Riddle Me this

Discussion in 'Amps and Cabs [BG]' started by hstiles, Jan 28, 2003.

  1. I have 2 amp setups:

    My 'old faithful' is a SWR Bass 350 old style red and black fascia.

    My rack consists of a Tech21 PSA-1, MAM parametric EQ, ART Dual Levellar and SOundtech 800W Digital power amp.

    I use 2 SWR Triads

    Now, I took the SWR to rehearsals after replacing the fan and was blown away by how much louder it is than the Soundtech. I usually run both channels of the soundtech at nearly full - the clipping LEDs always on, yet the SWR was only at halfway with the Gain just past 12 o'clock.

    I can;t work why it's so much more powerful. I've tried bypassing the compressor and EQ and going preamp to power amp. Even when the clipping LEDs showing up, it's powerful as anything, but never that Loud!
  2. As to why your SWR amp sounds louder than you SoundTech, when the specs say it should be the other way around? That is tough to say. As DR. Phil says, " there is no reality, only perceptions” The only logical explanation I can think of might be an EQ thing. If your SoundTech rig is putting out a lot more really low frequencies, that would soak up a lot of power without creating a lot of perceivable volume.
  3. redneck2wild


    Nov 27, 2002
    Memphis, TN
    Is the Soundtech a the Digital one space rack PS802 amp?
    I have a Soundtech PS802 that I purchased a few years ago because of the weight (around 16lbs).
    It clips at moderate volumes and it does not do well for full range sound. I compared it to a Peavey CS-800 a couple years ago and the CS-800 was several dbs louder before clipping.
    There are some things I have determined about the amp though. It works fine for a PA amp if there is not much Bass in the signal. If I run the Soundtech amp from the high channel of a crossover it can get pretty loud before clipping. This does not help for a Bass setup unless you are using another amp for the low channel.
    The amp also has weird artifacting at high volumes.
    Most of the artifacting can be cleaned up by plugging the power amp into an AC Line regulator. It also handles the lows a little better when running off a Line regulator.
    I use my PS802 as a PA amp or for the High channels if I am using 4 cabs (2 1x18s on lows and 2 4x10s on highs). I use a Peavey DPC 1000 (also a light digital amp) for a my normal 2 cab biamp rig or for the low channels if using a 4 cab rig.

    Many Bass amp heads are "tuned" to boost Mid Bass frequencies while most PA amps have a flat response. These boosted Mid Bass frequencies give the amp a "punchier" feel.
    If you hook a CD player up to both the PA head and the Bass head for a comparison you might be able to tell that certain Mid Bass frequencies are being boosted while other frequencies are not as pronounced. If you have a pink noise generator you could find the exact frequencies that are being boosted. Many guitar amps also have certain frequnecies boosted (as well as having poor deep lows) and are not very flat like PA amps.
  4. Petebass


    Dec 22, 2002
    QLD Australia
    I've decided that pre-amp / power-amp arrangements don't do a bass guitar justice. I've posted a couple of threads now titled "Watts Watt with power amp ratings" which asked why my 400w head coupld easily overpower a 4,000 watt PA. Lots of suggestions were offered but I think redneck has the best answer so far - Bass heads are made for Bass, Power amps are made for PA. I know I'mm gonna get shot down for saying that but I've tried both and I listen with my ears, not my eyes. I don't care for a spec war on paper, I just wanted know what works best.
  5. Petebass


    Dec 22, 2002
    QLD Australia
    Allow me to back-pedal a little bit......It seems that the pre-amp / power-amp is not only common in the USA, but most of you seem to use brands of amps more commonly associated with PA's.

    Here's something I didn't consider. Bass amplification companies such as SWR, Eden, GK etc all make power amps. It would be interesting to hear from those of you who have tried these out.
  6. Soundtech power amps aren't particularly well-regarded in terms of quality and they tend to overrate their power. Your SWR simply puts out more current more consistently. There was a Soundtech 1000 watt amp at a theater where I worked and the amp was crap. Same program material, same levels, same speaker cabs, I could bury it with a 300 watt BGW that was ancient. If you fed the Soundtech ANY kind of low freq's, there was an immediate and noticeable drop in volume.

    AMJBASS Supporting Member

    Jan 8, 2002
    Ontario, Canada
    If I am correct, the SWR Triads are not very efficient cabinets. That could account for lack of volume as well.
  8. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    In defense of the SoundTech, I use a PS802 also. I use it to drive a Musicman HD-210 and a Hartke 115XL. I use one channel to drive each cab. I have gigged with this setup and I was able to obliterate the drums volume wise.

    I won't claim that the SoundTech amp is the answer for everyone, but it has worked quite well for me.
  9. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Don't be amazed by one amp being at full gain and the other being at 12 o'clock or 1 o'clock or whatever. That just means that one has more gain than the other, but not necessarily more power. Different amps, different preamps, et al, may and usually do have different gains, but that's why the manufacturers put knobs on them--so you can adjust them and make them work together.