# NAD: Ampeg V4



## Patrice Brousseau (Aug 12, 2020)

Cut and paste from my post on TalkBass:

« Pure GAS as I absolutely didn’t need it (but wanted...):


I don’t gig neither I will in the near future (not even one year of bass playing...);
it’s for studio/basement practice;
I already have two 45 watts Traynors (YBA-1 and YVM-1). Master at noon and gain at 2 is plenty loud with the Traynors...

Oh, and I don’t even have a suitable cab for it actually. I’ll check the local classifieds and look for something small and not too efficient (space and volume level contraints).

The owner dated it to around 72-73 (metal knobs). It has a quad of Ruby 6L6GC-M-STR (not sure they’ll handle the measured plate voltage of 545 for long but anyway...).

Not sure the can caps are originals but not sure they’re recent so I’ll replace them. I plan to use one JJ 100/100, two JJ’s 50/50 and one [email protected] discrete cap. It’s really quiet though upon brief testing with an iPod and a sacrificial Realistic Minimus 7 bookshelf.

The standby neon doesn’t work but I’ve read I should check the 180k resistor in serie first. The pot on channel two pops, crackles and hums at around noon. I suspect that the wiper loose contact at this point or is really dirty. I’ll have to take a look at it.

Reading a lot here and on AmpegV4 forums, it appears that the small differences between the V4 and the B is:


3 caps being .01 instead of .1. Doesn’t make a difference for a 4 strings bass, right?
Ultra-hi switch has 3 settings instead of two;
no Ultra-lo;
no reverb obviously in the V4B. For what it’s worth, it functions well in my case;
something else in the first stage (cathode caps?).

The other tubes are JJ’s 12AX7’s (I can easily swap them with some in my collection but they looks to be quiet), an EH 12AU7 (same thing, having a lot of old ones), an old 12DW7, an EH 6CG7 and an original 6K11. I will order a 12DW7 and a spare 6K11 from the TubeStore with the PS cans.

I didn’t check the voltages apart the first PS can and the plates, I’ll do it later.

I will also check resistors values, replace the two bias caps and implement a master volume following the later schematic. I’ll probably put the pot in the polarity switch hole: three prong conversion was already done in the past. Even the utility outlet is three prong...

For the last weeks/months, I’ve looked often for something in the same wattage range but GAS was under control! I saw an YBA-3, a Fender PA 100 and even thought to buy a new YBA-100... but I prefer vintage amps and the proudness and fun to bring them back to life.

I will also have to clean and verify the PCB’s as some are, let’s say... dirty!

And, at last, this thing is a monster at around 65 lbs but you already know that. I’m 5’7’’ and 125 lbs when I wear my shoes so it will never leave my basement »


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## Patrice Brousseau (Aug 12, 2020)

Since I acquired it (last week):

- Received my order of three JJ cans 50/[email protected], a NOS 12DW7 and three discrete F&T [email protected] All from TubeStore to replace the PS electrolytics (old Mallory’s);
-Awaiting an order from Fliptops for two 1meg linear pots (ch2 pot was busted) and two 6K11 as spares from a TalkBass member.

I’ll have to replace a couple of cracked caps on the board: one .47 and one 0.1. Being in there, I’ll replace C3, C6 and C7 to 0.1, to match V4B values. Two electrolytics in the first stage will also be replaced (15uf).

I already replaced the 12AU7 and the two 12AX7’s in ch1 and 2 with old good tubes from my stash.

As it is, even with a busted pot (made a hack pot with spare parts but it doesn’t track equal as the other one, hence my order at Fliptops), it is quite good sounding and quiet as temporarily tested on a sacrificial Minimus 7 speaker.

I’ll put a 500k log master following the later master V4 schematic.

**Already bought a cab for it last weekend at Archambault: an SVT-210 AV, plenty of volume for the home studio.


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## Frenchy99 (Oct 15, 2016)

Any pics ???


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## Patrice Brousseau (Aug 12, 2020)

Was posting them when you asked, sorry! Just above your post...

**Re-posted them...


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## Patrice Brousseau (Aug 12, 2020)

I have the case BTW, just removed it to look inside and then took the pics. Not in a bad shape aesthetically.


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## Patrice Brousseau (Aug 12, 2020)

Pics, reprise...


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## jb welder (Sep 14, 2010)

Nice. Are the rubbers for the shock-mount wings still in good shape?
I just lock the reverb on mine and use as is for bass. If no one has monkeyed around with the bias, they run the tubes cool enough you shouldn't have to worry about the high plate volts.
One of the filter caps in the totem-pole configuration has to be isolated from chassis if memory serves (negative terminal/shell sits at half of B+). That's why the insulator and cardboard sleeves. Careful with that.


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## Patrice Brousseau (Aug 12, 2020)

jb welder said:


> Nice. Are the rubbers for the shock-mount wings still in good shape?
> I just lock the reverb on mine and use as is for bass. If no one has monkeyed around with the bias, they run the tubes cool enough you shouldn't have to worry about the high plate volts.
> One of the filter caps in the totem-pole configuration has to be isolated from chassis if memory serves (negative terminal/shell sits at half of B+). That's why the insulator and cardboard sleeves. Careful with that.


Rubbers still in good shape, yes.

As for the cans, the new JJ’s I’ll put there are not metal: I’ll keep the fiberglass bases anyway. They will be completely isolated from chassis and I’ll keep the same connections to ground underneath. 

I will parallel each sections of two cans (50/[email protected]) and put them in series to achieve [email protected] Then, two [email protected] in series under the hood for the screens. All of this with [email protected] balancing resistors (four total).

For the preamp/reverb filtering: the remaining JJ can, 50/50, and a discrete [email protected] (the old can is 40/40/40).

For the reverb, I won’t use it...

Bias resistor is supposed to be 75k. Didn’t checked it yet but I will. This and measuring bias (shunt method) once all parts will be replaced.

Thanks,

Patrice


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## Patrice Brousseau (Aug 12, 2020)

Or less dangerous: measuring OT resistance and voltage... or adding cathode sensing resistors...


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## keithb7 (Dec 28, 2006)

I own a V4B, the bass version. Man its tone is warm and nice. Heavy? Oh my. The transformers are the biggest I’ve ever seen. Its like dragging a Twin Reverb around. Why? Because its worth it. It sounds awesome.


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## Patrice Brousseau (Aug 12, 2020)

I didn’t really started the final resto: just received the pots today... I don’t want to try it until the work is all done.

Reading your reply and the reviews, I’ll be in heaven!


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## Patrice Brousseau (Aug 12, 2020)

Finished since one week: just waiting for a new set of power tubes from the TubeStore.
The actual Ruby’s will be kept as backup. I will also need a new 12DW7/7247 as the one I got began to sound like « frying bacon » two days ago. In the meantime, the old one does the job, albeit with an higher noise floor...

No master volume added finally.

Only (good) problem now: I find my two Traynors (YBA-1 and YVM-1) lacking in comparison.


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## Frenchy99 (Oct 15, 2016)

Get a YBA-3 !


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## Patrice Brousseau (Aug 12, 2020)

Frenchy99 said:


> Get a YBA-3 !


No more space... unless one goes and another one enters. One 100 watters is enough!


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## Hammertone (Feb 3, 2006)

The V-4 is a fine amp for bass or guitar. Here's mine (that's me standing next to it for scale):


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## Paul Running (Apr 12, 2020)

How long does it take to dust it?


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## Paul Running (Apr 12, 2020)

Any special equipment to replace a power tube?


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## Paul Running (Apr 12, 2020)

No offense to frenchy99 intended:


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## Paul Running (Apr 12, 2020)

That's supposed to be a giant amphibian, Godzilla size.


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## Paul Running (Apr 12, 2020)

Pulling two tubes at once.


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## Patrice Brousseau (Aug 12, 2020)

Hammertone said:


> The V-4 is a fine amp for bass or guitar. Here's mine (that's me standing next to it for scale):
> View attachment 344043


Really love mine... Now to improve my bass skills! Running with an Ampeg SVT-210AV and just received a quad of 6L6GC´s Preferred Series from The TubeStore.

At first, I’ve gone through two quads of the Tung Sol’s 7581A but if I was forgetting to flip the standby switch at least 30 seconds after power on, there was redplate of one or two tubes 5 times out of 10. Not related to their sockets, random!

I’ve replaced the bias supply entirely, obviously power supply caps and all coupling and signal caps, a bunch of resistors, all diodes. After the firsts redplate episodes, I’ve re-tensioned the power tube sockets, re-flowed a lot of solder joints on the boards and on the sockets, cleaning with alcohol and Deoxit, no go for the Tung-Sol’s! I know the workaround is to use the standby switch as intended (at least 30 seconds after warm-up) but it wasn’t fun when I forgot. Interestingly, flipping on and off the standby switch when the red plating occurred was another workaround, strange!

The Ruby’s 6L6GC’s that came with it never showed any hint of instabilities or red plating BTW. Recent quad testing good, go figure!

I’ll try the Preferred Series later today and report back.

Patrice


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## Paul Running (Apr 12, 2020)

Patrice Brousseau said:


> At first, I’ve gone through two quads of the Tung Sol’s 7581A but if I was forgetting to flip the standby switch at least 30 seconds after power on, there was redplate of one or two tubes 5 times out of 10. Not related to their sockets, random!


Tube rectifiers would provide the 30 second fail-safe.


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## numb41 (Jul 13, 2009)

Hammertone said:


> The V-4 is a fine amp for bass or guitar. Here's mine (that's me standing next to it for scale):
> View attachment 344043


^^comedy gold. I actually did laugh out loud


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## Hammertone (Feb 3, 2006)

I'm here all week. Enjoy the veal. 

In addition to the V-4, I also have a VT-22 (the "portable" 2x12" combo version - identical amp, weighing in at a mere 88 pounds).


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## laristotle (Aug 29, 2019)

Paul Running said:


> Pulling two tubes at once


or just the one


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## laristotle (Aug 29, 2019)




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## Patrice Brousseau (Aug 12, 2020)

Hammertone said:


> I'm here all week. Enjoy the veal.
> 
> In addition to the V-4, I also have a VT-22 (the "portable" 2x12" combo version - identical amp, weighing in at a mere 88 pounds).


Portable? With the added combo weight, it must be impressive!

The head alone is over 60 pounds...


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## Patrice Brousseau (Aug 12, 2020)

TubeStore 6L6GC’s report: no redplate behavior with the standby switch and really well matched.

Plates running at 527VDC, I get 34.4 ma for the lowest one (measured through 5.3 ohms plate resistors) and 35.3 ma for the highest. Sure, they are brand new and things will probably change in the following days/weeks/months... and I hope, years but so far, so (really) good.

It’s around 61-62 percent dissipation. How long they will last, that’s the only unknown variable?

Cool looking tubes with their blue base and thick glass envelope. Shuguang got it right I think.

Patrice


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## Patrice Brousseau (Aug 12, 2020)

Paul Running said:


> Tube rectifiers would provide the 30 second fail-safe.


You’re right but in the meantime, the Shuguang tubes don’t care (Ruby’s or TubeStore own series). Only the Tung Sol’s had this « problem »...

However, some long time Ampeg owners and techs on Talkbass told me that the bias circuit was just barely adequate stock with the originals 7027A’s. Add to this new production tubes where quality and specs varies a lot and you could have problems... It’s the only way I could understand it, correct me if I’m wrong.


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## cboutilier (Jan 12, 2016)

Hammertone said:


> I'm here all week. Enjoy the veal.
> 
> In addition to the V-4, I also have a VT-22 (the "portable" 2x12" combo version - identical amp, weighing in at a mere 88 pounds).


I want one of those!


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## Paul Running (Apr 12, 2020)

laristotle said:


> View attachment 344294


I wonder if that's a permanent body-tilt, from hauling that SVT around?


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## Hammertone (Feb 3, 2006)

cboutilier said:


> I want one of those!


One of these? Come on down anytime.








FS/FT: - Ampeg VT-22 - @1973-75 - IN YOUR FACE - & a...


I'm selling my Ampeg VT-22 2x12" combo. A true classic, but I have too many of these amps that are not being used. I have spent my time on the Ampeg mountain and now it is time to share the joy. It's no creampuff, but it's in great shape for a 45-year-old amp. Just back from the amp doctor...




www.guitarscanada.com


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## jb welder (Sep 14, 2010)

Patrice Brousseau said:


> Plates running at 527VDC, I get 34.4 ma for the lowest one (measured through 5.3 ohms plate resistors) and 35.3 ma for the highest. Sure, they are brand new and things will probably change in the following days/weeks/months... and I hope, years but so far, so (really) good.
> 
> It’s around 61-62 percent dissipation. How long they will last, that’s the only unknown variable?


Is that with the stock bias circuit values or did you install adjustable bias? Sound like they are running hotter than usual for factory values. This would also be why the plate voltage seems lower than the 545V (ballpark) I'm used to seeing for this model.
Did you happen to measure what kind of idle current the 7581A's were running at?


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## Patrice Brousseau (Aug 12, 2020)

Yes, stock bias with new components, not adjustable.

For reference (sorry, a lot of copy/paste from Talkbass!).

*- The Ruby’s that came with it originally:*

_Plate voltage: 533 vdc

#1: 94 mv through 5 ohms: 18.8 ma plate current (33 percent dissipation);
#2: 173 mv through 5 ohms: 34.6 ma plate current (61 percent dissipation);
#3: 150 mv through 5 ohms: 30 ma plate current (53 percent dissipation);
#4: 98 mv through 5 ohms: 19.6 ma plate current (34 percent dissipation)._

*- Then, the first quad of Tung Sol’s I got from The TubeStore:*

_one of them draws 25ma and the others, around 40 ma...!!!!_

*- Second quad of TS’s:*

_The new quad is better balanced and idles at around 50 percent dissipation.

and...

Ok, shunt method (yes, I'm careful): 

57ma on one side, 59, on the other. 527 on the plates. Respectively 50 and 52 percent dissipation rounded values._


60 percent dissipation is fine for me. Yes, I could bias the new tubes cooler (with a pot or replacing the 75k resistor) but it’s inline with my two EL34’s Traynors (YBA-1 and YVM-1. They are around 55-60 percent dissipation too.

Please note that I’ve increased the first node filtering from 40 uf to 140 uf to reduce 120 hz ripple and noticed that it dropped the voltage a fair bit.

Plate voltage with the old caps or only new JJ cans in series 50/50 (paralleled)@500 was more in the 545-550vdc range.

It’s now JJ cans with another two [email protected] in series, totalizing 140 uf. This and the hotter quad explains that...


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## Paul Running (Apr 12, 2020)

Patrice Brousseau said:


> However, some long time Ampeg owners and techs on Talkbass told me that the bias circuit was just barely adequate stock with the originals 7027A’s


You could add a separate PS just for the bias, supplied by it's own TFM. This would isolate the bias from the main TFM.


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## Patrice Brousseau (Aug 12, 2020)

Paul Running said:


> You could add a separate PS just for the bias, supplied by it's own TFM. This would isolate the bias from the main TFM.


You mean another power transformer?

Thanks,

Patrice

**Anyway, the Shuguang are up to the task I think. Now, if I wanna lower the bias (50 percent, closer to Ampeg original), do I have to increase or decrease the 75k resistor (more negative or less)?


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## Paul Running (Apr 12, 2020)

Yes. A small TFM, it does not have to be large, virtually no current required. I have done it with other amps. I use TFMs that I have salvaged from equipment. A 24VAC TFM can be doubled and it would provide the required bias for 6L6s.


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## Paul Running (Apr 12, 2020)

Here's an example. This TFM produces 54VAC which is capable of producing 76V peak...filtered and divided would be reliable for down to -65VDC.


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## Paul Running (Apr 12, 2020)

He's a working example. This is a power supply that I use for experimenting when verifying power amps. The middle TFM is the source for providing the bias for most power tubes.


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## Patrice Brousseau (Aug 12, 2020)

Honestly, thanks for the advice (supplemental PT) but unless you tell me I’m in trouble with a bit hotter bias and lower plate voltages, I’ll let it be. It was on my bench for two weeks and now, it looks to be able to survive for a while. Not to forget that it is not the most « serviceable » amp on the planet


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## jb welder (Sep 14, 2010)

The thing with the Tung-sols was just weird. If you upped the value of the filter caps in the bias circuit, that will make the bias take more time to ramp up. But you didn't mention that so I assume not. 
Do you have a good -62V from the bias circuit? Did you change the .047 that feeds the bias diode? That one is critical, and I wonder if it could give problems like you had with the Tung-sols.

The increased value of the main filter caps I would not expect to drop the B+ that much. Sometimes new caps have leakage issues, hopefully yours do not.
For cooler bias, yes, you could raise the 75K value. Or raise the 56K at the other end of bias diode.
But I wouldn't change it if you are at stock values. I just asked before in case you had put in a pot or changed the values from stock.
If you are not getting the -62V, and you haven't changed the .047, that is where I would look.


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## Paul Running (Apr 12, 2020)

Patrice Brousseau said:


> I already have two 45 watts Traynors (YBA-1 and YVM-1).


May I ask if you have one that you favour over the others...or what is it, that you prefer over the other in setup and feel?


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## Patrice Brousseau (Aug 12, 2020)

jb welder said:


> The thing with the Tung-sols was just weird. If you upped the value of the filter caps in the bias circuit, that will make the bias take more time to ramp up. But you didn't mention that so I assume not.
> Do you have a good -62V from the bias circuit? Did you change the .047 that feeds the bias diode? That one is critical, and I wonder if it could give problems like you had with the Tung-sols.
> 
> The increased value of the main filter caps I would not expect to drop the B+ that much. Sometimes new caps have leakage issues, hopefully yours do not.
> ...


-62v is what I get so it’s fine. Lower plates, no idea? I know I repeat myself but bias components were all replaced, except the 56k (I don’t have any 56k in my resistors drawer, it measures 58k BTW). Kept all at stock values.

The JJ can’s for the power supply were brand new and the 180uf are less than 10 years old. They were in my electrolytics drawer.

Thanks,

Patrice


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## Patrice Brousseau (Aug 12, 2020)

Paul Running said:


> May I ask if you have one that you favour over the others...or what is it, that you prefer over the other in setup and feel?


It’s hard to tell and remember that I use them exclusively for bass.

In the two cases, minimal work was done: power supply caps, bias components and a couple of out of spec resistors. The mustard caps were left alone.

The YVM-1 is paired with a custom cab (bought for 60 bucks) with a 15 inch CTS square magnet and an hifi 3 way speaker with upgraded drivers.

It sounds really clean so I had to build an Alembic F2B clone for a bit of dirt...


The YBA-1 weak element is the cab: a 15 inch Marsland in what was sold as a Traynor but I’m not sure. I guess that putting anything else inside, like some Eminence Beta or Delta, would help tremendously!

I like the fact that it has two different channels and so far, I use the « guitar » brighter channel to counteract the dull, dark cab.

I would have to try it with the SVT-210AV to make a good comparison.

The unknown cab (in case someone could identify the brand). Not showed but there is a back panel with like 24 screws...


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## Frenchy99 (Oct 15, 2016)

Patrice Brousseau said:


> The unknown cab (in case someone could identify the brand). Not showed but there is a back panel with like 24 screws...


Early 70`s Pine electric ported 15 cab that we often see under the Riviera brand. I have the unported version of this cab.


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## cboutilier (Jan 12, 2016)

Frenchy99 said:


> Early 70`s Pine electric ported 15 cab that we often see under the Riviera brand. I have the unported version of this cab.


Yep! That's the cab for the Riveria/Pepco/Pine Model 725. I won the lottery and got mine with the RSC/Jensen instead of the Marsland.


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