Let's talk resistors!

[overtone]

tubeswell -
I got it. Later, while I was walking the dog, it crossed my mind that might be what you meant!
Best, tony

[martin manning]

I've seen discussion about capacitors, but what are the thoughts on "break-in" of resistors? On my recent ODS build I was amazed at the difference in tone from initial power-up (quite bright) to just an hour or so of run-in. This was particularly apparent using the FET input. It's also full of Xicon MF (except for the Dale plate loads, Xicon wirewound screens, and some 1W Xicon CF in the signal path). Sounds fantastic.

Overall, I'm a little skeptical of discussions like this, since they tend to concentrate on one factor, like resistors, or coax cable, with the implication being that it is the sine qua non of good tone. That said, it seems that there is a consensus on the Dale plate loads, and MF cathode resistors, but the main factors there seem to be low noise and precision tolerance, with the particular brand of resistor being secondary (as long as the quality control is good).

[Andy Le Blanc]

A lot of vintage stuff demonstrates the opposite, its usually made as cheap as possible.

After so many loud bar gigs, can trust the ears of a guitar player anyway?

How can DIY test or measure the "blow" out of a amp?

[billyz]

I apologize if this discussion has disintegrated due to my side comments. It was originally about the merits of CF an MF type resistors. I pointed out that I have found not all CF or MF are constructed the same and do not sound the same.

Many old cheap amps were made, just like today, But old Fenders were not Cheaply made. Actually a very good balance of quality, construction and cost control. The same can be said for most other professional models, like Standel, Ampeg, Traynor, And even the quirky british models.

A single component is not the holey grail of all tone, capacitor, transformer, wire, chassis, construction, layout, pot, tube, or resistor.

I am glad there is not one consensus on the correct part for the building of amplifiers. I left the Flatland many years ago.

[Doctordog]

Hello,

I usually don't have much to add, but like to read everyone's posts. But I've read Keen's article mentioned earlier, and it brings some things to mind. It is my understanding that it is undisputed that CC's degrade and drift and get noisier with time, MF's not so much. The debate is whether CC's sound better. The argument so far is that MF's sound "harsh" or "brittle".
It seems to me that with the knowledge here, a little tweaking with some values could easily bring the sweetness back into the circuit and retain the reliability of having MF's.
My guess is that if the original circuit designers had the MF's instead of CC's, that they would have changed the circuit to be more musical.
Doesn't this sound reasonable?

JB

[Andy Le Blanc]

sorry about that... didn't mean put the kibosh on it

I think you mentioned holding a magnet your components to judge they're inductance.

I've been through to many amps,.

I do agree that there is an audible difference associated with resistor type
and where you choose to install them in a circuit, I've heard it in more critical
situations, nothing like loosing mid range detail, with a mu follower in a
SE design because you went too cheap.

quality in does mean quality out... but the merits of one type vrs another
can be very subjective.

[Structo]

Yesterday I got a good magnet and checked some of my resistors.

The Xicon carbon film 1 watt resistors were very magnetic.

The Vishay CF60 metal film were not.

Some of the cheaper metal oxide were but some of the other higher power resistor were not magnetic.

I only have about three of those Xicon carbon film resistors in my ODS amp.

The slope resistor and the two interstage V2 resistors (100K and 150K).

I do have the metal oxide 3 watt dropping resistors in my power supply.
But I've seen those used a lot in other clones.

[Andy Le Blanc]

The real issue is detail

CC are inferior when it comes to current noise, which is why you like them

they soften or mask the detail that makes an amp sound harsh

it is funny that the worst component choice makes the best guitar tone

MF and CF types are superior in this way but they are more detailed

so you hear the bright top of your pickups, not so desirable..

Inductance is something very different.
Resistor inductance is in micro henries, unless it wirewound...
Unless your into the mhz it shouldn't be a real issue.

Magnetic resistors, by mfg, is very interesting however.

[Structo]

What I meant by magnetic was that they are attracted to a magnetic.
They are not of course a magnet but must have some ferrous properties like steel that is attracted to a magnet.

I've read about this before in Hi Fi circles but not in guitar amps.

[coolidge]

I have been using PRP 1 watt MF's but have a batch of these AMRG CF's in for a new build. 3/4 and 2 watt, black anodized aluminum casings.

[img:399:237]http://www.coolidgeamps.com/pics/amrg.jpg[/img]

[Andy Le Blanc]

those are billed to reduce magnetic distortion...

funny seeing where hi fi meets guitar

$5 a pop?

takman and PRP are bit more affordable

[coolidge]

those are billed to reduce magnetic distortion...

funny seeing where hi fi meets guitar

$5 a pop?

takman and PRP are bit more affordable

They are not cheap but I have completed multiple builds using PRP's and want to try something new. I may try the Takman next, I'm using a hybrid PCB/Turret board and have to order a minimum of 10 boards so I have plenty of stock to experiment with.

[Andy Le Blanc]

I have a RMAA package, and you can get older version as a free down load

the hard part with any discussion is being able to validate your argument

I would love to see the difference between the resistor types demonstrated
with a simple gain stage, with quantitative test results.

let see...you'd need six resistors

grid return

grid stop

plate

cathode

a series resistor after the coupling cap

and one PS dropping resistor

Id like to see results by type

http://audio.rightmark.org/download.shtml

[Structo]

Sounds kind of complicated.

I just listen to it and if I don't like it I tear it out.

I had forgotten about the PRP resistors.

Thanks, I just ordered a bunch.

[Andy Le Blanc]

cool...