Mercury Transformer Upgrades? What's the real story?

[guitarmadman85]

I have been doing some reading on the mercury transformer website. I understand the importance of transformers, and I was not surprised to find replacements for cheat low wattage amps where undersized transformers could be a problem, I know the tiny terror mercury mod is very popular. I was surprised to find replacements for Mesa Boogie amps... Anyway.... I guess I would like to know how to figure out what ratio my amp is running at. I know that the higher the transformer to power ratio, the better the transformer. It sounds like 5:1 or 6:1 would be pretty high end, or most likely the best you can find. Any thoughts or advice would be helpful. I have a Jet City JCA20H, and I know there is a power rating on the back of the head that reads 60 watts. Maybe it has do with the difference with this number and the output of the amp... making it a 3:1 ratio... Any help would be great! Thanks!

[tunghaichuan]

I have been doing some reading on the mercury transformer website. I understand the importance of transformers, and I was not surprised to find replacements for cheat low wattage amps where undersized transformers could be a problem, I know the tiny terror mercury mod is very popular. I was surprised to find replacements for Mesa Boogie amps... Anyway.... I guess I would like to know how to figure out what ratio my amp is running at. I know that the higher the transformer to power ratio, the better the transformer. It sounds like 5:1 or 6:1 would be pretty high end, or most likely the best you can find. Any thoughts or advice would be helpful. I have a Jet City JCA20H, and I know there is a power rating on the back of the head that reads 60 watts. Maybe it has do with the difference with this number and the output of the amp... making it a 3:1 ratio... Any help would be great! Thanks!

Generally, you don't need to worry about any ratios. If you look at the EL84/6BQ5 data sheet, most of the Class AB stats say that you need to use a transformer with an 8K primary. The primary impedance is important because when a speaker is plugged into the secondary (4, 8, or 16 ohms) it will reflect the primary impedance back to the power tubes.

If you really want to find out what the impedance and turns ratios are for the OT in you amp, here is how to do it:

http://www.radioremembered.org/outimp.htm

If you've never worked on a tube amp before, print out that page and have a qualified tech do it for you. You do not want to be poking around in a tube amp if you don't know what you're doing. You can kill yourself dead, no joke.

I would think that the primary impedance of the OT would be around 8K, but I could be wrong.

Having said all that, I would not go with Mercury Magnetics. They make excellent transformers, but they are very expensive for what you get.

I would suggest Heyboer, their iron is much more reasonably priced and very highly regarded. If you have a tech replace the transformer, you might be able to send the stock unit to Heyboer and have them wind you a better sound duplicate that will match the mounting bolt pattern.

[FrankenFretter]

Generally, you don't need to worry about any ratios. If you look at the EL84/6BQ5 data sheet, most of the Class AB stats say that you need to use a transformer with an 8K primary. The primary impedance is important because when a speaker is plugged into the secondary (4, 8, or 16 ohms) it will reflect the primary impedance back to the power tubes.

If you really want to find out what the impedance and turns ratios are for the OT in you amp, here is how to do it:

http://www.radioremembered.org/outimp.htm

If you've never worked on a tube amp before, print out that page and have a qualified tech do it for you. You do not want to be poking around in a tube amp if you don't know what you're doing. You can kill yourself dead, no joke.

I would think that the primary impedance of the OT would be around 8K, but I could be wrong.

Having said all that, I would not go with Mercury Magnetics. They make excellent transformers, but they are very expensive for what you get.

I would suggest Heyboer, their iron is much more reasonably priced and very highly regarded. If you have a tech replace the transformer, you might be able to send the stock unit to Heyboer and have them wind you a better sound duplicate that will match the mounting bolt pattern.

I was waiting for you to see this post, Tung. I have also been looking at the Mercury Magnetics webpage. Your info is very helpful. I was considering upgrading the OT on my Vox Night Train. Now I know better than to buy something as expensive as a MM, when there are quality alternatives for less.

[tunghaichuan]

I was waiting for you to see this post, Tung. I have also been looking at the Mercury Magnetics webpage. Your info is very helpful. I was considering upgrading the OT on my Vox Night Train. Now I know better than to buy something as expensive as a MM, when there are quality alternatives for less.

Heyboer offers tremendous bang for the buck. They also will do custom winds.

MM makes great sounding transformers, but putting $300 into $100? (Valve Junior set) It doesn't mean you now have an amp worth $400. You have an amp that is still worth $100, but with $300 worth of parts in it. :thwap

Even putting a Vox replacement OT in your Night Train would be prohibitively expensive. Their least expensive Vox AC-15 replacement is $185. The most expensive is $275. I would be surprised if you spent more than $100 with Heyboer, and will be every bit as good as the MM.

[sunvalleylaw]

I can't tell you much about them, other than I have one in my old Fender Concert. It replaced an old bassman style OT, that I understand is desirable, especially if you are a collector. I think this one sounds darn good though.

http://i174.photobucket.com/albums/w92/sunvalleylaw/P1010013.jpg

[tunghaichuan]

I can't tell you much about them, other than I have one in my old Fender Concert. It replaced an old bassman style OT, that I understand is desirable, especially if you are a collector. I think this one sounds darn good though.



In your case, Steve, MM was a good choices as the transformer is an exact fit. For a collectible amp like your Concert, you don't want to have any extra holes drilled to make the transformer fit. Ideally, you want the amp to remain as close to stock as possible, but having an MM transformer in your amp is not a bad thing. And the amp will sound very good. Like I said, MM makes very good transformers, but in some cases they are way to expensive.

[duhvoodooman]

FWIW, I replaced the stock Fender OT in my Blues Junior with a Heyboer TO22 model as part of the group of "BillM" mods I recently completed (http://www.thefret.net/showthread.php?t=14948) on that amp. Really fills out/punches up the bottom end, plus this larger OT enabled me to do the octal tube conversion and run 6V6's or 5881's in the amp. It also allowed me to add a 4/8 ohm impedance switch so that I can add a second 8 ohm speaker cab in parallel with the onboard 8 ohm speaker and match up the output impedance.

Haven't had it long enough to really comment on the Heyboer's realibility, but zero issues thusfar and I have the sweetest sounding Blues Junior you will ever hear..... :thumbsup :dude :rockon: