Yeah, I was going to mention this. When my amp tech unmodded my Bassman (was modded w/ 6550s) he made sure to test the transformer. I wouldn't do this mod if you're going to play a lot.
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Ampeg V4-B: Any mods to make more output?
- Thread starter Groover
- Start date
Yeah, I was going to mention this. When my amp tech unmodded my Bassman (was modded w/ 6550s) he made sure to test the transformer. I wouldn't do this mod if you're going to play a lot.
What BassmanPaul said. Not only the power transformer, but the output transformer in any tube amp is designed to pass only so much current before it gets hot and melts down as well.
Advice: recap as necessary. Use quality tubes. Use efficient speakers of the proper total impedance to match the amp. Then rock out.
Advice: recap as necessary. Use quality tubes. Use efficient speakers of the proper total impedance to match the amp. Then rock out.
While I will agree that the V4B is loud as hell, and easily keeps up with my Mesa 400 as well, I have noticed that on hot outdoor gigs with long sets it starts to get pretty creamy quicker than bigger amps would. I've done a few sets now on hot nights where the V4B is ready to die by the end of the set. This isn't really an issue though unless you're playing in +45 degree (celcius, sorry I'm Canadian) for more than an hour. I suppose installing a decent cooling fan would also help.
Can you say Air Conditioning??
And don't you apologize to no one for being Canadian! It has been a strange summer eh!
Paul
It certainly has been hot. Air conditioning for outdoor gigs has yet to be invented though as far as I know. The band picked a bad summer to start playing outdoor festivals.
I do a LOT of outdoor gigs during the summer. Gets really hot out, but there's usually a breeze of some kind. I haven't had a problem.
It gets really humid around here as well, so that could be a contributing factor. And I'm also not saying that my v4 has ever failed me, it just breaks into distortion sooner near the tail end of a long set in extreme heat. It actually sounds pretty killer at that point, but it's not for everyone.
- Apr 3, 2003
- 35,516
- 19,953
- Disclosures
- Editor-in-Chief, Bass Gear Magazine
Okay, I realize that this post is not exactly on topic with the OP's original question, but this is the most current thread with active participation from my favorite "V-4B experts," so I thought I'd toss it out here, instead of starting a new thread.
I have a client who wants to sell me his V-4B and B40 cab. I just picked them up yesterday to give the rig a try and see if it all works. Well, it does, but it's in need of some TLC. It looks like everything's there, but the rocker switches on the top are a bit dodgy (particularly the hi boost, which seems to do nothing 90% of the time you switch it, but occasionally seems to work). From my best guess, this appears to be a mid 70's Magnavox era V-4B (white rocker switches for Power & Standby, square-corner black lettering).
My main questions would be what do folks think of the Magnavox-era V-4B's, compared to other V-4B's, and what things should I look for, service-wise. The jacks seem to be a bit intermittent, and likely need a good cleaning or maybe some solder work. The pots definitely need cleaning. It doesn't hum too bad, but it has sat mostly unused for probably 20 years (it's not mint, though - it has seen its share of gigs, just not recently). The seller did gig with it a good bit in the '80s, and unfortunately, he thought that it would be cool to paint the grillcloth black...
Lettering is good, though.
The B40 cab is a bit more beat up, cosmetically, but it sounds like all the drivers are functional. Actually, the brief time I played this rig last night, once I got all the switches/pots/jacks to play nice, it sounded pretty darned good!
I'll try to snap some cell phone pics over lunch.
Any feedback/comments/suggestions/estimates of value would be welcome.
Thanks, Tom.
I have a client who wants to sell me his V-4B and B40 cab. I just picked them up yesterday to give the rig a try and see if it all works. Well, it does, but it's in need of some TLC. It looks like everything's there, but the rocker switches on the top are a bit dodgy (particularly the hi boost, which seems to do nothing 90% of the time you switch it, but occasionally seems to work). From my best guess, this appears to be a mid 70's Magnavox era V-4B (white rocker switches for Power & Standby, square-corner black lettering).
My main questions would be what do folks think of the Magnavox-era V-4B's, compared to other V-4B's, and what things should I look for, service-wise. The jacks seem to be a bit intermittent, and likely need a good cleaning or maybe some solder work. The pots definitely need cleaning. It doesn't hum too bad, but it has sat mostly unused for probably 20 years (it's not mint, though - it has seen its share of gigs, just not recently). The seller did gig with it a good bit in the '80s, and unfortunately, he thought that it would be cool to paint the grillcloth black...
Lettering is good, though.The B40 cab is a bit more beat up, cosmetically, but it sounds like all the drivers are functional. Actually, the brief time I played this rig last night, once I got all the switches/pots/jacks to play nice, it sounded pretty darned good!
I'll try to snap some cell phone pics over lunch.
Any feedback/comments/suggestions/estimates of value would be welcome.
Thanks, Tom.
Initial service would most likely include replacing all electrolytic caps, Cleaning all pots and switches and resoldering all connections on pots and switches and any other questionable looking connections. Pots and switches may need replacing if cleaning does not take care of the issues noted. Preamp tubes are probably OK unless there seems to be a problem. They could be pulled for testing. The output tubes (if it was me) I would replace, keeping the old tubes safely put away. This along with a general cleaning should bring it back up to snuff.
Look to see if any modifications have been done as well. The 7027 to 6550 mod was common while 7027s were out of production. If it's a later magnavox (curved lines, post-'75) they were supposed to have beefier power transformers which were spec'd out for 6550s as part of a "performance package." I've seen that some people feel the older ones could suffer from long term 6550 usage (this also depends on who you ask, some experts on here say 6550s draw too much current from the PT, other techs I've talked to and read posts/articles from say they can handle the extra current just fine). Plus, if it's been around for a while, someone somewhere has probably opened it up and tinkered. Always good to have someone give it a once over and get things back to (or at least close to) stock IMO.
The jacks/pots may been cleaning. I have a friend who just picked up an early V4 and the sensitivity switches are a little squirrely. Probably worth it to clean out and re-tension the tube sockets if anything is wiggling around.
The jacks/pots may been cleaning. I have a friend who just picked up an early V4 and the sensitivity switches are a little squirrely. Probably worth it to clean out and re-tension the tube sockets if anything is wiggling around.
Not sure about late vs early V-4Bs but from what I have read they don't have substantial differences in the circuit over the years. I had two later models.
I had one fitted with 6550s and another with original 7027s. Those seemed crunchier when overdriven which I liked better. The one with 6550s which sounded a bit softer in the overdrive. Didn't notice much difference in clean tone, both were nice. Can't say that one was louder than the other.
They suffer from heat buildup especially with 6550s. Mine had a few traces lifting off the main circuit board. Once that happened, the solder points were subject to more mechanical vibration. A few components ended up getting a bit charred, mainly power resistors. The lifted traces can be hard to spot but the charring was easy to see.
If you can, pull the amp out of the box and give the boards a close inspection.
I had one fitted with 6550s and another with original 7027s. Those seemed crunchier when overdriven which I liked better. The one with 6550s which sounded a bit softer in the overdrive. Didn't notice much difference in clean tone, both were nice. Can't say that one was louder than the other.
They suffer from heat buildup especially with 6550s. Mine had a few traces lifting off the main circuit board. Once that happened, the solder points were subject to more mechanical vibration. A few components ended up getting a bit charred, mainly power resistors. The lifted traces can be hard to spot but the charring was easy to see.
If you can, pull the amp out of the box and give the boards a close inspection.
I have nothing to ad to this thread of a technical nature but only to chime in and agree with Spinal Tapper about the sweetness of the V4b thru the Orange 115. I bought my V4b a few years back looking for a good tube tone and hit pay dirt with the V4b. I believe I got very lucky because cosmetically, my V4 is in really fine condition. I'm not at all technical and have no idea what kind of tubes it has but it sounds (to me) great.
In the belief I might need more power, and out of curiousity. I bought an SVT CL and have to say that I never ever warmed up to the tone of the CL in comparison to the V4b. Age, back problems have meant that I don't get to use the V4b very much but if I get comfortable with one of my current projects enough, I may leave my O115 and V4b at practice and at least get the pleasure of its sonic heaven during rehearsals. If not, I may have to part with it.
In the belief I might need more power, and out of curiousity. I bought an SVT CL and have to say that I never ever warmed up to the tone of the CL in comparison to the V4b. Age, back problems have meant that I don't get to use the V4b very much but if I get comfortable with one of my current projects enough, I may leave my O115 and V4b at practice and at least get the pleasure of its sonic heaven during rehearsals. If not, I may have to part with it.
Tom - I have an early 70's V4 with the 7027's and this is most definately my favorite amp followed by my VB2 and LMIII. I think you should put money into and most likely you'll fall in love with the tone as many do.
I'd have to say it makes one of the best bass tones I've ever heard. I had mine re-capped and I added new JJ 7027's. Keep her around, you won't regret it.
I'd have to say it makes one of the best bass tones I've ever heard. I had mine re-capped and I added new JJ 7027's. Keep her around, you won't regret it.
Check out this link, go to the song "Trippers Anomally", I recorded this song on a Shure SM-27 Condenser. I'm using a P-Bass with Reissue 62 Pickups, an early 70's V4 and a V4cab loaded with Eminence Neodymium S2012's. This is exactly the tone I'm going for, straight vintage. This is a new band, so be easy. . ..
Link Removed
Link Removed
- Apr 3, 2003
- 35,516
- 19,953
- Disclosures
- Editor-in-Chief, Bass Gear Magazine
Thanks for all the feedback, folks! I'm definitely going to buy this rig. I had a V-4B a few years back, but it needed servicing, and the shop I took it to (in Cleveland) closed up shop and disappeared (with my V-4B!). 
This one is a keeper for sure, though. Here are the pics (cell phone, sorry for the lower quality):
It turns out that I also know the original owner of this head (my client is the second owner). It also turns out that the original owner etched his social security number in the back of the amp, so I had to edit that out. I'm not sure what inspired him to do that...
It looks pretty clean, and those appear to be the original tubes. My client did not know of any mods done to this amp.
Here's the back of the cab.
This one is a keeper for sure, though. Here are the pics (cell phone, sorry for the lower quality):
It turns out that I also know the original owner of this head (my client is the second owner). It also turns out that the original owner etched his social security number in the back of the amp, so I had to edit that out. I'm not sure what inspired him to do that...
It looks pretty clean, and those appear to be the original tubes. My client did not know of any mods done to this amp.
Here's the back of the cab.
Tom I'm envious. I've never had a chance to try mine thru one of the old Ampeg cabs, although I once tried it thru a Mesa 2x15 and it was pretty awesome.
Thanks for all the feedback, folks! I'm definitely going to buy this rig. I had a V-4B a few years back, but it needed servicing, and the shop I took it to (in Cleveland) closed up shop and disappeared (with my V-4B!).
This one is a keeper for sure, though. Here are the pics (cell phone, sorry for the lower quality):
It turns out that I also know the original owner of this head (my client is the second owner). It also turns out that the original owner etched his social security number in the back of the amp, so I had to edit that out. I'm not sure what inspired him to do that...
It looks pretty clean, and those appear to be the original tubes. My client did not know of any mods done to this amp.
Here's the back of the cab.
Tom
Those are GREAT amps. Those 100W go a long way. I really regret selling mine and I miss it to this day.
Those are GREAT amps. Those 100W go a long way. I really regret selling mine and I miss it to this day.
