HELP w/ Ampeg B3 115

Discussion in 'Amps and Cabs [BG]' started by heretic, Jan 23, 2005.

  1. I recently aquired an ampeg b3 115 combo (discontinued) from a pawn shop for $320. Did I do good?

    Ok, question: Is it safe to turn volume up past half (5)? I have done it a few times but every once and a while I will get this ungodly beep or a poppingcrackle noise. I play pretty aggressively and I like to dig in. Its 150 watts BTW. Not sure how to explain it. Kinda scared to test it out...

    Second: What exactly do the knobs do?
    Gain: ?
    Drive: ?
    Bass: duh.
    Ultra Mid: assuming its the same as mid.
    Treble: yeah.

    Its just Gain & Drive that need explaining.

  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Gain is probably the gain of the preamp to get the best signal to noise ratio. Drive would imply that there is some sort of onboard overdrive circuit...but I'm not sure. Ampeg Insider could give you an exact answer.

    My local Sam Ash has a very nice used one for $350...sounds like you did OK.

    A beep? Like something is vibrating and interrupting the circuit? If so, take a short instrument cable and jumper the effects loop first and test it, then take the same cable and jumper the preamp output/power amp input jacks (assuming that the amp has them. Other similar Ampeg models sometimes have problems with the switching jacks getting corroded...vibration could do some weird things too if they're not making a good connection.

    Is the nut on the input jack tight? If not, vibration could be making an intermittant ground connection.

    Have fun!!!!
  3. mikeyvr6

    mikeyvr6 Supporting Member

    Feb 19, 2002
    Plymouth, Wisconsin
    Hey Billy, is that the Sam Ash in Buffalo Grove? If so, that was mine! I traded it in on my V4 a few weeks ago. It is a solid little combo that served me well.

    I figured they'd slap a price like that on it. :scowl:
  4. Well its more of a screech than a beep... I'll try out what you said in the morning, parents are sleeping right now :meh:

    as for the cracking sound, that only happens when I play aggresively. I guess it has something to do with the gain/volume ratio? I'm not entirely sure on a good setting... im a newb :(
  5. well I messed around with the gain and its fine now. except for when I pull the master volume out (activates 2nd eq) it still does that screeching sound for a few seconds :meh:

    Thanks for the help
  6. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Gain is just really the input volume....use it to match the preamp to the bass by turning up until the preamp peak LED flashes when you play about as hard as you intend to.

    Drive is indeed an overdrive "harmonic enhancer". It adjusts overdrive AND does change the overall tone setting also when turned up. Adjust to taste........

    A screech might be any of a number of things....including just plain old feedback from speaker to the instrument. That's gonna happen at high gains if you get close to the speaker.

    If it is dependent on the setting of the various gain/volume/master etc on the instrument and the amp, that's probably what it is, feedback.

    I can send you a PDF of the manual for the B3 if you would like. It's about a 350kb file.
  7. I don't think its feedback, the guitar is nowhere near it. I have the gain at about 6 o'clock and volume is around the same. I cant mess with the second eq because everytime i touch it it gives off a pop/crack sound and when I pull out the switch it still makes the noise... kind of like a buzzer at a basketball game, very loud too. Sometimes happens when I just try to turn up the volume. All of the LEDs light up when it happens too. I think its crapped out... :crying:

    EDIT: I found the manual earlier, thanks anyways.
  8. Fujibot


    Feb 9, 2005
    i have recently gotten my hands on a ampeg amp, i am unaware of the year, but it is a B3 and it has some neat features,

    100/115VAC 50/60Hz~TSA SLO-BLO
    230VAC, 50/60Hz~T2.5A SLO-BLO

    ....? i have no idea what it's telling me here lol sopmeone help me, anyways there is a medal plate on the back that gives model number serial number line and watts

    Model: B-3158
    Line: 120 V~xx
    Watts: 500

    does anyone have an estimate on what i shold have paid for it lol so i know if i got a deal..... please e-mail me or post a
  9. kirki5443


    Dec 23, 2010
    i saw that you worked for ampeg and wanted to ask you why the b3 on my bench makes a pop/crackle sound when you crank the input and drive even at low volumes sounds like a cap motorboating,the gain also goes lower after 7-8 settings ,im suspecting ic1 a tlo74cn ic ,any ideas?
  10. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    My thought is that the clip light may be drawing down the 16V supply voltage. The 16V is a zener and resistor type supply, and if there is a worst-case set of parts, that already is marginal for supplying current, the LED may cause the 16V to drop and make a noise much like motorboating.

    if the input is high, the first stage at test point 1 can have a clipping level of output and drive the light
  11. kirki5443


    Dec 23, 2010
    you mean the limit or the peak led ? a quick measurement of the + and neg 16v rails shows no sign of going low infact they are both on the high side closer to 17v pos and neg?ok maybe a power supply issue?,the 42 v lines are also slightly higher 43v's
  12. kirki5443


    Dec 23, 2010
    the motorboat sound only happens when i use my tone generator at 300hz's,but when you play a bass or guitar aggressively threw it it pops and crackles hard ,plugged it into a different cab across the room still does it [rules out bad connect of any kind]
  13. kirki5443


    Dec 23, 2010
    turns out it was the tlo74's 2 of them are bad causeing that sound ,.they are quad opamps use in the preamp stages and some how were damaged internally cause some really bad clipping i replaced both of them and now the unit plays fine
  14. den_gerten


    May 18, 2011
    I bought a B3158 2 months ago.
    It has some noise, but I thought i could solve it, but no chance.
    The amp is silent when no notes are played. With every note, there is some noise-buzz in the sound.
    I got the speakers out and put them back in with no success.
    I tried the amp trough mij H&K 4x12" guitar cab and I think the noise is in there too (less because they are different speakers).
    I hear it best from the high output, but I think also from the low.
    Must be something in the circuit, anyone have an idea?
  15. kirki5443


    Dec 23, 2010
    the tlo's in there are your op amps and are cheap and failing when you put sound threw them i replaced ic1 and ic 3 with standard replacements from digi-key and the noise goes away! hope this helps:hyper:
  16. den_gerten


    May 18, 2011
    How can I find the OP amps easily?
  17. kirki5443


    Dec 23, 2010
    if your asking me where to purchase said op amps ,go to

    if you are looking for them in the amp ...the ones your looking for are on the same circuit board that the pots are on and they are labeled right on the board...ic1 and ic3 they are 14 pin ic chips and say tlo74 right on the chips you will have to get the board loose enough to flip it over and unsolder the 2 chips and replace them. They are static sensitive so you have to take caution as not to static the new ones ,although they are really inexpensive per chip,if you haven't done this type of soldering work you should take it to a tech who has and let him know what we think the problem is ,if you have then it is easy to swap these out,i would suggest purchasing 2 ic sockets to put in first,because of the circuit design is really hard on these 2 chips so you probably will have to replace them again if you play that amp at high volumes alot :bassist:
  18. den_gerten


    May 18, 2011
    Sorry I took so long to answer, I'm kinda busy.
    I found IC 1 and 3, but 1 is a "2060D JRC M0061G".
    IC 3, 4 and 2 are TLO74CN, IC 5 is TL07.

    On the other print (the back one) has IC 1 and 2 TL074CN, but I think I just understand something wrong.

  19. kirki5443


    Dec 23, 2010
    what model is this again?:confused:
  20. den_gerten


    May 18, 2011
    it is a B3158, 230V model.