PRP Resistors

[David Root]

Anyone tried PRP resistors, GP or PR9372, in a Dumble style build? Precision Resistor Products, Megalopolis IA. (Not Megalopolis, but something close). These are modern USA made metal films that I have used in a few non-Dumble type builds with success. They don't claim any US MIL-SPEC compliance, but the 1W is rated 500VDC so they are a quality item.

Only downside I can see is they are like RN 65s in that they are not color coded, you have to read them not just look at them.

They are a nice ruby red color tho'!!

[Plexibreath]

Sorry for the years late reply.
But yes, I've tried them, and will never use them again. Tonewise, I have no complaints, my problem is their construction.
The first and only amp I built with them, I broke several resistors where the lead is brazed to the end cap. They just break at that joint when I bend the lead to solder it into the board. Then I would try to use my needle nose pliers to hold the lead near the end cap in order to not place side torque pressure on the brazing, that certainly keeps the lead from breaking when bending the lead, but then the lead would break at the braze with the slightest final spread of leads to align with the turrets. This didn't happen everywhere, but three or four in a single amp is crazy, this after I've built amps for years with nothing like this ever happening.

By the way, that amp sounds fantastic, so I can't knock the tone of the resistors, oh, and another point in their favor, they look real cool! But I worry about that amp cutting out at the wrong time from a delayed braze break.

To be clear, the question was about using them in a Dumble build. I can't answer that because this amp was one of my own designs. I'd think they would sound great in a Dumble, just make sure you buy extra of every value, and don't dare gig the amp for fear of delayed failure.

Kelley

[Cantplay]

[img:540:720]http://a1.sphotos.ak.fbcdn.net/hphotos- ... 9962_n.jpg[/img]

I'm building something now with them, having no problems.

I use all 2W, just like the way they look.

John

[Plexibreath]

Nice looking amp! The amp I built using them was back in 2008, hopefully they've addressed this issue since then.

[David Root]

I have had one instance of that failure mode, which I posted here with a pic of the failed piece. This was at least two, maybe three years ago. The brazing of the lead to the body was defective. It actually came apart in my hand before it was even on the board.

I sent the pic to PRP's website, they did not respond.

I will continue to use them in appropriate non-Dumble builds, but my interests have moved towards period correct builds and for those I have been using Electra and Mepco-Electra metal films. If I ever build a pair of audio monoblocs which I have been toying with for years now, I would likely use PR9372s in those.

[Plexibreath]

I have had one instance of that failure mode, which I posted here with a pic of the failed piece. This was at least two, maybe three years ago. The brazing of the lead to the body was defective. It actually came apart in my hand before it was even on the board.

I sent the pic to PRP's website, they did not respond.

I will continue to use them in appropriate non-Dumble builds, but my interests have moved towards period correct builds and for those I have been using Electra and Mepco-Electra metal films. If I ever build a pair of audio monoblocs which I have been toying with for years now, I would likely use PR9372s in those.

I still have the pics I sent to PRP, I'll post them here when I get home tonight. They must have fixed it or I'm sure Cantplay would have had at least one lead break on his build.

[mojotom]

One of the best sounding Super Reverb I ever heard was one modded by Tony Bruno and feature those resistors on plates.

[toner]

i like them and think they sounded better then the rn65 dales most times.... but i also find if i use all hi end type resisters in an amp that i don't like it as much as if i were to just use them sparingly in select positions. if im gonna do all the same resisters in a amp i like more generic resisters better.. the perfect amp for me would have a mix of different brands.. just like cooking

[renshen1957]

Anyone tried PRP resistors, GP or PR9372, in a Dumble style build? Precision Resistor Products, Megalopolis IA. (Not Megalopolis, but something close). These are modern USA made metal films that I have used in a few non-Dumble type builds with success. They don't claim any US MIL-SPEC compliance, but the 1W is rated 500VDC so they are a quality item.

Only downside I can see is they are like RN 65s in that they are not color coded, you have to read them not just look at them.

They are a nice ruby red color tho'!!

Hi,

I've used them primarily as cathode resistors, and in a few places where I couldn't get the values I required by other brands.

I've read of another hi-end brand with internal breakage, the leads bent to close to the resistors body, the older Holco brand.

At $0.45 a piece 1/2 watt, these are inexpensive made in the USA metal film resistors. I never have the problem, but I use two forceps to bend leads.

Since I use some resistors that start at $3.50 and higher for 1/2 watt and 2 Watt at $15.00 and Vishay VAR-Series "naked" Z201 Z-FOIL RESISTOR 1% 0.4W start around $15.00, I don't consider 45 cents all that expensive.

Needless to say I don't use these Hi price for every resistor position.

The green Vishay Sprague/Kiwame 2W Carbon Film resistors make a nice color contrast to the PRP. Not that the electrons care what color resistor they flow through.

Best regards,

Steve

[markr14850]

The green Vishay Sprague/Kiwame 2W Carbon Film resistors

I thought the Kiwame's were KOA Speer?

[ToneMerc]

The green Vishay Sprague/Kiwame 2W Carbon Film resistors

I thought the Kiwame's were KOA Speer?

Yes they are KOA Speer, I've ordered "Kiwame" when I couldn't get the values from Mouser, not a hill of beans difference.

http://www.koaspeer.com/products/resist ... stors/spr/

http://www.hificollective.co.uk/components/kiwame.html

TM

[renshen1957]

The green Vishay Sprague/Kiwame 2W Carbon Film resistors

I thought the Kiwame's were KOA Speer?

My bad, these are KOA Speer.

I ordered both Kiwames from Parts Connexion (supposed to be the closest tolerance) and the KOA's from Mouser in the wider Tolerance and measured both.

The KOAs were the same tolerance as the Kiwame's, both almost dead end or off by only 1%.

Very smart marketing, make a great resistor and then sell these as the other listed tolerances and well.

Too Bad Mouser doesn't stock very many values.

Best Regards and Mea Culpa,

Steve

[diagrammatiks]

Anyone tried PRP resistors, GP or PR9372, in a Dumble style build? Precision Resistor Products, Megalopolis IA. (Not Megalopolis, but something close). These are modern USA made metal films that I have used in a few non-Dumble type builds with success. They don't claim any US MIL-SPEC compliance, but the 1W is rated 500VDC so they are a quality item.

Only downside I can see is they are like RN 65s in that they are not color coded, you have to read them not just look at them.

They are a nice ruby red color tho'!!

Hi,

I've used them primarily as cathode resistors, and in a few places where I couldn't get the values I required by other brands.

I've read of another hi-end brand with internal breakage, the leads bent to close to the resistors body, the older Holco brand.

At $0.45 a piece 1/2 watt, these are inexpensive made in the USA metal film resistors. I never have the problem, but I use two forceps to bend leads.

Since I use some resistors that start at $3.50 and higher for 1/2 watt and 2 Watt at $15.00 and Vishay VAR-Series "naked" Z201 Z-FOIL RESISTOR 1% 0.4W start around $15.00, I don't consider 45 cents all that expensive.

Needless to say I don't use these Hi price for every resistor position.

The green Vishay Sprague/Kiwame 2W Carbon Film resistors make a nice color contrast to the PRP. Not that the electrons care what color resistor they flow through.

Best regards,

Steve

Have you used any of the z-foil resistors?

[hitchcaster]

Anyone tried PRP resistors, GP or PR9372, in a Dumble style build? Precision Resistor Products, Megalopolis IA. (Not Megalopolis, but something close). These are modern USA made metal films that I have used in a few non-Dumble type builds with success. They don't claim any US MIL-SPEC compliance, but the 1W is rated 500VDC so they are a quality item.

Only downside I can see is they are like RN 65s in that they are not color coded, you have to read them not just look at them.

They are a nice ruby red color tho'!!

Hi,

I've used them primarily as cathode resistors, and in a few places where I couldn't get the values I required by other brands.

I've read of another hi-end brand with internal breakage, the leads bent to close to the resistors body, the older Holco brand.

At $0.45 a piece 1/2 watt, these are inexpensive made in the USA metal film resistors. I never have the problem, but I use two forceps to bend leads.

Since I use some resistors that start at $3.50 and higher for 1/2 watt and 2 Watt at $15.00 and Vishay VAR-Series "naked" Z201 Z-FOIL RESISTOR 1% 0.4W start around $15.00, I don't consider 45 cents all that expensive.

Needless to say I don't use these Hi price for every resistor position.

The green Vishay Sprague/Kiwame 2W Carbon Film resistors make a nice color contrast to the PRP. Not that the electrons care what color resistor they flow through.

Best regards,

Steve

Have you used any of the z-foil resistors?

i tried the texas instruments version, i think it was, of those resisters.. got them direct so not as much $... but they suck for everything ive tried them in that was guitar and amp related... they have a unique sound, but i guess its only good for hifi because they always sound worse then anything else basically.... id look elsewhere

[hitchcaster]

The green Vishay Sprague/Kiwame 2W Carbon Film resistors

I thought the Kiwame's were KOA Speer?

My bad, these are KOA Speer.

I ordered both Kiwames from Parts Connexion (supposed to be the closest tolerance) and the KOA's from Mouser in the wider Tolerance and measured both.

The KOAs were the same tolerance as the Kiwame's, both almost dead end or off by only 1%.

Very smart marketing, make a great resistor and then sell these as the other listed tolerances and well.

Too Bad Mouser doesn't stock very many values.

Best Regards and Mea Culpa,

Steve

they are the exact same resister.. just marketed differently... i still buy the expensive ones sometimes because can't find the right values.. .mouser also has the pink colored ones and those are just as cool too