A clone of the Lazy J J20?

[tzurby]

The Lazy J J20 by Jesse Hoff simply sounds fantastic: https://www.youtube.com/watch?v=v4_c...index=5&t=169s
I do not hear this 5e3 magic on other clones (except Speedshop - oh man).

I once built a clone (using the tubetown (Germany) kit - I only can solder), but it failed short of any 5e3 magic.

According to Jesse, one of the main components in that sound (apart from 6L6 output tubes, like Neil Youngs 5e3) is the power transformer.
Jesse says:

The tweed Deluxe has a very spongy power supply that results in a very subtle, organic compression even at low volume levels. There is sag in it that allows the harmonics to come up and bloom, and the power transformer has a huge role in affecting this. I experimented with different transformers and more efficient iron and it ruined the sound of the amp. It became really snappy and the harmonics were lost,…

Just like on the tubetown kit.

And more:

I bumped up the power supply, gave it an extra stage of filtering and bumped up the preamp voltages, among other things… I had to give the amp increased heater capacity because it runs hot with 6L6s, which is also why I included a fan. The transformer I use is made by Heyboer… But what blew me away was how much the power transformer influenced the sound, even if you keep all the windings the same and just change the steel… because the voltages drop in a very organic way and it acts like a little compressor. The importance of the inefficiency in the steel
used for the power transformer amazed me… You can work this all out mathematically, but in the end none of that matters. What matters is how it sounds.

The 5e3 is a rather simple circuit. There are so many kits around. It should be possible to get one, change it in order to built a clone of this clone. One would need to know the transformer (obviously custom ordered from Heyboer), which could be the hardest thing. Then the OT. And then some modifications on the circuit.

This repair guy from Australia doesn't like the Lazy J at all. (I don't care. The repairman obviously has no appreciation of amp magic, as he thinks with reverb and tremolo this now is a later Princeton. Also, he obviously did not read what Jesse said in the ToneQuest report about PTs. So he replaces the original PT, which is "too small", with a larger one instead of letting it rewind.)

With regard to the changes in the circuit, the repairman, who surely knows his stuff, here shows the modifications Jesse did. For you experts: there are some strange things going on in the circuit. Don't know it these are important.

What I thinks is needed: the right PT, OT, know the alterations on the schematic, probably the fan for the delicate PT - and then solder this thing together (I have done it before). Reverb and tremolo would be nice, but probably too complex and costly. Attenuation would be nice, though.

Any suggestions?

[Helmholtz]

What is the exact question?

[tzurby]

To get some hints by the experts here how to do it - if it can be done:
Which PT, OT, alterations in the schematic. With these info, I could do it myself. I would let it check with my amp tech, who knows everything regarding tube amps - but, as so often, has no understanding on tube amp magic - or maybe a different taste...

[The Dude]

If there is real mojo created by different PT's, results should be measurable. Sag can be calculated by measuring B+ at different output levels. IMO, mojo is not really any sort of voodoo magic. It's more or less a preference for certain circuit results. That said, it would require that you try a given amp with different transformers and make measurements. Then, see which measurements correlate to the sound and transformer you like. I'd also speculate that, even with different transformers, you could get similar results by using different power supply component values to either increase or decrease the amount of sag.

Edit: BTW, that's a great sounding amp in the video!

[g1]

The repairman obviously has no appreciation of amp magic, as he thinks with reverb and tremolo this now is a later Princeton. Also, he obviously did not read what Jesse said in the ToneQuest report about PTs. So he replaces the original PT, which is "too small", with a larger one instead of letting it rewind.)

That's not what he said. He said if you want such a different amp (reverb and tremolo), just buy a Princeton Reverb. And it's a good point. Everything he says is spot on.
The part of the PT responsible for the sag is separate from the part responsible for powering the heaters. Underpowering the heaters to the point where the PT will melt down without a fan pointed at it is either irresponsible or just plain ignorant of what the PT does. The technician said he rightly upgraded the heater part of the equation, which should not affect the sag.
The alterations are all shown on the schematic. If you want to build this amp, put them in. It's impossible to say what the PT and OT would be without their model numbers. You should be able to get a PT that has adequate heater capability without increasing the HV winding capability, which is the part that affects the sag. If you are not adding the extra preamp tubes for reverb and trem, it might not melt down anyway, although you should have extra heater capability to run 6L6 vs 6V6.

[tzurby]

The alterations are all shown on the schematic. If you want to build this amp, put them in. It's impossible to say what the PT and OT would be without their model numbers. You should be able to get a PT that has adequate heater capability without increasing the HV winding capability, which is the part that affects the sag. If you are not adding the extra preamp tubes for reverb and trem, it might not melt down anyway, although you should have extra heater capability to run 6L6 vs 6V6.

Thanks so much. I will discuss the rest with my technician. Any suggestions what MIGHT be the right PT to start with?

[Chuck H]

Any suggestions what MIGHT be the right PT to start with?

Probably the one you already have with a resistor added to increase sag in the HV supply. If there is any such thing as "tube amp magic" it's the effect of variable operating conditions for the tubes due to voltage shifts. The 5e3 design, including the PT characteristics, would of course be part of the amps tone and "feel".

Are you using 6V6's or 6L6's in your amp now?

EDIT: I did a little digging around and it looks like an original Fender PT would had a comparably high secondary voltage but a rather high DCR on that winding. The result would be "correct" voltage with more sag under current. Which seems to correspond to reports of what affects the feel of these amps. So if you do add a sag resistor your amp would probably have lower voltages than an actual Fender but it would introduce the sag effect that may be missing now. That said, the 5e3 is a cathode biased amp so the lower voltages will affect the bias condition. You may or may not need to adjust for this.

With the sag introduced (with an extra resistor), lower HV voltage and possibly a bias resistor adjustment you may get the tone your after at very slightly lower wattage compared to an actual 5e3.

It's not magic or alchemy. It's just design considerations about operating conditions and how that affects the tone and feel of the circuit in use.

[Helmholtz]

A saggy PT increases compression which may be desirable.
The only way a PT interacts with the amp is via its voltages and its internal DC resistance, which is the actual reason for the sag.
A somewhat undersized PT will have a larger effective DCR, resulting in more sag when current increases.
More sag means more voltage drop within the PT. This larger voltage drop together with the larger DCR significantly increases PT heating (dissipation).
In other words, the more sag a PT has, the hotter it will get inside. Of course this means risk of failure.

The same sag can be had with a stiffer PT + external resistor(s) as Chuck H suggested..
Huge advantage is that now most of the heat is produced in the resistors and not in the PT winding.

[Helmholtz]

The influence of the PT core:

The core (size and material) determines the number of turns required for primary and secondaries.
A smaller core or lower grade laminations necessitate more turns and - as winding space is limited - the use of thinner wire.
Result is increased DCR and thus more sag (and more heating).

[tzurby]

Thanks for all your expert comments. However, it is not just about sag. (We are talking about the tone gets compressed and then blossoms again, right? Like in Neil Young, famously here: https://www.youtube.com/watch?v=eNQnXS9—oM) It is about the sweetness of the tone in general, about harmonic content, a rich as opposed to a sterile tone. That’s what I call “tube amp magic”.

Most 5e3 clones I hear lack this. I listened to Fenders 57 Custom Deluxe. And I am not impressed. It’s a pretty expensive amp. For Peter Townsend and all the others who use the Lazy J amp (here is the client list: https://www.lazyjprojects.com/clients.html) it would not matter whether to spend the $$ on the Fender, which most probably is more reliable, or the Lazy J. They choose the Lazy J.

Peter Townsend does not use sag – at least not like Neil Young. The Lazy J was the only amp miked during the Who concert at the 2012 Olympics final ceremony: https://youtu.be/rsGQ8C64WlQ?t=508

Jesse talks about “more efficient iron” ruining “the sound of the amp. It became really snappy and the harmonics were lost”. This, it seems to me, is what I hear in most 5e3 clones – and other modern amps as well. Here, it seems to me, could be the deeper reason why people spend thousands of $$ on vintage amps. Listen to this; I cannot find this on most clones or modern tube amps: https://www.youtube.com/watch?v=vcQo9p-OHtM – O.K., there is a lot of sag going on. But listen when he turns down the volume at 2:40.)

Less efficient iron – what does that mean? Less iron? Or another kind of iron? Or both? The PT he uses is much smaller than a “suitable” PT: https://youtu.be/7elb2wG2zMA?t=31

Less efficient iron helps to get “a very subtle, organic compression even at low volume levels” (no “sag”, isn’t it?)

To quote Jesse again: “But what blew me away was how much the power transformer influenced the sound, even if you keep all the windings the same and just change the steel… because the voltages drop in a very organic way and it acts like a little compressor. The importance of the inefficiency in the steel used for the power transformer amazed me…”

Is that what you are talking about, and it is all about sag? And the same result could be achieved either by less iron/a smaller PT, or by using external resistors, so with the one or the other solution the amp would sound the same? If so, why did nobody do it?

Apart from this, what I don’t understand is: “I bumped up the power supply, gave it an extra stage of filtering and bumped up the preamp voltages, among other things…”

By the way, I would go for an 6L6 5e3. I don't have an amp to work on right now. I plan to get a kit, possibly a used one and change the PT and other components. There are many around.

[Chuck H]

Thanks for all your expert comments. However, it is not just about sag. (We are talking about the tone gets compressed and then blossoms again, right? Like in Neil Young,

You concede to ask again later if sag is the missing and seemingly secret ingredient in the magic. It isn't ONLY about sag but it is largely about sag. I know "sag" is not a pretty sounding word so that may have something to do with why people creating floral terms for tone prefer not to use it

Most 5e3 clones I hear lack this. I listened to Fenders 57 Custom Deluxe. And I am not impressed. It’s a pretty expensive amp. For Peter Townsend and all the others who use the Lazy J amp (here is the client list: https://www.lazyjprojects.com/clients.html) it would not matter whether to spend the $$ on the Fender, which most probably is more reliable, or the Lazy J. They choose the Lazy J.

And yet the whole magic mojo Deluxe amp thing has it's strongest roots in Neils actual 5e3. I'm going to grant that the Lazy J probably captures "that" sound some players are after where other clones don't. But it's still just an amp. The power transformer is just a power transformer and operating conditions for the circuit have been at least explained, if not actually measured.

Less efficient iron... what does that mean? Less iron? Or another kind of iron? Or both?

In this case I'll guess that no one is referring to the "iron" itself but rather using the word iron to indicate the whole transformer. This is actually common nomenclature in the genre. Even if the actual iron laminates have been referenced for particulars at times let's be careful not to assume that in every case where the word iron is used. In the exact case above I believe it simply means a less efficient transformer. Efficiency in this case is almost certainly in reference to the PT's ability (or rather, lack of) to meet the current demands of the whole amplifiers signal chain.

Is that what you are talking about, and it is all about sag? And the same result could be achieved either by less iron/a smaller PT, or by using external resistors, so with the one or the other solution the amp would sound the same? If so, why did nobody do it?

With a "less efficient" PT the primary effect on an amplifier would be voltage "sagging" as current demands increase. Largely due to resistance in the HV winding. Something for which an actual vintage 5e3 PT (like Neils) is known and many if not most modern clones lack for many reasons. Chief among them would be the extra expense of developing a reliable transformer that still chokes under current in the circuit it's intended for and also the more attractive price of redily available transformers that are less likely to cause product failure. A byproduct of sag is heat. Transformers are more limited in their ability to manage heat than resistors. Since resistance is the primary factor in the sag effect it's entirely possible to add resistance at the right point in the power supply circuit to accurately emulate a less efficient power transformer. This has the benefit of placing the heat demands on a resistor. Which is both better suited to handle that chore and less expensive than a power transformer in the event of failure. And...

Designers HAVE used sag resistors in their designs. My own most popular amp design uses one. Most of the solid state rectifier tube substitutions include a resistance to emulate the sag introduced by an actual rectifier tube due to resistance. The reason you don't see it in the 5e3 magic tone search and clone kits is because guys like you prefer to keep things nebulous and sprinkled in fairy dust. Treating the properties of tone like it's a black art only possible through alchemy or accident and choosing to diefy only certain individuals or specific amplifiers with only vague reasons using terminologies that are subjective and avoid the understanding of technical aspect. In such an environment your more likely to hear "NOS", "rectifier tube", "harmonic bloom", etc. than the comparably ugly sounding reference to a "sag resistor". It just doesn't sound magical enough and it's out of place where vintage mojo is worshipped over actual understanding.

I (he) bumped up the power supply, gave it an extra stage of filtering and bumped up the preamp voltages, among other things

This makes sense and would be where the Lazy J gets it's extra goodness. It basically makes the circuit want to perform with more dynamics while the sag effect simultaneously limits that performance. The overall compression effect is enhanced so that now the sag and recovery (swell or bloom if you prefer) have a greater dynamic. In amps that do it well this can be a very musical effect. Again mentioning my own amp design. I do use a sag resistor and at one point in the design phase did increase preamp voltages to get some of these properties being discussed. Though it's a great deal more subtle in my design than what the 5e3 aficionados are looking for. I'm just trying to explain that I (and many others here) do understand some things about what makes tone and have had some success in measuring for it, doing repairs to preserve it, modifications to achieve it and even designing for it.

We aren't wizards, gurus, alchemists or magicians and don't typically suffer fools long when they choose mojo over measure. If you want to learn what makes amps behave in this way or that then you could do worse than listening to what the members here have to say. If you prefer to shroud amplifier properties in mysticism you're not going to like us much

[Pedro Vecino]

I don't understand the concept "sag" in a cathode bias amp in which from the first quartet of a watt its power tubes handle the maximum intensity.
If the current demand does not increase, how can it happen?

[Helmholtz]

I don't understand the concept "sag" in a cathode bias amp in which from the first quartet of a watt its power tubes handle the maximum intensity.
If the current demand does not increase, how can it happen?

Current demand increases when the power tubes leave class A operation at some medium output.
The increase in current shows as a rise in cathode voltage. This is how you can verify class AB operation.

All cathode biased PP guitar amps I've seen actually run in class AB. Otherwise output would be very low.

[Chuck H]

What Helmholtz said. Current demands do increase in push pull cathode biased amps that shift into AB. Which is probably all guitar amps. There is a strong misconception floating around on line communities that "cathode biased" equals "class A". It doesn't. You can cathode bias for AB operation as well. And while there are many class A push pull guitar amps the shift to class AB is basically unavoidable once an amp begins to overdrive.

[Helmholtz]

And while there are many class A push pull guitar amps ..

Please show me at least one (schematic?).