The Jazz Guitar Chord Dictionary
  1. #1

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    I bought this from a local Kijiji for-sale ad from someone selling a pair of them. It's loaded with a stock Celestion GK12-100 speaker. I wanted a 1x12 cab to handle a humbucker a little better than my little 1x10 cab and I bought this mostly for the cab thinking that I'd probably change the speaker to something a little more Blackface-like. It turns out that I don't think I have to do anything to it. Plugged my Superblock US into, stuck my mic in front, and plugged in my blue Gosling and it sounded just fine, both in the recording and in the room. This is a first take without any experimenting with the mic position and no after the fact EQ. The amp is running in '61 mode.

    One interesting odd-ball factoid about the cab ... It turned out to be a great lesson in how false information gets to be accepted truth on the internet. At some point someone (probably Crate) posted the wrong dimensions for this cab. Those wrong dimensions got copied by someone else and pretty soon every mention pf this cab described it as being 21" wide x 26 1/2" high x 12" deep. One look at the photo should have told anyone that those couldn't be right but they just kept getting posted that way through the age old process of cut and paste. The actual dimensions are 20" w x 17" H x 13 " D.

    The price on the used market was a very reasonable $160 CDN (about $125 US). That's not much more than the value of the speaker alone.

    New Cab Day yesterday: a Crate GT112SL-crate-gt112sl-jpg


    The Jazz Guitar Chord Dictionary
  3. #2

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    Nice Jim!

  4. #3

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    I believe this is the companion cabinet to the Crate PowerBlock CPB150 amp. It came out in 2005 and discontinued a short time later. If I remember right, the blowout price for the cab was $99. It had a pouch in the back of the cab to store the amp.

    A lot of people were surprised it was discontinued. It seemed to satisfy a couple of needs at the time. A lot of the amps were relegated to backup use.

  5. #4

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    Quote Originally Posted by Dave24309
    I believe this is the companion cabinet to the Crate PowerBlock CPB150 amp….A lot of people were surprised it was discontinued. It seemed to satisfy a couple of needs at the time. A lot of the amps were relegated to backup use.
    Yes indeed! I bought a PB at list when they first came out, intending to keep it in my trunk as a backup. But it was so good I started using it regularly. I was amazed when they D/C’ed the line but thrilled to get 2 more for $99 each when they did. The head had a stereo option. And when I needed more power, I used a pair in stereo for my Roland synth.

    I just sold all 3 heads for $85 each. No more 5 pound monsters to schlep around - now it’s an Elf or a Microblock for me. Ain’t technology wonderful???

    The speaker cab is also excellent, especially for jazz. It’s a nice general purpose unit and great value. Enjoy it, Jim!

  6. #5

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    An open-back 12" cab can be of any make and sound good, provided the speaker inside does. About seven years ago Thomann revealed that they had sold 12,000 Harley Benton 1x12 units. That figure must be a serious multiple by now.

    I remember the Crate PowerBlock all too well. It was lightweight by the standards of the day and looked cool, but I was deeply disappointed with the sound.

  7. #6

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    Quote Originally Posted by Gitterbug
    An open-back 12" cab can be of any make and sound good, provided the speaker inside does...
    ...and provided its physical characteristics are right for open back use. I know you know this, Markku - but a review may be helpful for those who don't.

    The same speaker can sound fabulous in one type of cabinet and terrible in another. The woofers in acoustic suspension (sealed) cabinets are floppy in free air because they need and use the trapped air in the cabinet as a damping force. So a driver designed for a sealed cabinet will sound terrible in an open one because it will have far too little cone control. And a driver with a lot of inherent damping and cone control will not be able to move enough air if it's installed in a sealed cabinet, because the cone will be grossly overdamped.

    The Thiele/Small parameters (defined about 60 years ago by Neville Thiele and Richard Small, two Austrailian speaker engineers) are a set of mathematical parameters that describe speaker behavior and offer objective guidance for selecting ideal enclosure characteristics. To a large degree, it's the "Qts" that determines whether a given speaker is better suited for an open or closed cabinet. Q encompasses a set of paramteters that express how tightly the movement of the voice coil and cone is controlled. This is a combination of the electrical damping (which is determined by the electrical and magnetic characteristics of the VC and magnet) and the mechanical damping of the cone and coil (from the surround, suspension etc). Other factors affecting the choice of cabinet include the mechanical force exerted by the suspension on the cone, the linear excursion of the cone, etc.

    The industry rule of thumb is that a total Q (electrical + mechanical) over 0.7 means a speaker is better suited for an open cabinet. A Qts below 0.4 generally means a speaker is best suited for a vented / ported cabinet. And a Qts between 0.4 and 0.7 suggests a sealed cabinet. There are actualky a few dozen T/S parameters, and they all have meaning to a speaker engineer. But the bottom line is that a speaker and its enclosure must be matched properly to get the desired sound. You can't simply pull the speaker from your old open back combo, throw it into a sealed or ported enclosure, and expect it to sound great.

  8. #7

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    Thanks, Never... To be honest, I'm not too conversant on all the Thiele-Small parameters. Have found my way around empirically and listening to good advice. What you are saying is certainly relevant and probably even more so for bass speakers. But it's rarely either or. Many guitar and bass speakers work in all environments (just look at Eminence's recommendations), and there are convertible cabs for both open and closed use. I believe the most popular guitar speakers (at least in the jazz context) are found in open-back cabs. It's safer to put one of those in a ported/closed cab than the other way round. But why?

    Acoustic suspension is an important factor. Looking at the frequency response charts of 6" speakers, the curves are often measured using a ported 18-litre cab, which provides such suspension and enhances the bass end, while larger guitar speakers are measured from the face side using a standard "indefinite baffle". To use my own minuscule Metro cabs as an example, the 6.5BG (for bass & guitar) has one 50 mm port in the back panel and four layers of felt acting as a pressure valve, making the speaker think it's in a larger closed chamber. The parallel 6.5GP+ (Guitar Ported) has four ports and just a single layer of felt on each to filter nasal mids, so 1/16th of the BG's air resistance. The difference: both are fine for guitar, the BG darker, more directional and a tad less loud. It handles even a fifths-tuned double bass (i.e. low C) on moderate volumes, while the same speaker starts to break much earlier in a GP on bass frequencies.

    Apologies if this smacks too much of a commercial.

  9. #8

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    Quote Originally Posted by Gitterbug
    Apologies if this smacks too much of a commercial.
    No worries, mate! Knowledge is valuable - we'll take it gladly and without judgment.

    Especially now that we're all using smaller and smaller speakers, it's critical to align all the stars before setting sail. I've watched too many of my friends and fellow players end up disappointed after haphazardly swapping speakers from open back combo to ported cabinet to closed back combo. I recently bought a Jensen Tornado 10" from a fellow JGO member and checked the Qt before buying it to be sure it was optimal for guitar through my ported RE 10" bass cab (it is - the Qts is 0.58 and the free air resonance is 82 Hz). But this would clearly not be a great speaker for a bass player, because the free air resonance is an octave above low E on a 4 string bass.

    Stay safe, my friend!