I'm worried about my 70's Ampeg V4b

3l3phantstomp · #1 06-29-2011, 02:46 PM

Lately, after practice, the back metal plate (where the jacks for speaker outputs, cord wrap braces, etc are) feels MUCH hotter than normal. Even with bass fingers, I can't touch it long.

Its not "smoking" or making strange noises, but once over the last month it did cut out for a couple notes.

I've practiced at least weekly and giged about once a month for the past three years with this thing and its been BEYOND surefire.

Funny thing is, I got more compliments on its sound last saturday night than ever. So its sounding good.

My question: Circumstantial due to hotter months upon us/playing harder due to recent surf gig preparation (IE is use a factor?), or is it time to bite the price bullet and get it checked out by a tube amp tech?

I appreciate your time, Sages of Tube Amps.

JimmyM · #2 06-29-2011, 02:48 PM

Probably not a bad idea to take it in. Cheaper in the long run than blowing a transformer.

beans-on-toast · #3 06-29-2011, 03:16 PM

Having the sound cut out is a concern. Like Jimmy said, have it checked out.

It is possible that the tubes are running hotter because the bias has changed. See if the tubes are glowing red while you are playing.

If a tech goes over the amp and all is well, consider buying a small portable fan that you can tilt up and blow towards the back of the amp. Also, don't position the amp so that the back is boxed in, it needs room for air to circulate.

MAMMOTHvolume · #4 06-29-2011, 04:22 PM

Quote:

Originally Posted by beans-on-toast

Having the sound cut out is a concern. Like Jimmy said, have it checked out.

It is possible that the tubes are running hotter because the bias has changed. See if the tubes are glowing red while you are playing.

If a tech goes over the amp and all is well, consider buying a small portable fan that you can tilt up and blow towards the back of the amp. Also, don't position the amp so that the back is boxed in, it needs room for air to circulate.

careful with using a fan to keep your valves cold, you might end up breaking them.

+1 on circulation though, you been keeping anything on top of your amp lately?

3l3phantstomp · #5 06-29-2011, 05:35 PM

The one time it cut out was for three notes in a riff and only once. Honestly I doubted myself at first for the amp is clutch. Thought maybe it was the overwound pickups in a ratrodded squire pbass I don't use much. But there's no denying the heat.

Appreciate the advice. It isn't boxed in (open air behind, stairway), and they fore sure glow but closer to blacklight party style than a red filament in a lightbulb).

I don't keep anything on the amp to save it from beer punishment. But the thing roars and most items get tossed off from vibration so I've learned the hard way thru broken phones, bottles, tunes,etc.

I love this thing like an appendage and am not hesitant to get it checked over. It's just money's tight and the good Doctor charges upfront for evaluation.

J-O · #6 06-29-2011, 05:54 PM

Take it in to reputable shop and have it looked at. Once I got some new pre-amp tubes and had them properly biased my V4B put out a lot less heat. I have mid 70' s model, and I absolutely love it. Totally worth the tlc it took to get it set up right.

3l3phantstomp · #7 07-13-2011, 08:11 AM

Just heard from the good doctor. Turns out I needed extensive work on the pre-amp circuit, pre-amp tubes, bias love, etc. Thank gawd I got it in there! Can't wait to get it back and fire it up.

JvN · #8 07-13-2011, 09:31 AM

3l3phantstomp, check out Ampeg V4.com | All Ampeg All The Time, too. That's where the specialists for this model live. Apparently your amp needs some repair anyway, but overheating is a common problem with the V-4, especially the bass version. So if you're going to have it worked over, think about having a fan installed, too. That would be the best solution to cool down those huge transformers and their surroundings.

3l3phantstomp · #9 07-13-2011, 09:40 AM

Good advice. I'll take a $50 fan installation over my $289 repair bill anytime. And ill start vamping those sites. Gotta give it a go on the TH too, however, for these knights of bassface are wonderful. And most likely members/participants there as well.

JvN · #10 07-13-2011, 10:58 AM

Can't be helped that playing vintage stuff costs money and muscle. But you can't beat the sound once you've heard it... Only thing that doesn't do that to you is a vintage bass guitar, probably. Those bastards even stay tuned over the years...! I'm gonna put my tuner on eBay and buy myself a spare tube

.

pgk · #11 07-13-2011, 12:23 PM

it's just me, but i think fans are to be avoided whenever possible. if one is needed then so be it; if i owned a vox ac100 the first thing i'd do would be to add a fan. anyway, if i needed one i would think of wiring it backwards, so that it's pulling excessive hot air Away from tubes and transformers, rather than having it blow Towards those parts. if is very very hard to position a retrofit fan so that it is blowing equally on everything. side mounting is particularly bad, because you're blowing the bulk of the airstream across only one tube while the others get very little, simply because that first tube is blocking the airflow. and that could actually make matters worse than before, due to the now very different temperatures from tube to tube. just food for thought is all...

iiipopes · #12 07-13-2011, 12:31 PM

Don't forget power tubes. As power tubes die, the grids can go first, soaking more amperage which means more heat. That happened to my Marshall 2203 guitar head I got for cheap because the prior owner did not do that, and the plastic vent grill on top of the amp actually melted. It's OK, however: it looks cool, and I have a place to put spare preamp tubes in the "well" created as the plastic sagged from melting.

Regarding the above posts: fans - not needed if you keep a few inches clearance to the heads as you set up. Remember, they all had to get a UL rating when new for such. Also, fans can add much unwanted electrostatic noise to the amp. So unless the amp is designed for a fan, don't add one.

JvN · #13 07-13-2011, 12:34 PM

Absolutely right, pgk! You gotta think about it an be careful. From the thread I understood 3l3phantstomp had a good tube doctor though. I'm no techician at all myself, and there have been threads on Ampeg V4.com | All Ampeg All The Time on the subject - also on positioning the fan.

Epidrake · #14 07-13-2011, 12:43 PM

I know I have to bring my V4 in for servicing. I have been avoiding giving it up for any length of time. Any good techs for these in the NYC or Long Island area?

Glad you fixed yours before you had a serious problem. Hope I can too.

3l3phantstomp · #15 07-13-2011, 12:57 PM

Sound advice yet again! Luckily it was only heating up in the back, and its mostly metal back there. I'll update next week when I get it back and play its face off in honor of our reunification.

Love the melted marshal! I'm all about melting audience face, but am wary of melting amp face...

On a side note, one rad thing that happens is when I flip the power on, it spits a spark straight out from the bottom of the switch...nothing big, but something its always done. Maybe that will change as well when I get it back.

Epidrake · #16 07-13-2011, 01:01 PM

Can't wait to hear how it works out.

3l3phantstomp · #17 07-13-2011, 01:21 PM

That ampegv4.com site has a section on the forum with workshops listed by state. Ohio only had heads up on for sale units, but ny may be more active...either way Id toss a new thread out on the main amp TB page.

3l3phantstomp · #18 07-22-2011, 12:01 PM

This head is back like a vertibre! As J-O stated, its runs cooler than it ever has. I now not only have a greater appreciate for how the amp works but for how the amp sounds when serviced properly as well. The rebirth is upon us.

anonymous02282011 · #19 07-22-2011, 12:02 PM

Quote:

Originally Posted by 3l3phantstomp

This head is back like a vertibre! As J-O stated, its runs cooler than it ever has. I now not only have a greater appreciate for how the amp works but for how the amp sounds when serviced properly as well. The rebirth is upon us.

so what was done to rebirth it?

3l3phantstomp · #20 07-22-2011, 12:36 PM

Retubed, rebiased, connections and switches cleaned. The doc even replaced a nut that had fallen off an external speaker cabinet input jack. The heat was caused by it getting out of bias, most likely from taking a face dive two years ago while leaving a gig, combined with a pre-amp tube fading out.
I can't say enough about how rugged old tube heads are. Mine fell from the top of the 4x10 cab face first into sidewalk concrete and the only visual damage was some dings on the metal corner covers. Worked perfect for weekly practice and twice monthly giggin for two years until this summer. My guitarist uses a old fender dual showman head and while driving when he shouldn't (way late, after a gig, intoxicated, to see a lady) launched his car off the road, into the grassy median, back onto the road and then limped it to a waffle house parking lot with a messed up axl, wheel well body damage, wires hanging down all over the wheel, etc. The head was in his front seat and was floating around in the air the whole time (knocked his rearview mirror down). The amp was fine, not a tube jostled! My v4b ate concrete face and didn't even break a tube. While I agree there is a TON of luck involved in these situations, I give most of the credit to the manufacture. I for sure agree with this oldschool poster.