Ampeg V-4B: The All Tube Bass Amplifier

In the last couple of months, Drink the Long Draught has become much more tangible; you might say that we are now a band. With that realization comes a certain amount of excitement and the anticipation of playing live again. Except for the three songs Ant, Nic and I did at Jesse and Tara’s party back in January, it’s been quite a few years for me. In fact, I still have all the same equipment that I had in 1998, when I last played and recorded with The Fontanelles. The time has come to think about some new gear.

This upgrade process really took off when I went to Guitar Center to look for a case for my 1977 Gibson G-3 Grabber. I ended up trying out a bunch of new amp heads, including one of the Ampeg solid state models and the well known, tube driven SVT (model 3 Pro, I think). Ampeg has long had a reputation for exceptional bass tone; and today the company puts a good deal of effort into perpetuating the air of superiority that survives in the bass-playing world. Nonetheless, these amps sound quite good. I left the shop tickled with the idea of Ampeg but discouraged by the high price.

A few days later I found myself in Ken’s Music Center, my local store in Lititz, where I spotted a gorgeous looking Ampeg B-15 from the early 1960s. I asked to play through it, which they kindly obliged. Amazingly warm and solid, but still well defined. That tone, combined with the cunning flip-top design makes this one of the most sought after amplifiers for recording bass. But at only 30 watts—and with a price tag of $1300—I left the shop confused. I want this amp. It is not right for me. Damn.

Enter the Ampeg V-4B also known as Ampeg V4B or Ampeg V4-B

While fretting of the choice of bass amplifier, I found the product review database at Harmony Central to be really helpful for getting an overall impression of the various product lines. I honestly don’t know where I first came across the Ampeg V-4B, but I do remember someone writing that it was the next best thing to the SVT. Not long after that I found one for sale in Philadelphia—a 1973 unit with new power tubes, a new power cord and in rather nice shape for a 35 year-old amp.

The Ampeg V-4B is a two-channel, all-tube, 100-watt beast of an amp head. I weighs a good bit…maybe 70 pounds. Like many electronics of the early and mid 70s, the design of the cabinet and control face is Spartan—black and silver. On the far left are two input jacks. Five knobs in the center of the panel control channel 1 gain, channel 2 gain, treble, mid-range, and bass, respectively. Above the EQ knobs you’ll find three boost switches: High frequency boost; a three-position Mid-range boost that emphasizes 300Hz, 1kHz, and 3kHz; and Bass boost. Finally, on the far right are Standby, Polarity and Power switches, with indicator lights above standby and power.

Having spent several years playing bass through a Hartke 3500, I became accustomed to using—but never entirely happy with—the graphic equalizer. Sure, a graphic EQ is precise, but I tend to spend too much time fiddling with it. With the Ampeg V-4B controls, I find I can ‘dial in’ a very distinct tone in few seconds. The boost switches have a particularly dramatic effect on overall tone.

Around back of the Ampeg V-4B

First thing you notice from the back is that the amp chassis is upside-down, that is, the tube and transformers ‘hang’ down from the chassis/circuit board. I guess this is a fairly common design strategy that allows for, among other advantages, the positioning of the front panel controls near the top of the unit.

The back of the amplifier features two 10k Ohm line outputs, two external speaker outputs and a hum balance potentiometer. Also printed on the rear of the chassis are the tube designations. This unit uses a quartet of 7027 power tubes. I understand that 7027 power tubes were no longer made after some point (mid 1980s?). For that reason, many V4-Bs have been converted to use 6L6 power tubes. My unit was never converted; and the recent re-introduction of 7027 tubes by Sovtek means that this amp should sound as close to Ampeg’s original design as possible. (Barring the use of expensive vintage 7027 tubes).

The pre-amp section of the V4-B employs 2 ECC83/12AX7 tubes, one ECC82/12AU7 tube
, one 12DW7, and a 6K11 tube.

But how does the V-4B sound?

Warm, creamy, and throaty, with a pleasant distortion at high gain. And that’s using my frakencabinet—what once was a Hartke 210 combo, from which I yanked the 3500 head, removed the carpet, cut off the head enclosure, and spray-painted a metallic charcoal. The drivers are missing their dust caps, too. This thing is ugly, but temporary; I’m sure the amp will be much happier with 4 or 6 10s, or 2 10s and a 15. The current set-up is ample for rehearsal.

Ampeg SVT-15E speaker cabinet on the way…

At our last rehearsal, I noticed that I was having a little trouble cutting through the guitar. A few samples of the rehearsal recording bore that out, i.e., it wasn’t just me. I think we all have a tendency to play more aggressively and crank up as we become more comfortable with our material. So it seems my 2×10 cab isn’t going to cut it for rehearsal; it starts to blat (I think then Jesse Lundy term was “shit the bed”) when the V-4B is set somewhere between 4 and 5 on the volume knob. I’d like more control of my tone and also avoid “digging in”, which I am prone to do.

« Here’s the Ampeg bass rig as it appears in July, 2008.

After some dawdling, I decided that I should add a 15-inch cabinet like the Ampeg SVT-15E Classic Series 1×15 Bass Enclosure as the next step toward improving my sound. The band has an outdoor gig coming up at the end of July, and it is time to provide more power and presence. I’ve come very close to buying a new 4×10 bass cabinet, but since I have the 2×10 cab, I’d like to get some more use out of it…I am hopeful the SVT-15E will be the right complement. At 8-ohms and 200 watts, it seems like it should be a good match. And, if I ever need more power, I’ll replace the 2×10 with a 4×10…maybe a Ampeg SVT-410HLF Classic Series 4×10 Bass Enclosure.

29 thoughts on “Ampeg V-4B: The All Tube Bass Amplifier”

  1. I have the same amp only replaced the tubes with kt-66 (EL-34s on steroids) Great sound same power limitations. I suggest getting a THD Hotplate and running the line out function into a large rack power amp. I use a 1000 watter. Run that into any 4×10 and you should be way good. I like that way more than using my SVTcl. Seems like a lot of extra gear but well worth it.

  2. Ahhh… if you like that amp, see if you can find a Music Man 115RH loaded with a 15” EV. I got one used for about $175, it’s not too heavy, comes with wheels & sounds awesome.

  3. Ah, So I have V4-B That I’ve had since 1976 with an 810 cabinet, I had it repaired a couple of times. Once the stanby switch got stuck in the on position and I played it that way for years I would just turn it off, The other time a busted fuse holder and a new power cord. I always liked it but always remembered the sound of the SVT. I stopped playing for some time (got a real job) but recently went to get together with some friends to give the old chops a work out, needless to say they need a lot of practice, Anyway the amp had a lot of noise (leaky cap) and I took it to a local guy who got rid of the noise but somehow the amp does not sound the same, there is no treble presence and does not seem to have any attack or punch. He says he set the bias correctly to the new old stock 7027A’s that I found on the web from some government surplus stock.
    Last weekend I went to someone’s house and there was an SVT-VR which just blew me away and quickly started to look for one. They’re very expensive!!!
    So, in the interim I found your blog and was glad to hear your fondness for the V4-B.

    I just think I may send it to NJ to get it checked out by Dennis Kager, he can bring it back to life.

    Thanks for the inspiration.


  4. JJ/Tesla now makes the 7027A power tubes for the Ampeg V4 and V4B amps. What a great amp. Match it with a pair of good 15’s for that thick classic rock bass sound.

  5. Thanks for the tip, Rich. It’s almost time to re-tube my V4-B, and greater tube availabilty is definitely a good thing.

    I’ve been using an SVT3-Pro as my main gig rig lately, and a very happy with it. The tube preamp and driver give a nice warm tone and the solid state power section is a bit tighter and much more powerful than my V4. Still, the V4-B is a fine creation. I do love the high gain sound, particularly with my Gibson Grabber. It’s pretty tough.


  6. Don’t F with the V4-B! SURE, the SVT is nice. You can pay a TON for one, and have a nice sound. You can also spend the same money on a PC and Pro Tools……but we are talking about a thing of History here. A Bass Monument.

    Why is it called the V4-b?

    Because of the origional V4. A guitar head. That kicked so much *ss BASSISTS had to have them. That is something to think about in itself! After realizing this, Ampeg created the v4-b. A thing of majesty. Thirty years later, STILL melting face.

    In my completely biased view, the V4-B is the reason Ampeg became the bassist’s rocket launchers of choice. Sure, you can dump a load of cash on the SVT and sit upon the modern throne of Pricey Provided Providence. Or you can spend time in the trench of historic elbow grease: find a V4-B andtube it out any and every way that scratches your itch.

    I fell asleep to this amp reverberating the heating ducts below my crib while my father practiced with his band. I played with my GI Joes all over it. I danced to it growing up. And ever since it was handed down to me five years ago I rock the thing out three days a week. Hard. Last year it fell off my stack (damn end-of-gig concrete door jam) four feet and landed flat on its face in a parking lot.

    The tubes didn’t even break. The metal corner gards have some new dimples. That is all. I still can’t believe it.

    I’ll stop. V4-B for life (or hernia from carrying. Then its time to hand it down to my son, buy an SVT and drive the complimentary Cadillac that comes with it).

  7. I bought my 1977 V-4B and have since paired it with my 1975 (Eminence loaded) V-4 cab and I’ve played it at gigs with my 1972 810 Squareback (CTS loaded).

    You can have all the new, flashy gear you want. I LOVE MY Ampeg rig and it’s never leaving my possession. Mine still has all the original tubes (7027’s rock) and works like a champ.

    Pics of my stuff are at this website:

  8. I have a Schafer 100 W bass Amplifier and it is the only thing that this Upright Bass Player can be satisfied with as far as pleasing my own ears with as well as a Punk Rock audience which I havn’t done since the Early 80’s with T.S.O.L. when Music was in its Pugilist Stage…. How Quaint .. I am an Offshore Roughneck Now Days….

  9. I bought a V4-B about 19 years ago. It was used heavily,
    the faceplate is worn off clean, te lettering long gone. It has RCA
    tunes in it. I have played this head through a 60’s Traynor 6-10
    cabinet for about 16 years, loading it into a 1962 Willys Jeep
    Utility wagon and bouncing it from Philadelphia to Connecticut
    without a hitch! Finally after all this time it blows fuses, it is
    going to Central Jersey Music Service and Dennis Will fix it, and
    on will come another 19 years of amazing tone, clarity, warmth and
    in my opinion the best bass head ever made–you only need a SVT if
    your ego demands more watts. I also feel the smaller wattage makes
    this head possibly more reliable than it’s SVT bigger brother. I
    could never use another amp period! The only thing that would be
    better is a footswitch for this amp to switch the boost
    settings…If you see one BUY IT!

  10. hi fellas!! I´m from buenos aires , argentina, and of course have a vintage v4 b in perfect condition. still has the complete original magnavox set of tubes. only a small resistor’s been changed, and I changed the ac plug for a strong three pronge hubbell. cabinet is copy of an svt 18, with the original square dual magnet jensen driver. it sounds like a locomotive no matter which bass one could plug in it. I’m 66 now and I play bass since about 1969. be sure I’m gonna die but my v4b´s sound will last till the end of time. many times people offered fortunes, but never thought on getting rid of the beast. I really lovit!!
    an advice from an old timer rocker: KEEP ON PLAYING AMPEG TUBE BASS AMPS…bye

  11. PLEASE Help me!! I bet my boyfriend I could find a Manual for the V4B – free! Guess what…
    I haven’t been able to…YOU seem like just the person with expertise and experience to give me a healthy link OR perhaps even you might have one I could copy?? Please let me know …Thanks, CARLA

  12. I have owned my 1970 Linden, NJ V4B for several years and I play through an SVT 8×10. Love the sound – so much so, I bought a second one from 1976 with matching 4 x 12 and I’m having it gone through by Eldery Amplification in Des Moines, Iowa. Robert is fantastic. I can’t wait to get it back. The one from 1970 is so nice that it will live in my studio and be played often but not lugged around. I’ll get a road case for the other one. Anyone have a recommendation for a quality road case for the head?

  13. I have a V4B (1970) a few yrs ago (maybe 20) I changed the power tubes (couldn’t get orig around here) to 6550’s. Great sound. Had to change some other components to match but suits my needs. I play all kinds of country (classic to curren) old rock and bluegrass. It gives me a sound as near to a stand up bass as I can get. as long as I can carry it I will use it. Orig it had a 2 15 cabinet (still have it) but bought a 1 18 (liked the deep sound). Altho the V4B is a 100 watt amp, I’ll put it upside a 300 watter anytime. Well, you can see I like it so…………..

  14. I have a 1971 V4 which has never had any tube replacement. I was recently told by a tech at a music store that the 7027,s need to be replaced every 80 hours. If this is true then my amp is around 4/500 hours overdue! Another local tech disagreed and said that if it’s not broke then don’t fix it! HELP!, what is the straight scoop? What about the other tubes? Do they need periodic replacement? Within the last two years the power-on light has started flickering, the local tech says this may indicate a problem. What do you think? I have read so much stuff about all this that I’m not sure what to do. I purchased the V4 amp and matching V6 Cab 2×15,s for $500 in 71.It’s in excellent condition. A recent bout of,”Temporary Insanity”, caused me to consider parting with it, but I started back on my meds and that passed,(Whew!). The very positive comments on this blog have helped me to decide to never sell it. (Besides I’ve held on to it longer than anything else in my life!) Thanks, Johnny

  15. Thanks for the post, Johnny. I doubt very many players replace tubes after 80 hours these days. A quartet of 7027s isn’t exactly lunch money. 🙂 It also depends on how hard the amp has been driven and handled. If I were you, I’d consider getting a new set of power tubes and try them out, but don’t discard the old ones (mark their positions, because the biasing depends on the tubes’ locations). The preamp and driver tubes only need to be replaced if you (or a tech) suspects a problem—often easy to diagnose by tapping on the tubes or swapping out one at a time (don’t do this with the power tubes, always swap them as a set).

    In my limited experience, the power capacitors on most vintage amps will need to be replaced eventually. They dry out and become less effective at filtering. Generally not a DIY job unless your comfortable working with high voltage capacitors.

    I highly doubt the flickering power light means anything other than the lamp itself is failing. If the thing turns on and sounds good, then it IS good! Who needs a pilot light? You’ll know when this this is ON.

    Keep giving that Ampeg the TLC it deserves!

  16. Just an update on my V4-B. It went to Dennis Kager and he gave it a once over, replaced a few things and gave it a cleaning. It is also a Linden (Pre Magnivox) amp. I recently had to re tube it, the sylvanias finally gave out. I put in a set of JJ 7027 tubes. They sound a bit brighter, though maybe it’s me but I feel like some warmth has been lost. When these burn out (one year if gigged, up to 5 if played at home/occasionally) I think I am going to pay the extra green for USA made vintage tubes.-just my opinion for anyone considering JJ tubes–

  17. Hi, I´ve got a V4B which doesn´t work anymore. So i gave it in repair. The guy told me, that it seems to be that there are still the original tubes in it and they all have to be changed. Also some contacts on the board have to be soldering.
    So it will cost 400€.
    Is it worth to repair the amp ????

    ( I hope you understand what i want to say, cause i don´t know the right words in english)

  18. Hi Ben,

    In the US, a full set of tubes for the V4-B currently costs around $170 US. If the tubes are original, then it is also likely that the board will need to be re-capped (new filter capacitors) which could easily run over $100 US. Factor in labor, and availability of parts in Europe and 400 Euro may not be unreasonable. It may not be worth it to you, but someone will want this amp and be willing to repair it, because it is legendary!

  19. Thanx for your quick response,
    I think I spend the money for reparation. I realy like this amp, but i found some sites were it was sold for $500 or 700€, so this was the reason, why I didn´t know if it is worth to repair it. And 400€ aren´t less money for me.
    While searching for the price of n V4B I also looked for other ampeg-amps, I started thinking about how to use the second input chanel, cause I didn´t use it when I played this amp years ago! On new amps the second often has -15dB. But i think this isnt the same at the V4B. Can you tell me somethink about it?
    Thank you very much !

  20. You can do some of the work yourself to save some money: order the tubes, replace the preamp tubes, etc. But the amp will still need to be biased and probably re-capped by a professional.

    Regarding the two inputs, you are right: They both have the same gain, i.e. one is not -15dB.

  21. Question for all you passers-by: if you have had a V4B professionally repaired, who did the work? We’re you satisfied? Don’t forget to mention where you are located!

  22. Im in the process of nagotiating a trade for my 1981 silverface Fender Bassman 135 for a mid 70’s V4B. The question here is: as a bassplayer is it the right move? I like my fender tone, but have obviously wanted to play ampeg alltube for a while now. Convince me guy!

  23. Stephen, if you like your Fender tone, maybe you should keep the 135, because it’s a very good amp, the best for bass that Fender ever made. Repeat, ever made. The V4B is a better amp, and it can do things a Fender can’t, like have really deep, fat, clean lows, but it doesn’t drive like the Fender unless you dial those lows out, and it uses a weird pre-amp tube (6K11) that is no longer made and can’t be “converted”. Today, the price for a 6K11 is $30 US. The good news is, it only needs one, but if you like the Fender blues/rock drive, you may already be home. FYI, the V4B is happiest on top of a B25 cabinet, it fits perfectly underneath and usually has 2 Altec 421a drivers in a ported baffle, switchable 4 or 16 ohms. The cabinet designed for the V4B was a rear loading folded horn with the same two drivers, but because of the configuration, it couldn’t be heard on stage. The wave length was so long, the front 20 rows couldn’t hear it, either. In outdoor shows, legend has it, you could still hear it miles away.

  24. The V4B with its matching V4B cab containing 2X15’s is the way to go with those heads. I used one for 10 years during the 80’s and only got rid of it when I moved long distance and couldn’t haul it with all of my other gear so had to sell it.

    I replaced the original eminence speakers in the cab with 15″ Altecs with the metal domes. That made all the difference in the world over stock speakers. I played every club on the Jersey shore and never had an issue with volume and in fact the sound men we used were always asking me to turn down.

    100W tube power is a whole lot different that transistors. Tubes don’t create thet freakish resonance many tube amps create. Power wise you need at least 500W or more transistor power to compete with a V4B using 7025 tubes.

    I’m not sure why they used 6l6 tubes in the reissue. You can buy the newer 7025 tubes now and the extra 20 watts they produce and the kind of tone they produce would make me double think buying a reissue head. Still the Ampegs have the best bass amp tone of them all. After all, they were the first to amplify bass. Their name comes from amping the peg (the peg is the bridge area of and upright bass) and they have had the correct tone for bass in nearly all their models.

    Its good to see they are reviving the workhorses preferred by most bass players. All thet fancy circuitry is fine for guitarists who have to be versatile. Bass simply need to be a solid as the drummer. His playing skill can do the rest.

  25. Bill, today’s production of 7027A’s is nothing differrent than 6L6GC relabeled. There is no current production 7027A tube which handles more B+ voltage or power than 6L6GC, so they’re pretty.. identical… just with different naming.

Leave a Reply

Your email address will not be published. Required fields are marked *