Author Topic: Power Amp to pair with my Alembic F-2b and Custom Cab  (Read 513 times)

Rhythmdoctor

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Power Amp to pair with my Alembic F-2b and Custom Cab
« on: October 04, 2021, 10:29:31 PM »
I play an Alembic Spoiler with hopes of upgrading to a Series I someday :drool:  I finally found a used (red knob) Alembic F-2b preamp on Reverb that is now in my possession.  At the moment, I have commissioned a handmade Bass Cab from RevSound.  This cab is a 4x10 vertical at 8 ohms of impedance.  The other relevant specs of this cab are pasted below.  I have done some research on this topic and from what I've gathered, the F-2b requires a power amp with a high input impedance of 10k ohms or greater.  I've also read but not sure if true, that the power output of the amp should be double that of the cab.  I'm a total NEWB when it comes to bass gear, so a lot of this is out of my element from a technical aspect.  At the end of the day, the question I need answered is: what Power amp should I get to use in conjunction with the F-2b and the cab I listed above with specs below? My other question is what is the ouput wattage of this cab because 1400 seems high? I appreciate any and all help. 

I'm very new to bass, only a year but been a rhythm guitarist for nearly 30 years.  After starting on a Fender jazz and being a tone junky, I quickly knew I needed something much better in tone, especially having been enlisted to play bass in a Grateful Dead tribute.  Once I got the Spoiler in March of this year, my search for the ultimate tone began.  Now I'm essentially one piece away, although the cab has an 8 week build process.  I'm PUMPED though!

RevSound RS410V applicable specs (I opted to not get the tweeter so I'm not sure how to read the output wattage on this):
(4) Celestion Neo 10s and (1) 300 watt titanium bullet tweeter
L-pad for tweeter adjustment
1400 watts power handling
Sensitivity: 102 db 1 watt/ 1 meter
55-20Khz
Dimensions: 48" H X 16" W X 12" D

Weight: RS410VT 59 lbs  RS410V  55 lbs
« Last Edit: October 04, 2021, 10:32:48 PM by Rhythmdoctor »

rv_bass

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #1 on: October 05, 2021, 06:01:03 AM »
Welcome and congratulations!  I use a QSC GX7 power amp with my F-2B and it works great for me.  Others like Crown power amps or the Crest Prolite power amps (which I believe is Class D and lighter).  Is your cab 4 ohms or 8 ohms? Either will work with the power amps listed above.
« Last Edit: October 05, 2021, 06:07:57 AM by rv_bass »

keith_h

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #2 on: October 05, 2021, 07:19:48 AM »
I've always liked the QSC PLX/PLX2 power amps. I could not find the cabinet impedance on the company website but it should be within the bridged capability of either a PLX or PLX2. The same should apply to Crown power amps with bridging capability.

That cabinet is rated in AES which will always be higher than the RMS rating. Depending upon the version of the Celestion 10 bass speaker 1400 watts AES does not seem unreasonable. That would be an RMS rating of 1000 to 1200 watts RMS and aligns with the individual speaker ratings for the BN10-300X if that what your cabinet uses. 

Accidentally hit reply.

Have you contacted the cabinet manufacturer? They are usually willing to provide a recommended amplifier power rating range to use for optimal results.
« Last Edit: October 05, 2021, 07:22:16 AM by keith_h »

Rhythmdoctor

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #3 on: October 05, 2021, 09:34:53 AM »
Thanks for the replies!

I think the cabinet is using four of these: https://celestion.com/product/bn10-200x/
I don't believe he's using the 300x because those are 4 ohms and my 410 cab is an 8 ohm cab, but I'm guessing at this point.  It has to be eitehr the 200x or 300x. I know for sure he's using the Neodymium speakers.

Let me ask this, I've been looking at the QSC PLX series because that brand/model keep popping up.  There is a PLX 3602 and a PLX 3102.  My tendency is to always go with the bigger/badder one (3602) but for this project, I'm already over $2500 so trying to pinch a bit.  Will the 3102 be powerful enough?  Or could I even go down another model to the PLX 2502?  Another question I have is what are the differences in the QSC models?  They have a GS series, a GDX series, the PLX series and a Powerlight series.  I want to make sure I'm getting the right component.

Here is the spec/comparison sheet for the 4 PLX2 models (1802, 2502, 3102 & 3602).  I really appreciate the help.  I'm new to bass and certainly new to bass rigs.  I've been playing through a combo amp since I started playing last year, so my knowledge base is small and limited.

QSC PLX series spec sheet: https://www.qsc.com/solutions-products/power-amplifiers/portable/2-channel/plx2-series/plx3602/
« Last Edit: October 05, 2021, 09:42:27 AM by Rhythmdoctor »

Rhythmdoctor

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #4 on: October 05, 2021, 09:48:13 AM »
Welcome and congratulations!  I use a QSC GX7 power amp with my F-2B and it works great for me.  Others like Crown power amps or the Crest Prolite power amps (which I believe is Class D and lighter).  Is your cab 4 ohms or 8 ohms? Either will work with the power amps listed above.

Do you know the difference between the GX7 and say the PLX 3102 or 3602?  I know there is wattage differences but there are so many different models from QSC, my head is spinning.

keith_h

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #5 on: October 05, 2021, 11:13:28 AM »
The GX series of amplifiers do not support bridge mode so with a single cabinet you will only use one channel of the amplifier. The second channel would be unused. For the PLX series amps the only difference between the PLX3102 and PLX3602 are the power ratings.


The PLXxx02 series of amplifiers support stereo or bridged operation. With a single cabinet I would look at using bridge mode which would use both channels through a single connection to your cabinet for more power. Based on your cabinet specs a PLX1802 or PLX2502 in bridged mode would be a good match. There are pin differences as I recall for the amplifier speakon connections when in bridged mode but it has been a long time since I've looked at that so look it up before buying cables.

I use a PLX3102 for my bass rig. My old big rig was run in stereo with one channel driving two 18 inch subs and the other two 2X10 cabinets. Today my big rig is two 2X10 cabinets where I run one cabinet off each channel.

I use bridged PLX2502's in my PA system with one amp per JBL MRX528 sub. For the mains I use a PLX3602 running stereo.

Rhythmdoctor

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #6 on: October 05, 2021, 10:08:56 PM »
I've read good things about the Crown amps, specifically the XLS 2502.  I can't find the input impedance on the spec sheet though. I've read with the F-2b you need something with 10k+

hammer

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #7 on: October 05, 2021, 10:55:47 PM »
I've read good things about both the Crown and QSC.  Personally, I use a Yamaha P3500S in bridged mode through an F1-X and an SF-2.  I'm a big Phil Jones PJB cab fan so the amp is pushing 24 5" speakers.  The Yamaha amps are reliable and known for a very flat response.   

Rhythmdoctor

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #8 on: October 06, 2021, 12:08:35 AM »
I made an offer on Reverb for a Crown XLS 2502.  Hopefully the seller accepts so I can get one step closer to full rig.

edwin

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #9 on: October 12, 2021, 05:50:46 PM »
I've been using all kinds of PA style power amps, with my favorites being Crest, but at this point, I just bring a Quilter Bass Block 800 if mono is acceptable. It's insanely light, powerful, and sounds great. The only downside is that it's not easily racked. The upside is that it will work well as a complete head, if needed.

bigredbass

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #10 on: October 13, 2021, 03:47:56 AM »
With the advent of powered cabinets in most PA these days, commercial stereo power amps can be had for cheap, and any of the mentioned choices would certainly work, but . . . . I would very carefully approach slamming 1400 watts (!!!) through a 410 cabinet, I'd start at half that.

edwin

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #11 on: October 26, 2021, 03:03:03 PM »
Can't wait to see pictures of this rig!

Rhythmdoctor

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Re: Power Amp to pair with my Alembic F-2b and Custom Cab
« Reply #12 on: November 12, 2021, 11:05:36 PM »
Can't wait to see pictures of this rig!
Thanks! I can't wait to play through it.  I have all components except the cab which will hopefully be completed soon!  I told the guy I have a gig on 11/27 and he seems optimistic I'll have it in time.

Here's a recap of the rig (not including my bass which is an Alembic Spoiler 1983).

$3,136.00 - Bass Rig Costs:
$815 - Alembic F-2B Preamp USED
$1,609 - RevSound RS410V Bass Cab NEW
$388 - Crown XLS 2502 Power Amp USED
$100 - Furman M8x2 Power Conditioner NEW
$40 - Hosa Neutrik Speakon Cable 10' NEW
$184 - Road Runner Effects Rack 6u + TS 1/4" cable NEW
« Last Edit: November 12, 2021, 11:07:46 PM by Rhythmdoctor »