resistors

[rutledj]

In search for the lowest noise, is it better to use 1/2w metal films like this:
http://www.vishay.com/docs/31021/cpf.pdf

or use 1watt carbon comp?

Rut

[mlp-mx6]

For a Dumble, use Vishay/Dale RN65 resistors.

[tele_player]

Shouldn't that be prefaced with something like, "in my opinion, based on my experience"? It sounds so... absolute.

[keithrick]

To answer the original question, the metal films should have a lower noise floor then carbon comps, even though the CC are 1 watt rated.


MLP-MX6 is right though, RN65 are preferred as plate resistors in Dumble style builds.

Cheers

[bnwitt]

To answer the original question, the metal films should have a lower noise floor then carbon comps, even though the CC are 1 watt rated.

based on what?

[v00d00blues79]

Based upon numerous confirmations the Dale RN65 1% Metal Film resistors add a nice sparkle to the tone, whereas the Carbon Films and Carbon Comps do not.


Andy

[Bob-I]

Building a Dumble is somewhat "absolute". You can come close with other components but if you want a Dumble, stick to the right components. Dumble used a variety of compoents through the years, but one constant was the RN65's on V1 and V2 plate loads.

Cathode resistors he's used have been wire wound, carbon film and metal film. Signal carrying resistors are mostly CF 1 Watt. PI plate loads are mostly CF also.

Caps are as critical as well. I personally like Xicon MPP's and MP's but most agree that PS6 Orange drops are the Dumble correct caps, although Dumble used a variety on the PI and output couplers. pF value caps should be ceramic only.

Oh... and ... JMO... but I've been here awhile (listening to others) and I've built a few.

[rutledj]

So would it be ok to just use the rn65's everywhere or is the 1 watt in the signal paths critical?

[glasman]

My 2 cents.

For the plates on the Clean and Overdrive stages, I use RN65's from KOA. As others have said they had a sparkle to the tone. The generic XICON metal films add a nasty harshness to my ears. A 1 watt CF also sounds good in this position although they are a bit noisier than the RN65's. The only down side for the RN65's is that they are not RoHS compatible.

For cathodes I normally use a generic MF 1/2 watt resistor. Might try CF's in a future A/B build to compare the sound quality.

For signal path I was using 1/2 w high quality MF resistors. I have since switched to 1/2 and 1W carbon film resistors (depending on value and absolute location). They offer up much better harmonics than do the MF resistors.

For caps I have used both XICON PP / MPP combinations and Sprague PS series. I much prefer the PS series over the XICON. They sound bigger, more 3D openiness and seem to add less distortion as they have a clarity on the top end that the XICON's (IMO) can't match. The other plus side is that they are RoHS compatible and the XICONs are not.

Gary

[rutledj]

OK. Thanks. And you are up pretty early this morning for AZ?

Rut

[glasman]

So would it be ok to just use the rn65's everywhere or is the 1 watt in the signal paths critical?

I think you would end up with a very sterile sounding amp. More is not necessarily better.

1/2W is all that is needed in the signal path, the use of 1 watt resistors is strictly to control noise figure.

Gary

[Fischerman]

So, the PI plate loads are 'supposed' to be CF? Does it matter if the amp has BM PI values? I have RN65 and 1W CF in those values so I could use either.

What about the Return stage plate load for the FX loop? I had been pretty much 'always' using RN65s when mounting a plate resistor on the socket (like in a CF/GS pair and/or an FX loop tube). In my amp I plan to mount that plate resistor on the socket.

Or is the signal so big and late in the path at that point that it won't matter much?

[dogears]

No Vishay Dale?? Typo maybe?

For the plates on the Clean and Overdrive stages, I use RN65's from KOA. As others have said they had a sparkle to the tone.

[galtjunk]

Since the RN65 are not ROHS compliant will they be going away soon?
Should we stock up on them?
Are they available from anyone other than Mouser?

[glasman]

No Vishay Dale?? Typo maybe?

For the plates on the Clean and Overdrive stages, I use RN65's from KOA. As others have said they had a sparkle to the tone.

A total Brain Fart on my part.... Too much Dutch beer last night.


Vishay Dale not KOA for RN65's.