2004 SLO w/Deyoung Transformers versus New Bad SLO vid.

[ms17a]

Well, the HR vs SLO is a very simple yet potent comparison since the two amps are pretty much the same other than the transformers; hence my previous post.

They are not identical. For example, I explained the switch from AC heating to DC heating and the influnece on the sound. That's far from the same thing. Other comments note that the pots are different. There may be more differences in parts and layout. But simply repeating that only the transformers are different doesn't make the statement any truer.

But this whole thing about transformer brands seems to be taking on almost religious overtones. Now I understand what Dave Friedman meant when he talked about the technical discussions on Rig Talk. I give up, because you can't argue with dogmas. Have a nice day...

 

[fusedbrain]

AC Heating

• The "Vintage" Vibe: Often associated with the traditional, classic tube character. In guitar amplifiers, the slight residual heating fluctuation and the 50/60Hz modulation add to the "grungy" or "spongy" harmonically rich tone many players prefer.
• Hum Factor: Can result in a steady, low-level buzzing or humming sound in the background when no music is playing.

DC Heating

• Higher Fidelity & Clarity: The audio signal experiences significantly less distortion and noise, resulting in a cleaner, more transparent, and crisper sound.
• Lower Noise Floor: You get a pitch-black background with zero unwanted hum, which is essential for audiophile hi-fi systems, ultra-sensitive horn speakers, and low-level recording gear.

Sounds like that may be the 3D-thing that was mentioned before.

Very interesting info. I did not know this.
Thanks for posting

 

[harddriver]

The 2004 SLO with the Deyoungs and 20+ year old filter caps does sound more open, airy, less tight but in a good way, and somewhat more dynamic. With the said... the BAD SLO sounds like an SLO with upgrades.

If Heyboer has duplicated/cloned the Deyoungs I imagine they got them pretty damn close. I think Onetics was another transformer that was close to a Deyoung and I'm not sure Onetics is even in business any longer.

After playing SGTThumps Mezzabarba Trinity I think if I was in the market for an SLO with alot more really great options, like channel boosts and two master volumes, NFB control, depth mod, great loop I'd probably look at the Mezzabarba Mzero or Trinity if you want those SLOish tones.

 

[Shask]

Very interesting info. I did not know this.
Thanks for posting

Yeah, this is interesting. I do know on Fractal Axe-Fx Units, one of my tricks is to switch from AC to DC for the power supply because I noticed it sounds clearer. I didn't think tube amps had that much of a tone change due to this. I figured it was just for noise/hum.

 

[Racerxrated]

They are not identical. For example, I explained the switch from AC heating to DC heating and the influnece on the sound. That's far from the same thing. Other comments note that the pots are different. There may be more different than you think. But simply repeating that only the transformers are different doesn't make the statement any truer.

But this whole thing about transformer brands seems to be taking on almost religious overtones. Now I understand what Dave Friedman meant when he talked about the technical discussions on Rig Talk. I give up, because you can't argue with dogmas. Have a nice day...

I can always tell when an engineer of any discipline gets involved in any gear conversation. They simply take on a very condescending and 'know it all' attitude. That's fine; engineers aren't dumb by any stretch. But, you also don't know everything, do you?
I'll give you an example. A very smart individual on this forum stated that, a 68 Marshall clone, with the exact same modern resistor/cap type/ and VALUES with the same modern reproduction transformers created to mimic 1968 Marshall Dagnalls would sound IDENTICAL to a real deal 1968 Plexi. There should be no difference between them, IF the same exact layout, type parts, wiring, pots, chassis, layout etc etc were used.
Except, when this theory was actually put to the test and this smart engineer actually A/Bd a great clone with Merren iron and all the great parts to a real 68 Plexi, the vintage Plexi blew the clone out of the water. It wasn't close; the clone sounded flat and uninspiring by comparison.

I get that you consider the heaters, and pots to also contribute to the tone and while I agree to some extent, I do not agree that it contributes to anywhere CLOSE to the extent the degree of an output transformer change. I've swapped OTs in amps and the change in tone is very apparent and obvious to my ears.
We'll just have to agree to disagree. If Dave Friedman doesn't agree, well that's ok too. I could care less.

 

[harddriver]

Here's the same 2004 SLO same guy from the upper video. SLO through a Mesa V30 cab.

 

[marvcus]

They are not identical. For example, I explained the switch from AC heating to DC heating and the influnece on the sound. That's far from the same thing. Other comments note that the pots are different. There may be more different than you think. But simply repeating that only the transformers are different doesn't make the statement any truer.

But this whole thing about transformer brands seems to be taking on almost religious overtones. Now I understand what Dave Friedman meant when he talked about the technical discussions on Rig Talk. I give up, because you can't argue with dogmas. Have a nice day...

Maybe a more apples to apples comparison would be a pre-BAD SLO with DeYoungs vs another pre-BAD SLO with a Heyboer swapped in.

 

[thegame]

In the OP clip the 2004 SLO has superior mid content and detail. And that will obviously be even more pronounced in person.

 

[FourT6and2]

I can always tell when someone copy/pasted some BS from an AI chat.

I'd love to learn, without someone using AI, how AC and DC heaters impart different "harmonics" to the tone of a guitar amp. The filament heats up and when the cathode is nice and toasty, the tube conducts. All other things being equal, do the electrons flowing through the control grid care if the filament was heated up via AC or DC?

I've built amps using both methods. I've converted amps from one to the other. I've haven't noticed anyt magical differences in harmonics. But then again, I also can't hear the difference between 18 AWG and 16 AWG wire like some of the dog-eared folks here...

 

[LPMojoGL]

I've had 2 OGs, and have a BAD with Classictone trannies.
I prefer the newer one, mostly due to the updated effects loop. It also seems a bit easier to get the tone I shoot for, compared to the OGs.
I compared my SLO to those with Heyboers. Mine sounded better, in everyone's opinion that heard them both.

The Heyboers had 6L6s, vs 5881s in mine because 5881s weren't available at the time. The differences heard could have been that.
Ruby JJ 6L6GCs actually sound really good in mine, louder, bigger, more open. So who knows.

All this is to say, are the same pre/power tubes and bias settings being ran in both amps above? Is the effects loop engaged on the BAD model? If so, where is the loop volume set? It gets darker and needs higher volume settings if the loop volume is below 2-3 oclock. I'd be willing to bet turning the loop off, or having the loop volume at 3 o'clock or above would even things up.

 

[LPMojoGL]

The 2004 SLO with the Deyoungs and 20+ year old filter caps does sound more open, airy, less tight but in a good way, and somewhat more dynamic. With the said... the BAD SLO sounds like an SLO with upgrades.

If Heyboer has duplicated/cloned the Deyoungs I imagine they got them pretty damn close. I think Onetics was another transformer that was close to a Deyoung and I'm not sure Onetics is even in business any longer.

After playing SGTThumps Mezzabarba Trinity I think if I was in the market for an SLO with alot more really great options, like channel boosts and two master volumes, NFB control, depth mod, great loop I'd probably look at the Mezzabarba Mzero or Trinity if you want those SLOish tones.

I have lots of clips comparing my SLO to the Mezza MZero. I dont know that I would have bought the SLO if I had bought the MZero first. They're super close.
I decided to keep my SLO, when I could've kept the MZero instead. The SLO has a sweetness to it the MZero doesn't. Probably down to the power tubes?
The MZero has a bit more bark and versatility, due to the boost and NFB options. I found hitting the SLO with a Klon matched the boost function of the MZero. I'd really like to have the NFB knob on the SLO. I dig the way it helps dial in the overall feel and sound.
Both killer amps, differences probably undiscernible in a mix.

 

[BlueParfait]

Holy shit the BAD one sounds good.

Man, those crisp highs

 

[rstites]

I can always tell when an engineer of any discipline gets involved in any gear conversation. They simply take on a very condescending and 'know it all' attitude. That's fine; engineers aren't dumb by any stretch. But, you also don't know everything, do you?

Sadly, a lot of engineers feel their expertise in a narrow field extends to all fields. It's a case where the stereotype tends to fit much closer than I really like to admit. I say that as an engineer, and hope to steer way clear of acting that way. (The most I've done is noted my background to someone trying to play the internet-spew-bs game, which I find immature and pointless. It's transparent sitting on the other side of the discussion.)

I'd also note that when in school once, I did decide to do a demonstration to a room of engineers playing through different amps. The vast majority couldn't really hear the difference. It was an important epiphany to realize that it takes way more than just technical expertise to really master how something works in real life, such as an amplifier. It requires a trained ear and experience in actual usage - or the humility to listen to the people using it, one of Fender's geniuses so far as I can tell.

 

[rstites]

I can always tell when someone copy/pasted some BS from an AI chat.

I'd love to learn, without someone using AI, how AC and DC heaters impart different "harmonics" to the tone of a guitar amp. The filament heats up and when the cathode is nice and toasty, the tube conducts. All other things being equal, do the electrons flowing through the control grid care if the filament was heated up via AC or DC?

I've built amps using both methods. I've converted amps from one to the other. I've haven't noticed anyt magical differences in harmonics. But then again, I also can't hear the difference between 18 AWG and 16 AWG wire like some of the dog-eared folks here...

I thought the biggest reason of the switch to DC heaters vs. AC heaters is a change in tube design that introduced more noise using AC heaters in modern amps. AC heaters are easier, so it's natural they were used in the early days, and in the even earlier days you had to since the heater was integrated into the cathode (? - think that's correct).

It's always interesting to read about how X was done for some kind of sonic performance, when the reality is it was just a convenience of design or for something fairly mundane, though critical, like noise.

 

[RedPlated]

I've had 2 OGs, and have a BAD with Classictone trannies.
I prefer the newer one, mostly due to the updated effects loop. It also seems a bit easier to get the tone I shoot for, compared to the OGs.
I compared my SLO to those with Heyboers. Mine sounded better, in everyone's opinion that heard them both.

The Heyboers had 6L6s, vs 5881s in mine because 5881s weren't available at the time. The differences heard could have been that.
Ruby JJ 6L6GCs actually sound really good in mine, louder, bigger, more open. So who knows.

All this is to say, are the same pre/power tubes and bias settings being ran in both amps above? Is the effects loop engaged on the BAD model? If so, where is the loop volume set? It gets darker and needs higher volume settings if the loop volume is below 2-3 oclock. I'd be willing to bet turning the loop off, or having the loop volume at 3 o'clock or above would even things up.

6L6’s vs 5881 in a SLO makes a big difference. Less mids with the 6L6. I prefer them, actually. The 5881’s can be too much.

The SLO is pretty much a midrange machine. More than I care for, personally. I pull some of it out with the mods.

 

[LPMojoGL]

6L6’s vs 5881 in a SLO makes a big difference. Less mids with the 6L6. I prefer them, actually. The 5881’s can be too much.

The SLO is pretty much a midrange machine. More than I care for, personally. I pull some of it out with the mods.

Agreed! I liked the 6L6GCs, much more than I thought I would after comparing the SLO with Classictone/5881s to Heyboer/6L6s.
I'm missing some that openness of the 6L6s with the 6p3se.
Am I wrong in thinking a NFB knob would help open up the SLO, shifting the mids?

 

[FourT6and2]

I thought the biggest reason of the switch to DC heaters vs. AC heaters is a change in tube design that introduced more noise using AC heaters in modern amps. AC heaters are easier, so it's natural they were used in the early days, and in the even earlier days you had to since the heater was integrated into the cathode (? - think that's correct).

It's always interesting to read about how X was done for some kind of sonic performance, when the reality is it was just a convenience of design or for something fairly mundane, though critical, like noise.

It's simply for noise. And mostly for preamp tubes, not counting the PI position. Power tubes don't benefit from DC heaters, as far as I know.

I think what you're talking about might be DC elevated heaters. This is something different. And it's usually done to reduce the heater-to-cathode voltage differential in cathode follower preamp tube positions. Mostly in Marshall-style circuits. The cathode follower can be hard on preamp tubes, causing modern tubes with spiral filaments to die quicker.

The heater circuit's center tap is typically referenced to 0V (chassis ground). When you reference the heater's center tap to some higher, elevated DC point (like 45v DC, typically an already filtered/smoothed node), the AC heater circuit "floats" on top of a DC-referenced voltage instead of 0V/ground. This elevation helps reduce the strain on tubes in cathode follower positions. It can help reduce some noise, but it's really not intended to do that and the heaters are still AC.

Think of a sine wave. It's oscillating from +3.15v to -3.15, centered at 0v.

When you elevate the heaters, 0v is no longer the center reference. You reference the wave to... let's say +45v DC. Now your "center" is +45v. So the 6.3v AC heater circuit oscillates from +48.35v DC to -41.85v DC, with 45v DC being the new "0". The AC wave is still only 6.3v, it's just floating higher.

Because the new reference is +45v, the DC voltage differential between the cathode and the heater circuit is 45v lower, thus lowering the stress on the tube. The maximum voltage differential is listed in the tube's data sheet. So it's easy to calculate if you need to elevate the heaters and by how much.

 

[rstites]

I've always run my SLO with 6L6GC's.

It's simply for noise. And mostly for preamp tubes, not counting the PI position. Power tubes don't benefit from DC heaters, as far as I know.

I think what you're talking about might be DC elevated heaters. This is something different. And it's usually done to reduce the heater-to-cathode voltage differential in cathode follower preamp tube positions. Mostly in Marshall-style circuits. The cathode follower can be hard on preamp tubes, causing modern tubes with spiral filaments to die quicker.

The heater circuit's center tap is typically referenced to 0V (chassis ground). When you reference the heater's center tap to some higher, elevated DC point (like 45v DC, typically an already filtered/smoothed node), the AC heater circuit "floats" on top of a DC-referenced voltage instead of 0V/ground. This elevation helps reduce the strain on tubes in cathode follower positions. It can help reduce some noise, but it's really not intended to do that and the heaters are still AC.

What I was thinking of is directly vs indirectly heated cathodes. I've only read about direct heating of cathodes in vacuum tubes but never had a reason to work with that type of tube design. It does us a DC voltage at the cathode to heat it, as opposed to a separate heater.

The dc elevated heater isn't a term I recognized but it understand the concept.

 

[Metlupass2]

6L6’s vs 5881 in a SLO makes a big difference. Less mids with the 6L6. I prefer them, actually. The 5881’s can be too much.

The SLO is pretty much a midrange machine. More than I care for, personally. I pull some of it out with the mods.

How many have you modded now?

 

[FourT6and2]

What I was thinking of is directly vs indirectly heated cathodes. I've only read about direct heating of cathodes in vacuum tubes but never had a reason to work with that type of tube design. It does us a DC voltage at the cathode to heat it, as opposed to a separate heater.

I think some rectifier tubes are directly heated, but I don't believe I've seen this done with octal-based power tubes in Class AB guitar amps. Maybe it's been done before, but I'm unaware of it.