18Watt.com

Yeah, it's Mathe the serial resistor decapitator! Scary or what!
In over 30 years on electronics, all the carbon comps I've ever seen have that square-edged cylindrical shape. Just remember, they're for your PI plate resistors only...

Gabi wrote:Ouch!!!!

Mathe... that picture is horrifying!!! You show those nice resistors layong there and the very next picture shows them decapitated!!!

Oh man, have some mercy, will ya! hehehehehe

gab.

Ha, you like horror? Then take a look here http://home.kabelfoon.nl/~mathe/parts/p ... index.html

Marc

"""Just remember, they're for your PI plate resistors only... """

Why is this Phil...?
Richie

Heres a flow chart.. even though it isn't an 18 watt marshall, it may help show some of the things similar..I know someone asked about this.. but can't remember where it was in the posts.. Oh.. while here which i know alot have probably visited this site.. But he has some really good helpfull info..well worth looking around.
http://www.hoffmanamps.com/currentflow.htm

Richie

Richie beat me to it . .

Why only the plate? I ask out of pure ignorance, not to be confrontational.

I have seen an 18 watt clone that is one of the best sounding amps I've every heard at it was CC's at R2, 7,10,11,13,14,17,27 & 28. Going off the chart that we seem to sharing here.

Is this over kill, or will these positions make a difference in tone.

dboul wrote:Richie beat me to it . . Why only the plate? I ask out of pure ignorance, not to be confrontational.

No problem - just read this article by R.G. Keen. I think it will then all make sense. http://www.geofex.com/Article_Folders/c ... oncomp.htm

First like to say, R.G. is very helpfull.. I've read R.Gs explaination... so i guess i fall into the "people that amuse him" catagory:) And into themore nutcase mojo bunch. And will use them in other places besides just plate resistors. Or the only place he says makes a difference..
To me all that just asks more questions that wern't answered. Was this all the tests he made?..What brands.. or is it just certian values? So many ifs that maybe he didn't try... the voltage and swing.. What about current,as he was saying they change in value when they heat up.. and low voltage cathode sure gets hot. swings not as much.. Now to point out the good things he says.. in some places they do,and can make an amp sound to the ear..or harmonic..a sweetness to the tone.. or to the human ear. So thats the part i like. How do you test this? Its hard to measure what a person hears..or what it sounds like to that person,or what sounds good to him for a guitar tone. .. This is almost the same thing when you get into asking about caps.. and all the people can show you how great the caps may be. And that may be so..but when you use them, they don't sound good,to your ear. So as i said.. it almost always, no matter what anyone says or tests.. your going to use what you like..or you think sounds good to you. That way everyone is happy Theres more to a puzzle than one piece, before its done. An amp will kinda be like this.
I know it sounds goofy or overboard, but to make it come out right,there are alot of things that come into play,and all add together.

Richie

Thanks Phil! Sorry you had to post that twice for me to actually read it.

That's a very interesting and logically written article. Thanks again!

Plexi wrote:First like to say, R.G. is very helpfull.. I've read R.Gs explaination... so i guess i fall into the "people that amuse him" catagory:) And into themore nutcase mojo bunch. And will use them in other places besides just plate resistors. Or the only place he says makes a difference..

Where in our circuit do you notice a difference Richie? Afterall , this is only an opinion poll. Your amp clips were some of my favorites! Where do you like the CC's? Where do you hear the added sweetness and harmonics?

The reason I press so hard is I have quite a supply of CC's, a few different brands, mostly Allen Bradleys with some Ohmites, Stackpoles and IRC's mixed in. But I don't really have enough experience to know the difference!

Thanks!!

Richie, a few comments to yours. The great thing about RG Keen's article is that he takes a very balanced view of the use of CC resistors. You ask about which brands he has tried. In fact what he is showing is based on well-known characteristics generally common to all CC resistors,, and applying that from the spec sheets rather then going by his own subjective listening 'tests'. I don't know how he works out the mimimum level of distortion that we can hear - presumably the hi-fi folks have done lots of research on this. The important point is that the even-order harmonics which are widely known to sound sweet to human ears are created when you get a large signal voltage swing across the CC resistors, best found at plate resistors. The heating effect of largeish amounts of current just affect the static value of the resistor, rather than altering in time with the swing of your actual guitar signal. Lots of folks will testify that CC resistors make an amp sound sweeter, but have they tried with only the late preamp or PI load resistors being CC? Most likely not? And have they A/B-ed tested the difference they get if they then make the other resistors CC, as well as those plate resistors. Again, almost certainly not.

Intersting discussion. I'd just like to add that while I favor the use of CCs, I'm much too lazy to try and figure out exactly where they'll sound best and simply use the perhaps faulty logic that if they sound good in some places, they'll sound good in all.

Also, I believe that there is much to electricity and to the way these components influence/interact with the signal/other components that we just do not understand. And I've heard EEs give very logical, convicing treatices on the theory of this and that and why something I'm hearing just cannot be.

So I think the best thing is to compare for yourself and let your ears be the judge. Despite what the math etc. may say. Becasue as I said, I don't believe that we completely understand every aspect of all the interactions involved, since my ears often tell me something different from engineering theory.

Hey Psalm,

Well you know the Maths is always right. I mean ALWAYS. Only trouble is, Mathematicians are often wrong (I should know, I’m supposed to be one, LoL!). On the other hand an EE has about as much relation to a mathematician as Astrology has to Astronomy! What’s that? You like astrology? Oh well, I tried!

Ian.

Hey guys...

I need help!

Would anyone be so kind and add the names of the components on the 18 watt component lists, please?

I always hear terms like "PI tail rezistor" or "coupling cap", or "plate rezistor", etc.

I made an microsnot word document and placed it here
http://www.18watt.com/storage/Components_Naming.doc

with a table for rezistors and one for caps ready to be edited. You'll have to download it first. Can't save online.

I think it would be helpful for some of us to know all that lingo...

Many thank yous...

gabi.

Great Idea Gabi! This would definitely make our discussions a little simpler and clearer.

Thanks!

Yeah . . okay . . . maybe I'm missing it . . . but I'm not seeing a "plate" resistor on our schematic, only a resistor on the grid of each EL84 . . . am I reading it wrong?

Dan... I think they talk about R18 and R19 of V2...

gab.

Ian,

the plate resistors (100k) and some others in your amp ARE CC´s.
R7, R18, R19, as well as R17 in the PI being the "most important" ones.
And, I bet it´s just by chance...

Thanks Gabi . . . was getting a little confused there . . .

So the 100k's?

Just tried to find some info about Kamaya CC resistors and stumbled over
this:

http://www.18watt.com/modules.php?name= ... ght=kamaya

BTW, any comments on Kamaya´s??

It appears to be the only stuff being available from electronic component distributers around here. There is some hope not to get ripped off that way, though.

Psalm150 wrote: I'd just like to add that while I favor the use of CCs, I'm much too lazy to try and figure out exactly where they'll sound best and simply use the perhaps faulty logic that if they sound good in some places, they'll sound good in all.

And faulty it is. Put a CC on the grid of a tube and all you do is potentially make your amp more hissy over time. And here's the easy answer, just make R18 and R19 carbon comp. That's all you need for your amp to have the sweet carbon mojo!