Pull 2 tubes on the 2466?

[Phil M]

Can the 2466 be run with just two of the KT66s by pulling one of the pairs (inside or outside)?

[nitrous12]

According to SteveD in another thread on this a little while ago...No.

You are in Rochester? I live in Webster and gig in the Rochester area. You in a band around here?

[Phil M]

Hey man! Walworth resident here.

I am currently rehearsing a new modern rock cover band, but we'd like to replace the drummer ... possibly add a 2nd guitar player. Anyway, I played guitar in a band called Circus Boy up until we folded in April after a gig at Baird Road. I see that you're in Download--funny story, I contacted Jay Tarmino about trying out but I couldn't get down to A-Pub the night of the auditions. I checked them out a week or two later at Baird Road and could not see myself playing Rush, VH, etc. Ah well. I'm assuming I saw the guy that you replaced. He had a Strat into what looked like a DSL.

[SteveD]

Can the 2466 be run with just two of the KT66s by pulling one of the pairs (inside or outside)?

Here is my reply to this question in the Myth Busters section

mety wrote:
Here's another one...

If you remove the two outside poweramp valves (tubes) from a 100w amplifier, you can use it as a 50w amp.

Over to you Steve

This is definately a NO NO on the 100 Watt Vintage Modern. The HT (B+) on this amp is very high; - approx 530VDC and this is about as high as the KT66s will live happily at. If you remove the two outer or inner output valves the HT rises by about 20V due to less current getting pulled out of the Power Transformer and therefore less loading. The output valves will more than likely arc over causing damage to themselves as well as other components in the power stage.

A 100W amp is designed to be just that. not 50W. Everything is optimised to work together efficiently - output valves, output transformer primary winding etc.

I wouldn't advise anybody to do this to any amp!

[ville]

Hey guys

If you replace the KT66 with KT88 then you can do it, right?

Atleast with svetlana
http://www.drtube.com/datasheets/kt88svet1999.pdf

the maximum DC plate voltage is 800V...

Correct me if I'm wrong?

- Ville

[nitrous12]

Hey man! Walworth resident here.

I am currently rehearsing a new modern rock cover band, but we'd like to replace the drummer ... possibly add a 2nd guitar player. Anyway, I played guitar in a band called Circus Boy up until we folded in April after a gig at Baird Road. I see that you're in Download--funny story, I contacted Jay Tarmino about trying out but I couldn't get down to A-Pub the night of the auditions. I checked them out a week or two later at Baird Road and could not see myself playing Rush, VH, etc. Ah well. I'm assuming I saw the guy that you replaced. He had a Strat into what looked like a DSL.

Yeah I was there that night at Baird Rd....I played a few songs at the start of the second set, but at that point I was still cramming for the 60 songs I had to learn. The guy with the Strat was the old guitarist.
I was strictly a modern rock player myself before this venture. I came from a set list of stuff like Lit, Bowling for Soup, Toadies, Bush, Weezer, etc. Download does some modern rock, but we cover rock from the 70s up to today so there is a good mix. I had my reservations at first, but I brushed off my lead skills and buckled down on a lot of new stuff and now I actually enjoy some of the older stuff more. Probably cuz I haven't been playing it for 15 years now.
Good luck with the new band and that VM. I have been using the VM for about 2 months now and I love it!

[Phil M]

For now the Splawn Quickrod stays. We'll see.... thanks for sending good thoughts about the new band. It can be really hard to put the right pieces in place. It's much easier to join an existing band that you've decided you can fit into than start one from scratch.

My old band played a mix of classic and modern rock and it seemed to confuse the hell out of the audience sometimes. That's why this new project is a little more focused. Velvet Revolver, STP, Weezer, Lit, Chili Peppers, Snow Patrol, Pearl Jam, Three Days Grace etc.

I'll try and come check you guys out soon.

[nitrous12]

For now the Splawn Quickrod stays. We'll see.... thanks for sending good thoughts about the new band. It can be really hard to put the right pieces in place. It's much easier to join an existing band that you've decided you can fit into than start one from scratch.

My old band played a mix of classic and modern rock and it seemed to confuse the hell out of the audience sometimes. That's why this new project is a little more focused. Velvet Revolver, STP, Weezer, Lit, Chili Peppers, Snow Patrol, Pearl Jam, Three Days Grace etc.

I'll try and come check you guys out soon.

I hear ya on all accounts. I tried different lineups and genres to get bands together in the past and never had a lot of luck. I was in an original band for a while that did 'ok', but started to fizzle out. Stepping into this band was a great opportunity and it has been great!
And the mix of music has become what seperates us from other bands, but on a few occassions it didn't work as well. We went out to Syracuse for a gig recently...had a decent crowd for first time there, but they were totally about the modern rock. We don't have enough of it on the set list to only do that for the entire show. Our AC/DC always kills around here....they were bored. But then again they didn't seem to enjoy the Rage like the crowds around here do.
Let me know when you get this band out...and if you make it to one of our shows introduce yourself :)

[Phil M]

Will do. I see you're playing tonight actually--not sure I can make it out but I'll say hi if I do. Is it a Halloween party at A-Pub?

[SteveD]

Hey guys

If you replace the KT66 with KT88 then you can do it, right?

Atleast with svetlana
http://www.drtube.com/datasheets/kt88svet1999.pdf

the maximum DC plate voltage is 800V...

Correct me if I'm wrong?

- Ville

Actually, two KT88s would probably work out OK on the 2466; they could handle the extra voltage, the output transformer primary is near enough the correct inductance for a pair of 88s and two of them alone wouldn't strain the heaters. I think I'll have to give that a look when I get in next week.

BTW, EL34s sound absolutely terrible in the Vintage Modern even with an output transformer with the correct primary inductance. They also put a strain on the resistor that takes the place of the choke. Pins 1 and 8 also have to be linked on the valve bases. Believe me guys, it's not worth the effort, it sounded trebly, thin and metalic and totally crapped out when the guitar volume was lower than 6!

[ville]

ok

Let us know how it goes, if you have time to try it...

-Ville

[SteveD]

Just tried the 2466 with a pair of KT88s in the output and was very impressed with the result. :) This is a viable option for anybody who wants a different sound characteristic from their 100W Vintage Modern head. The sound was more edgy and crunchy and the dynamic reaction to the guitar volume pot was retained. The power amp gives a bit more linearity at higher volume which some people may prefer or not; Kt66s have a fatter mid and smoother treble response. Both valve types yield good tones, it's just a matter of personal taste which suits you better. Personally I prefer the KT66s but I know there will be people who prefer the KT88s; especially those who like EL34s.

There are no mods to be done to the PCB. Bias for the KT88s can be set at 60 to 64mV per valve (at Connector 10 pins 1 and 3). There is no real significant reduction in power and therefore volume to be had with this configuration, just a different sonic texture. The amp will live quite happily with either configuration.

[nitrous12]

That's great. Thanks SteveD. Which sockets would you put the pair in? Inside pair or outside pair?
And on the initial swap would the KT88s be about in that bias zone or are you saying we should expect it will immediately be higher or lower and need a biasing?

[SteveD]

I had them in the inside pair but the outside pair would do just as well. The stock bias setting will be too cold so you will have to adjust it to within the range I specified above.

[ville]

Thank you indeed, that's something worth trying.

Some tech told me once about pulling 2 tubes on a 100 watter, that it's better to pull the center pair. So the tubes are further apart, more efficient cooling...

About the cabinet ohm selector. With 2 x KT88 I run the ohm selecter on the same settings as with 4 x KT66?

Do you think that there is too much strain on the heater supply with 4 x KT88? Is there enough bias range for four of them?

What do you think about 6550? That should work too?

-Ville