year. So they basically didn't get any.
     
  11. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    well finally they came out with the micro vr, which helps ease the sting of not having a bass power block. but i think it would have been brilliant. i never need more than it can put out anyway. and an ampeg sounding little amp like that would have been great.
     
  12. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    I had a power block for a few days. It used a specialized IC for the Class-D power amp, at a time when those components were just beginning to show up in products. I fed it into a nominally 8-Ohm speaker in bridge mode. Then I treated it to the same torture test that I apply to all of my gear, including DIY -- dropping bombs on the E string at full volume. A respectable amp should be able to handle this, as it really doesn't stress the thermal capabilities of an amp very much.

    The power block would go into protect mode and then reset itself after a few seconds. Unfortunately, it developed a noticeable distortion, even at low volume levels. So it didn't survive running at its own rated power. It went back. I also did some oscilloscope tests with a dummy load. The power amp circuit had a rather interesting soft clipping response.

    I wrote to Crate at the time, and suggested developing a bass power block. But the guitar version could not have been scaled up to a gig-worthy bass amp because of its IC based design. And if you're going to put money into product development, you might as well spend it on the product line with better brand recognition.
     
  13. 1n3

    1n3

    Sep 13, 2007
    USA
    You can use two 8 ohm cabs; one per side. You won't get 150w, but it might be loud enough. I tried one for a while, into a single 4 ohm cab (one side only). It wasn't clean enough for what I was doing at the time (jazz), but it probably would've worked for some other styles.

    It's a shame that Loud dropped the ball on the bass version. Jerrold has said before that the design was done; they just didn't carry it to market. Wonder how it would've compared to a GK MB200.
     
  14. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Speaking of the gkmb200 I have its bigger brother the mb500 and really dig it. The powerblock really isnt on my radar at all anymore as a result.
     
  15. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    the power block wasn't on your radar two years and 19 amps ago ;)
     
  16. 1n3

    1n3

    Sep 13, 2007
    USA
    Understandable. I didn't notice how old your OP was.
     
  17. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Ha. Well it actually was. I actually bought one from Florida on Craigslist, but the seller took my money and never sent the amp. Paypal eventually recovered my funds though.

    ...And 19 amps? That might be a *little* off. :cool:
     
  18. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    On the low side? :D

    I can't keep up with you Torin, but I was once accused of changing amps more often than my socks!
     
  19. will33

    will33

    May 22, 2006
    austin,tx
    Cabbage eats ohmage. So, if you need more ohmage, you get less cabbage. Or you can buy cabbage that already has more ohmage in it so it doesn't eat so much.
     
  20. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Well, gee whiz Beav!

    I had my last amp (bx1500) for about a year. Now I'm onto the gkmb800.
     

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