Favorite Express caps and resistors?

[Cliff Schecht]

My searching around the forums hasn't led to as much information as I expected to find about Ken's favorite choice for resistors and caps. Since I'm mostly interested in building another Express, I'm going to focus on this amplifier only.

So what did Ken prefer for resistors (brands, wattage, tolerance, composition, etc..) and capacitors WRT his Express builds over the years? The pictures I have seen obviously show Orange Drop caps and carbon com/carbon film resistors, but I'd like to learn more.

Also, what do you cloners prefer for your Express builds? I'm seeing the PS series caps available at tubesandmore and am wondering if these will actually sound any better/worse than the 715P caps I used in my last build. Also, what brand/style of resistors should I be looking at? I'm hoping to find what I need either on Mouser or on tubesandmore, depending mostly on price and availability.

What pots should I be looking at?

Keep in mind that I'm not set on building a dead clone, just a good sounding amp that will endure the abuses of stage/studio use. I'll probably avoid the solid core wire but am going to use PVC wire instead of Teflon for this build for added mojo .

[Bruciep07]

If you look in the files section, they're are some great pictures of Francesca and show the caps used. Also, if you haven't already yet, check out the express build guide in the files section, tons of great info there on component choice. From all the pics/schematics Ive seen (never seen a real wreck though) Ken used mostly Mallory 600V PVC series caps, though there is a Trudy schematic kicking around somewhere that shows a few 600V CDE caps mixed in (which are probably also polyester film PVC series). The actual "mallory" brand PVC caps are nearly impossible to find, they stopped mfg years ago but the CDE PVC's that replaced the mallory brand ones are fairly easy to locate. I'm not sure about the resistor brand, but how could you ever really tell anyway, they all look the same to me

[ckpop]

The only way to test resistors is by ear. Seeing resistors are mostly not made by manufactures for sound it is trial and error. Resistors are like tubes these days and only made by a handful of manufactures. The difference is the spec for the company they are made for and the actual process and grade of raw materials used to make the resistor. This is what seperates some resistor from others.

I remember ken mentioning about speakers and tubes how raw materials would change from different suppliers in the manufacturing process and you would get something sounding different.

[Cliff Schecht]

I'm wondering if the AB 1/2W 100kOhm resistors I found would be safe to use as the plate resistors in an Express.. Anybody know what these are rated for voltage-wise?

[ampgeek]

Hey Cliff,
FWIW: I have used AB CC 1/2W plate resistors in numerous Fender and Marshall circuits with no issues. They tend to be common fare in those plans.

They have a propensity to be noisy so it might be hit or miss in V1 of an Express build. My first attempt at a D'style circuit used all CC plate resistors and they didn't stay in for very long!

Cheers,
Dave O.

[Cliff Schecht]

Hrmm.. Perhaps I will stick with carbon films for the first few stages and use the CC's later on in the circuit where they will actually make a difference. I can always swap them out later for better quality parts. OTOH, David has offered to trade some metal film resistors for an Express for some of those AB pots I'm offering so I may go this route. I used metal films in my last build and don't find it to be cold, brittle or harsh sounding.

[ckpop]

[quote]Hrmm.. Perhaps I will stick with carbon films for the first few stages and use the CC's later on in the circuit where they will actually make a difference

Cliff you have the right idea to tweak in key locations with different type of resistors. Also look at your amp design to determine which type is best depending on what you want from the amp. It's a balancing act. You have a design that is more modern sounding metal films work at the same time you try all AB's in a marshall not so good.

[FYL]

I'm wondering if the AB 1/2W 100kOhm resistors I found would be safe to use as the plate resistors in an Express.. Anybody know what these are rated for voltage-wise?

AB's EB, RC20 and RCR20 series were rated at 350V.

[FYL]

I used metal films in my last build and don't find it to be cold, brittle or harsh sounding.

I use low noise Dale CMF55 at the input, BCcomponents PR01 (1W) in most positions, PR02 (2W) for some anode loads and PR03 (Cu-leaded version 3W) in PS decoupling nodes. Plus of course larger R's when needed.

[Cliff Schecht]

Rereading this thread, I 100% agree with you guys that good quality metal film resistors are hard to beat. I used some mil-spec 1% TI metal film resistors in a 5W acoustic amp and thought they worked great. The amp was very low noise for a SE cathode biased amp. Another plus is how solid the leads are, I'm very comfortable floating these resistors around in PTP amps because they stay put after being soldered.

I think my initial bitterness towards metal films was because the first ones I used were the cheapo Xicon metal films, in an Express attempt no less. Like everything Xicon makes, the parts are a bit cheaper in price AND construction. They're not all that low noise, the flimsy leads break easily and IMO they don't sound all that good. If you're going for a high quality build, you can get a lot of return by spending just a little bit more on better quality resistors.



Also, I have a question related to this thread. Which OD series caps are the "right" ones to use in an Express? I have a tubesandmore order setup and wanted to play around with Orange Drops. They have the 715, 716 and 6PS series in most common values. I think I read that the 6PS series over 1000V are polyester. Is this true? Would these be the right choice for an Express build?

[rhinson]

Rereading this thread, I 100% agree with you guys that good quality metal film resistors are hard to beat. I used some mil-spec 1% TI metal film resistors in a 5W acoustic amp and thought they worked great. The amp was very low noise for a SE cathode biased amp. Another plus is how solid the leads are, I'm very comfortable floating these resistors around in PTP amps because they stay put after being soldered.

I think my initial bitterness towards metal films was because the first ones I used were the cheapo Xicon metal films, in an Express attempt no less. Like everything Xicon makes, the parts are a bit cheaper in price AND construction. They're not all that low noise, the flimsy leads break easily and IMO they don't sound all that good. If you're going for a high quality build, you can get a lot of return by spending just a little bit more on better quality resistors.



Also, I have a question related to this thread. Which OD series caps are the "right" ones to use in an Express? I have a tubesandmore order setup and wanted to play around with Orange Drops. They have the 715, 716 and 6PS series in most common values. I think I read that the 6PS series over 1000V are polyester. Is this true? Would these be the right choice for an Express build?

it's the opposite---below is polyester. the 1600v and up are polypropylene.

http://orangedrop.sbelectronics.com/ima ... series.pdf

and yes the polyester 600v are the right choice for an express build, since they are the same as the mallory pvc series. rh

[JamesHealey]

Mallory PVC or CDE PVC

Now people use Sprague 6PS, which are basically the Mallory PVC caps.

1/2w Carbon Film resistors for pre-amp.

these sound fantastic.

[bigbeck]

Keep in mind that I'm not set on building a dead clone, just a good sounding amp that will endure the abuses of stage/studio use..

Over the years I've used 1,000's of 1/2 watt CF resistors from Tube Depot in all of my builds without any problems. I have no idea who the manufacturer is though.

[Colossal]

Cliff said: I used metal films in my last build and don't find it to be cold, brittle or harsh sounding.

Hey FYL, why the face? Or are you saying that you are surprised too that metal films have (for some reason) a reputation as cold and brittle sounding? Just wondering.

Cliff, I've used Vishay Dale 1 and 2W metal films but I really like the IRC GS-3 series 3W metal glaze. They are wonderfully warm and very quiet. I love metal films and my amps are not cold or brittle at all.