Got my V4-B, But, volume is lacking

Discussion in 'Amps and Cabs [BG]' started by degroove, Oct 27, 2003.

  1. degroove


    Jun 5, 2002
    Wilmington, DE

    Got my V4b today! It is in good condition - still with factory RCA tubes. I have deduced its about a 73. Brought the amp home, plugged it into my SVT-HLF cab, and plugged in my P into slots one and two.

    Basically, the volume seems lacking and it distorts as soon as I crank past 3 o'clock. Is there anything I should check? Think it needs a retube?


  2. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    getting warmer
    Sounds like a V4B to me. Although, I'm actually surprised you got it up to 3 oclock before it distorted.

    Keep in mind that after all is said and done, the V4B is a 100 watt amp and it isn't difficult to hit its limits, especially if you're used to something with more power.

    You may want to consider adding a second cab.
  3. degroove


    Jun 5, 2002
    Wilmington, DE
    Wait, sorry!! I meant three notches past zero, not three. If zero is Six O'clock, then its more like nine o'clock. Not much clean headroom at all.
  4. chadds


    Mar 18, 2000
    Adding a second cab, is not a smart idea as it is not working the one you have. What is ohms of your cab? You might have some one who knows tube amps check it out. I've heard SVTs sound wimpy and gritty when they weren't biased properly.
  5. degroove


    Jun 5, 2002
    Wilmington, DE
    The amp has a selector. I tried 4 Ohms to match my cab and 2 ohms. Appartently with tube amps, matching impedance doesn't increase volume like on SS amps.
  6. You must match impedance. The amp has an output transformer which has multiple taps, so you can set the transformer to match the exact speaker load. This is important for the health of the amp, I won't explain the details here.

    Several things can cause poor volume and distortion. Bad tubes, or internal components going bad (a fried plate resistor from cranking it up with the impedance set on the wrong setting...or a coupling capacitor going, for example)

    Get the amp to a qualified tech, not just some clown at the local music store, but a real amp repair tech. Spend a few hundered and then you'll have a great amp.

    Depending on where I've set the imput sensitivity switch, my V4 stays pretty clean up till 12:00 or maybe a little past.
  7. notanaggie

    notanaggie Guest

    Sep 30, 2003
    P bass isn't too likely to distort the amp so fast as an active...had to re-read your post because I figured you had an active bass at first.

    Matching to speaker should produce the best results power-wise...mismatches change tone and can be bad for power tubes.

    Depending, you might want to try new tubes, if that has really old ones....old tubes lose emission and get weak. The best old ones worked a long time though, they might be OK.

    But no matter what, hold onto the RCAs even if the repair guy says they are never know. Do not let them get away under any circumstances, even if you end up getting it re-tubed for cause.

    Other issues include possible Ampeg version of "Fenderitis", one symptom of which is low bias on preamp tube due to cooked plate noted by NVB, although I doubt that an output mismatch would do it. That would distort faster than it should.
  8. degroove


    Jun 5, 2002
    Wilmington, DE
    Thanks for you input!

    I am going to get it chekced out by a tech!
  9. Mine starts to distort at about 11 o'clock on the volume knob, which is about the 3rd tick mark, so I think you'll find out that the amp is working fine. I'm not familiar with your cabinet, but if it's one of the modern kilowatt-rated cabs, it's not going to be very loud with 100 Watts going into it.

    The old tube amps really need big efficient cabs to get high volume with low input power. Can you try it out with a big old Ampeg or Peavey 2x15 or something like that? The tradeoff is that you have to get a huge heavy cab with high quality speakers to get high efficiency, but the improvement in sound is well worth it. The original V4B cab was a 2x15 folded horn, so 100 Watts through it would probably sound like 500+ Watts through a modern low-efficiency designed cab.

  10. LarryJ

    LarryJ banned

    Dec 12, 1999
    Encino, CA (LA)
    I wanted to post from a player's POV rather than
    offer a technical opinion, but first, yeah, by all means have the amp checked out by a competent tech (maybe PBG makes house-calls!)-A re-bias, a new set of power tubes or a pre-amp tube, etc. could all be a big factor.
    OK- from a player who uses a new SLM V4BH-
    This head is the 'grail, one of them anyways, for my style, again one of them, of music-R&B, Blues-Rock and hell, everything.
    IMO, it's not about volume, although it can go there, It's about the tone from that Ampeg circuit. If you need max volume, then the SVT takes care of that, but I feel that the V4 gets proportionate headroom to its 100-watt RMS all-TUBE power section. At either 4 or 8 ohms, it should have enough volume equal to a SS amp with a higher rating.
    If you play music that requires thundering bass, the V4 may not be the right choice. Tone-wise it's a keeper for ANY style, and if its volume and headroom are enough for your band, enjoy sounding great.
    Hope you get the power you need technically so the amp works for you as well as mine does for me.
    Peace Out!:D
    BTW: I only get distortion when I want it, by overdriving "volume" and controlling it with "master". Other than that it stays real clean. Believe the older V4's had volume pot only.
  11. degroove


    Jun 5, 2002
    Wilmington, DE
    My amp specs:
    Frequency Response (-3 dB): 48-18KHz
    Maximum SPL: 125dB
    Nominal Impedance: 4 ohms
    Program Handling: 800 Watts
    RMS Handling: 400 Watts
    Sensitivity: 98dB
    Usable Low Frequency (-10dB): 28Hz

    Here is my problem - I don't want to change the whole rig. I love that cab. I could add a 15. I just don't have the money to all that.

    What would a huge heavy cab with high effiency be?
  12. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    I wouldnt worry about the speaker you have... its already heavy enough and plenty efficient. Leave the impedance selector at 4 ohm. Best advice is to get it to an amp tech.
  13. Well, that cab looks pretty efficient if it's 98 dB/1W/1m.

    There's a pic of the original V4-B 2x15 cab at the GG Jaguar site, but he must be over his bandwidth limit cause it's inaccessible right now.

    Like others have said, maybe your amp is a little out of whack, but I bet that servicing it is not going to make a night and day difference on the volume level. New caps may help the headroom a little bit and while not really doubling power output or anything magical like that, they can definitely improve the overall sound and response.

    Just for giggles, you ought to find a really big old 2x15 or 1x15 cab and try the amp out with it to see if it makes a difference. The older Peavey 2x15 Black Widow cab and the 1x15 Black Widow cab can usually be had for $150 to $200 bucks and they sound amazing with a V4B. Be on the lookout for one of those and it just may replace your 4x10.

    I realized about 10 years ago that the speakers are just as important, if not more important, than the amp. Some of the old speakers are simply amazing at what they do to help your sound.

  14. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    getting warmer
    98 db is sensitive?


    the Eden 410XLT handles something like 700W and has a sensitivity of 110. My Aggie 410 handles 700W and has a SPL figure of 104. Just using one of those casb will increase the volume noticably, with the Eden, theoretically, being twice as loud.

    If what you are looking for is a relatively clean tone, the V4B is not going to give it to you unless you play very softly.
  15. Are those SPL's 1Watt/1meter? Or maximum SPL at full power?

    In other words, since those numbers come from different manufacturers, we don't know how they truly compare. I think 100% efficiency (impossible in this imperfect world) would be like 108dB/1W/1meter, so I think that 110dB SPL is at 700 Watts or so. Just my guess.

  16. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    Either way I dont think the problem is cabinet efficiency. The 410 HLF is fine with the V4. He said the amp starts distorting when turned up just past 3 o'clock. It sounds like the amp is definitely the problem. Im only speculating but it may be a bias issue, old tubes, or a combination of the two. Best of luck...
  17. All Ampeg V4B's (and I think all old Ampegs) run out of clean-room at the 3rd notch (about 11 o'clock) in my experience, so that in itself is not a sign of a problem. They are very sensitive amps.

    Here's what I'm basing this on, my Ampeg V4B and B25B:


  18. The Eden's sensitivity is 106dB 1W/1M. Theoretically it'd be a lot louder than the 410HLF but the sensitivity spec doesn't tell the whole story. The way the cab is voiced makes a huge difference. The Ampeg cab has a lot more midrange than the Eden. I ABed a 410HLF and a 410XLT using my SVT a couple of years back. The Ampeg cab sounded just about as loud as the Eden at the same amp settings.
  19. my guess is that the amp is fine. I had one, but you can't expect them to get as loud as an SVT, or (IMO) even a 200 watt solid-state amp. I don't buy the whole tube is 300% louder than SS debate; I have experience with both. I'm just trying to save you money, tube amps don't generally require work unless something is wrong. This from my old tube amp tech guru.

    Nothing I've ever played thru sounds as sweet as an old V4B. I'd keep it and just know that it's not the volume monster you hoped it would be, but in a lot of situations it will do fine. I ended up selling mine because I thought I needed more volume (I didn't really, I had other options), and now miss it greatly. Matched with a good Fender, it's a great pair.


  20. degroove


    Jun 5, 2002
    Wilmington, DE
    I will try it Thursday with my band at rehearsal. See if I get drowned out or not.

    I could always mic my cab and run it into our PA like we do our drums.

    But, I still think its quiet.