Don't assume that a ''beefier'' transformer set is going to get you more power output. The tubes may be being driven for all they are worth already. The tube power output is the limiting factor. There are maximums on plate power dissipation you need to understand before you start throwing more transformer capacity into the mix. You will be wasting money by over engineering because you will find that the tube can't deliver any more power.
If you can obtain at least 430 volts, you can get more power by eliminating the 6V6 tubes, and replacing them with 6L6 tubes. Same pinout, more power.
I've been following this thread (and his earlier one) since I recently pulled a 185 from a console. Since I have other PP 6V6 amps, including another Maggie, I'm planning on converting to 6L6GC (well, the Russian 6n3c-e actually), as you suggest. Possibly with an entirely different front end too.
I found something puzzling about the power supply too. The schematic for the 185 shows a B+ of 305v. I also have a schematic for the 175 which uses the exact same power supply - same transformer, same rectifier, same 40uf C1, same choke - yet the B+ is 345v. I suspect the 175 version may be more accurate and with line voltages being higher than 117v today, I'm guessing the actual B+ might be more like 365v or so. An earlier post suggested that subbing a different rectifier tube (5V4?) might add another 25v so that might get me around 390v B+. Of course I could switch to SS rectification.
The only experience I have with the 6n3c-e is a DIY SE amp that I originally built using 6V6s and then converted later, so I don't have much experience with this tube. Although I've got plenty of experience working on amps, my level of technical/theory knowledge is somewhat lacking too.
So here's a question: if B+ is less than you are suggesting as ideal for a 6L6, what output transformer primary value would be best?
The outputs on the Maggie are listed as 6k primary and 4-6 ohm secondary. Assuming the use of an 8 ohm speaker, would they work well?
I also have a pair of 4k transformers which were pulled from a Harman Kardon. Would that be a better choice in terms of primary impedance?
. . . . Charlie
Just curious, but why would you want to spend $400 to recreate an amp that you already have? Once they are rebuilt these console amps usually sound great and building a clone with new parts is not likely to make any significant difference.
Since you're new to all this, I would humbly suggest that you just rebuild this first and listen for a while. Then, if you feel there are aspects of its sound that you would like to change, you might do some research. Eventually you might get an idea about how the sound of different designs (Single-ended or Push-Pull) or different output tubes (there are many) might mesh with your needs. DIY is a lot of fun but I think you'll learn more and be more satisfied if you build something that is different from what you already have. It's a lot more fun to switch amps and have them sound different than to switch and have them sound the same.
Just my opinion . . . . Charlie
Interesting observation. There is a difference on the 185 as it also supplies a 175v to some other circuit. That may be enough additional load to pull down the B+.
The 175 model voltages do seem to compute correctly for a supply not overloaded.
- Status
- Not open for further replies.