AMPEG V4B..more CLEAN headroom?

eyeballkid · #1 12-18-2010, 07:38 PM

ok.. so i searched for this, but all I found was a bunch of people talking about modding V4Bs for 6550s, or for more overall volume or so on...

What Im wondering is this: I LOOOOVE my V4B. Its loud enough. Its got 7027s in it and thats FINE.. but what can I do to get a tad more clean headroom out of it before it breaks up? Its got a 12AU7, 2x 12AX7s, a 12DW7, and a 6K11 in it. If I change out a 12AX7 for an additional 12AU7 would that help? I saw some posting that talked about changing a Linear pot to a vintage ampeg audio pot with a curve ratio.. would that do it?

or????

basically I like to get it where the amp cooks along punchy and awesome as it can be and just get a touch of overdrive when I dig in, but it seems that when Im riding that spot where the clean tone is GORGEOUS if I dig in or hit a pedal that a little hot the tone goes into full overdrive that breaks up toooo much. Id like to ease into it more OR just get more clean headroom before that happens.. btw I usually am running it at about 11pm on the volume dial, so it would SEEM like I should be able to go a good bit more before it breaks up. Its hard to believe that in the 70s amps were being made to have less than half of their available volume be clean..

any ideas?
thanks in advance.

coreyfyfe · #2 12-18-2010, 07:56 PM

6550s wont give you more clean headroom. They have a different tone, certainly, but the output is limited by the transformer. My advice is a bigger cab.

JimmyM · #3 12-18-2010, 08:09 PM

Quote:

Originally Posted by coreyfyfe

6550s wont give you more clean headroom. They have a different tone, certainly, but the output is limited by the transformer. My advice is a bigger cab.

he's using a fender 610 now.

there's not a whole lot you can do, ball. it's still going to be a 100 (some say 120w) amp, and any little extra gains you might get out of it will be meager.

coreyfyfe · #4 12-18-2010, 08:09 PM

Quote:

Originally Posted by JimmyM

he's using a fender 610 now.

there's not a whole lot you can do, ball. it's still going to be a 100 (some say 120w) amp, and any little extra gains you might get out of it will be meager.

Time for an 8x10

jellymax · #5 12-18-2010, 08:14 PM

some brands of output tubes break up earlier than others...

eyeballkid · #6 12-18-2010, 08:23 PM

yeah, Im not looking for 6550 mods or anything, or to get more power out of it.. just wondering if changing preamp tubes or something will give me just a touch more clean before overdrive. Im not going for any more volume, just wanna stave off the overdrive for a teeny bit more..

so its not a bigger cab issue either cos the overdrive/grind would happen at the same point on the dial even if it was thru a 210.. (well, maybe not cos it would probably kill a 210 at that volume...but.. you know)

eyeballkid · #7 12-18-2010, 08:24 PM

jelly: can you recommend a brand with "late breakup"?

I<34080 · #8 12-18-2010, 08:26 PM

Quote:

Originally Posted by coreyfyfe

Time for an 8x10

two of em

coreyfyfe · #9 12-18-2010, 08:40 PM

Quote:

Originally Posted by eyeballkid

so its not a bigger cab issue either cos the overdrive/grind would happen at the same point on the dial even if it was thru a 210.. (well, maybe not cos it would probably kill a 210 at that volume...but.. you know)

You wouldn't have to turn up as loud with 2 more speakers pumping thus you may have the slight bit of room you're looking for. I read the first line in your original post about the 6550s as being on your list for consideration, my bad.

With the V4, it really depends on the type of distortion you are hearing. My guess, if you are putting the volume that high you are getting power amp distortion, which means you'd have to get some really late-distorting 7027s. If you're heading pre-amp distortion (just as likely, but I'm guessing you're hitting power tube distortion) then you could try swapping in some lower gain pre-amp tubes in the 12ax7 slots (maybe a 12au7?).

eyeballkid · #10 12-18-2010, 08:44 PM

yeah, Im thinking its preamp distortion cos the break up is a little on the thin side (loses a little low end) as preamp tubes are more likely to do than power tubes IME...
I think I will try out the lower gain pre tubes...

does anyone know what some "really late-distorting 7027s" would be? cos I would be willing to try that too.

Jim C · #11 12-18-2010, 08:45 PM

My V4B would break up at about 11:00 on the volume knob with a standard Fender bass.
More effecient speaker cab(s) is the only solution other than going to an SVT which sounds different. Personly, I like the sound of the V4B with 7027's best but the 100 watts didn't work that well with my new ineffecient, small cabinets.

coreyfyfe · #12 12-18-2010, 08:53 PM

Quote:

Originally Posted by eyeballkid

does anyone know what some "really late-distorting 7027s" would be? cos I would be willing to try that too.

Some sellers rate their tubes for distortion characteristics (I think groovetubes is who I'm remembering, and it was 6L6s that were rated). With 7027s you're kind of limited, I think sovtek and JJ are the only ones making them, and I tend to prefer JJ tubes over sovtek just based on personal experience/preference.

pharaohamps · #13 12-18-2010, 09:08 PM

It seems like you're looking for more volume before breakup, right? Right now you don't really know where the distortion is coming from: preamp, power amp, transformer, speaker, etc.

The first thing to try is an efficient speaker cabinet. A newer cabinet with high power handling capacity will probably not be as efficient as the type of cab that was originally sold with the V4B. A lot of older low-wattage speakers could produce 95 dB of SPL with a 1W input at 1 meter, where a newer driver might do 87 or 89 dB. That's a big difference when it comes to keeping up with a drummer on stage. I've got a couple of 1x15" cabinets with Eminence Legend 1518's that are 101.8 dB SPL at 1kHz at 1 m. The cabs are also 2 feet by 3 feet, so they're pretty much impossible to move around compared to an LMII or something

That said, I've run these two cabs with a 120W 4 x 6L6 power amp and it hangs with a drummer and a loud guitar player just fine.

You can certainly reduce the amount of gain in the preamp by changing tubes, but the 6K11, 12DW7, and the 12AU7 should be left alone. The two 12AX7's are the individual channel preamps and these are the ones to try. I would probably put a 12AY7 or a 12AT7 in the channel 2 slot and then you can A/B the changes. You might even be able to use an A/B switch to select the two channels for different amounts of gain if you're feeling frisky.

I'd try a couple different cabs first, that will make the most difference in your tone and volume. If you have some other tubes lying around swap them out, by all means, but I'd probably not waste a bunch of time with it especially if you have to buy anything.

I'm with Jim C - the V4B sound with 7027A's is one of my favorite rock bass tones, and I'd rather just get the right cab(s) to pair with it. Good luck!

eyeballkid · #14 12-18-2010, 09:18 PM

thanks for the tip Pharoah on changing just one of the 12ax7s to A/B it.. thats the best kinda of genius..the simple kind!

I agree that tonally it is the SHIZNIT!!!! It sits in the mix in a way no amp ever has. Ive tried it with lots of cabs, tone wise my fave is the fender 610 for it, and the compliments I get back that up.

At first I thought it was the speakers getting overmaxed by the amp, but then I sat with it and listened and watched and listened and watched and... well... you get it.. and realized "nope, not the speakers".. Im pretty sure its preamp tube break up.

Jim C · #15 12-18-2010, 09:25 PM

Don't mean to rain on your parade but I think you are asking too much from a 100 watt amp. if you have access to a 100 watt Bassman, this would illustrate the point. Totaly agree with Pharaoh about speaker cabs.

eyeballkid · #16 12-18-2010, 09:29 PM

Point taken Jim, but I dont think so.. Im really not trying to get it louder, and I know what you mean.. really.. I do... I understand the limitations of 100-120 watt tube amps and headroom.
Im not trying to get SVT power and headroom, just a smidge more OR a gentler transition into overdrive. you know, those minor tweaks that can make a world of difference in an amp. So, Im just looking for folks' experiences that may nudge me into the magic "AHA!"
On the cab front, Im really hoping to lock down a Berg NV to put with it.

jastacey · #17 12-18-2010, 09:30 PM

I've had a V4-B and did all kinds of tube rolling and the only way I could get good volume with-out break-up is running it through a very efficient cabinet, I used a Berg. NV425 and/or a NV610, the sweet spot on those amps is very narrow

eyeballkid · #18 12-18-2010, 09:42 PM

aint it the truth.. that was one thing i saw in a previous posting that I mentioned that seemed to work for one fella where he switched out a pot from linear to curve and it gave a much wider sweet spot... I may have to track that fella down and ask him a few questions cos it seems like a cheap and easy switch to get a big payoff. how can you not like those words together??

JimmyM · #19 12-18-2010, 09:50 PM

i so don't get that move. your amp is still going to put out 100 clean watts no matter what you do.

eyeballkid · #20 12-18-2010, 09:58 PM

Jimmy: post 79 on this thread: Early '70s Ampeg V-4B Impressions

I take it that, yeah, youre right, the amp will only put out 100-120 watts no matter what, but by doing the switch the fella was talking about you would be changing the way the signal hits the amp thereby giving it a much more forgiving sweet spot. does that make sense?