Recent Posts

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Q & A / Re: Did I Blow My 200s?
« Last post by loudthud on Yesterday at 07:58:03 pm »
Try the amp with the speaker you normally use. Same noise? Do you see any flashes of light in the big tubes?
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Q & A / Did I Blow My 200s?
« Last post by Smoothwound on Yesterday at 05:44:54 pm »
Hello everyone, its been awhile since I've been here as I have been playing my 200s with love for years since I first acquired it. Now I may have gone and done a stupid thing. We acquired a floor monitor for free, which I think (and I know I should have taken a pic of this before i posted) said 100 watts 8 ohm. It looked passive. So I plugged it into the external speaker to see if I could get my speaker and it working together. Next thing I know the 200s is dead. If I turned it all the way up to 7 it made this horrible cranking noise. Did I mess it up for good? Please tell me its just a fuse or tube or something.

thanks for any and all help on this one.

Dave
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Q & A / Re: 6AN8A Substitute/Replacement
« Last post by Soundmasterg on Yesterday at 01:07:29 pm »
The 7199 is similar enough that with some socket rewiring it would work in the circuit without major changes. However they are very expensive these days and the new manufacture ones aren't very good.

Any change to a twin triode like a 12AX7 would change the gain structure of the amp considerably, especially if you stayed with the gain stage + cathodyne inverter setup like the Sunn has. If you went with a long tail pair arrangement or a floating paraphase inverter arrangement then some of the gain could be brought back but I still think there would be a net loss as the pentode in the 6AN8 supplies a lot of gain. That would also be a major change to the amp and would require some troubleshooting and voicing time to dial it in sufficiently.

There are probably some other triode pentodes that could be used, but I don't know of any offhand. The 6AN8 supply is still good for NOS stuff and will likely be for quite awhile. I wouldn't worry about it that much myself. Its not a tube that is used in a ton of stuff so the supply won't dry up super fast.

Greg
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Q & A / Re: 6AN8A Substitute/Replacement
« Last post by GrannyGremlin on Yesterday at 11:22:19 am »
It can be done, but personally I love 6AN8s.  It is half pentode half triode vs dual triode like a 12A_7 so it would be a significant mod.

There are no drop-in substitutes, but there are workalikes: 7258 (same pinout but diff heater current 13.5V vs 6.3 so nonstarter I'd think) and the 6AV8 (diff pinout - not a hard change).

I coulda swore the 6JW8/ECF802 was a drop in compatible but looks like it isn't.  The pinout is very different at least.

Anyway, as the OP said, they are not too expensive and there is still supply.  Not hugely in demand.  I just buy them up whenever I come across them (have a few things besides my Sunn amps that use them) - last year I came across a NOS Rogers 5 pack (rebranded RCAs) in a local radio repair shop and snapped it up.
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Q & A / Re: 6AN8A Substitute/Replacement
« Last post by Isaac on Yesterday at 08:25:44 am »
The original Model T uses a 12AX7 as a phase inverter. I have toyed with the idea of converting one of my older amps to that configuration, but I haven't done it.
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Q & A / 6AN8A Substitute/Replacement
« Last post by D.M.N. on July 16, 2018, 09:57:40 pm »
While 6AN8/6AN8A valves can still be found pretty cheap at the moment, there are no current tube companies manufacturing new ones. Though they can be pretty long lived tubes, I have been thinking about what will happen once the supply starts to dry up, as they are used in a few other guitar amps as well Hi-Fi stereos as well. Has anyone gone about rewiring or converting their early Sunns to use a different phase inverter with any success?
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Q & A / Re: Beta Lead - loud hum with no signal
« Last post by loudthud on July 14, 2018, 08:22:11 pm »
There is a -15V source on the power amp board. Make sure it is steady and has good connections to the preamp board. The channel LEDs run off of the -15V supply.
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Q & A / Beta Lead - loud hum with no signal
« Last post by porcupine on July 14, 2018, 03:30:33 pm »
I recapped my Beta Lead and am now having some problems with it. After putting it back together I plugged into channel A. It sounded great for a few seconds and then there was a loud thump/pop sound. The channel LED went out and the amp stopped passing guitar signal, now just putting out a loud hum (which can't be controlled by any of the knobs). I shut the amp off immediately and opened it back up. Everything looked ok, nothing burnt and the fuses weren't blown, so I tried again.

Channel A worked great, and I played through it for a few minutes with no problem. Channel B worked but had a lot less gain at the exact same EQ/drive settings. I plugged into the Both input and I got the loud pop/hum again, no LEDs lighting up, and no guitar signal passing. Went back to the individual channels and I'm getting the same result. Any clues what could be wrong?
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Q & A / Re: Sunn Stinger 100 Amp
« Last post by Blue1Solo on July 07, 2018, 08:51:58 am »
We went to a club last night and the Lead Player was using a Fender Stage Lead II..and its exactly the same set up as my Sunn Stinger 100! I guess it is a re-branded Fender amp with a Sunn Label on it! The only difference on the amps was the Name Brand, and his is made in Japan, and mine is made in Tiawan..otherwise they are the same amp! I learn something new every day! Thanks to All..!
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Q & A / Re: Newer 215 bass cabs vs Older
« Last post by GrannyGremlin on July 06, 2018, 09:20:06 am »
Garnet up in Canada did that too (compression drivers in guitar cabs, often mated with 1-2 12" or a single 15").

They also did a couple reflex horn (sideways 215S style) cabs.





As well as this obvious take on Acoustics horn loaded cabs:

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