Screen grid and cathode resistor layout in Tubedepot 5E3 design, any good??

[digdown2001]

Hi,
I note in the Tube Depot kit, the resistor layout for the power tubes are different to all other build styles on the net, instead of just running a 1.5K 2W cathode resistor direct off the socket, they use a 1.5K 1/2W resistor for the cathodes, and also a 470 Ohm 2W resistor for the screen grids. Is this a good layout, is it better or worse than the usual single 1.5K 2W resistor as seen in most other kits/builds?? I'm not using a kit per se, just kind of winging it based on the many designs available out there. But, this was something I noted in the Tube Depot layout that is significantly different to all other styles...

I figure this is the best place to pose the question. I'm a newbie at builds, so nice basic answers are most helpful!!

Thanks in advance!!
Steve

[digdown2001]

And for the record, I've already asked TD, their tech guy gets back on Monday, and besides, an objective viewpoint is always a good thing
Thanks

[Enzo]

I downloaded the manual for the build. It looks very thorough.

I would suggest you build it just exactly as the instructions tell you. If you go changing things, then they cannot help you if problems arise, because your amp will not be like the others. Once you know something about amps, you can change stuff.

They appear to have taken the eyelet board of a traditional Fender amp, and translated it over to a printed circuit board. I can think or a number of advantages that gives the kit seller.

I think you are confused what resistors you are looking at. From the screen supply, they have a 470 ohm 2 watt resistor going to each screen. This is like Fender has done it for over 50 years. It works as well as any Fender works. I see no reason to change it.

The 1.5k resistor between pins 5 and 6 on the power tubes has nothing whatever to do with the cathode. Pin 5 is the control grid - the pin your signal enters the tube. Pin 6 is not used on that tube, so they used pin 6 on the socket as a convenient place to mount that resistor. it is what we call a "grid stopper" and is an important part of the circuit. It also is something Fender has done for decades. It works, it is a needed part, don't change it. And I have to say I do not know what single 1.5k 2W resistor in other amps you are referring to.

So basically this is NOT different from a zillion Fender amps. SO it is neither better nor worse.

But a word about that. "Is this better?" is a tough question to answer in general. Usually it is a matter of opinion. And when it comes to amp circuits, unless it is flat out wrong, you can usually find someone to argue just about any way you like is better. But to be better, you have to define what better means. Just because I think something sounds better doesn't mean you will think so too.


Ah, I see you are not building their kit. Well, a 5E3 is pretty much a 5E3. There are kits of higher quality and kits of lower quality on the market. And some may look different from others, but the basic circuit should be pretty consistent

[digdown2001]

Thanks Enzo, My apologies, I was confused, I meant the resistor between pins 5 and 6. I just haven't seen any other Fender 5E3 builds with the two resisitors on the socket (Weber, Triode, Ceriatone, Mission, and the original Fender layout), only the usual 1.5K 2W (pins 5 and 6), whereas TD uses two, the 1.5K 1/2W (pins 5 and 6) and the 470 Ohm 2W (pins 1 and 4), in fact I can't think of any other build I've ever seen with this setup.....(a 1/2W resistor for pins 5 and 6, instead of a 2W, to be precise, or did Fender originally use a 1/2W resistor there???)...... I am looking at the layout for the original 5E3 and I don't see the second resistor between pins 1 and 4?

Thanks again for your patience for a newbie,
Steve

[digdown2001]

I see the mechanics of TD's use the 470 Ohm 2W resistor from pins 1 to 4, unlike the original builds, which just tied pins 4 of V3 and V4 together, without the 470 Ohm resistors....

[Enzo]

well, you are right, the Fender 5E3 lacks screen resistors. Lots of other Fenders have them, including the AA763 Deluxe. The AA763 has the screen resistors but not the grid stoppers, but the AB763 has the grid stoppers as well. As do all later versions. I have to admit I am not an amp fan, so I don't have all the variants committed to memory. I have the later versions in my mental images. These are things added to the original design over time. They do good things so I suggest you include them.

Here, look at the AB763 layout on page 2.
http://www.webphix.com/schematic%20h...b763_schem.pdf

Pins 1 and 6 are free on the tube socket, so the Fender layout crosses the resistors while the tube depot makes them diverge, it matters not.

And I still don't know where we are getting a "usual" 2 watt 1.5k resistor. Fender used 1/2 watts.

In fairness, as far as I can see, the Deluxe kit at Tube Depot just says Tweed Deluxe, not 5E3. There are many revisions of Deluxe.

[digdown2001]

Thanks Enzo, ALL valuable information!! I have always seen a size of 2W applied to the 1.5K resistor, but now knowing it was originally a 1/2W resistor, I think I'll go with those!! Even better to know why you said what you did, it adds MUCH more information to why TD applied those resistors where they did, I think I'll follow through and use that part of their layout Sometimes in error, we learn more And in that regard, your first reply is golden information to me!! I tell you what, if you have all that committed to memory, I think you're undervaluing your understanding of Fender Deluxe models!!
Thanks once again, you've helped me to decipher why those 470 Ohm resistors are in there, obviously an upgrade based upon improved tone over time.....

Steve

[digdown2001]

Just for the record, I love your signature, I'm a systematist/taxonomist by trade, and never a truer word spoken I can't count the number of times I've had to go back to basics to figure a problem out, be it biogeographical history of a clade of taxa, or complex relationships involving reticulation as opposed to divergence (enough scientific rambling)........ you're speaking my mantra......