WHY ALUMINIUM CHASSIS?

[drz400]

Interesting that on an "Ultrphonics mod" he spaces the OT transformer away from the chassis with a thick shim. So he must think there is something to it, or maybe just a quicker way of getting components/wires further away from the OT. Have also understood that because a steel chassis is ferromagnetic the transformer can induce a hum into the chassis.

[j-po]

True. I have experienced it myself with a very high gain build. I would have never guessed it beforehand as both transformers were far from the preamp.

...Have also understood that because a steel chassis is ferromagnetic the transformer can induce a hum into the chassis.

[talbany]

I think this is one of those rare topics that can easily turn into a 20 page thread topic and no real definitive conclusion..

This battle seems to rage between the engineers and players.. Engineers will often point out a particular metals electromagnetic and conductive properties, they can never really say or prove the theory on say how the increased conductivity of a certain metal directly relates to TONE!!.. Take for example Gary's mention (Not to jump on Gary just an example) of how he prefers aluminum over steel since it's is a better conductor which we all know it is..Given that it is a better conductor we can derive that this changes the RC time constant of our star grounds, it speeds them up..So how does changing the RC time constant directly relate to tone, is it a change we can actually hear or feel...The argument there has been it makes for a quietier amp..I don't know I've built some pretty quiet high gain amps on a Steel platform so I don't buy it..The same goes with Steel and how it's electromagnetic qualities provide better shielding against RF (which by the way I'll bite on this one) but mostly how it shields the preamp from the flux lines being generated by the transformers and helps with noise mostly hum!!...I don't know I've built some hum free amps on an Aluminum platform... Ken Fisher even disputes this by saying how a Steel chassis disrupts the flux lines effecting high frequency response was the reason he chose aluminum...Ken was by the way a huge Plexi fan..
On the other side of the coin we have the players who maybe in some cases have the ability and have played so many different type amps that they can describe the sonic anomalies between the two (Steve Kimmock being one stating aluminum gives a kind of ping on the top of a note) yet cannot point to the source..Other than it's just Aluminum...And Around We Go!!
And in the end is there really a better or worse here.. There has been benchmark amps built on both platforms... I think not just subjective..A forum like this would be a good place to start a vote!!! Just Kidding

Tony VVT

[briane]

There has been benchmark amps built on both platforms... I

Yep, both different, both can work perfectly...nuff said.

[thyx]

*burp* WHY NOT!!!?

[odourboy]

One more item in favor of aluminum that I didn't see... it's also a better conductor of heat, which hopefully means tubes-down amps run just a little bit cooler with less wear & tear on the components.

[ayan]

Interesting that on an "Ultrphonics mod" he spaces the OT transformer away from the chassis with a thick shim. So he must think there is something to it, or maybe just a quicker way of getting components/wires further away from the OT. Have also understood that because a steel chassis is ferromagnetic the transformer can induce a hum into the chassis.

I wonder if the "shim" is actually as an interface plate between the already drilled chassis and a new transformer with different mounting bolt centers.... I would suspect that to be the case, and it would save HAD from having to drill a vintage, steel (although galvanized, not stainless) Fender chassis.

Gil

[heisthl]

Aluminum causes Alzheimer's - when you play an amp with an aluminum chassis the amp forgets to amplify certain notes, unfortunately it does seem to remember to amplify my mistakes.

The steel chassis are dipped in zinc which is known to reduce the severity of cold symptoms so those amps are better for people north of the Mason-Dixon.

[talbany]

Aluminum causes Alzheimer's - when you play an amp with an aluminum chassis the amp forgets to amplify certain notes, unfortunately it does seem to remember to amplify my mistakes. Very Happy

Henry

You need more Iron in your diet... LOL!!

[jaysg]

Some good answers...lol.

fwiw, early dumbles are steel...they're in Fender Bassman amps...yes? The next generation are in thick alumiunum without ends and groovy graphics. Somewhere in time, he figured out welded ends and black paint or anodizing. It's Ken Fischer who made a big deal about using aluminum. Dumble's silence on the subject leaves you with any number of reasons, from the spiritual and philosophical to lazy habit.

[jaysg]

Interesting that on an "Ultrphonics mod" he spaces the OT transformer away from the chassis with a thick shim.

I made a blunder with my Liverpool and had to resort to the headphone technique for OT placement. Lifting the OT up a quarter of an inch was more effective than rotating it to the quietest placement. I assumed it's because it took the two pieces off of the same plane.

[martin manning]

I wonder if the "shim" is actually as an interface plate between the already drilled chassis and a new transformer with different mounting bolt centers.... I would suspect that to be the case, and it would save HAD from having to drill a vintage, steel (although galvanized, not stainless) Fender chassis.

Gil

To adapt to miss-matched holes, such a plate would have to be on the inside, wouldn't it? No wait... I see, FH screws counter sunk on opposite sides- that would work.

Is this shim plate metalic? If not, raising the core up off the chassis could reduce eddy currents in the chassis, and therefore reduce power losses (?).

MPM

Simul-posting with Jaysg... Hmmm. I guess this is the PT coupling to the OT via the chassis... Interesting how the end bells on some OT's space the core away from the mounting plane (see ODS #124, e.g.).

[talbany]

I made a blunder with my Liverpool and had to resort to the headphone technique for OT placement. Lifting the OT up a quarter of an inch was more effective than rotating it to the quietest placement. I assumed it's because it took the two pieces off of the same plane.

jaysg

Here is what you have to do!! Francheska ... Express

[RHGraham]

Aluminum causes Alzheimer's - when you play an amp with an aluminum chassis the amp forgets to amplify certain notes, unfortunately it does seem to remember to amplify my mistakes.

The steel chassis are dipped in zinc which is known to reduce the severity of cold symptoms so those amps are better for people north of the Mason-Dixon.

So, when I order a Redplate, I need to request zinc-dipped steel.... just to make sure the amp doesn't get a cold in this cold canadian climate?



Randal

[jaysg]

Thanks talbany...my LP is not in a Trainwreck chassis, so I can't orient them that way. To my surprise, the quiet position has them aligned parallel. I can't post a pic of it right now...which would make it clear.