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#38496 by Shredd6
Sat Aug 09, 2008 9:30 pm
Nathanial Hughes wrote:
Hey Shredd, thanks for the compliment! I went to school for Audio Engineering and Producing so that's the reason it sounds like it does. Plus I have a little obsession with layering things :) (Beatles fan). Very cool, thank you for helping me out. It means a lot! I'd say the ideal tone/sound I'm going for is that vintage "Invasion" sound but with a little more beef to it. I'd be interested to know what I would need to get for it to sound like it was originally stocked as well, because I might want to compare the differences and choose which one I like best.

Well Nathanial, that certainly is a good question.. I can't find anyone who knows what originally came stock in the vintage Vox amps.. So what I'm really forced to do is give my best guess. And that would be that they came stock with Mullards or Brimars.

The fact that Vox originated in England, it would only make sense. Mullards have been extremely revered since the 12ax7 was first introduced, and still are today. I don't see any reason to think that an amp company would want to import what they have right in their backyard. the early 60's mullards have a huge worldwide following for being the best 12ax7's ever made. Although that may be subjective, the Blackburn plant in Gt Britain produced great tubes.

As far as el84's go, Mullards and Brimars were also considered some of the best in the world along with the Sylvania 6BQ5/El84. And once again, I would think it would be highly unlikely that an amp company based in England would import Sylvanias for their productions.

From what I read, in 1960, Vox first introduced in production the AC30 tube amp that used 12ax7's. Considering that time period, and the popularity of Mullards, why would it be anything else?

I would have to think by deductive reasoning, that the original Vox amps came with Mullards. Especially the ones used by The Beatles. I just can't for the life of me imagine why they wouldn't. Unless in that time period, it was more feasible to use Brimars which were also made at the same Blackburn plant. I really have no way of knowing. That could very well be too. Either way, they both have the same sonic characteristics, date codes, and eia codes.

Now, if you really want to have that kind of vintage tone in your AC15cc, at least there aren't a ton of tubes to buy to accomplish it. (My Mesa has 11-tubes in it).

The first thing to seek out would be a matched pair of NOS Mullard or Brimar el84's. But there's a catch..(there's always a freaking catch). You would need to take the amp to an amp tech, and make sure your amp is biased right for your new tubes. And just to be safe, I would seek out a Vox tech (or possibly ask someone in the Vox forum) who can answer whether it's ok to use NOS Mullards in your amp.

Although my amp uses 6l6's, if I went and bought NOS 6l6wbg's as opposed to 6l6gc's, I would fry the 6l6wbg's pretty fast. They weren't made to handle the modern circuitry of my modern amp.

It may not be the same for el84's, but I'm not an amp tech, and I have no experience with el84's. So I personally would want to know that before shelling out the cash for NOS Mullard el84's. They do cost some coin.

Mullard ecc83's are no problem. You just plug them in and go. They'll work in anything that takes 12ax7s, and preamp tubes don't need to be biased or matched.

So do a little homework on your power tubes as far as what is safe to use. And before we get into what will give you a beefier sound in your preamp, I need to know how many are in there, I believe there are two. That would mean that one would be a phase inverter, and the other one your V1. But if there's 3- that's a whole different ballgame.

#38497 by Nathanial Hughes
Sat Aug 09, 2008 10:53 pm
Wow, thanks again for a very thorough post. There are only 2 preamp tubes. See... the problem is that there are no forums for Vox amps. So that's a little bit of a bummer! I know I'm pretty clueless as far as it comes to maintenance work to amps, but I'm also wanting to switch out the stock speaker for a Celestion Blue 16 ohm. All I have to do is disconnect some wires and unscrew the speaker and place the new one in and re-drill the screws in and I'm done right? I'm also wanting to replace the stock power/output transformer with a Mercury Magnetics one, but I'm thinking that will be my last project to do when I'm done with the rest. I'm also afraid of shocking myself haha so maybe any tips would be good! Any thoughts? Thanks again!

p.s. I found a pretty good mod page for the AC15 at this site... I'm also thinking about doing the V1 Plate Resistor Mod that's on the site.

here's a pic of the chassis

#38498 by gbheil
Sat Aug 09, 2008 11:01 pm
Wow, I just noticed you are a fellow Texan. Howdy! :D

#38499 by Nathanial Hughes
Sat Aug 09, 2008 11:36 pm
sanshouheil wrote:Wow, I just noticed you are a fellow Texan. Howdy! :D

Yeah, I'm a new Texan. I'm originally from Ohio, I just moved here last month. I'm enjoying it a lot more than Ohio! Thanks for the welcome :)

#38503 by Shredd6
Sun Aug 10, 2008 1:10 am
You can try asking some of your questions here:

Also, some of the people on the Mesa Boogie forum are really knowledgeable amp techs, and a lot of members who own multiple amps.. There's a section for non Mesa amps that you can visit here:

If you feel like you're not getting any responses in either forum. Ask in the "Modern Amps" forum (on the Boogie board). It's the busiest part of the forum, and I'm sure nobody will mind you asking about your Vox.

As far as the speaker, yea, it should be pretty much that easy.

As far as the transformer, I really couldn't tell you. I'm afraid of getting shocked myself, so I try to stay away from doing any mods myself at the moment.

Paleopete is the only guy I know of that can help you on this forum. But there are amp techs on the boogie Board.

#38524 by Shredd6
Sun Aug 10, 2008 10:14 am
OK Nathanial.. I'm going to start looking for some good Mullard ecc83's for you..

If you don't have any experience with NOS tubes you can be taken. Mullards are probably the most faked tubes out there, and it takes someone with experience to spot them.

I'll give you an example.

Looks like a completely legit auction doesn't it? Bogen labeled Mullards are quite common. But if you read the listing, the seller isn't quite sure what tube #2 is..

"It has THAT sound when plugged into an amp without a doubt. There are no seams on top or date code left so I am guessing this is a late manufacture Mullard but I am not guaranteeing it."

1. Does it REALLY have "that sound"??

2. No seams ??

3. No date code??

4. No guarantee??

No wonder.. That's because it isn't really a Mullard.

In this picture, you'll notice a tilted halo inside the tube, and a tilted protective layer on the top of the tube.


Now take a look at this picture of a tube I bought earlier today..


It's a Japanese Matsushita 12ax7 labeled as a Bogen labeled Mullard..

Matsushitas are really cool tubes, and they do sound somewhat similar to a Mullard. But not quite.

Now look how much I bought the Matsushita for:

This seller may or may not know what he has. But one thing is for sure, any buyer will be overpaying quite a bit for a tube that isn't really a Mullard ecc83.

So I'll keep on the lookout for you man. I'll find you some good Mullards.

I don't have any here to sell at the moment. The two I have are already spoken for. But rest assured, I'll get you the real deal ok.

#38535 by Nathanial Hughes
Sun Aug 10, 2008 4:05 pm
Very cool, for like the hundredth time I really want to say thanks for all the information and for you helping me out. I really appreciate everything!

#38542 by Shredd6
Sun Aug 10, 2008 7:27 pm
The first one could very well be legit. The labeling on NOS tubes come off very easily. You barely breathe on them wrong and it freaking comes off. Hahaha..

If they had fingerprints on them, then they would have to be cleaned. Fingerprints on power tubes causes an uneven emission dispersion, which causes a shorter tube life. As long as the etched codes were still visible, it would be legit.

But there are no test numbers to show you how closely matched they are. And that would turn me off to it. What are the chances that they will be in close range with each other? And there's no telling how much life is left in them.

Not everybody has a tube tester, they just know they work. So I don't get the sense that the seller is dishonest. But looking at his Mullard ecc83 auction, he's way overpriced on selling untested tubes. I don't think this seller will be making any sales anytime soon. But I don't think he's a scammer either.

In your list of legit looking listings, all seem ok, the 3rd one looks the best to me. The Valvo label on the 3rd one is ok, it still has a Blackburn code. You want your tube emissions to be within 5/ma of each other. That would still be considered a matched pair. In that auction, you would have two matced pairs that would stay more closely within that range. The problem is, if you read the auction, and look at the pictures. The center pin is broken off of the first tube. If you were to put that tube in your amp the wrong way, it'll fry your amp. That guider pin is very important.

The first one falls within that range, and would be ok. They have a double getter, so my guess is that the auction will most likely get hot in the end. They could get expensive.

The second one, you could only have one matched pair, and one mismatched pair.

The last one doesn't fall within that range.

So, of those listings, I would go for the first one.

Now, the next process after you buy your tubes that are within that range. An amp tech will use a biasing tool to bias the amp correctly to the tubes. That's when your amp is at it's optimum performance. It's actually a pretty quick process for any tech with any amp.

#38543 by Shredd6
Sun Aug 10, 2008 7:55 pm
Damn man... Someone actually bought the fake Mullard ecc83.

Poor guy.

#38567 by Nathanial Hughes
Sun Aug 10, 2008 11:57 pm
Crap, I actually posted EL 34's and not EL84's. I'm glad I caught my goof!

#38713 by Shredd6
Wed Aug 13, 2008 5:04 am
Any luck on finding some good el84's Nathanial??

Mullard ecc83's are starting to go up in price these days. It's getting hard to get 'em for under $40 right now..

Sanshouheil scored man. The type I sold him has gone up to no less than $60-$65.

#38747 by Nathanial Hughes
Wed Aug 13, 2008 8:40 pm
No, not yet. I'm thinking about changing the speakers 1st but I'm not for sure if I want to do that before the tubes. How much does it usually cost for a tech to bias an amp to older tubes? I just want to get a price range so I don't get screwed out of my money. Right now I'm trying to think what I want to do 1st. If you get some I'd be happy to buy them from you.

#38765 by Shredd6
Thu Aug 14, 2008 1:02 am
I honestly couldn't tell you what they get for biasing these days. I've had my Mesa for 10-years now and it's a fixed bias amp.

It's not COMPLETELY necessary right off the bat. You might pop em in and find that it sounds just fine. But it's not something that will blow your amp if you don't do it. It's a good idea to because your amp will be running at it's best. But I couldn't imagine anyone doing it for over $50 for a 4-tube power section. 2-tubes should go really fast. $25 should do it. It'll literally take them 10-minutes tops.

Here's the procedure.

I'll keep on the lookout for you ok.

#38771 by Nathanial Hughes
Thu Aug 14, 2008 2:27 am
What are the best companies for the new tubes?

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