5E3 too clean, no distortion

[paulj]

Guys,
As you can see this is a rather unusual layout. My first, so please don't bash me. I know about long leads, upside down board, not very thought out layout. This amp will be standing upside down compared to the photos, with tubes and transformers standing up. Anyway, With the shielding and lead dress, the hum has been mostly eliminated. I am just saying this because I know that this is not what you are used to

One important thing is, the pots are upside down so all the connections will seem reversed to you. Sorry, this is how it had to turn out with this chassis.

[paulj]

Oh, before you start beating me up...some wires don't follow the color code. I ran out of the proper colors.

[g1]

It would be helpful if you could upload the exact schematic you are using. Although it is a standard circuit, perhaps there is some subtle difference or even a typo that may be more obvious from the actual schematic you used.

[paulj]

It would be helpful if you could upload the exact schematic you are using. Although it is a standard circuit, perhaps there is some subtle difference or even a typo that may be more obvious from the actual schematic you used.

Tis is the layout that I have used:

http://site.triodestore.com/5E3Delux...-18017120V.pdf

The transformer is slightly different. No artificial CT for heaters. I used the real CT and it has international voltage taps so you will see more wires. I also rearranged grounds but other than that, I followed this layout.

[MWJB]

Push the plate wires to the 12A#7 tubes so that they lie on the chassis floor, away from grid wires & heater wires.

Your upside down board has given you the perfect opportunity to shorten your grid wires. Disconnect the grid wires from pins 2 & 7 of the 12A#7 tubes & from pin 6 of the 6V6s. Now run them directly over the back of the board, straight from the turret to the tube pin, elevate a little off the board...you should be able to halve the wire length.

Remove the 1500ohm grid stoppers from the 6V6 sockets, remount them with no lead length from the resistor body to pin 5, stand them up from the socket & connect the grid wire to the free end (you won't be able to use pin 6 as a mounting point, because your 470ohm 1W screen grid resistors will be living there).

Looks like your OT lives behind the input jacks, bad move, can you move it down the chassis towards the PT any?

It's a difficult thing to convey, but beyond the value of components and where they terminate, the actual positioning of wires & routing affects the sound your amp makes.

Where are your 470ohm 1W screen grid resistors, fit them.

Maybe you can salvage this...?

[paulj]

Push the plate wires to the 12A#7 tubes so that they lie on the chassis floor, away from grid wires & heater wires.

Your upside down board has given you the perfect opportunity to shorten your grid wires. Disconnect the grid wires from pins 2 & 7 of the 12A#7 tubes & from pin 6 of the 6V6s. Now run them directly over the back of the board, straight from the turret to the tube pin, elevate a little off the board...you should be able to halve the wire length.

Remove the 1500ohm grid stoppers from the 6V6 sockets, remount them with no lead length from the resistor body to pin 5, stand them up from the socket & connect the grid wire to the free end (you won't be able to use pin 6 as a mounting point, because your 470ohm 1W screen grid resistors will be living there).

Looks like your OT lives behind the input jacks, bad move, can you move it down the chassis towards the PT any?

It's a difficult thing to convey, but beyond the value of components and where they terminate, the actual positioning of wires & routing affects the sound your amp makes.

Where are your 470ohm 1W screen grid resistors, fit them.

Maybe you can salvage this...?

There is an OT CT wire running under the board, so I can't move those grid connections any closer to it. I think the benefit of shorter wires will be cancelled by oscillations. That is why I shielded this wire. There is a serious high voltage 120 HZ ripple running in it.

I don't have the 470 ohm screen grid resistors. This kit followed the original 5E3 schematic, where they don't exist. Can you explain what this does compared to the original setup?

[paulj]

I know, bad move on the OT location. Can't move it now but I have been able to dress/shield things in such a way that there are no oscillations etc. Second amp will be much better thought out.

[MWJB]

Long grid wires are more likely to cause oscillations. I said elevate them over the board, I don't see why following my advice would run the grid wires any nearer to the CT wire than they are already?

That amp, in the 12AY7/5751/12AX7 shootout YT vid that you think sounds so good, watch it again, see the note about the 470ohm screen grid resistors. If you buy a 5E3 from Fender (57 Deluxe), Victoria or Kendrick, or anyone who builds them for a living, they have these resistors.

The original 5E3 had a daisy chain, single wire heater set up too...you didn't copy that, nor the OT placement, nor the grounding...it's a a bit late to start quoting the "original schematic/layout"...;-)

[paulj]

Long grid wires are more likely to cause oscillations. I said elevate them over the board, I don't see why following my advice would run the grid wires any nearer to the CT wire than they are already?

That amp, in the 12AY7/5751/12AX7 shootout YT vid that you think sounds so good, watch it again, see the note about the 470ohm screen grid resistors. If you buy a 5E3 from Fender (57 Deluxe), Victoria or Kendrick, or anyone who builds them for a living, they have these resistors.

The original 5E3 had a daisy chain, single wire heater set up too...you didn't copy that, nor the OT placement, nor the grounding...it's a a bit late to start quoting the "original schematic/layout"...;-)

They are running over the board or directly to the board. If you mean elevating them a little, that would elongate them. I don't think I understand.

I tried to read about the 470 ohm resistors but I could never find the straight explanation. Can anyone chime in on this?

I am not quoting anything. I just didn't get them with the kit nor they appear on the provided layout. I just wanted to explain to you why the kit came without those resistors.

[MWJB]

Your 6V6 grid wires run from the coupling caps right out to the left hand side of the board, to an eyelet on the far left, then turn back on themselves to angle right again, to go to the tube sockets. They do this on the original amp because there are components in the way, your board has the components on the other side, there is nothing in the way to necessitate this elongated routing. Run them in a straight line from the coupling cap turret to the tube socket pin 5. Even if you elevate them a quarter of an inch above the board they will be much, much shorter than they currently are.

Here is some reading with regards to the 470ohms screen grid resistors..."fit them, your amp will function better for having them". Happy now? ;-) They act like little shock absorbers on the screens, they should improve screen reliabilty and make the amp a little more stable.

[paulj]

Your 6V6 grid wires run from the coupling caps right out to the left hand side of the board, to an eyelet on the far left, then turn back on themselves to angle right again, to go to the tube sockets. They do this on the original amp because there are components in the way, your board has the components on the other side, there is nothing in the way to necessitate this elongated routing. Run them in a straight line from the coupling cap turret to the tube socket pin 5. Even if you elevate them a quarter of an inch above the board they will be much, much shorter than they currently are.

Here is some reading with regards to the 470ohms screen grid resistors..."fit them, your amp will function better for having them". Happy now? ;-) They act like little shock absorbers on the screens, they should improve screen reliabilty and make the amp a little more stable.

I understand now about the 6V6 grids and agree completely.

I will mount those resistors when I get them. I would prefer a more scientific explanation to be happy completely though

Shock absorbers work well on cars, they shouldn't hurt in a guitar amp.
That is unless the amp gets "too bouncy" from trying to absorb the shocks caused by my playing.

[trobbins]

Although probably not related to any sound character you are hearing, I found it difficult to appreciate what your 0V cabling was doing on the path from PT secondary through the filter cap arrangement to ground star point. Would you mind sketching the layout of the 0V circuit and post a photo of the sketch? As MWJB highlights, there is a lot to appreciate about the layout of the cabling and why those recommendations are made.

[paulj]

Although probably not related to any sound character you are hearing, I found it difficult to appreciate what your 0V cabling was doing on the path from PT secondary through the filter cap arrangement to ground star point. Would you mind sketching the layout of the 0V circuit and post a photo of the sketch? As MWJB highlights, there is a lot to appreciate about the layout of the cabling and why those recommendations are made.

trobbins,

I believe you are asking about the grounding scheme, correct me if I am wrong.
I am not doing anything unusual though. I have 2 ground connections, one dirty and one clean for inputs, preamp part. I have experimented with different locations and this is what I came up with. Works well, despite ugly looks with long wires etc. I am rebuilding it now and I can only appreciate the good choice to leave all the wires long. After cleanup, it will make more sense to you and others. I could draw the scheme but it is no different that what many others already posted on this board.

[gardbla]

Hi Paulj
I have a similar problem to yours – a 5E3 circuit that produces too less distortion and have a farting speaker instead. I would very much like to hear if you ever got a solution to your problem? I've tried to lower the values of my coupling caps from 0,1 to 0,047, 0,022 and finally to 0,010 uF, but to no avail, the speaker still farts and no creamy overdrive is present. What was the solution to your problem?

[Jazz P Bass]

Try lowering the value of the first stage cathode bypass capacitor.
Standard is 25uf.
On most Fender amps, especially the lower powered ones, that value simply lets too much of the bass frequencies through.
Start by using a 15uf & then a 10uf, or even a 4.7uf.
Use which one sounds best.