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ST-70 Custom Died - Where To Start?

nj pheonix said:
I don't know what's ailing you Hal, but I hope for that kind of Money, it's a cure and not a treatment. Also I hope your heath insurance covers the lions share and then some. Feel better my friend
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Thanks. Yes, cure, but doesn't undo damage done - will prevent further though, if I'm in the lucky 95%. [First med, same cost, a few months ago, I missed the lucky 90%. Hep C, apparently from one of several surgeries back in the dark ages. One very lucky thing - my copay is zero.]

And good news!! Fuse replaced, amp singing like new, no noise or hum and as quiet as ever. Hooray!

Yeah, now it looks obvious where the fuse goes... doh!! Pulled a Homer. Thanks for helping the simple-minded, guys.
 
Ive used a few of the plug/fuse combos. And where space allows I use the one with the switch on it too. sneaky hidden little buggers ain't they? Glad to see it was a simple fix. Nice looking amp. :thumbsup:
 
Happy to see it all worked out. May think about having a spare set of tubes on hand, along with extra fuses, for good luck :)

Best of luck with the medical treatment... hopefully you can enjoy some music in the meanwhile
 
Glad everything was that easy and simple! You got lucky this time. :thumbsup:
To be honest a part of me wanted to see some more in-depth investigation though,...just saying. :naughty:
 
maxhifi said:
Happy to see it all worked out. May think about having a spare set of tubes on hand, along with extra fuses, for good luck :)

Best of luck with the medical treatment... hopefully you can enjoy some music in the meanwhile
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Well, I am thinking of buying a second set of spare tubes - already have a full, new set in the audio closet. I use the new Mullards that run about $100/matched quad set. I keep being told to buy superior used tubes, but have had such a run of bad luck ordering used stuff... and NOS - how do you really know? Besides, I'm very happy with the new Mullard EL34s. And the fuse came in a 5-pk, which I stored with the spare tubes.

And a nudie:

st70-3.PNG
 
Maybe consider a different flavor for your new spares. A 6CA7 or a KT77 will sub for an EL34 just fine, and you'll have a little variety to try out. I have a set of Electro Harmonix 6CA7's and like them just fine.
 
musichal said:
Well, I am thinking of buying a second set of spare tubes - already have a full, new set in the audio closet. I use the new Mullards that run about $100/matched quad set. I keep being told to buy superior used tubes, but have had such a run of bad luck ordering used stuff... and NOS - how do you really know? Besides, I'm very happy with the new Mullard EL34s. And the fuse came in a 5-pk, which I stored with the spare tubes.

And a nudie:

View attachment 833501
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That amp is heavily modded. If it weren't for the ST-70 transformer stacks in the rear, I'd have a difficult time calling it an 'ST-70'.
 
gadget73 said:
Maybe consider a different flavor for your new spares. A 6CA7 or a KT77 will sub for an EL34 just fine, and you'll have a little variety to try out. I have a set of Electro Harmonix 6CA7's and like them just fine.
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I am running a set of JJ kt77's I like. Im thinking about a pair of EH6CA7's. Sonic differences?
 
8xlaxx said:
That amp is heavily modded. If it weren't for the ST-70 transformer stacks in the rear, I'd have a difficult time calling it an 'ST-70'.
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That's why I call it an ST-70 Custom, though I don't write it out fully every time; see sig. It sounds great to me, and is about as quiet a tube amp as I have heard - no noise even up close with Khorns. I've been very pleased with it, and absolutely love that all connections and the switch are on the back panel - I'm not a fan of looking at cables. Mr. Lang does nice work.
 
musichal said:
That's why I call it an ST-70 Custom, though I don't write it out fully every time; see sig. It sounds great to me, and is about as quiet a tube amp as I have heard - no noise even up close with Khorns. I've been very pleased with it, and absolutely love that all connections and the switch are on the back panel - I'm not a fan of looking at cables. Mr. Lang does nice work.
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Thanks for posting those pics Hal.

I have a newly acquired ST-70 that's been unmolested. Kinda funny that you posted this thread because I was eager to learn some things from the tech brethren here in case I run into trouble. I bookmarked the Curcio site.

Yesterday, I swapped out the selenium rectifier for a diode and re-capped the bias section, then rebiased the tubes. It's holding at 1.56V DC and plays nicely.

Hope you are feeling better and get the meds all sorted out. :bigok:
 
If you've got a spare set of tubes already you're all set. New old stock is great, but at this late date when the last major American tube factory (GE) closed down 25 years ago, and prices sky high it's hard to recommend getting into it as a hobby,

I wouldn't worry too much about the fuse blowing unless it's happening frequently.

Slow blow fuses are a potential answer but I would say just run it as it is for now - maybe if another fuse blows time to order some 3A slow blow fuses.
 
I ordered my third set of Russian Mullard EL34s last night - I like the sound and the price, and don't figure they'll be getting cheaper in the future.
 
Lavane said:
I am running a set of JJ kt77's I like. Im thinking about a pair of EH6CA7's. Sonic differences?
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Having never heard a KT77 or an EL34 to compare my 6CA7's to, I have no idea. I only know they are all usable in an ST70. If I ever buy another set of tubes for my Pilot SA-260, it'll be either an EL34 or KT77 simply for variety.
 
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