Ampeg SVT Cabinet Questions

Discussion in 'Amps and Cabs [BG]' started by Mr Cup, Apr 24, 2001.

  1. Mr Cup

    Mr Cup

    Mar 2, 2000

    I am trying to decide between 2 cabs to use with an SVT Pro 3 amp, either SVT 410HLF or SVT 410HE. I have read the specs for both from the ampeg page, but don't understand them totally.

    The HLF is bigger in dimensions and weighs more, fine. The problem I have is trying to understand what the following are:

    HLF HE
    Freq. Response (-3 dB) 48-18KHz 62-18KHz
    Maximum SPL 125dB 122dB
    Nominal Impendance 4 ohms 8 ohms
    Program Handling 800 watts 400 watts
    RMS Handling 400 watts 200 watts
    Usable low freq. (-10db) 28Hz 43Hz

    I don't understand what these mean exactly, if anyone could help me with any of this, I would appreciate it. I am assuming that the HLF is more powerful because of the higher wattage, but am unsure.

  2. Well, if you plan on using only one cab with your SVT-III then it makes more sense to use the HLF cause its a 4 Ohm cab where the HE is an 8 Ohm cab. The difference being that you'll get more power out of your amp at 4 Ohms than you will at 8 Ohms.
  3. cb56


    Jul 2, 2000
    Central Illinois
    If you are planning on using 2 cabs get the 8 ohm cab. that way you can add another cab later.
    2 8ohm 410 cabs at 450 watts will be louder than 1 4ohm 410 cab at 450 watts
  4. MikeyD


    Sep 9, 2000
    The HLF is designed to have a deeper bottom end below your A string (whose pitch is typically at 55 Hz.). It can also take twice the power of the HE, which is why its max. loudness appears to be 3 dB higher.

    BTW, I notice big discrepancies in specs for the HLF between Ampeg's catalog and their web site. I tend to believe the latter, which gave (last I looked): freq. resp. 50-18kHz (-3dB) and 40 Hz. (-10dB).

    You should also consider the other comment in this thread relative to impedance.

    - Mike
  5. I_Dream_Of_Bass


    Feb 8, 2001
    For simplicity sake, I will only explain the meanings for the HLF, but the definitions are the same.

    The first spec is the Frequency Response of the cabs. It will reproduce frequencies between 48Hz and 18kHz with a deviation of 3dB. I think that the frequency of a low B on a five string is about 30.87Hz (You were right Oysterman...just found the page with all of the note frequencies...doh!), just so you have a reference. The -3dB means that over that entire spectrum of frequencies, the overall difference in level is within a tolerance of 3dB. For instance, 800Hz might be at 0dB, but 100Hz might be at -3db (thus sounding quieter) and 5kHz might be at -1dB. Ideally, you would want the largest frequency range possible, with the lowest deviation for that range, as close to 0dB as possible.

    The next spec is the maximum Sound Pressure Level tolerated by the speakers before severe damage occurs. At 125 Max SPL, you would have to be beyond the threshold of pain for normal ears. Typical rock concert sound levels are approximately 110-115dB at the speakers.

    Nominal Impedance is the expected resistance level of the input signal. It is EXTREMELY important that this level matches the output on your amp, and that you realize how connecting additional cabs to your amp will affect this level. Generally speaking, for two cabinets whose only difference is resistance, the higher the resistance, the more power a cabinet can safely handle. If you plan on using more than one cabinet, you should opt for both cabs having 8-ohm resistances. This will keep you from melting an incredibly expensive amp. The more resistance that you have, the more power you will require to achieve the same sonic volume.

    Program Handling would be the Peak Level of power that the cabinet can handle. Peak power being a very short very loud increase in wattage going to the cab. This might be a slap, pop, or possibly, plugging into the amp while it is on and at full volume.

    RMS Handling is the sustained level of power that the cabinet was designed for. For example, the cab is designed for 400wattRMS. That means it can safely handle 400watts of power continuously while you play, with short, occasional spikes up to 800watts. So if you were running 1100watts at full volume into this cab, it would be toast.

    As I stated, I'm a little rusty on the technical side of this so I may not be exact on some of my definitions. If you have any other questions, or someone notices some errors with this, please post and I will edit mine accordingly.

  6. Oysterman


    Mar 30, 2000
    One correction I could come up with: it's 30.9 Hz. :)
  7. MikeyD


    Sep 9, 2000
    Dream, I thought most of your comments were good. I have a few to add...
    I don't think power handling and resistance (impedance) are necessarily related. You can have a tiny 8-ohm speaker, for example, that will fry with 10 watts RMS input, or you can have an 8-ohm speaker the size of a house that will sneeze at 50,000 watts.
    I think what you have in mind is that the amplifier must be capable of higher voltage in order to achieve the same power output at a higher impedance. Given two speaker cabinets of the same design, one with a 4-ohm impedance and the other with 8, both will be equally loud with the same *power* input. However, the 8-ohm cabinet will need 1.4 times the voltage input as the 4-ohm cabinet to receive the same power.
    - Mike
  8. I_Dream_Of_Bass


    Feb 8, 2001

    The first comment I did in the opposite direction. I'll change my post accordingly for that. What I meant was that for two speakers whose ONLY difference is resistance, the higher resistance will generally be able to handle more power than the lower resistance.

    The second comment was related to a dB measurement. If you increase the resistance, for the decibel measurement to remain constant, you must increase the wattage accordingly. I do not remember the exact calculation, so I cannot say if it is voltage or current being increased. I think though, that you are right about it being voltage.
  9. Nino Valenti

    Nino Valenti Supporting Member Commercial User

    Feb 2, 2001
    Staten Island NYC
    Builder: Valenti Basses
    I don't know about all this technical stuff, but I had an SVT III PRO & an SVT 410 HLF & it sounded great!!!! It handled my B string extremely well. When I bought it, I compared it to 2 410 HE's & a 410 HE+115 & I like the sound better from the HLF & there was less to transport!!!!
  10. MikeyD


    Sep 9, 2000
    Thanks for your reply, Dream, but I'll stick by my previous comments (i.e., I still disagree). I guess we can cordially agree to disagree. :)
    - Mike
  11. Mr Cup

    Mr Cup

    Mar 2, 2000
    Firstly, thankyou to everyone for your advice, it has been very helpful to me, particularly I Dream of Bass. At the moment, I am leaning towards the HE (its HEN, is that the same?) mainly because its cheaper. I intend to buy another cab later on, but at the moment I think it will have to do. Is it a good cab, does anyone know?

    I have just a few more questions. IDOB, you said that a cab with a program handling at 800 watts, and RMS at 400 would take short spikes at 800. So what your saying is that the 800 is a safe guard, am I right? That you wouldn't run close to 800 watts continually or it would destroy the speaker?

    Also, you said that a higher resistance cab would be able to handle more power than one with a lower resistance. I don't understand, I would have thought that the opposite made more sense!

  12. MikeyD


    Sep 9, 2000
    The 400 watt RMS rating corresponds to the continuous rating of the speaker. It means you can run an amplifier rated for up to that power output (into the impedance of the speaker you are using) without incident unless you overdrive the amp into clipping. If the amplifier clips regularly, you can damage a speaker in some cases. I would ignore the peak or program rating, since it is mainly marketing hype. It has to do more with either the momentary (i.e., non-continuous) power handling of a speaker or the peak sine wave power corresponding to the average power of the same sine wave. I recommend simply looking at RMS continuous ratings.

    This is why I took exception to the other post. A cabinet rated for a higher impedance will not draw as much power from a given solid-state (non-tube) amplifier. This does NOT mean it can handle more power. It means that, in order to get the same power into it as a cabinet with a lower impedance, you need to get an amp that *would* put more into the lower impedance cabinet. It gets confusing, which is why I replied before. Simply look at the amplifier's RMS output rating for the impedances you are considering connecting to it. If that rating is reasonably close to the cabinet's RMS power handling, then you'll probably be fine, as long as the amp is not driven into clipping.

    - Mike