Point-To-Point Amps: What They Are and What They Aren't
Published on
January 21, 2021 at 1:58:59 PM PST January 21, 2021 at 1:58:59 PM PSTst, January 21, 2021 at 1:58:59 PM PST
Any guitarist who has paid much attention to the reviews and manufacturer write-ups of tube-based guitar amps in recent years, and so-called “boutique” amps in particular, will have encountered the term “point-to-point” (PTP). And while that term has a very specific meaning, it is often used somewhat loosely to describe any amp with a hand-wired circuit, or one that doesn’t use a printed circuit board (PCB). There’s a lot more to it than that, though, so let’s dig in and see what PTP really is… and what it’s not.
The Golden Age of Hand-Wired Amps
Through the first three or four decades of guitar-amp manufacturing, the question of whether or not a guitar amplifier was a PTP design, wasn’t even an issue. Up until the early ’70s, all of the major tube amp manufacturers loaded their circuit boards by hand, and soldered all the connections, all the wires between board and sockets, and all the switches by hand. Although Fender kept making tube amps this way throughout the mid ’80s, Vox Sound Ltd. Started making the AC30 and other models using PCBs in 1970 (having taken the reigns from original Vox manufacturer JMI). Additionally, Marshall started using PCBs in its amps around 1974. A few other British makers like WEM and Orange had switched over to PCBs even earlier than that.
Slowly but surely, some players began to hanker for the older designs and gripe that, “they don’t make them like they used to” (we always do, don’t we?). And in so doing, many guitarists noticed that one obvious difference between the old builds and the new ones was the way the circuit boards were constructed, and the way the guts of the amps were wired up. Thus, by the mid ’90s or so, the PTP vs. PCB issue caught fire.
Some Simple Definitions
Before diving in deeper, though, let’s lay some groundwork by way of a few definitions. A “printed circuit board” is a glass-epoxy or phenolic-resin board with a thin plate of copper on one side (sometimes both sides), onto which circuit components are soldered. Electrical connections between components on such a board are created by “etching” away certain portions of the copper plating to leave copper “traces” (this is the so-called “printing” process)—which look like narrow tracks—in patterns that determine the signal and power and grounding paths around the circuit.
Manufacturers moved over to PCBs for amplifier construction for a number of reasons: If you plan to make a lot of the same design of amp, etching PCBs to a precise and carefully laid-out pattern will often provide more consistent and reliable results than wiring up each circuit individually; with slight variations in wire positions and lengths according to which worker on the line assembled the unit. Often PCBs, in more recent years especially, can also have components loaded onto them by machine, and have their solder connections made all at once in a process called “dipping”. In short, PCBs are used because, in some cases, amp manufacturers consider them the best option for consistency and reliability, while in other instances they are used simply because they are a more cost-effective means of manufacturing an amplifier.
On the other hand, the term point-to-point is often used colloquially to describe a circuit in which all connections between components and the trace-less (i.e., non-etched) circuit board are hand-wired. Strictly speaking, though, a genuine PTP circuit is one that uses no circuit board at all, but makes all of its circuit connections directly between components—between points, in other words—using the leads of those components themselves and very little wire. Example: A resistor connects the input jack to the preamp tube socket, a capacitor connects the output from that preamp tube to the volume potentiometer, another capacitor connects the output of the volume pot to the next stage in the circuit, and so on.
True Point-To-Point
In truth, this kind of circuit is extremely rare. It is most commonly seen today in amps made by Matchless, Bad Cat, Carr, and a few others; in some vintage amps from Gibson, Valco, very early Fender models, and a few others (most of the very earliest guitar amps of the late ’30s and ’40s used PTP construction, in fact, because they were generally simple enough not to require the imposed logic of a circuit board at all). In the genuine PTP amp, the signal path is usually as short as possible, which -- when done right -- can help minimize interference and noise in the circuit, and will allow the circuit to flow logically from input to output. The circuit itself, therefore, tends to look very much like the schematic diagram from which it is built. Fans of PTP manufacturing say the logical signal flow and short wire runs make for a bolder, richer tone and an immediate playing response.
There are potential downsides to PTP circuits, too, when they’re not designed and built with great care. If done poorly, they can be prone to a lot of noise and electrical interference, since an inexperienced builder might not adhere to critical considerations such as keeping signal wires and power supply wires from running close or parallel to each other, and so forth (rest assured the makes of the above-named modern PTP amps, however, are experienced builders!). Also, even in high-quality, well-built PTP amps, components can sometimes be more difficult to access and disconnect than those in other hand-wired circuits using non-printed circuit boards of one type or another, because of the somewhat “rat’s nest-like” intertwining of components and connections. Also, physical stresses—such as the heat from tube sockets, or the movement that occurs in a tube socket terminal when a tube is wiggled loose for replacement—might impact directly on components in the PTP circuit, rather than on the more flexible wires making connections in other types of hand-wired circuits. Of course the labor-intensiveness of PTP circuits also contributes to very expensive amplifiers.
Other Hand-Wired Circuits
Often when guitarists—or, indeed, manufacturers—discuss so-called PTP amps, however, they mean amps that are made with other types of hand-wired circuit boards. These might be eyelet boards, as most commonly seen in vintage Fenders and Ampegs, or tag or terminal boards, as seen in vintage Marshalls, Voxes, Hiwatts, Traynors, and plenty of others. All of these are some form of insulated, non-conductive fiber board into which metal eyelets, posts, or terminals are mounted. Signal-shaping components in the circuit—primarily resistors and capacitors—are soldered between these terminals, as are the wire connections going from points in the circuit to other components within the amp which are mounted on the chassis itself: jacks, switches, potentiometers, tubes (via tube sockets) and transformers. It’s these direct wire connections that lead many people to mistakenly refer to such amps as “point to point,” a slight misnomer that’s easily forgiven.
When built right and laid out logically, with an economical signal flow, these still yield extremely toneful amps, even if they might involve a few more inches of wire through the course of the circuit (a minimal, possibly inconsequential consideration). Good examples of this kind of construction have the advantages of being easy to repair, since almost any component can be changed out by desoldering just two easily accessible joints and removing the part from the board; and of being extremely rugged and hard-wearing, since the circuit board offers the components some insulation against heat and vibration.
In truth, any of these methods done right, have few significant down sides, other than that they are also rather labor intensive, due to all the hand-soldered joints and hand-wired connections required to manufacture them, and therefore result in expensive amplifiers. Makers that use this type of circuitry today, therefore, generally fall into what we call the “boutique” realm, which includes brands such as Friedman, Komet, Victoria, Dr Z, Clark, 65amps, Reeves/Hiwatt, Redplate, Ceriatone, and many others—including anything you would build from a Mojotone kit—and also up-market models from major makers, such as Marshall’s Hand Wired series, many of Fender’s Custom Shop amps, and Vox’s Hand Wired reissues.
In Defense of PCBs
Although they often seem to be denigrated in any such discussion, a well-designed and constructed PCB can also yield an excellent, professional-grade guitar amp. A rugged and well-laid-out PCB can present an efficient and low-noise signal flow, as can a well-designed hand-wired circuit; and the use of a PCB in itself isn’t necessarily evidence of a “lower quality” product. Randall Smith used PCBs in his Mesa/Boogie combos way back when he founded the company in the early ’70s, and still does. These early Boogies can be considered among the forefathers of boutique amplifiers (a lot of hand wiring still went into constructing these high-gain lead monsters).
Other makers of high-end amps such as Soldano, Bogner, Rivera, Fuchs, Budda and others also use PCBs, as do the “standard” lines from Fender, Marshall and Vox, and all contemporary amps from Supro, Ampeg, Peavey, and several others. But you will generally notice a difference between the PCBs in the highest priced tube amps that carry them, and those in the most affordable. A thick PCB with wide tracks, a fluid layout, and easily accessible parts can still make for a great sounding and easily serviced amplifier. Not all PCBs are created in this way, though, and some are much harder to service than others, or certainly than almost any good hand-wired amp.
In many cases, the quality demarcation is found not necessarily in the circuit board, but in other places. For example, whether tube sockets and/or pots, switches, and jacks are mounted directly to the circuit board or to the chassis, with flying leads between sockets and board rather than with direct solder connections to the board. More economical production often sees sockets, switches, and pots soldered directly to either the main PCB or, slightly better, to one or more secondary PCBs. When this is done, however, these boards can be prone to cracking with excessive vibration or movement (the kind that occurs when you wiggle a tube to remove it from the socket, flip a switch repeatedly, or just throw it in and out of the van gig after gig). Boards can also be damaged over time from too much direct heat passed on from tubes. Build an amp, however, with a thick, rugged, well-designed PCB carrying high-quality components; mount the switches, jacks, potentiometers and tube sockets to the chassis itself—which provides excellent heat dispersal and resistance to physical stress—and you’ve got a product that should run with many of the big boys of the hand-wired world.
Component Quality
In addition, the make and quality of components used in the circuit often vary widely according to price and construction technique. PCBs that are machine loaded with these parts, and which have their terminals all soldered at once in a “solder-dipping” process, usually don’t carry the higher-end components, which are often physically bigger and less efficient to work with (in addition to being more expensive). Instead, these use the smaller, more generic components that the rest of the consumer electronics industry works with and with which the loading and dipping machines are designed to work. These also tend to be the amps that are harder and more time-consuming to service. Sometimes, in fact, as is so often the case with the PC or DVD player you send back to the factory for repair, a technician might simply pull the entire circuit board and replace it, rather than try to diagnose and repair the individual problem itself.
None of this is intended to imply that you need to take out a second mortgage and run right out to buy a PTP or hand-wired guitar amplifier. Hand-crafted and US or European-made goods in any corner of the consumer market cost a lot more than mass-manufactured or assembly line goods, and this article doesn’t intend to imply that the extra expense is justified for every player out there. Makers of quality tube amplifiers that use PCBs still employ a lot of hand assembly in the manufacturing process, and clearly plenty of great pros record and tour with amps such as Fender Bassman Reissues and Hotrod Deluxes, Vox AC30TBXs or Custom Classics, Marshall JCM800s or TSL100s, Mesa/Boogie Triple Rectifiers and Mark Vs, Soldano SLOs, Bogner Shivas, Peavey 6505s and plenty of other righteous models that carry printed circuit boards.
That being said, plenty of pros and hobbyists alike derive massive pleasure and righteous tones from any of a number of hand-wired tube amps available, and this is also a big part of what inspires many guitarists to build their own amps, which are invariably hand-wired… by you! Whichever machine you turn to for your tone, at least now you can walk the walk and talk the talk. More to the point, when it comes time to research, test, and eventually make your next major amp purchase, or plan your next DIY building project, you can more intelligently assess the elements in the models you are drawn toward; and hopefully you’ll understand a little more about what makes them tick, and why.
The Golden Age of Hand-Wired Amps
Through the first three or four decades of guitar-amp manufacturing, the question of whether or not a guitar amplifier was a PTP design, wasn’t even an issue. Up until the early ’70s, all of the major tube amp manufacturers loaded their circuit boards by hand, and soldered all the connections, all the wires between board and sockets, and all the switches by hand. Although Fender kept making tube amps this way throughout the mid ’80s, Vox Sound Ltd. Started making the AC30 and other models using PCBs in 1970 (having taken the reigns from original Vox manufacturer JMI). Additionally, Marshall started using PCBs in its amps around 1974. A few other British makers like WEM and Orange had switched over to PCBs even earlier than that.
Slowly but surely, some players began to hanker for the older designs and gripe that, “they don’t make them like they used to” (we always do, don’t we?). And in so doing, many guitarists noticed that one obvious difference between the old builds and the new ones was the way the circuit boards were constructed, and the way the guts of the amps were wired up. Thus, by the mid ’90s or so, the PTP vs. PCB issue caught fire.
Some Simple Definitions
Before diving in deeper, though, let’s lay some groundwork by way of a few definitions. A “printed circuit board” is a glass-epoxy or phenolic-resin board with a thin plate of copper on one side (sometimes both sides), onto which circuit components are soldered. Electrical connections between components on such a board are created by “etching” away certain portions of the copper plating to leave copper “traces” (this is the so-called “printing” process)—which look like narrow tracks—in patterns that determine the signal and power and grounding paths around the circuit.
Manufacturers moved over to PCBs for amplifier construction for a number of reasons: If you plan to make a lot of the same design of amp, etching PCBs to a precise and carefully laid-out pattern will often provide more consistent and reliable results than wiring up each circuit individually; with slight variations in wire positions and lengths according to which worker on the line assembled the unit. Often PCBs, in more recent years especially, can also have components loaded onto them by machine, and have their solder connections made all at once in a process called “dipping”. In short, PCBs are used because, in some cases, amp manufacturers consider them the best option for consistency and reliability, while in other instances they are used simply because they are a more cost-effective means of manufacturing an amplifier.
On the other hand, the term point-to-point is often used colloquially to describe a circuit in which all connections between components and the trace-less (i.e., non-etched) circuit board are hand-wired. Strictly speaking, though, a genuine PTP circuit is one that uses no circuit board at all, but makes all of its circuit connections directly between components—between points, in other words—using the leads of those components themselves and very little wire. Example: A resistor connects the input jack to the preamp tube socket, a capacitor connects the output from that preamp tube to the volume potentiometer, another capacitor connects the output of the volume pot to the next stage in the circuit, and so on.
True Point-To-Point
In truth, this kind of circuit is extremely rare. It is most commonly seen today in amps made by Matchless, Bad Cat, Carr, and a few others; in some vintage amps from Gibson, Valco, very early Fender models, and a few others (most of the very earliest guitar amps of the late ’30s and ’40s used PTP construction, in fact, because they were generally simple enough not to require the imposed logic of a circuit board at all). In the genuine PTP amp, the signal path is usually as short as possible, which -- when done right -- can help minimize interference and noise in the circuit, and will allow the circuit to flow logically from input to output. The circuit itself, therefore, tends to look very much like the schematic diagram from which it is built. Fans of PTP manufacturing say the logical signal flow and short wire runs make for a bolder, richer tone and an immediate playing response.
There are potential downsides to PTP circuits, too, when they’re not designed and built with great care. If done poorly, they can be prone to a lot of noise and electrical interference, since an inexperienced builder might not adhere to critical considerations such as keeping signal wires and power supply wires from running close or parallel to each other, and so forth (rest assured the makes of the above-named modern PTP amps, however, are experienced builders!). Also, even in high-quality, well-built PTP amps, components can sometimes be more difficult to access and disconnect than those in other hand-wired circuits using non-printed circuit boards of one type or another, because of the somewhat “rat’s nest-like” intertwining of components and connections. Also, physical stresses—such as the heat from tube sockets, or the movement that occurs in a tube socket terminal when a tube is wiggled loose for replacement—might impact directly on components in the PTP circuit, rather than on the more flexible wires making connections in other types of hand-wired circuits. Of course the labor-intensiveness of PTP circuits also contributes to very expensive amplifiers.
Other Hand-Wired Circuits
Often when guitarists—or, indeed, manufacturers—discuss so-called PTP amps, however, they mean amps that are made with other types of hand-wired circuit boards. These might be eyelet boards, as most commonly seen in vintage Fenders and Ampegs, or tag or terminal boards, as seen in vintage Marshalls, Voxes, Hiwatts, Traynors, and plenty of others. All of these are some form of insulated, non-conductive fiber board into which metal eyelets, posts, or terminals are mounted. Signal-shaping components in the circuit—primarily resistors and capacitors—are soldered between these terminals, as are the wire connections going from points in the circuit to other components within the amp which are mounted on the chassis itself: jacks, switches, potentiometers, tubes (via tube sockets) and transformers. It’s these direct wire connections that lead many people to mistakenly refer to such amps as “point to point,” a slight misnomer that’s easily forgiven.
When built right and laid out logically, with an economical signal flow, these still yield extremely toneful amps, even if they might involve a few more inches of wire through the course of the circuit (a minimal, possibly inconsequential consideration). Good examples of this kind of construction have the advantages of being easy to repair, since almost any component can be changed out by desoldering just two easily accessible joints and removing the part from the board; and of being extremely rugged and hard-wearing, since the circuit board offers the components some insulation against heat and vibration.
In truth, any of these methods done right, have few significant down sides, other than that they are also rather labor intensive, due to all the hand-soldered joints and hand-wired connections required to manufacture them, and therefore result in expensive amplifiers. Makers that use this type of circuitry today, therefore, generally fall into what we call the “boutique” realm, which includes brands such as Friedman, Komet, Victoria, Dr Z, Clark, 65amps, Reeves/Hiwatt, Redplate, Ceriatone, and many others—including anything you would build from a Mojotone kit—and also up-market models from major makers, such as Marshall’s Hand Wired series, many of Fender’s Custom Shop amps, and Vox’s Hand Wired reissues.
In Defense of PCBs
Although they often seem to be denigrated in any such discussion, a well-designed and constructed PCB can also yield an excellent, professional-grade guitar amp. A rugged and well-laid-out PCB can present an efficient and low-noise signal flow, as can a well-designed hand-wired circuit; and the use of a PCB in itself isn’t necessarily evidence of a “lower quality” product. Randall Smith used PCBs in his Mesa/Boogie combos way back when he founded the company in the early ’70s, and still does. These early Boogies can be considered among the forefathers of boutique amplifiers (a lot of hand wiring still went into constructing these high-gain lead monsters).
Other makers of high-end amps such as Soldano, Bogner, Rivera, Fuchs, Budda and others also use PCBs, as do the “standard” lines from Fender, Marshall and Vox, and all contemporary amps from Supro, Ampeg, Peavey, and several others. But you will generally notice a difference between the PCBs in the highest priced tube amps that carry them, and those in the most affordable. A thick PCB with wide tracks, a fluid layout, and easily accessible parts can still make for a great sounding and easily serviced amplifier. Not all PCBs are created in this way, though, and some are much harder to service than others, or certainly than almost any good hand-wired amp.
In many cases, the quality demarcation is found not necessarily in the circuit board, but in other places. For example, whether tube sockets and/or pots, switches, and jacks are mounted directly to the circuit board or to the chassis, with flying leads between sockets and board rather than with direct solder connections to the board. More economical production often sees sockets, switches, and pots soldered directly to either the main PCB or, slightly better, to one or more secondary PCBs. When this is done, however, these boards can be prone to cracking with excessive vibration or movement (the kind that occurs when you wiggle a tube to remove it from the socket, flip a switch repeatedly, or just throw it in and out of the van gig after gig). Boards can also be damaged over time from too much direct heat passed on from tubes. Build an amp, however, with a thick, rugged, well-designed PCB carrying high-quality components; mount the switches, jacks, potentiometers and tube sockets to the chassis itself—which provides excellent heat dispersal and resistance to physical stress—and you’ve got a product that should run with many of the big boys of the hand-wired world.
Component Quality
In addition, the make and quality of components used in the circuit often vary widely according to price and construction technique. PCBs that are machine loaded with these parts, and which have their terminals all soldered at once in a “solder-dipping” process, usually don’t carry the higher-end components, which are often physically bigger and less efficient to work with (in addition to being more expensive). Instead, these use the smaller, more generic components that the rest of the consumer electronics industry works with and with which the loading and dipping machines are designed to work. These also tend to be the amps that are harder and more time-consuming to service. Sometimes, in fact, as is so often the case with the PC or DVD player you send back to the factory for repair, a technician might simply pull the entire circuit board and replace it, rather than try to diagnose and repair the individual problem itself.
None of this is intended to imply that you need to take out a second mortgage and run right out to buy a PTP or hand-wired guitar amplifier. Hand-crafted and US or European-made goods in any corner of the consumer market cost a lot more than mass-manufactured or assembly line goods, and this article doesn’t intend to imply that the extra expense is justified for every player out there. Makers of quality tube amplifiers that use PCBs still employ a lot of hand assembly in the manufacturing process, and clearly plenty of great pros record and tour with amps such as Fender Bassman Reissues and Hotrod Deluxes, Vox AC30TBXs or Custom Classics, Marshall JCM800s or TSL100s, Mesa/Boogie Triple Rectifiers and Mark Vs, Soldano SLOs, Bogner Shivas, Peavey 6505s and plenty of other righteous models that carry printed circuit boards.
That being said, plenty of pros and hobbyists alike derive massive pleasure and righteous tones from any of a number of hand-wired tube amps available, and this is also a big part of what inspires many guitarists to build their own amps, which are invariably hand-wired… by you! Whichever machine you turn to for your tone, at least now you can walk the walk and talk the talk. More to the point, when it comes time to research, test, and eventually make your next major amp purchase, or plan your next DIY building project, you can more intelligently assess the elements in the models you are drawn toward; and hopefully you’ll understand a little more about what makes them tick, and why.