#NOS GE 6550 tubes

[guitarbomb]

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[audio-luddite]

Tired of tube Hunting.

Aren't you too?

As it sits right now I can wait. That saves money and stress. The ARC amp sounds fine. I have learned some things though.

Depending on who looks at it different power tubes make no difference or a big difference. A and B tests in guitar amps have proven both sides, so nothing is proved. A&B tests in audio amps are hard to impossible to do. It takes over an hour to swap and bias a set. The guitar guys often have two or more amps to use in a session.

There is another ARC Cl60 for sale in Vernon BC (5hour drive from here) for almost three times the money. OK weird thing, there is a photo of the cage off and it has exactly the same tubes as in mine. Philips 6550 power tubes and Toshiba drivers. The jungle drums say the stock factory tubes were Russian. So why do these two units a great distance apart have exactly the same tube complement?

Are they actually original? Did ARC buy up the Philips / Sylvania production when they shut down? Does that mean they can last 35 years? Was there a single tech handling both units and this is the stuff he used? The Internet is silent on that.

I like the idea they can last decades. Kinda doubt it. One reason I jumped for the 60 was it ran lower voltage and in a triode configuration and had fans to cool the hot bits. I figured it would outlast the 100 Watt ARC beast also for sale at the time. But decades?

Finally there is a tube vendor in Oregon that sells 6550s for a lot less than other guys. They test and match too. Oh and they only sell JJs which they compared to a large set of classic NOS tubes including real Mullards and GEs. They say they are just as good as the NOS. They are guitar guys, and want to let people get good deals. I think there is more than a bit of old hippy spirit there. Tubular dude!

The other side is guitar guys like how tubes clip and break up and the sound that results from abuse. Not really my basis for choice. Hey to each their own. The savings is very attractive and JJ is current non Russian Production.

So I am putting a cork in it. No more tube shopping BS.

Xmas is almost here and I got other things to do. I should shop for LPs. I wonder if I can find any Mercury Living Presence?

[grannygremlinaudio]

These just came in last night.  I ordered them because my Sunn 1200s (70s, not the Fender reissue) crapped out 2 jams ago and the tech said the (vintage, possibly original) GE 6550 power tubes are done.  One of them definately tested weird last I checked so....

Debated replacement options, including KT90s and 120s (but whoa, those are spendy) and then came across these (very good deal - cheaper than new JJs or EHs, which is amazing).  It’s a matched quad of NOS military grade Teslovak ( aka Tesla, which folded in 1989 - JJ started in 1993 using some of the old Tesla equipment, but is otherwise a completely unrelated company) KT88s which are the Euro  equivalent to the 6550 but were developed later so have a smidge more headroom and HiFier tone.  Being military surplus, they are rather heavy due to thicker-than-normal glass (nice for added peace of mind in a guitar/bass amp that will be gigged) and where most likely QCed to a higher standard than regular audio stuff.  They ain’t no NOS Gold Lions (like, who can afford those anyway), but I expect good things; can’t wait to fire up the Sunn with these puppies installed.

Sunn amps originally used KT88s (were a clone of the Dynaco MkIII HiFi power amp - with an instrument preamp tacked on the front).  They switched to 6550s to save money in the early-mid 70s.  Either will work in any Sunn amp of any era; some swear NOS GE 6550s are the only thing that sound right in them, others swear by KT88s (a large contingent using JJs).  I’ll soon see about that, but I suspect the people who prefer 6550s do so because they break up earlier than KT88s, and in a Sunn (especially the 4 power tube models vs 2), it can be hard to get power section to overdrive (think Fender Super Twin; which also has an  ultralinear power section).