Personally with respect to guitar amps, I haven't found that feedback from speaker to tubes was ever really useful, to me, in creating a more euphonic sound. I always preferred the sound of head based amps over a combo because of the reduced microphonics/feedback (however you would like to describe it). The feedback from speakers to the guitar strings(and in some cases to semi hollow body guitars), well now you have something that can be harnessed for musical expression. In the case of feedback to preamp tubes the result is not controllable, at least not at a musical performance level............however there is certainly many ways to reduce the problem(rubber o-rings over the tube, shock mounted tube sockets, etc.
Vintage mojo... What is it exactly?
- Thread starter SamuelPepys
- Start date
Help Support GroupDIY Audio Forum:
Bo Deadly
Well-known member
Feedback from speaker to guitar is very important yes. Especially at really loud levels. But feedback from the speaker output to the PI (like in a twin, deluxe, "presence" control in a JTM-45s, etc) expands and flattens the frequency response considerably. Consider that J. Garcia played through only the pre of a twin and then fed that into McIntosh amps that were way tighter than a honky guitar amp.
Agree with you on the FB loop from OT sec to PI. I was talking about acoustic feedback from the speaker causing "pleasing" microphonics in the preamp tubes. I'm not sure I get your point about the twin pre into McIntosh amps, but then I wasn't a fan of Jerry's guitar sound.
soapfoot
Well-known member
The 21-year-old version of me would've bristled at what I'm about to say, but... I've come to believe that the most consistent source of "vintage magic" might be the way the overall user experience colors our expectations.
I'm sure many of us have had experiences where with there were two mixes of a song--one that accompanied a fantastic-looking video, and a different mix for audio-only album release. With the impressive-looking video playing, that first mix sounds great. With the screen off, it's usually markedly inferior to the "album release" mix.... even if nothing changed except turning off the video!
In a similar vein, using something like a Fairchild 670 or old Marshall Plexi is something of a total sensory experience. It's very easy to be drawn into the overall feeling created by the giant bakelite knobs, huge VU meters, iconic make/model name, large price tag, awareness that we've long coveted this thing (or that our heroes used it)...
True objectivity under these circumstances seems almost superhuman. Younger, cockier me would've thought myself an exception to this, but that's just ego. The more experienced I become, the more uncertain I become of the distinction between "extreme discernment" and "superstition."
I'm sure many of us have had experiences where with there were two mixes of a song--one that accompanied a fantastic-looking video, and a different mix for audio-only album release. With the impressive-looking video playing, that first mix sounds great. With the screen off, it's usually markedly inferior to the "album release" mix.... even if nothing changed except turning off the video!
In a similar vein, using something like a Fairchild 670 or old Marshall Plexi is something of a total sensory experience. It's very easy to be drawn into the overall feeling created by the giant bakelite knobs, huge VU meters, iconic make/model name, large price tag, awareness that we've long coveted this thing (or that our heroes used it)...
True objectivity under these circumstances seems almost superhuman. Younger, cockier me would've thought myself an exception to this, but that's just ego. The more experienced I become, the more uncertain I become of the distinction between "extreme discernment" and "superstition."
Soap,
Very important aspect here. This also why glittering user interfaces are so freakin' important to how plugins sounds
(I reuse this recent GS post):
And yes, I'm very aware that with my commercial Gyraf range I'm harvesting some of this effect too, BUT: I defend myself with the fact that I go out of my way to ensure maximum coherence between user interface and its description of actual (although often subjective) function as primary goal - trying NOT to mislead my user's ears by going the other way around. And as I mention above - "the other way around" has been seen in hardware pro audio, some times to a scary degree - and not at all always purposefully deceitful.
/Jakob E.
Very important aspect here. This also why glittering user interfaces are so freakin' important to how plugins sounds
(I reuse this recent GS post):
Do not underestimate the function of the user interface - it is of primary importance in the quest to have emulations sounding like their origin
Reason is that perceived auditory impression is strongly informed from environment cues and habits - to a degree where it sometimes resemble hallucination
This what hifi lives off. And no, it's not make-believe or want-to-believe - it's nature is suggestional, closer related to hypnotically induced hallucinations. This also why hifi discussions tends to get so emotionally heated: They actually and really HEAR that effect that we can't measure or demonstrate - and that can't be repeated in blind tests.
To understand the effect, think of that time you turned the treble up on that hihat during that wildly stressed recording session, only to later discover that eq was bypassed. Rethinking the situation, you WILL remember actually hearing the boosting going on. But as I did, you probably passed it off as a temporary flaw. It's not.
Emulation-plugin user interfacing simply harvests effects like this.
Last time I talked to one of Soft tube's development engineers, he told me that they still extract something like half the perceived sound quality from the interfacing - off course depending on how such aspect is quantified. And mind you, these guys are not kidding, if anything they're among the heavier players in good-sounding emulation business..
Another aspect forming environmental cues to plugin perfection is telling the ever-occurring very public story about how NOW the plugin is fully perfect (the old version wasn't), and with this and that celeb endorsing it, we're legitimizing your use of it..
I just recently realized that if we could somehow harvest this effect for music, not gear, we could make things shift to a whole new level.. Still working on that part though
/Jakob E.
edit:
Note that I'm not in any way implying that using this effect is limited to plugins/emulations - I see examples of pro audio hardware that heavily preys on this effect too..
And yes, I'm very aware that with my commercial Gyraf range I'm harvesting some of this effect too, BUT: I defend myself with the fact that I go out of my way to ensure maximum coherence between user interface and its description of actual (although often subjective) function as primary goal - trying NOT to mislead my user's ears by going the other way around. And as I mention above - "the other way around" has been seen in hardware pro audio, some times to a scary degree - and not at all always purposefully deceitful.
/Jakob E.
I like that idea.Something along these lines might have been partially attempted already by the many 'remastered' classic albums. Some of which, at first listen, might be 'better' or more 'modern'-sounding from a purely technical or engineering point of view, but which often fall short in aesthetic terms -- or let's say they run a risk of losing 'their mojo' (here aesthetic expectation). Personally I like things ('music) that has some sort of quirk (clearly noticeable or not). But I guess you mean something different.
![Electronics Soldering Iron Kit, [Upgraded] Soldering Iron 110V 90W LCD Digital Portable Soldering Kit 180-480℃(356-896℉), Welding Tool with ON/OFF Switch, Auto-sleep, Thermostatic Design](https://m.media-amazon.com/images/I/41gRDnlyfJS._SL500_.jpg)
I alluded to perception bias back about 40 years ago but probably didn't call it that, when discussing the "Meter readers" vs "Golden Ears" debate. I suggested decades ago that product designers need to study the ergonomic or psychological factors that influence how people perceive products and use those tools in new designs to increase product satisfaction.
Over the years I had many deep discussions with a fellow console designer (now RIP) about the sundry subtle factors that influenced console user's perception of quality.
JR
soapfoot
Well-known member
I appreciate that these "user experience" factors are being approached here in a manner beyond dismissiveness, because I do agree that it matters--even to the end result of the work.
Assuming a vintage analog synthesizer versus a plug-in emulation: Even in a world where the two could be definitively proven to perform identically, interacting with the old piece of hardware would almost certainly impact the creative and thought processes of the performer. They'll produce different work!
This is not trivial.
Assuming a vintage analog synthesizer versus a plug-in emulation: Even in a world where the two could be definitively proven to perform identically, interacting with the old piece of hardware would almost certainly impact the creative and thought processes of the performer. They'll produce different work!
This is not trivial.
Some have described the hand stamped faceplates I make as retro. I find that interesting as they don’t reference any past pro audio design I’ve ever seen. They are home made looking. Besides the OKW knobs and NKK switches made from modern looking plastic there is only aluminum. The only indicator as to era is plastic of a type that wasn’t used more than 30 years ago. Handmade is assumed to be old.
One of the many aspects of circuit design I know nothing about is electromagnetics, but I won't let that stop me having a crack at describing an idea I've had running around in my head for a while now...
Sometimes I play around with imagining a piece of vintage gear, for example a Gates STA-Level, not as a collection of tubes and wires through which audio signals pass, but as an assemblage of all the electromagnetic fields created by each component and the current. Each would contribute to the whole field of the device, and things like component placement and wiring influence of the overall shape and behaviour of this field, through which the audio passes. If this is a useful way to imagine a circuit's behaviour, then maybe the best sounding pieces of gear (with 'mojo') create an electromagnetic field that has its own input to the overall sound, kind of like harmonic resonance but magnetic rather than sound waves. Spacing of transformers and alignment of cores is something that springs to mind, but I might be overstating the influence of these factors in overall sound...
Stephen
Sometimes I play around with imagining a piece of vintage gear, for example a Gates STA-Level, not as a collection of tubes and wires through which audio signals pass, but as an assemblage of all the electromagnetic fields created by each component and the current. Each would contribute to the whole field of the device, and things like component placement and wiring influence of the overall shape and behaviour of this field, through which the audio passes. If this is a useful way to imagine a circuit's behaviour, then maybe the best sounding pieces of gear (with 'mojo') create an electromagnetic field that has its own input to the overall sound, kind of like harmonic resonance but magnetic rather than sound waves. Spacing of transformers and alignment of cores is something that springs to mind, but I might be overstating the influence of these factors in overall sound...
Stephen
Indeed, all components in a piece of hardware react together in a way that is not on the schematic.
One quite notable case is guitar combos, where the loudspeaker's vibrations are transmitted to the tubes and introduce a specific distortion that several musicians have noted as being part of the sonic signature.
To a lesser point, layout impacts the distribution of parasitic coupling between stages, which often results in instability or even oscillations. Fixing these issues often result in changing the overall tone.
A famous example is the Fender amps of the CBS era, where the layout was changed for productivity reasons, which resulted in very retive amps that needed drastic measures to tame. These amps were not considerd sounding as good as their predecessors.
Usually, these effects are really of second order and may be perceptible to a fraction of users/listeners. Anyway, since they are not easily predictable, most designers tend to minimize them from the start, by caerfully separating power stages from low-level ones, thoroughly decoupling power rails and orienting transformers in a way that minimizes interaction.
Most of the designers of coveted vintage gear were very much aware of this and tried to minimize unpredicted behaviour.
One quite notable case is guitar combos, where the loudspeaker's vibrations are transmitted to the tubes and introduce a specific distortion that several musicians have noted as being part of the sonic signature.
To a lesser point, layout impacts the distribution of parasitic coupling between stages, which often results in instability or even oscillations. Fixing these issues often result in changing the overall tone.
A famous example is the Fender amps of the CBS era, where the layout was changed for productivity reasons, which resulted in very retive amps that needed drastic measures to tame. These amps were not considerd sounding as good as their predecessors.
Usually, these effects are really of second order and may be perceptible to a fraction of users/listeners. Anyway, since they are not easily predictable, most designers tend to minimize them from the start, by caerfully separating power stages from low-level ones, thoroughly decoupling power rails and orienting transformers in a way that minimizes interaction.
Most of the designers of coveted vintage gear were very much aware of this and tried to minimize unpredicted behaviour.
matriachamplification
Wall Thomas
Barn Finds. Although I lost my mojo a decade and a half ago I do recall enjoying random finds. Tube Amps and Pedals mostly.
Rowboat
Well-known member
Re: AC30
Alas, I parted ways with my 1962 (pre-top boost) AC30/6 in 1987, and have regretted doing so ever since.
Currently have an AC30 C2X and try to like it - but it fails. No.1 *no valve vibrato*! No.2 *yes I can bridge channels but it's nothing like that '62! No.3 I may ship the guts off to Psionic Audio when I have enough $ - but I'm not expecting a miracle.
Ó Draighnáin
Well-known member
I still have a '64 AC30 (not topboost). Original speakers were blown and were replaced with modern blue alnicos. This combo had a hard life gigging (most of its life). However, it has been gathering dust for years now. Not sure what to do with it. I have played and built quite a few of the classic amp flavours (Vox, Fender, Marshall, Hiwatt, Supro, Matchless (modern Vox-like)) and still love the original AC30 sound most of all but have been in love with all the others at various stages.
I build all my Vox-styled amps in heads now using a Hiwatt-type layout. It allows me to incorporate an EF86 channel if I want.
There is something in the way the bottom E of a guitar sounds through an AC30 (turned up) when you hit that string really hard. It sort of quite distinctively initially phases in and out of tune with growl as the note resolves.
In respect of combo and speaker cabinet sonics, I never really thought about it so much until I built and started pairing open and closed back cabinets with heads. I built an open-backed 2 x 12 cabinet for a valve rectified JTM 50 head I built and it just did not work (too boomy). On the other hand I find closed backed 4 x 12 cabinets too tight and focused. For me, the mojo was in the smaller open-backed combos (15w to 30w) and lower watt heads with open backed-cabinets. It is really a matter of taste though and there are no absolutes.
Rowboat
Well-known member
The essence ["mojo"] is indeed heard/found in lower output wattage + smaller open-backed cabs. That's key to AC growl, and I greatly doubt a Thiele/EVM 12L box, a quad, or any other combination can get close to the beloved roar of an AC30 through two old bluebells in standard cab format.
The nutter I am just wants my coppertop back, but I have an idea.
Maybe - just maybe - if I can get rid of the Boogie, and Korg AC30, I could buy your '64?
The nutter I am just wants my coppertop back, but I have an idea.
Maybe - just maybe - if I can get rid of the Boogie, and Korg AC30, I could buy your '64?
The modern vox circuit is here ,preamp is more like a Marshall ,
getting rid of the treble bleed cap across the TB volume would be a start for getting out the harshness .
Maybe bypassing all the opamps in loop send /return might be possible also.
There should be the makings of a good amp there , trouble is the makers , to compete with every other screechy transistor amp
have boosted the treble so all the balls is gone .
getting rid of the treble bleed cap across the TB volume would be a start for getting out the harshness .
Maybe bypassing all the opamps in loop send /return might be possible also.
There should be the makings of a good amp there , trouble is the makers , to compete with every other screechy transistor amp
have boosted the treble so all the balls is gone .
Last edited:
The coupling cap( 470pf) C10 is another component that strangles the life out of the tone , kills the bass completely on the TB channel , try 0.002uf
As I said if this were mine I'd do surgery to make the op amp loop true bypassed
Id probably rearrange the tone stage O/P to drive the phase invertor directly and do away with all the other garbage in the signal path .
Id do the mixing just like in a Marshall after the input stages , now both channels feed the tone stage ,
The drive for the reverb tank can be left as is , the reverb recovery could be handled by the Normal input channel in parrallel with the direct pickup input .
As I said if this were mine I'd do surgery to make the op amp loop true bypassed
Id probably rearrange the tone stage O/P to drive the phase invertor directly and do away with all the other garbage in the signal path .
Id do the mixing just like in a Marshall after the input stages , now both channels feed the tone stage ,
The drive for the reverb tank can be left as is , the reverb recovery could be handled by the Normal input channel in parrallel with the direct pickup input .
At its simplest for a test you could solder a wire from the lower end of C39 , tone stage output , lift C17(phase invertor input) where it meets the 33k resistor and IC18 , join that to the junction of C39 and R17 , you wont have reverb recovery , although the tank will be driven , the two op amp buffers are gone from the signal chain , its tube from input to output .
It only remains to add a mixing stage after the first preamp tube .
It only remains to add a mixing stage after the first preamp tube .
Ó Draighnáin
Well-known member
Ha! I would love for it to be played by somebody, and I don't think I'll be playing it much any more. However, the idea of letting it go is confronting. I started with that amp over 30 years ago. That amp almost taught me to play the electric guitar.
Hi!Hi! Sorry if this isn't the right forum for this question... it's my first post here.
Sorry, but this is going to be a sort of long read, but I'll put this here for background so you can understand why I'm asking, and then phrase the question at the very end if you want to jump to that. I'll post a line of dashes where my question begins.
Alright. I've got a background working at one of the large recording studio complexes in Scandinavia, and we had several well kept Neumann m49's, a couple of nice original u47's, a C12 and most of the other classic mics (except the ELAM for some reason, never knew why).
I was new to the recording world and had no idea how old any of that stuff was, and honestly thought the old m49's etc were cheap, old, crummy microphones that ruined our sessions from suddenly developing weird sounds or lots of self noise etc. I much preferred the new ones, as they looked more expensive and seemed to always work (this was before I started actually learning about the gear I was using every day).
Then, I was recording our upright one day, and the pair of m49's was already up in a wide stereo configuration. I wanted to get rid of them to make room for the reissue C12 VR's I so often used, but was lazy and said fudge it and decided to just use the old Neumann's so I didn't have to do a lot of prep.
When I started listening to that piano that I was so very familiar with through modern microphones played on the m49's, I was asolutely mind blown.
How could something sound that ALIVE, and not detailed or bright, but just musically alive! It was like the microphones stretched out and got right into the keys being played so you could not just hear the fingers on the keys, but sort of feel it in a weird way. I'd never heard this before, so I started using them almost every day, and discovered the same thing on other instruments, and voice... holy shit. I heard the same in various intensity in the other old microphones, but not in any of the modern ones.
Fast forward to 10 years later, today. I am not living in the same country that the studio is in, so I have no access to that stuff, but I am slowly building an audiophile studio to record expensive, old and historical instruments (for example ridiculously sweet sounding and original baroque violin from the 1700's etc).
My sound ideal is somewhere between Gary Paczosa, Decca and old jazz records from the 50's, and after researching heavily and buying a pair of near mint Gefell m582's, I came up with the plan of recreating some of the magic I remembered by buying a pair of expensive m49 clones.
So after listening to a few, I decided on the Flea 49. I bought one first to get used to it and see if I wanted to buy another one, and to be honest I'm not sure. There is some family resemblance sound wise from the m49's and the Flea 49, but none of the magic.
It is a very bright microphone, and not just in the very top end, it seems to go down all the way to the high mids, and it does lack quite a bit in the lower mids as well. The lower mid magic in the originals was (I think) what created the feeling of almost putting my ears on the piano keys from the above mentioned example. I've listened to all shootouts I could find with old m49's, and while it is safe to say that no m49 sounds exactly the same, there is still some magic there in the mid range that just doesn't happen in the clones, and I've NEVER heard it happen in any modern microphone I've heard.
And also, the top seems smoother and more elegant on the old ones in general, something that doesn't happen in the clones, and in general is also something I have yet to hear in that way in a modern mic.
----------------
So, you incredibly knowlegable people - experts at repairing, maintaining, modding and even building audio gear - here follows two phenomena I've noticed with older tube microphones that I want to understand what is, and what is causing it, and also if this can be replicated authentically today.
The first is the "magic" I mentioned that happens in the mid range. When you sing into old m49, u47 and u67 microphones, I've noticed there is often a threshold where if the vocalist sings louder than that threshold, the volume doesn't increase, but the signal instead gets compressed a bit and thickens instead of getting louder. I hear this often in the mids or lower mids, and it really gives some serious weight and body to even thinner female voices. It already feels like there is a vintage LA-2A, but it is happening in the microphone. I've tried to do this countless times with EQ, but it always seems to get muddy, while with the m49 for example, it still felt clear, even with this happening.
Also, that threshold is often not very difficult to reach, and it almost feels like it is close to where the microphone starts to distort. Once you hit that threshold, it sounds like you are sort of pushing the microphone and the components, but you don't have to scream to reach it. With my Flea 49, I don't get this effect. The microphone seems a lot more open, and that just sounds weird and off to me, especially since I'm not recording an orchestra and need that open sounded headroom.
The second is the incredibly kind, elegant and classy, mellow top end on a lot of these older microphones. They aren't dark or muffled, but they don't have that top end hype that I hear on almost every single expensive boutique clone out there, and even more so on the cheaper, sub 4k microphones. So what the hell is up with this extended, sparkly top end on microphones today?
So my last question is this: Could the internal compression effect on the old microphones be due to their low SPL limit? If so, is there anyone out there making nice tube mics with a really low maximum SPL or otherwise lower specs that could help acchieve this effect? I don't want a technically superior microphone with better specs and measurements, I want a thick sounding and musical microphone with lots of mojo and classy, elegant sounding top end that really brings life to the music, not a technological feat of wonder with incredibly low self noise and with a frequency response range of 2-700,000,000,000 hz or anything like that. Where should I look if I want that?
So, I'm guessing the ultimate question is this: What EXACTLY is it in old microphones that make them seem more musical to our ears than modern "perfect" microphones, and can we achieve that same sound today? Because this far, I haven't heard anyone succeeding. I've heard people make really technically impressive and clean sounding microphones, but nothing like an old m49.
I'm no expert. In fact, the most technically complicated thing I ever did was change a hard drive in my computer to an SSD, seriously... So that's why I came here. I brought this up on another more production-centered gear forum (not the one full of children arguing, the more grown up one), and people there just guessed and pulled stuff from out of their behinds, so I figured to get a more straight answer, I needed to find the people who actually knows how the gear works and can build it themselves. Thanks for reading this far
I don't know if it is possible but you should try to sand the diaphragm of your capsule like Johan segeborn with that speaker in this video :
The plastic will be thinner and maybe you can get the compression effect you need.
If someone try it let me know!
Cheers.
MadJack.
Last edited:
