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Alembic Club » Alembic Basses & Guitars » Archive: 2007 » Archive through March 05, 2007 » Need some power amp help « Previous Next »

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Username: tsosboom

Post Number: 1
Registered: 1-2007
Posted on Monday, January 29, 2007 - 10:26 am:   Edit Post

I have used an Alembic F1-X preamp for about 7 or 8 years now, running it through a USA 900 power amp into various cabinets over the years. I finally picked up an Ampeg SVT810 (800w at 8 ohms per side, I think) and hooked it up and knew I found my setup.

Well, as I was loading my gear to play a gig the other day, I dropped the hardcase containing the power amp and it fell from the top of the cabinet. As you can imagine, the power amp didn't fare too well. Channel 2 is shorted out and Channel 1 is providing only intermittent power. It's got to be fixed or replaced, and the bench fee to even crack open the power amp has me wondering if I shouldn't just pick up a new or "new to me" (used) power amp.

So, since about all I know is that I like the ability to run the output of the preamp into two separate channels of the power amp, which in turn drive the separate 4x10s so I get two distinct tones, I'm seeking advice on a suitable power amp to accomplish this task. I love the Alembic preamp, my cabinet and my bass. The power amp, not so much.

What kind of power amp do I need to properly drive the 8x10, to handle the distinct signals from the full range and high pass outputs of the preamp and to give me plenty of volume for some of the sub-par venues my band plays?
Username: cozmik_cowboy

Post Number: 85
Registered: 10-2006
Posted on Monday, January 29, 2007 - 10:46 am:   Edit Post

Hi, Ryan - welcome!
I would suggest that you look into Yamaha power amps - they give clear, uncolored sound, they aren't overly pricey, they come in a wide enough range of power ratings that you can no doubt find one to meet your needs, and, based my experience with them, a Yamaha probably would have survived that fall with no ill effects (they're the most reliable amp I've ever used.)

Senior Member
Username: kmh364

Post Number: 2062
Registered: 9-2003
Posted on Monday, January 29, 2007 - 11:47 am:   Edit Post

QSC. Durable, American-made, readily available parts/service, reasonably priced. They're the choice of most pro sound services for the above reasons. Oh yeah, and they sound good!

Lots of Alembic Club memebers use 'em...myself included.
Senior Member
Username: kmh364

Post Number: 2063
Registered: 9-2003
Posted on Monday, January 29, 2007 - 11:48 am:   Edit Post

Sorry, duplicate post

(Message edited by kmh364 on January 29, 2007)
Senior Member
Username: dannobasso

Post Number: 451
Registered: 3-2004
Posted on Monday, January 29, 2007 - 2:24 pm:   Edit Post

I too have a number of qsc's (5 in fact) and they are backed by a great service dept. I did just order for a school pa install, a crown xti 4000. They make a 1000, 2000 as well specs:

Output Power (1 kHz, 0.5% THD)
Stereo Bridge-Mono
8 Ohm 4 Ohm 2 Ohm 8 Ohm 4 Ohm
XTi 4000 650W 1200W 1600W* 2400W 3200W*
XTi 2000 475W 800W 1000W* 1600W 2000W*
XTi 1000 275W 500W 700W* 1000W 1400W*
*With 1% THD.
Voltage Gain at 1kHz, 8 ohm rated output:

XTi 1000: 30.5 dB
XTi 2000: 32.9 dB
XTi 4000: 34.2 dB

Frequency Response: +0/-1 dB from 20 Hz to 20 kHz at 1 watt into 4 ohms.

Load Impedance: Safe with all types of loads. Rated for 2 to 8 ohms in Stereo mode, 4 to 16 ohms in Bridge-Mono mode.

Sensitivity: 1.4V

Signal to Noise Ratio (below rated 1 kHz power at 8 ohms):
100 dB (A weighted).

Damping Factor: Better than 500 from 20 Hz to 400 Hz.

Crosstalk: > 70 dB below rated power, 20 Hz to 1 kHz.

Input Stage: Input is electronically balanced and employs precision 1% resistors.

Input Impedance (nominal): 20 k ohms, balanced;10 k ohms, unbalanced.

Maximum Input Signal: +22 dBu typical.

AC Line Voltage and Frequency Configurations Available: 100V, 120V, 220-240V
50/60 Hz.

AC Line Current:

XTi 1000: 6.5A
XTi 2000: 6.9A
XTi 4000: 8.0A

At Idle: Draws no more than 90 watts.

Operating Temperature: 0° C to 40° C at 95% relative humidity (non-condensing).

DSP Section

EQ: 4-band paragraphic per channel, boost/cut ±12 dB. Also adjustable high and low shelving filters.

Filters: Highpass and lowpass per channel. Butterworth 6/12/18/24 dB per octave. High and low shelving filters, one per channel.

Delay: For signal alignment of driver; 50 mS total delay.

Subharmonic Synthesizer: Adds low-frequency content.

Output Limiter: Prevents clipping.

Presets: 10 user speaker presets.

Front Panel Controls and Indicators

Level: Detented rotary level control, one per channel.

Power Switch: On/off switch applies AC power to the amplifier.

Sel/Prev/Next Buttons: Three buttons near the LCD screen are used to access menu items.

LCD Screen: Backlit liquid crystal display shows speaker presets.

Signal Indicator: Green LED, one per channel, flashes when a very low-level signal is present at input. May be used for troubleshooting cable runs.

–10 Indicator: Green LED flashes when output signal exceeds –10 dB below clip.

–20 Indicator: Green LED flashes when output signal level exceeds –20 dB below clip.

Ready Indicator: Green LED, one per channel, illuminates when the amplifier is ready to produce audio.

Clip Indicator: Red LED, one per channel, turns on at the threshold of audible distortion.

Temp/Fault Indicator: Red LED, one per channel, illuminates under Fault or excessive temperature conditions.

Power Indicator: Blue LED illuminates when the amplifier has been turned on and has power.

Rear Panel Controls and Connectors

AC Line Connector: NEMA 5-15P (15A).

Input Connector: XLR, one per channel.

Link/Out Connector: Loop-thru signal from input connector for linking to another amplifier, one per channel.

Output Connectors: Two Neutrik® Speakon® NL4MP (mates with NL4FC) output connectors. Channel-1 Speakon® is wired with Ch. 1 and Ch. 2 outputs for use with optional single 4-conductor cable. Two binding post outputs (in parallel with Speakon® connectors).

HiQnet USB Connector: Type B, connects to a HiQnet network.


XTi-Series amplifiers are protected against shorted, open or mismatched loads; overloaded power supplies; excessive temperature; chain destruction phenomena; excessive output current, input overload damage; and high-frequency blowups. They also protect loudspeakers from input/output DC, large or dangerous DC offsets and turn-on/turn-off transients.


Chassis: Steel.

Cooling: Proportional speed fan with front-to-rear airflow.

Dimensions: EIA Standard 19-in. rack mount width (EIA RS-310-B), 3.5 in. (8.9 cm) high and 12.25 in. (31.11 cm) deep behind mounting surface.

Net Weight:
18.5 lb (8.4 kg)
Username: tsosboom

Post Number: 2
Registered: 1-2007
Posted on Monday, January 29, 2007 - 6:07 pm:   Edit Post

Thanks for the help, folks. I'm going to see what I can scout out around here for used gear, paying particular attention to Yamaha power amps. I don't know if I communicated well that I have been using a QSC amp, which I like, but since all the specs and stuff are like white noise to my eyes (hey, I just play the bass - I'm no electrician) I thought I'd see if I'd been using the wrong setup.

Oh, and I took a look at my cabinet. It's a SVT-810EN. I can't seem to find any documentation for that particular model, only the SVT-810E and SVT-810AV. Anyone have any thoughts on how to get some kind of manual to make sure everything is as it's supposed to be from the factory? I have a feeling the previous owner may have done something creative with the wiring inside.

Thanks again.
Username: worldfamousandy

Post Number: 96
Registered: 3-2004
Posted on Wednesday, January 31, 2007 - 6:59 am:   Edit Post

What is "paragraphic" eq? I'm surprised to see any eq on a power. Low-pass filters, and features like that have become common, but adjustable eq is something I have not seen.

Andy Calder
Senior Member
Username: keith_h

Post Number: 681
Registered: 2-2005
Posted on Wednesday, January 31, 2007 - 10:33 am:   Edit Post

"Paragraphic eq"
Would that be a spell checker?

Username: essenceman

Post Number: 46
Registered: 10-2002
Posted on Thursday, February 01, 2007 - 9:04 am:   Edit Post

Hi guys,

I recently changed to a F1-X, SF-2 Yamaha P5000S rig, which sounds great through my baby (2x8 & 1x10) Euphonic Audio cabs. So I can certainly recommend Yamaha power amps.

Also with regard to Keith's post about spell checkers, some of you might have seen this before.

A Little Poem Regarding Computer Spell Checkers...

Eye halve a spelling chequer
It came with my pea sea
It plainly marques four my revue
Miss steaks eye kin knot sea.

Eye strike a key and type a word
And weight four it two say
Weather eye am wrong oar write
It shows me strait a weigh.

As soon as a mist ache is maid
It nose bee fore two long
And eye can put the error rite
Its rare lea ever wrong.

Eye have run this poem threw it
I am shore your pleased two no
Its letter perfect awl the weigh
My chequer tolled me sew.

I liked it!

Senior Member
Username: dannobasso

Post Number: 453
Registered: 3-2004
Posted on Thursday, February 01, 2007 - 9:45 am:   Edit Post

"Paragraphic eq"
Would that be a spell checker?

That is direct from Crown's website.
Senior Member
Username: keith_h

Post Number: 683
Registered: 2-2005
Posted on Thursday, February 01, 2007 - 10:17 am:   Edit Post

Well you learn something new everyday. ;-)

Googled this explanation:
Paragraphic Equalizer
Basically this is an EQ that combines the user interface of a graphic equalizer with the functionality of a parametric equalizer. The EQ adjustments are made with sliders (so you get a visual graphic representation of your settings), but each band has adjustable frequency and Q like a parametric. Plus there are often other attributes that can be set. Very few hardware based paragraphic EQ's have been built over the years because they require a lot of components (thus are expensive) and space to lay them out in a usable fashion (especially if long throw faders are employed). However, in software based systems, the paragraphic EQ doesn't need to cost much more than any other type and are more popular, though they still can take up a lot of space on screen.

Senior Member
Username: kmh364

Post Number: 2065
Registered: 9-2003
Posted on Thursday, February 01, 2007 - 11:02 am:   Edit Post

This is nothing new: ADC offered paragraphic analogue eq's for home use back in the '70's. The difference now is with today's cheap DSP chips, this and virtually any other sound processing function can be done in the digital domain. I believe this is what the Crown amps, mentioned by Danno above, offer.
Username: somatic

Post Number: 55
Registered: 11-2003
Posted on Thursday, March 01, 2007 - 4:56 am:   Edit Post

I agree with cosmic cowboy. I have a Yamaha P7000S (2 x 700W @ 8R: 12kg) and whilst the others mentioned (QSC, Crown etc) are very well priced in the US, outside there, the Yamaha's are much better value. In 20 years I've never killed a Yamaha poweramp, and for these two reasons they're my first choice.

You'll never hear the difference between to well designed and made SS poweramps within their envelopes, so buy what you can get locally for the best price and weight.
Advanced Member
Username: lothartu

Post Number: 209
Registered: 8-2003
Posted on Thursday, March 01, 2007 - 1:46 pm:   Edit Post

I'm personally using a QSC RMX series power amp (1850HD). The PLX and PLX2 series are the nice lightweight power amps. The RMX series isn't too heavy but it's not the new fancy PLX line so the RMX series amps can normally be found for a very good price.

I picked up my QSC RMX 1850HD for about $325 brand new a couple of years ago. It's heavier than the PLX series but I don't mind at all when I look at the cost difference.

- Jim
Username: tsosboom

Post Number: 3
Registered: 1-2007
Posted on Friday, March 02, 2007 - 5:17 pm:   Edit Post

Thanks for the additional information, guys. As far as the Yamaha power amps are concerned, I'm not finding any in my area (probably just not looking enough).

At the music shop the other day, I spied some Mackie power amps, and the price is right, but are their amps durable? I've used their mixing boards, but I never had to move one and depend on it working after transport...
Senior Member
Username: byoung

Post Number: 513
Registered: 12-2004
Posted on Saturday, March 03, 2007 - 11:35 am:   Edit Post

Rumor has it that the Mackie power amps are not durable. I don't have this first hand, but it's what I've heard.

Senior Member
Username: lbpesq

Post Number: 2150
Registered: 7-2004
Posted on Saturday, March 03, 2007 - 11:51 am:   Edit Post

My Mackie 808s P.A. has dual 600 watt power amps. I love it. It's never given me any trouble.

Bill, tgo
Username: 5stringho

Post Number: 90
Registered: 11-2006
Posted on Saturday, March 03, 2007 - 1:16 pm:   Edit Post

I've used a Mackie M1400i for over 3 years now, both in my Bass rig and PA application, moved it once or twice a week, and never had a problem. I'm quite happy with it.


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