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Amp guts


Daehtihs

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They kind of all do, unless you get an old skool ptp amp.

Modern Princeton.

 

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Fender Deluxe older and new.

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"drri_and_rebuild_chassis.jpg","data-attachmentid":32164939}[/ATTACH]

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They kind of all do, unless you get an old skool ptp amp.

Modern Princeton.

 

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"406.jpg","data-attachmentid":32164938}[/ATTACH]

Fender Deluxe older and new.

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"drri_and_rebuild_chassis.jpg","data-attachmentid":32164939}[/ATTACH]

 

The old ptp stuff is so awesome! It costs over $3000 for a good new one now. :cry:

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That's because PTP is far more labor-intensive to build.

 

There's no reason why a modern PCB amp can't sound as good or be as reliable as a PTP. Their main disadvantages are that they're harder to work on and they're more difficult to modify.

 

 

That's true, but there's something about seeing ribbon cable and tube sockets and pots mounted directly to pcb boards that makes me sad. :(

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That's true, but there's something about seeing ribbon cable and tube sockets and pots mounted directly to pcb boards that makes me sad. :(

 

Although it's usually easy to fix if it goes bad, pots mounted directly to the main PCB can definitely be a point of failure in the long run. IMHO, they should be panel-mounted (or at least mounted to a daughterboard instead of the main PCB), with wires or ribbon cables (as seen in the Princeton images above) running to the main PCB.

 

Ditto that for tube sockets mounted directly to the PCB. Ideally, they should be mounted separately, and wire used to connect them to the PCB. I also prefer ceramic tube sockets. Again, look at the Fender images above - it looks like they're doing all of those things on the new Princetons.

 

In fact, it would probably be fairly easy to drop in an old-style Fender eyelet board and convert a modern Princeton Reverb to a fully P2P amp. It would be much easier if you started with all new parts and didn't try to scavenge them off of the old PCB.

 

 

 

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Here's a pic of my new stereo *uhm*:D I mean guitar amp the JSX. :cool:

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It looks like kind of a mixed bag - it has panel mounted pots, but PCB mounted tube sockets. I have never personally worked on one, and haven't heard anything about their reliability either way, :idk: but Peavey amps are generally pretty reliable.

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Yeah, that would be the main reason to do it - it's not going to significantly change the sound of the amp, and it's not going to be cheaper than buying a used Silverface once you buy the reissue amp, eyelet board and all of the parts - you'd have to do it for the fun of it, and for the personal satisfaction you get from a job well done.... but a fair amount of people actually do convert some of the modern Fenders to P2P, and there's a small cottage industry that's developed who provide parts, eyelet boards, replacement cabinets, etc. etc.

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there are some myths around p2p vs circuit board

 

circuit boards aren't harder to repair per se. if you need to replace a part its fairly easy cause each solder joint normally has only one wire and with the right tools its easy to be cleaned for resoldering.

yes if its get too hot cause you have the wrong soldering iron or not enough practice, you could damage the pcb

 

on the other hand fixing a p2p, where more than one wire is soldered together can also become a PITA to put together again

 

yes a p2p is most of the time easier accessible, uses bigger parts and modding the circuit can be much easier

but a clean non-smd pcb can be also easy to work with

 

pots mounted on a pcb can put physical stress on the solder joints, as pots are meant to be turned and the movement propagetes to the pcb mounting points...

tube sockets mounted on the board almost everytime cause a heat issue over time

 

both facts are not the fault of pcb technology itself, or make a pcb worse than p2p, pcb can be manufactured even with more quality, more consistency and less noise so to be really better sound wise than an average p2p.

 

but mounting pots and tube sockets on the pcb saves space and parts placement and soldering can be automated by robots, which can't be done when they are connected with wires.

so it saves a lot of costs, where the possible issues are accepted

 

so its costs over quality and only something is wired p2p does not always mean it is quality

 

compare it with the effects business, even small boutique builders in small series built with pcb's because they are easier to built with more consistent quality than doing handwired p2p circuits, but most of them provide great quality

 

like the above picture of the old/new deluxe, you can built quality using either way :)

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All of this is accurate information. But it sure gives me a happy face to open an amp and see well laced PTP wiring. I don't why' date=' but I just smile more.[/quote']

 

I appreciate the love and care that goes into a hand built P2P amp, no question about it. Especially if it's clean and well-dressed.

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since i was little i was always interested how things work, i love to look at things inside no matter what they are. amps, efx, guitars, bikes, cars, ships, elevators, trains, ball point pens, watches, computers, machines in factories, nearly anything

 

so i see in anything the beauty, if its a robot build pcb, i see the craftsmanship behind building such a "robot"

 

yes some things are nicer than others and i admire handmade stuff as specially, but not only the craft, but also the creative process how things can be built in general

 

and i love gutshots of anything :)

 

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That's because PTP is far more labor-intensive to build.

 

There's no reason why a modern PCB amp can't sound as good or be as reliable as a PTP. Their main disadvantages are that they're harder to work on and they're more difficult to modify.

 

 

Tell me about it. You have to be oh so very careful with the traces on the PCB, where you're trying to mod something. Say you're trying to change the bias resistors to convert from 6550 to EL34. You need just the right amount of heat from the iron to get the old resistors out without damaging the trace on the other side of the . Screw that up and now you have a repair, and not just a resistor replacement job. That's why I prefer a tagboard set up. Ideally PTP is the best to work on. It's just so straight forward.

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They kind of all do, unless you get an old skool ptp amp.

Modern Princeton.

 

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"406.jpg","data-attachmentid":32164938}[/ATTACH]

Fender Deluxe older and new.

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"drri_and_rebuild_chassis.jpg","data-attachmentid":32164939}[/ATTACH]

 

Just looking at those pics makes me want to have sex!! :sm-heart::love::sm-heart::love::sm-heart:

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A Pro tech should have no problem with soldering a PCB. The key to a clean job is properly de-soldering. You want to see a real butcher job its done may and amateur who doesn't know how to use a solder sucker.

 

I'd agree with Phil and having the tube sockets mounted on the chassis instead of the PCB itself. I've done many repairs on amps that have PCB mount sockets and the results are always the same. The amps lifespan is greatly reduced and the failure rate super high on PCB mount sockets. The sockets heat the boards so hot they change color to the point where the fiberglass carbonizes and shorts out.

 

This is made even worse because heat rises and cool air is drawn in bringing dust, much of which are various types of artificial fibers from rugs, furniture, cloths which shed these fibers and the heat from the tubes melts these fibers and causes the boards to become sticky attracting even more dust until it bakes and becomes conductive providing the high voltage to arch out across the board to ground frying everything in its path.

 

Its therefore a really bad idea to combine tube and PCB builds together, It always has been and the manufacturers know it. They only need them to last 8 to 10 years however and then they can stop supporting the products repair so they typically target lower cost combos amateur's may buy because they know they aren't going to be running those amps 24/7 like a pro would.

 

What's even worse the PCB mount sockets is SS and tubes combined. SS needs to stay cool and Tubes tend to overheat SS circuits. Only amps that use a design that separates the tubes from the SS Circuitry work well. My Music Man head for example has Chassis mount tubes. The SS Preamp also uses High Temperature Transistors which have a ceramic casing which will take the heat of the big bottle 6CA7 tubes running high voltages. Still not my favorite design but I'm not complaining since I got the amp for free and after some small repairs it works flawlessly.

 

For the rest of the parts in a tube amp, caps and resistors there is absolutely no problem having those PCB mounted. You just don't want to mount anything heavy on there like a transformer because a hard physical shock to the amp can either crack the board or rip it right off the board. (done many of those repairs too) How the boards are chassis mounted can be important too. Plastic mounts have the advantage of being flexible and giving as the chassis flexes but they can eventually dry out and crack and they aren't overly sturdy and shock resistant. Brass/steel mounts have the benefit of being strong but a thin chassis that is flexed will crack the board.

 

I also prefer chassis mount pots and metal jacks over PCB mount pots and plastic jacks any day of the week.

Metal jacks will last 3 lifetimes. Plastic only needs one good cable tug and its toast. They tend to fail quickly too because the stainless steel connections are welded into place with plastic rivets which simply weaken and fall apart.

 

The PCB mount pots are always much lower quality too. I've yet to find any that have a lifespan that comes close to come close to a CTS, or even Alpha. Finding a generic fit for many PCB's can be a PITA too.

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there are some myths around p2p vs circuit board

 

circuit boards aren't harder to repair per se. if you need to replace a part its fairly easy cause each solder joint normally has only one wire and with the right tools its easy to be cleaned for resoldering.

yes if its get too hot cause you have the wrong soldering iron or not enough practice, you could damage the pcb

 

on the other hand fixing a p2p, where more than one wire is soldered together can also become a PITA to put together again

 

yes a p2p is most of the time easier accessible, uses bigger parts and modding the circuit can be much easier

but a clean non-smd pcb can be also easy to work with

 

pots mounted on a pcb can put physical stress on the solder joints, as pots are meant to be turned and the movement propagetes to the pcb mounting points...

tube sockets mounted on the board almost everytime cause a heat issue over time

 

both facts are not the fault of pcb technology itself, or make a pcb worse than p2p, pcb can be manufactured even with more quality, more consistency and less noise so to be really better sound wise than an average p2p.

 

but mounting pots and tube sockets on the pcb saves space and parts placement and soldering can be automated by robots, which can't be done when they are connected with wires.

so it saves a lot of costs, where the possible issues are accepted

 

so its costs over quality and only something is wired p2p does not always mean it is quality

 

compare it with the effects business, even small boutique builders in small series built with pcb's because they are easier to built with more consistent quality than doing handwired p2p circuits, but most of them provide great quality

 

like the above picture of the old/new deluxe, you can built quality using either way :)

 

 

I don't recall ever replacing an input jack on a p2p Fender amp, which would have been easy, but the common practice of simply resoldering the jack on a Hot Rod Deluxe is a time consuming PITA.

 

 

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When I opened up my Mustang 1 a couple years ago i was surprised. I siaid you've got to be kidding,that's it !.

[img2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/www.harmonycentral.com\/forum\/filedata\/fetch?id=31247112"}[/img2]

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I don't recall ever replacing an input jack on a p2p Fender amp, which would have been easy, but the common practice of simply resoldering the jack on a Hot Rod Deluxe is a time consuming PITA.

 

 

some worse than others and when space is tight its very cumbersome.

anyone every tried to open up a peavey classic 30 and to remove the amp from the cabinet?

that alone takes you an hour and you haven't toucehd any soldering iron :)

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