About amp "immediacy"

[galaxiex]

I've worked on a couple of those YGM-3 lately, very similar to a Twin Reverb. Last one was a 2x12 combo. Had a rare follow up call from its owner, he was really lovin' it - in spite of very rattly 6CA7 output tubes he decided to keep in place for now. Had Celestion G12-80 speakers. Heavy rig, but a big "in your face" sound all right.

Would be interesting to A/B it with a healthy Twin sporting a pair of JBL's.

Cool!

Not sure, but I think you mean a YGL-3 (Yorkville Guitar Lead) as opposed to a YGM-3 (Yorkville Guitar Mate)?

The YGL-3 came as a 2X12 combo, the YGM-3 was a 1X12 or 4X8 combo.

I used to have a YGL-3. Sold it a long time ago, still wish I had it.
Ya, very big in your face sound.

Been looking at them on Reverb, some there for an ok price.
Loud amp tho, I just don't need that much amp.

I think the Traynor is a "Twin Killer".

Sorry for the thread de-rail.

[Leo_Gnardo]

Cool!

Not sure, but I think you mean a YGL-3 (Yorkville Guitar Lead) as opposed to a YGM-3 (Yorkville Guitar Mate)?

The YGL-3 came as a 2X12 combo, the YGM-3 was a 1X12 or 4X8 combo.

WOOPS! Yes YGL-3 I meant... now corrected, thanx! Thread, and brain, back on track.

[Randall]

I don't know how to quantify it, but I have a Deluxe Reverb and a Musicman 210 SixtyFive, which is like a DR, but with a SS rectifier and preamp. I like them both, but I have always thought of the MM as faster and better for chicken picking.

[olddawg]

“I never heard an old Gibson/Epiphone amp I thought sounded worth a damn.” Lol! It isn’t just me! I did have a mid 60s Skylark that wasn’t awful once.. but I gave it to a friend to play harp through. It was better for that...

[Enzo]

Aha. They may sound fine for harp or accordion, but for guitar? Suck city.

Just my opinion.

[alexradium]

I don't know how to quantify it, but I have a Deluxe Reverb and a Musicman 210 SixtyFive, which is like a DR, but with a SS rectifier and preamp. I like them both, but I have always thought of the MM as faster and better for chicken picking.

absolutely,Carl Verheyen,top player,prefers his dr Z amp with an ss rectifier instead of the original tube,he says that the amp can't keep up with his playing,figure that.

[yldouright]

So, slew rate is only one of dozens or hundreds of amp behaviors and psycho-acoustic effects that impact how someone "hears" an amp.

The focus of his question was on immediacy alone and what is responsible for it. How does introducing all these other issues help here? Are you making the claim that slew rate is not the main factor in determining the immediacy of an amp?

Another way to answer the tube/SS question is to suggest you play a bunch of both and then decide what's different and what's preferable for yourself.

Maybe he wants to build his own amp and doesn’t want to take a lifetime seeking out and playing bunches of amps to decide which way to go. The prospect of reading the nearly infinite conflicting diaspora of internet research is equally inefficient. A forum where players and technicians interact would seem a good place to get correctly informed more quickly. It’s a pity there are so many characters here posturing more than knowing.

Well one reason is that "immediate" has no particular definition here.

I’ve heard this difference defined by many musicians. Are you dismissing this description as nonsense?

Chuck said he thought slew rate might be a factor, that is a far cry from slew rate being the whole deal.

Chuck suggested tube amps with a lower slew rate sound more immediate. There is evidence to suggest higher slew rate and the quality of immediacy are corresponding. This information conflicts so which is right? If you now concede that immediacy is a “real” quality, what other factors contribute to it in an amp?

But if you try to compare a Lab Series amp and a Hot Rod DeVille just on the basis of tubeness or solid stateness, you are missing the boat.

Please explain how this relates to his original question and in what way this member is “missing the boat”.

First, a slower slew rate doesn't sound more immediate than a faster slew rate. That's just something someone said somewhere at some time.

Yes, it was YOU that said it, in this thread on 10/7/2018 around 4:13PM.

Why and how do tube amps sound different from SS amps? Well guess what.?. I'm not going to answer that. Not because I don't know, but because the web is already chock full of tomes on the subject ranging from guru flavored lore to technical discussions. If you just search "tubes" "SS" you won't even be able to go any further without tripping over a discussion on the matter.

See the reply to uneumann for why this question was probably posed here. Tubes have ~1,000x faster rise times than transistors which gives them greater potential for higher slew rate circuits. The two pitfalls which will limit slew in tube circuits are insufficient grid current and/or input capacitance. In other words, if you have a slow tube amp, look there. If it’s 'not because you don’t know', why did you assert that tubes had lower slew rates than chips?

Whenever possible use your own ears to find out if sound quality is good. When the so-called experts start throwing around terms like "immediacy, PRAT, slew rate" and other such malarkey, you know they're trying to snow you, move on.

Slew Rate is a quantifiable electrical parameter. PRAT (Pace, Rhythym and Timing aka Immediacy) is a psycho-acoustically observed and repeatable phenomena with real electrical signal attributes. Circuit time delay and signal smearing provide a theoretical basis for these and other psycho-acoustically observed qualities. Just because we can’t measure them well doesn’t make them non-existent. On the one hand, you suggest to use your own ears and then go on to dismiss a real psychoacoustic attribute. Are you purposely trying to confuse readers here or hedging to obfuscate your ignorance on the subject? By the way, a person can also be snowed by an attitude of move along, nothing to see here.

[Malcolm Irving]

... PRAT (Pace, Rhythym and Timing aka Immediacy) is a psycho-acoustically observed and repeatable phenomena with real electrical signal attributes. Circuit time delay and signal smearing provide a theoretical basis for these and other psycho-acoustically observed qualities. …

Can you give any scientific/technical references for that?

[yldouright]

Can you give any scientific/technical references for that?

Please be more specific. I'm assuming you aren't challenging the theoretical concepts of circuit time delays and as of yet unmeasurable signal wave smearing. Do you want scientificly quantified corroboration of PRaT or proof of its audible repeatability?

[Dave H]

The problem was all in their power amps, some fly-by-night brand "Time Square" made in Alabama, that were supposed to be the hot ticket - because they had a whomping stomping slew rate 200V/microsecond.

I've got too much time on my hands today. I've worked out that 200V/microsecond is the max slew rate of a 320kHz 100V peak sine wave. I'd have trouble hearing that at my age.

[Chuck H]

Hey looky! I've got my first thumbs downs and been misquoted on the same thread. Did someone leave the gate open at the jackass farm?

[netfences]

Thank you to all for your spirited responses. I think the input from the musicians here are the most valuable. When dealing with psycho-acoustic phenomena, they are closest to the truth. A big thanks to yldouright for pointing out the rise time of a VT and how a bad design can slow it down. My research indicates that 10V/uS is sufficient slew for any 50W amp, VT, SS or Op-Amp. Unless you're one those who believe we can sense >50Khz the slew rate bar is low for a common music amp. Slew seems to be the main reason for the psycho-acoustic feel originally asked about but I'm willing to hear of others. I am aware that things like dominant 2nd or 3rd order harmonics will flavor an amp. I am also aware of the unpleasant harshness introduced with higher order harmonic distortions. In this thread, I only wanted to learn about amp immediacy and how to achieve it. As was correctly pointed out, my goal is to build an amp that is pedal friendly, uber clean and fast/present. The players in here seem to know what I mean if others don't.

[Dave H]

Hey looky! I've got my first thumbs downs

Never mind a thumbs down from the Unholy Trinity shows you must be doing something right. I'll give you a thumbs up to cancel it out.

[Chuck H]

BTW... Any difference to be made in the slew rate of a tube circuit to make it faster than a transistor is indeed mitigated by coupling requirements. The high voltage power supply requirements also pose a limitation. I don't know that tubes are indeed 1000 times faster than silicooties, but I'm not technically learned on the subject. I can only point out then that circuits to direct couple tube stages are analogous with consequences like limitations in available stage gain (so what's the point?) and transformer coupling is typically associated with consequences like additional noise and/or phase difficulties (signal smearing?) (so what's the point?). This is surely why the good old, slow capacitor coupled circuits, with their slow time constants and grid current limitations prevail for tubes. Further, I don't think I've ever seen a voltage amplifier that instigates significant grid current.?. Power stages yes. But that's only one part of an entire circuit where MOST of it still relies on other limiting factors. Relative to SPLAT or PRAT or whatever I would think that slew rate would be a secondary consideration to phase alignment within the predictably achievable time constant. But again, I'm not technically trained on the subject.

Perhaps someone could post an example of a tube circuit, complete with power supply, that exploits their fast rise time potential.?.

[Chuck H]

Never mind a thumbs down from the Unholy Trinity shows you must be doing something right. I'll give you a thumbs up to cancel it out.

Nice. Almost like "it" never happened