John Mayer Two Rock build

[Bombacaototal]

RN70D are the blue plate resistors.

Thanks a lot. I assume they are Vishay / Dale

[M Fowler]

The new resistors are Vishay / Dale (brown looking)

Those old Robin egg blue RN70D resistors I ordered off ebay and gave away to a TAG member friend to use in his high end Dumble builds, where they belong, not in my builds.

I also ordered recently Draloric resistors off ebay to have in stock.

Mark

[Bombacaototal]

The new resistors are Vishay / Dale (brown looking)

Those old Robin egg blue RN70D resistors I ordered off ebay and gave away to a TAG member friend to use in his high end Dumble builds, where they belong, not in my builds.

I also ordered recently Draloric resistors off ebay to have in stock.

Mark

Got it. Which resistors would you recommend for a high end dumble built?
1) Xicon Metal Film
2) Vishay / Dale RN70D
3) NOS Robin Egg RN70D
4) Vishay Draloric

Any othets?

[M Fowler]

If you look at Tony Albany's/Martin Manning #124 layout in Dumble files section is tells you what is used in Dumble circuit

https://tubeamparchive.com/viewtopic.php?t=5719

Dale plate load resistors for V1 & V2.

Precision metal film resistors for cathodes.

Carbon film resistors for all others.

BOM's I've seen shown and what I ordered from Mouser myself if not being able to find old precision metal film resistors

Vishay/Dale 71-RN65D-F-221K

Vishay/Dale 71-RN65D-F-150K

As well as other values needed such as 110K

[Bombacaototal]

If you look at Tony Albany's/Martin Manning #124 layout in Dumble files section is tells you what is used in Dumble circuit

https://tubeamparchive.com/viewtopic.php?t=5719

Dale plate load resistors for V1 & V2.

Precision metal film resistors for cathodes.

Carbon film resistors for all others.

BOM's I've seen shown and what I ordered from Mouser myself if not being able to find old precision metal film resistors

Vishay/Dale 71-RN65D-F-221K

Vishay/Dale 71-RN65D-F-150K

As well as other values needed such as 110K

Thanks for the help again
Just a question: I always read thst metal film was better then carbon (less noise). Any recommendation as to using carbon for the majority pf the resistors?

[M Fowler]

Those robin egg blue are Electra RN70D

There are metal film IRC, Electra, Mepco, KOA, Dale CCF60, Dale CMF60, and RN65D.

Holy Grail of Resistor types

BEYSCHLAG CF resistors
DRALORIC CF resistors
PIHER CF resistors

Many use Xicon CF resistors but a few people have said they don't like them sound wise.

Maybe Tony Albany or others will comment.

Spread sheet came from this thread: https://tubeamparchive.com/viewtopic.ph ... 152602+xls

[ToneMerc]

BEYSCHLAG CF resistors
DRALORIC CF resistors
PIHER CF resistors

I can identify just about every resistor brand/type HAD ever used and complete value sets of period correct "Holy Grail" parts for Dumbles are basically unobtainable to find. In my D builds I have used a fair amount of period correct resistor parts and I turned over rocks to find them.

For a modern CF resistor that's easily obtainable I would chose the KOA CF1/2 series.

TM

[M Fowler]

Thanks for posting Mike.

Recently I have been scrounging up various values of resistors of the DRALORIC and PIHER brands just so I can build a more original looking Dumble amp. Vary hard to find what a guy needs and I started 10 yrs too late.


Mark

[Bombacaototal]

BEYSCHLAG CF resistors
DRALORIC CF resistors
PIHER CF resistors

I can identify just about every resistor brand/type HAD ever used and complete value sets of period correct "Holy Grail" parts for Dumbles are basically unobtainable to find. In my D builds I have used a fair amount of period correct resistor parts and I turned over rocks to find them.

For a modern CF resistor that's easily obtainable I would chose the KOA CF1/2 series.

TM

Hi TM, thanks for the input. Those Koa look like carbon. Would you use carbon in the entire built instead of Metal (except for cathode and load resistors which should be metal). Any recommendation against using metal in the entire project? Which moder MF would you recommend?

As far as filters I am in doubt between Illinois and md Sprague Atom or even a combination of both. Any recommendation in this regard?

Thanks again

[martin manning]

IMO people obsess over this a bit too much. If you are building for sale period correct is certainly a mojo factor, but that is marketing, not engineering. I think HAD used Mil spec resistors for the plate loads for low noise and precision, MF for cathodes for precision. CF everywhere else because they were readily available in low tolerance. I'd keep the RN65's for plate loads; nothing wrong with using MF everywhere else. For power supply electrolytics, read the specs. High temp (105C) and long life ratings are real, and available for much less than Atom TVA, which are 85C rated and stupid expensive. F&T (although 85C rated at high voltages) and Nichicon are much better parts. I would pay attention to the selection of the film caps, and stick with polyester Orange Drops.

[Bombacaototal]

Thanks everyone for the help so far. This is a built for personal use but I want to source the best parts I can soundwise

I have been unable to find 4.7uF Sprague, Illinois, or F&T. Is Vishay 030 AS good enough? Any other recommendation?

As far as resistors this is what I am thinking: cathode/plates and tonestack slope Metal Film: Electra/MEPCO-Electra (for cathodes) and Vishay/Dale 71-RN65-F (1/2W for plates and tonestack slope) and for the other resistors for example on pre-amp (1W), screen grids (5W) and power supply (2W) carbon film KOA CF 1/2 Series (preferably) or alternatively Xicon Carbon Film. Any recommendation regarding my choices

Any opinions on Welwyn and/or generic metal films?

For the presence (1uf) i am thinking Kemet Tantalum cap with vishay MKT1813's as a second option but less preferable. 330R / 380R presence resistors xicon metal film

For the eletrolytic the recommendation is the F&T and Nichicon instead of Sprague Atom, correct?

Coupling caps i am going for 6PS Orange drops and pF caps Silver Mica

[TUBEDUDE]

Solen makes a nice metalized film in 4.7uF, but size might be an issue. The 400V ones are smaller than the 600V caps if you can get away with it.

[Bombacaototal]

Solen makes a nice metalized film in 4.7uF, but size might be an issue. The 400V ones are smaller than the 600V caps if you can get away with it.

Unfortunately I could bot find any Solen in the UK. Is nichicon good enough?

[TUBEDUDE]

I think construction is more importan than brand. If in a power supply, electrolytics will suffice. If signal path, use electrolytic if nothing else is.available. value is more important than construction. For signal path try to use mylar, polyester, polypropylene, silver mica, or even ceramic.

[Bombacaototal]

Thanks for posting Mike.

Recently I have been scrounging up various values of resistors of the DRALORIC and PIHER brands just so I can build a more original looking Dumble amp. Vary hard to find what a guy needs and I started 10 yrs too late.

Mark

Where are you sourcing the Draloric from?