Question about re-tubing

First of all, say hello to everyone since it's been a long since i read the forum, but it's the first time i decide to register and participate.

Second, i must apologize for my english, i'm spanish and i still have a lot of work to improve my english. I understand better than i write or speak.

All this said, here i go.
I've already used the search engine and have not seen anything clear enough about this.
I've been using tube amps for years, and a couple of years ago i went for my first mesa. A triple recto.(not bad )

It's time to change tubes now, and as i've been a Eurotubes customer for some time i decided to contact Bob so he could recommend eme some tubes to improve a bit my sound. I'm going for the KT66 in the power section, but not a sextet but a quad so i'll pull out a couple of tubes. Which ones do you recommend? I've read it doesn't matter, but i prefer to confirm. And also to confirm if i can pull the rectifier tube i want, no matter wich one.
Would this affect if i use diodes or tube rectification?

And for the preamp i'm going for the ECC83S gold pin (i know many of you would recommend me another configuration instead of a whole JJ preamp, but at this moment i want to try this config, since it's the first time i'm retubing my triple recto). Do you think i should use all of them balanced , matched or both of them?

And well, the most important question, since its relative to the impedance.
Bob told me this:

Bob said:

You can pull either the outside two tubes or the inside two tubes in a 100 watt amp and then set the impedance on the amp to one half the value of the cab. Example, using a 16 ohm cab set the amp to 8 ohms.

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Is this correct? I don't get the point of having double the impedance of the amp in the cabinet...

Thanks a lot for your help! I'll try to help from now on with whatever i can.

In the manual it says you can pull the INNER pair and any one of the rectifier tubes in the Dual Rectifier, it mentions nothing about impedance or doing it to a Triple. If you don't have it in writing from Mesa don't do it is my advice. They should really have a FAQ section on their web site to clear all this up.

Thanks a lot for your answer Animated Suspension.
I'm really confused, since Bob is a guy i think i can confide in, but in this forum i've read some people saying it's safe to pull a couple as long as they're symetrically pulled.Don't know if i explain myself.

About the impedance, here i read a guy telling something near what Bob has told me, but afterwards a guy saying the impedance doesn't vary so much to change the impedance of the output. So, now, i'm really messed up.

I'd really like to use the KT66 since i think they'd give me the kind of sound i'm looking after....so, don't know what to do

Anyway, thanks for your response.

Get a sextet of KT66's is the safest (and more expensive) option, but not as expensive as damaging your amp !! :lol:

ANIMATED SUSPENSION said:

Get a sextet of KT66's is the safest (and more expensive) option, but not as expensive as damaging your amp !! :lol:

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+1

As far as KT66 tubes themselves.. I recommend the Saratov KT66's. Those are TRUE KT66 tubes. The Sovtek KT66 have a different internal construction and are basically a 6L6WXT+ in a bigger glass bottle. The same goes for the Tung-Sol reissues.

Your other choices are the Chinese "Shuguang KT66", or the Russian "Genelex Gold Lion KT66". I would go with the Russian one. JJ also makes a KT66 now, not sure how good it is. The best are the Saratov, then probably the Golden Lion.

I currently use the Saratov KT66 that I got from thetubestore, and they kick ***.

Saratov:


Sovtek:

The reason to go for a quad instead of a sextet is that i usuallly reharse at low volumes and i think i'm not getting what the valves can give, so i planned to take the power of the triple recto down to 100W.

The question about the impedance is clear to me now, Bob answered me yesterday i should use the triple recto's output at half the impedance of my cabinet. I'm using a 8Ohm cabinet, and he tells me to use the 4Ohm output of the Recto. I suppose this will be safe, since i'll be putting double the impedance the amp is expecting at the output and what i always read was that the dangerous way was the opposite, using less impedance in the cabinet than the one expected by the amp.

About the rectification tube, Bob told me i should pull a rectification tube if i was going to use the amp in the tube rectifier mode.

I know many of you will think this is going to be risky, but what the hell! if i don't try i'll never know if it's worth it.(this is what i tell myself not to go to the mesa tubes )

dmt, i'll be using the JJ KT66. If i'm happy with the sound, i think i'll follow your advice and try the Saratovs.

Thanks for your help. Anyway any advice will be welcome!

dmt said:

I currently use the Saratov KT66 that I got from thetubestore, and they kick ***.

Click to expand...

dmt: .. If you don't mind saying, what amp(s) do you use them in?

BigMuzzy: The rectifiers are wired in parallel and are used only to provide DC current to your other tubes. It's safe to run both of them at the same time. Now as far as your power section goes, if you have any doubts about what you're being told, ask Mesa. Email them and get an answer from the source, its the safest way.

I run my dual rec solo head with the center pair of power tubes pulled. This gives me about 50 watts. I could pull one, but I leave both rectifier tubes in because I like how it sounds better than with just one. I switched to the 4 Ohm out on the amp, my cab is setup as 8 Ohm. This is safe according to the factory.

I hope this helps you.