Mercury Magnetics Mod for Epi Valve Junior?

[Steve A.]

Mercury Magnetics is selling a kit to upgrade the iron in these amps, starting at $289. It looks like there is a choke in the picture, along with a PT and OT and a few resistors and capacitors.

I was wondering if we could source out some of these parts, and come up with a half-way decent kit for maybe $100... This amp has a single EL84 for an output tube and a 12AX7 preamp tube.

Thanks!

Steve Ahola

[bob p]

Hi Steve! Nice to see you back on the forum!

[J Martin]

There are plenty of transformer makers around, but what is needed is someone to capitalize the project so that sufficient quantities could be purchased to get the economy of scale. (small scale but .....) Other parts woud be even easier to source.

[galibier_numero_un]

Hi all,

Obviously, I'm not the only person going round 'n round over a Valve Junior project.

On one hand, I think it's a cool platform to take off on.

At the other extreme, I look at a full blown mod (especially if Mercury iron is in the picture), add up the cost, and then come to realize that the only stock parts left might be a switch and a couple of pots, the knobs, cabinet and power cord.

At that point, I start thinking of a scratch build again. I didn't say round 'n round fer nuthin'

Cheers,
Thom

[Steve A.]

There are plenty of transformer makers around, but what is needed is someone to capitalize the project so that sufficient quantities could be purchased to get the economy of scale. (small scale but .....) Other parts woud be even easier to source.

I was thinking that Bruce at Mission Amps probably has some decent transformers and chokes that would work fine in this amp. A lot of people have been modding these amps without changing the transformers, but I guess that they would be even better with upgraded iron.

BTW I strongly recommend that people get the head version since Epiphone corrected some of the noise issues with the combo version (if you already have a combo, the head should slide right into the cabinet).

While many people have been going for Mondo Gain, I cut back on the gain in mine, in morphing it over to the new Gibson Les Paul Junior design with the bridged-T filter ahead of the volume control.

Steve Ahola

[steve]

Steve,

I took on a Valve Junior rebuild project:

http://www.diycustomamps.com/valvejunior.htm#vjrebuild

A couple of thoughts off the top of my head:

As Thom said, it is a great platform, but I personally wouldn't want to spend a lot of money on it. Taking a $100 amp and putting $300 in parts into it doesn't make it worth $400.

The OT in the VJ is a real weak link. It is very small, and with a 7.5K primary, it isn't well suited to the circuit. A 5K primary is a better match.

I've tried a few transformers in the VJ circuit: a Champ 12 OT that I got from Bruce, a Hammond 125CSE, a Hammond 125ESE, and a Heyboer SE OT I got from Doberman amps. The best bang for the buck is the Hammond 125ESE. It's about $30-$35.

Edcor makes an appropriate transformer:

XSE-15-MS-5K

It isn't listed on their website, you have to ask for it. It is their 5K, 15w SE OT with a UL tap, but it has 4, 8, and 16 ohm secondaries. The downside is that there are exposed solder tabs, not flying leads. I bought the 5K to 8 ohm version and it is about the size of the Hammond 125CSE. I haven't had a chance to try it out in anything though.

As far as the PT, it is a very robust unit. So it really doesn't need to be changed. One guy on the 18watt.com site report using a hacked in KT88 with minimal voltage drop. Some guys run a parallel 6V6 with the EL84.

One of the engineers on the 18watt site said that a choke isn't really needed. They stiffen the power supply, but bigger filter caps essentially do the same thing, and are less expensive. I run two 120uF/400v filter caps in my VJ head and it is dead quiet.

I think the noise issues in the combo have been worked out. The original version 1 PCB had the noise problems. AFAIK, all the new VJs ship with the version 2 PCB, which is a greatly improved version. I went with the combo because I think 8" speakers suck. I've never heard one that I though was good sounding.

I've tried a few things with my production VJ head. The best improvements are to change out the OT for a better one, and to change out some of the parts values in the amp, revoicing the preamp mainly. I ended up putting in a larger value for the first dropping resistor in the PS to get the B+ down.

I think I have about $150 total in parts in my amp, including the VJ itself.

steve

I was thinking that Bruce at Mission Amps probably has some decent transformers and chokes that would work fine in this amp. A lot of people have been modding these amps without changing the transformers, but I guess that they would be even better with upgraded iron.

BTW I strongly recommend that people get the head version since Epiphone corrected some of the noise issues with the combo version (if you already have a combo, the head should slide right into the cabinet).

While many people have been going for Mondo Gain, I cut back on the gain in mine, in morphing it over to the new Gibson Les Paul Junior design with the bridged-T filter ahead of the volume control.

Steve Ahola

[Steve A.]

... As Thom said, it is a great platform, but I personally wouldn't want to spend a lot of money on it. Taking a $100 amp and putting $300 in parts into it doesn't make it worth $400...

True... most people think that it is worth about $1500 with the Mercury Magnetics mod. LOL

Thanks for the reality checks here- the PT is fine so why replace it? As you suggest it is really just the OT that needs to be upgraded.

It is good to hear that Epiphone is using the Version 2 circuit board in the newer combo amps... except that I already bought 3 of the original combos since I never learned to say no to a $100 tube amp.

Steve Ahola

[bob p]

True... most people think that it is worth about $1500 with the Mercury Magnetics mod. LOL

No doubt! I've had lots of experience with MM. I buy their iron at what the industry calls "end column" pricing. Even though I buy at their max discount price point, I've noticed that the wholesale prices on their iron have risen out of proportion to everyone else's iron in the past 5 years or so. I attribute this largely to predatory price increases that have followed a little name-brand recognition on the internet fora.

It used to be the case that MM offered hard to find products at fairly reasonable prices. My barometer for that is the Mercury vs. Hammond comparison price. If as a dealer I can buy their premium application-specific product at a price that's cheaper than the retail price of a generic Hammond, then its cost-effective to buy Mercury. But now their iron is priced so that even when you buy at end column prices, you could buy multiple generic Hammonds for what it costs to buy just one Mercury. More than anything else, THAT goes to show that MM iron is no longer reasonably priced -- now MM iron is priced as if its something that will magically transform your amp (pun intended) into something it never was before. To me, its just not worth it anymore. There is other iron out there that is just as good but doesn't cost so much.

I won't go as far as to say that iron is iron, and all iron is the same. There is definitely a difference between quality iron and cheap iron. But having had LOTS of MM iron pass through my hands, I can no longer justify paying the prices that they ask. There are other iron options out there that are just as good but don't cost as much. So my opinion on this project would have to echo @steve's, but I would go one step farther: don't buy MM unless you don't care how much it costs.

[Chris / CMW amps]

I've talked with MM about the VJ-mod-kit because the price is higher than the amp it self but I just did have to order a set for a DIY-customer.

I'm located in the Netherlands so shipping-costs are also a bigger part of the cost-price but I just love the sound-quality (and my customers too). I also do notice that my amps with MM iron do sell way faster than my other amps with other transformers.

I also do think that the price from a MM transformer (let's say a plexi 50 Watt OT) from $ 200 retail is reasonable if you do campare it to hand-wound/boutique guitarPUs from $100 - 200. Afaik building (great) Pus does costs way less regarding materials, time and weight/shipping costs.

@Steve:
Hope everything is ok with you, greetings from the Netherlands!!!

[bob p]

I also do think that the price from a MM transformer (let's say a plexi 50 Watt OT) from $ 200 retail is reasonable if you do campare it to hand-wound/boutique guitarPUs from $100 - 200. Afaik building (great) Pus does costs way less regarding materials, time and weight/shipping costs.

Personally, I don't like the $200 price tag. I liked it a lot more when I paid $75 for them.

[Steve A.]

I've talked with MM about the VJ-mod-kit because the price is higher than the amp it self but I just did have to order a set for a DIY-customer...

Any chance that you can post the contents of this kit here when you get it? Just wondering what the guys at MM are up to...

I remember the Plexi guys arguing whether it was better to get an OT from MM or Obsolete Electronics.

I've been pleased with the results I've gotten from non-boutique transformers...

Steve Ahola

[galibier_numero_un]

Hi Steve,

Any chance that you can post the contents of this kit here when you get it? Just wondering what the guys at MM are up to...
Steve Ahola

I don't know if you've been to Mercury's site recently (http://www.mercurymagnetics.com/pages/mainframe.htm), but they typically run banner ads all over their site advertising the Valve Jr. mods.

Until you get a reply from a hands-on inspection of the kit, you may be able to do a bit of detective work on the site. As you probably know their information can be spotty. Some parts have more complete specifications than others.

Oh yeah ... about other iron. Bruce at Mission is using Heyboers in his new Auroras, and all I can say is "wow" about my new 6V6-based issue. I decided to buy from Bruce rather than to build something for a couple of reasons: I'm strapped for time, and am somewhat forced to limit my soldering time to building turntables (my night gig). Also, I'm such a hacker on guitar that I need all the help (practice time) I can get His amp brought me to tears.

We all know that it just begins with soldering up the first iteration. That's when the fun just begins as far as time and mods are concerned. There ya go again ... getting me to ponder buying a Valve Jr. I can be my own worst enemy at times. So much for practice time

Cheers,
Thom

[Steve A.]

...
Oh yeah ... about other iron. Bruce at Mission is using Heyboers in his new Auroras, and all I can say is "wow" about my new 6V6-based issue. I decided to buy from Bruce rather than to build something for a couple of reasons: I'm strapped for time, and am somewhat forced to limit my soldering time to building turntables (my night gig). Also, I'm such a hacker on guitar that I need all the help (practice time) I can get His amp brought me to tears...

No need to defend your decision to buy an assembled amp from Bruce here- great designs, excellent workmanship, decent prices...

So which Aurora did you get- the MA-18 FB with a Jensen C-12Q?

Steve Ahola

[galibier_numero_un]

Hi Steve,

No need to defend your decision to buy an assembled amp from Bruce here- great designs, excellent workmanship, decent prices...
So which Aurora did you get- the MA-18 FB with a Jensen C-12Q?

My Aurora is indeed a mid-power 6V6 (fixed bias) version. The amps have evolved slightly over the months.

He's now using a slightly bigger Heyboer output trannie in the non-reverb unit I ended up with. It's the output trannie he dedicated to the reverb version of the 6V6 amp, but yes, it's in the 18-20W range (fixed bias).

IIRC, he's been tweaking the tone stack a bit too.

I all was set to buy the reverb version. When I asked Bruce about it, he commented that he preferred the non-reverb's sound to the reverb amp's dry sound. It took me about 15 seconds to agree with him when I demoed it. Now, the reverb amp's dry sound is very, very good, but the non-reverb's is better ... enough for me to decide to give up the reverb.

Deciding to buy rather than build (for a guy who hasn't owned a gee-tar amp in some 15 years) was a difficult decision. Ya see, I love making solder fumes

Hearing an amp that brought me to tears - even with my miserable technique - made it an easy decision, however. Sometimes, ya gotta reward a guy who has worked his butt off to create a mature design.

BTW, I've wired my Strat up per your Blue Guitar Sup'r Strat schematic. Very nice. I encourage others to try it.

I'm still not sure if I like the extra parallel positions, but I'm going to leave them in for a while and get to know them better. The series positions are way cool and really extend the instrument's voice.

Now, If I could keep track of where I am (switch-wise), I'll be all set. It's quite logical, but I can be easily confused

Cheers,
Thom

[Steve A.]

BTW, I've wired my Strat up per your Blue Guitar Sup'r Strat schematic. Very nice. I encourage others to try it.

I'm still not sure if I like the extra parallel positions, but I'm going to leave them in for a while and get to know them better. The series positions are way cool and really extend the instrument's voice.

Now, If I could keep track of where I am (switch-wise), I'll be all set. It's quite logical, but I can be easily confused

There is not a lot of flexibility in the design since it uses a regular 5 position strat switch (the original was wired onto a megaswitch but I figured out that it wasn't necessary).

I've moved on the various switches that Deaf Eddie makes- the Fat-O-Caster version 2 is probably the easiest one to figure out and memorize. The Chromacaster has the most positions but it is a real bear to operate without the chart in front of you:

http://www.deaf-eddie.net/

Steve Ahola