• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Power Amps...

RobbieK

RobbieK

Jun 14, 2003
2,474
1,626
Smellbourne, Oz...
#1
I've had a [Invalid or Expired Link Removed] for 5-6 years as a backup rig. But after a few minor back issues, I've retired my beloved Australian Monitor 1k2 (20kg), and shifted up the QSC (8kg) into my main rig.

The problem is, that even though it is rated higher than the old (class AB) Aussie Monitor, it really struggles on certain gigs. There's a couple of larger stages that my (3-piece working) covers band plays, and when pushed it becomes very compressed and the treble sort of dies away too. On these stages with everything else the same, the old amp was fine. (FWIW, I run no pedals, and the EQ is usually set flat or close to it.)

In general, I find the plx's tone a little processed sounding and sort of phoney, but I can live with that. I'm really mostly concerned with how it handles higher volumes.

I've tried it with various combinations of all 4 of my bass cabs, three different preamps - valve and SS, and also in different amp configurations - one channel into two cabs, a channel for each cab etc.

So I'm after some rack power amp recommendations from some other gigging pros out there. (No combos please, I'm happy with my preamps.)

Cheers!
 
Last edited:
#2
I have a Carvin HD1000 power amp. It's a great amp. It can be unbelievably loud if need be, with plenty of headroom to spare. They don't make the HD1000 any more but do make the HD3000, And the DCM1000. Both are fantastic amps. They weigh in at 9 pounds, so not too heavy in the rack. They're stereo amps so they are quite versatile. In stereo mode they can handle down to a 2 ohm load all night long and not really heat up, so it takes just about any cabinet combination you throw at it. In bridge mode is a little less versatile, but easily handles a 4 ohm load without breaking a sweat. Not to mention the price doesn't break the bank, 'bout $350 give/take a couple bucks. Check 'em out, they definitely won't disappoint.

[Invalid or Expired Link Removed]

Oh yeah, I'm not afiliated with Carvin in any way, just love their amps.

HD3000
OUTPUT POWER
1 CHANNEL RMS continuous
- 8 ohms: 500 watts
- 4 ohms: 750 watts
- 2 ohms: 1200 watts
BOTH CH RMS continuous
- 8 ohms: 340/340watts
- 4 ohms: 550/550 watts
- 2 ohms: 1100/1100 watts
BRIDGED RMS continuous
- 8 ohms bridged: 1100 watts
- 4 ohms bridged: 2200 watts

DCM1000
OUTPUT POWER
1 CHANNEL RMS continuous
- 8 ohms: 210 watts
- 4 ohms: 325 watts
- 2 ohms: 520 watts
BOTH CH RMS continuous
- 8 ohms: 200/200 watts
- 4 ohms: 325/325 watts
- 2 ohms: 500/500 watts
BRIDGED RMS continuous
- 8 ohms bridged: 650 watts
- 4 ohms bridged: 1000 watts
 
#11
I move up to QSC PLX 3002 and have never had an issue and never looked back. It's a great amp. Make sure all your dip switch selections on the back are correct. Ive used mine extensively and outdoors with no issues. (With the exception of the low out put of my SVP-CL, still not the amps issue) otherwise maybe think of going to 3402.
 
#12
No, wait, I did have one issue and it was my own bone headed fault. When using my SVT 8x10 cabinet for the first time I had plugged in the cabinet using the separate 4x10 inputs and using bother channels of the amp ... so I thought. I was plugged into the single input and one of the separate channels on the cabinet and the amp was doing some very strange things and getting hot fast... and even with my bone headed move the amp came out unscathed.
 
#14
murphy said:
I had the same experience or similar with my PLX...I suspect a gain match voltage issue from my preamps as everyone else loves their PLX
Click to expand...
This. The input sensitivity of the PLX series requires more voltage from a preamp than many other power amps. I had a 3402. I got it for power and light weight. It replaced my use of Crown and Crest power amps. The Crown Power Bass 1 and Crest VS 650's (3) and CA9 had an input sensitivity of .775 volts. The PLX3402 was 2 volts. I now use an early SWR Stereo 800 and a Stewart World 1.2. Love them.
 
  • Like
Reactions: Arthur U. Poon and murphy
#15
murphy said:
I know..and that is why I bought it
I realize my Alembic F2b did not have enough juice to drive it...but found that out years later
Click to expand...
The output impedance of the Alembic is way too high to drive most modern solid state power amps. I would not expect them to sound very good, weak on the low end and not very smooth with excessive distortion that may not be wanted. This has nothing to do with sensitivity.

I have a couple dozen PLX's in PA use, they are a very hard amp to beat on a variety of applications.
 
  • Like
Reactions: murphy and jazzbass_5
#16
I have had great luck with a Peavey IPR 1600 and preamp (BBE B-max). Very clean, light, transparent and fairly inexpensive. Coincidentally, I used a QSC GX3 for a short time, and that came up short on everything but the weight.
 
  • Like
Reactions: murphy
#17
PLX 3402 works great as long as you have the dip switchs correct ,a preamp giving it some good input voltage.. I use a quasi balanced cable between my preamp and PLX too.. Very clean!
IMAG0254.jpg
 
  • Like
Reactions: AlexanderB and jazzbass_5
#19
agedhorse said:
The output impedance of the Alembic is way too high to drive most modern solid state power amps. I would not expect them to sound very good, weak on the low end and not very smooth with excessive distortion that may not be wanted. This has nothing to do with sensitivity.

I have a couple dozen PLX's in PA use, they are a very hard amp to beat on a variety of applications.
Click to expand...
just wish I had known this when I bought that power amp...it was expensive at the time...and so raved about.....very disappointing
 
#20
murphy said:
just wish I had known this when I bought that power amp...it was expensive at the time...and so raved about.....very disappointing
Click to expand...
There's nothing wrong with your amp, it's a great amp. The problem is with the preamp, which does not adhere to any modern standard for sensitivity and output impedance. In fact, it did not adhere to many of the older power amps as well. This has been a big issue for decades.

This is directly from Alembic's own website:

The signal loss of the passive tone controls and the volume control is made up by the second stage, also a common-cathode vacuum tube stage. The second stage plate circuit feeds the output jack. Since the output impedance of the tube circuit is fairly high, the power amplifier(s) should be located adjacent to the F-2B so that short connecting cords can be used. While the output circuitry of the F-2B can satisfactorily interface with the vast majority of power amplifiers, the F-2B does not work well if the power amplifier input impedance is lower than 10 K Ohms or if the power amplifier has very low sensitivity.

The PLX preamp, IIRC is about 10k ohms (single ended input) and is a lower sensitivity compared with power amps of 3 years ago which were often 500-750mV for rated output compared with the more typical 1.4-2V today. IIRC, there was a mod (maybe a factory mod) for adding a low impedance line driver to the output to get around this issue. I know I have done this a few times for touring clients and it was not difficult for a well equipped service shop. I believe the newer F-1X has the line driver installed from the factory.
 
Last edited:
  • Like
Reactions: Downunderwonder, Pbassmanca and murphy

Latest posts

Top Bottom
Back