5x3 6L6 deluxe

[wyatt]

I spoke with Patrick at Mercury and He put these 2 together for the 6L6 5E3.
So at this point what can I do with these trannies?I thought at least they could work for the Ceriatone layout.?You feel that they wont,

Here's the deal.

There are 5E3's with 6L6's, lots of boutiques and DIY'ers build their 5E3's with robust iron and multi-tapped OT's to allow safe swapping of 6V6GT's and 6L6GC's. The idea is a well-biased 6V6GT will stay well biased for 6L6GC's if you swap out the 5Y3 rectifier for a GZ34 to increase the B+ voltage for the larger tube. If one plans to stay with 6L6"s for a while, then you can swap the speaker tap on the OT to create a more optimum 4,000-ohm load for the tubes. Typically, these average 12 watts with 6V6GT's and 18-20 watts with 6L6GC's.

But the 5X3 and 5E3P is NOT a 5E3 with 6L6. These are hybrid amps designed to pair the traditional 5E3 preamp with a higher headroom 6L6GC poweramp. The 15-watt OT is swapped out for a 35-watt OT and the power supply is altered much like above to make sure the 6L6GC's get enough plate voltage to take advantage of their higher dissipation.

I'm guessing MM didn't understand you want to build a hybrid. Otherwise they would have at least recommended a larger OT.

Both of your transformers will certainly work for the 6L6GC, if MM isn't worried about current, neither am I. And it's 380-0-380 spec is unloaded, so it should run lower voltage than suggests. But that OT isn't going to give you the same output as a 5X3, instead you'll just be using a 5E3 with 6L6's. But you can build the amp with the parts you have and then assess if it's loud enough as is.

Note: I suppose I shouldn't say Tweed Pro transformers when talking about the Ceriatone and Weber designs. Neither Ceriatone nor Weber use "cloned" transformers in their designs, they use transformers spec'ed to work across as many platforms and amp models as possible. I'm guessing they are wound with 8,000- or 4,000-ohm primaries in mind (depending on how you pair up the multiple secondary taps).

[ampmike]

Thank Wyatt,I appreciate you help.Like you said I think I rushed into the thing a bit to fast and what you just posted gave me a hole new perspective on the build.So Ill really just have a 5e3 with 6l6"s.And it will have the same power as a 5e3 so we aint getting much of a bigger sound.Im guessing its going too not have the nice breakup of the 5e3.More headroom expected.So I think Ill build it that way a see how it sounds.At this point the output tranny or even the power tranny would not do the 6V6 anymore correct??Cause I would do that if the option is open.I have not touched the leads on the Mercs yet.Ill wait to see what you think and Thank Man for your help and guidance,Mikey

[martin manning]

Wyatt, do you have info from MM on the output power capability of this OT? Seems like if the MM guy chose this combination for a 6L6 power section they are a matched set, no?

Mikey, you have 5k and 8k taps on the OT- use 5k for 6L6 and 8K for 6V6... that is what MM is recommending.

I haven't messed with MM and have no plans to do so, as much because of their lack of transparency with specs as the high prices. Asking 2x the price for something while refusing to provide basic information needed for design work just stinks!

[wyatt]

Wyatt, do you have info from MM on the output power capability of this OT? Seems like if the MM guy chose this combination for a 6L6 power section they are a matched set, no?

Mikey, you have 5k and 8k taps on the OT- use 5k for 6L6 and 8K for 6V6... that is what MM is recommending.

I haven't messed with MM and have no plans to do so, as much because of their lack of transparency with specs as the high prices. Asking 2x the price for something while refusing to provide basic information needed for design work just stinks!

No, as noted, they are great at posting their spec's.

The FTDO-59 is supposed to be a straight clone of the late '50's Tweed Deluxe OT (iplease include grain of salt). And I have one, it size was and appearance it's pretty close (right down to one side of the secondary being grounded the OT frame) to that of my original 1960 5E3's OT. It's not a big OT, not a lot of iron there. So, the FTDO-59M is supposed to be the same thing with extra taps for more universal application...I haven't seen one in person.

I have to offer the caveat that I am basing my replies solely on MM's marketing that it's a '59 5E3-sized OT.

The FTDP is their uncompensated "copy" of the late '50's Tweed Deluxe PT. It gives you roughly the same 10% higher HT voltage you would get if you plug the old 110V PT into a modern 120-watt outlet.

I really don't look at transformers as matched sets. They each have their own spec's that are applicable to the situation. Multiple transformers can be combines for a variety of outcomes.

[wyatt]

...At this point the output tranny or even the power tranny would not do the 6V6 anymore correct??...

People use the FDTP for 6V6's all the time, despite the higher voltage. All you are doing is running the amp hotter like you would if you plug a real 5E3 into modern 120V outlet (which I did for over a decade with my '60). Check the voltages, do the math and make sure the don't dissipate too much.

The FDTO-59M is suppose to e the exact same Tweed Deluxe transformer with extra taps for more options. As noted, it'll work optimally for the 6V6's when set up for a 8000-ohm primary and for the 6L6's when set up for the 5000-ohm primary.

OT's are all baed on primary and secondary impedance and output capacity. How to people like Rienhardt build 30-watt Plexi's and JCM800's? They use smaller 30-watt OT's.

[martin manning]

I really don't look at transformers as matched sets. They each have their own spec's that are applicable to the situation. Multiple transformers can be combines for a variety of outcomes.

But you should! The power tubes you put in between are just valves throttling the current from that PT directly into that OT ;^)

[JazzGuitarGimp]

Don't know if it's been mentioned yet, but Mercury will take transformers back as long as the leads haven't been cut.

[rdjones]

Note the difference between the layouts, with regards to the B+ connection taken from the rectifier tube socket.
The CeriaTone layout perpetrates a well known Fender 'mistake'.
The B+ should be taken from pin 8 of the rectifier socket, not pin 2.

Using pin 2 for B+:
When using a 5Y3, 5U4 or other directly heated rectifier the circuit will work normally either way.
If using a 5AR4 (indirectly heated cathode) the B+ current will flow through the filaments in parallel with the 5V winding.
When using the SS diode plug the current flows through the 5V winding.

Better to just wire pin 8 for B+.

rd

[wyatt]

I really don't look at transformers as matched sets. They each have their own spec's that are applicable to the situation. Multiple transformers can be combines for a variety of outcomes.

But you should! The power tubes you put in between are just valves throttling the current from that PT directly into that OT ;^)

I pick my PT with respect to voltage desired and current needed. And I pick my OT with respect to primary impedance needed and output desired. While the primary impedance is tube dependent, the rest is relative to what I want to achieve. Typically PT's are a lot more versatile, which is why Leo probably spec'ed less than half as many different PT's compared to OT's in any given model year

Matched set would imply there is a objective, optimal transformer spec for a specific tube for a specific circuit and that's not true. There is no such thing. It all depends on what the desired result is. More touch responsiveness? More aggressive feel? Less headroom? More headroom? 12 watts? 22 watts? 45 watts? 2-ohm secondary? 16-ohm secondary?

[martin manning]

The output power requirement for the OT is in direct relationship to the power delivered by the power transformer. Is that not a legitimate definition of "matched?" The other requirement for the OT is that its primary impedance matches the requirements of the power tubes, which also have to be capable of handling the desired output power. All three of these components are matched in that respect.

[wyatt]

If you want to get the maximum output at the minimum THD, then yes...everything has to be just right.

But power tube output isn't an absolute, it is reactive. Tubes will not put out more power than the OT can handle (not without unreasonibly high late voltages). You can take a 45-watt Super Reverb and substitute in a 35-watt OT and leave everything else the same (maybe rebias) and you'll have a 35-watt amp, the tube efficient will decrease because of reduced demand. Are you getting the most out of the tube? Hell no. But you are hopefully getting the result you want.

But, I doubt we are disagreeing as much as looking at this with different view points.

So, let's back track, you asked whether the transformer set from MM was matched, well, I was you match toward what result? What would you expect if you were to buy a set of iron for a 6L6GC-driven 5E3?

[martin manning]

Ignoring the preamp, there are two numbers that ultimately determine the output power and the power required from the supply: the B+ and the OT primary impedance. One comes from the PT and one comes from the OT (to be compatible with the power tube choice), so I'll argue that there is an optimum combination. You can of course oversize either one while keeping the same B+ and load impedance, providing more HT current capability for a stiffer supply, or a bigger OT for more bandwidth.

For the original 5E3 with two 6V6's B+ is ~370V and the load is 8k. It's cathode biased, so the Va-k is more like 350V. If you just replace the 6V6's with a pair of 6L6's, you still have ~350V and an 8k load. The output power and the demand on the power supply will be essentially unchanged, give or take the increased idle and filament current, and the 6L6's will easily handle the required plate dissipation.

If you go to 6L6's and change the load to 5k, then the power capability required for the PT, the OT, and the tubes increases by 1/Zpri, so by a factor of 8/5 or +60%. I'd want a PT with a 160mA rating instead of the stock 100mA at the same HT voltage, and a 5k OT that is good for 32W instead of 20. The 6L6's will still have excess capacity with respect to plate dissipation, since the max along the load line is only going to be a bit over 80%.

[ampmike]

Well,I certainly learned a lot from you guys and as always grateful to have such sharp guys to bounce these issues at.So Im going to build it like a 5E3 and will replace the 270/5watt to a 20 watt and put a voltage pot to be able to bias this down if you will.Ill get some help with that a bit later in the build.I did get the Jupitar caps and most of my board parts.I promise to do something as far as sound clips or vids when its done.Thanks Fellas,Mikey

[billyz]

Well,I certainly learned a lot from you guys and as always grateful to have such sharp guys to bounce these issues at.So Im going to build it like a 5E3 and will replace the 270/5watt to a 20 watt and put a voltage pot to be able to bias this down if you will.Ill get some help with that a bit later in the build.I did get the Jupitar caps and most of my board parts.I promise to do something as far as sound clips or vids when its done.Thanks Fellas,Mikey

You do not want a fixed bias voltage adjustment with Cathode bias . The
Weber layout is for a fixed bias circuit the standard 5e3 circuit is for a cathode bias circuit. DO NOT mix the two. Build one or the other not both. There is a way to have an adjustable cathode bias circuit but I would not try it.

[billyz]

If you are going to use 270 Ohm instead of 250 Ohm Bias resistor then your Power tubes will run a shade cooler anyway. Personally I like the 250 ohm. Don't get hung up on nailing the exact voltage of some circuit. I have measured hundreds of vintage amps and none of them are the same. For 6v6's keep it at or under 400vdc and you will be fine and happy. 400 is also great for 6l6's .
If it is 370 or 368 or 387 or 410 . Don't sweat it. If it is 575 then you can worry.

For a 6l6 tweed cathode bias I like the Tweed pro OT at 6k primary. It is great for a 6v6 pr too. Mercury # FTWPRO-O

Z