Bottlehead Forum
General Category => General Discussion => Topic started by: Downhome Upstate on February 01, 2014, 08:23:59 AM
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Got the itch to play with something for rock 'n roll. Anybody build the Triode ST70, the Dynakit Parts ST70 or the K&K rethink of that amp?
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And I guess I should throw mods of stock ST-70's in the mix, like the one from Welborne Labs. I didn't think to include those because I haven't found a stock ST-70 for sale at a good price. Ebay prices for these amps seem consistently pretty high.
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How much power do you need?
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How much power do you need?
Well, the room is 14w x 18l x 9h. The rig will be centered on the 14' wall. I don't have any speakers picked out yet. I was thinking about either factory refurb'ed Zu Omens - avg. 12 ohm, 97 db) at $999 a pair, or the Tekton Mini Lores (avg. 8 ohm, 95 db) at $650 a pair.
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With a room that size and speakers that efficient, an ST-70 is not going to be all that useful.
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Yeah, it will.
I drive 95 dB/W Tangbands with a 3.5 watt Stereomour. It sounds wonderful, but it don't rock & roll.
35 watts would be better.
To really R&R I use 93 dB/W speaks and drive them with half a kilowatt each. Yeah, that's close, but still not concert level.
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I drive 95 dB/W Tangbands with a 3.5 watt Stereomour. It sounds wonderful, but it don't rock & roll.
35 watts would be better.
If we take the Tang W8-1772 as an example, specified excursion is 3mm. Assuming a perfect 8" cone diameter, this will allow low-ish distortion performance at:
89dB @ 40Hz
93dB @ 50Hz
96dB @ 60Hz
99dB @ 70Hz
105dB @ 100Hz
These numbers hold for a sealed box or IB alignment. A vented alignment can help the numbers around 50Hz, but not so much as you move up from there, and actually worse below.
This would suggest that ~8 Watts is a good power level for these drivers, though there's a big difference between linear Xmax and mechanical Xmax.
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Yeah, with single drivers you can forget X max. Just adds to doppler distortion. Not good for rock & roll loud. Not good for anything loud.
For loud you need at least a 2 way.
In my bedroom, 12 x 12 x 8 feet, they sound good to ~80 dB average at 3 meters. I listen to ~67, got plenty of room. Classic rock every night. They give me tingles - :)
That badass system is in the garage. It has brought tears to my eyes. It hit's ~115 when the clip lights are blinking.
I don't do that much, not good for the ears. Just a song or 2. Once in a while. For old times sake. Damn it sounds good though - :)
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Hey Mike, I think that with the speakers your looking at, it will work fine.
I know that when I drag the Streaght 8's out, and hook then up to an ST 70 size amp. It is pretty impressive...John
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Football is a brutal game. Seattle, my home town, secured their position in the Super Bowl at home where we have the loudest fans in the league. I'm an acoustical engineer, so I may be the only person in Seattle who's not proud of that. I can guarantee that all 100,000 fans went home with some degree of permanent hearing damage.
Many serious rock fans are the same. And 35 watts is only 10dB more than 3.5 watts, not really enough to get to rock concert levels even in a modest size room unless you have fullrange horns at 112dB/w/m - which won't actually fit in a modest size room.
Nobody will care, but anything over 85dB-C sustained over a career will leave you just able to understand your corporate master's voice until the day you retire. At that point you become functionally useless to your corporate masters, so deafness is not an economic issue. Fortunately, even serious rock fans don't spend 8 hours a day for 40 years at rock concerts. Roadies and musicians however suffer the same fate as football players. It's a brutal game.
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Yeah Baby!
Yup, you know R&R.
I love my bedroom system. It's on every nite when I go to bed. I go to bed now at least an hour earlier than I used to just to listen to R&R. The Stereomour & the Tangbands give me much of the garage w/o the hearing damage. This system gave me insight to people who said they judged systems by how they sounded at low volume.
Yup, to get much of the same feel w/o the hearing damage is a good thing - :)
I don't think you can appreciate this fully w/o doing the 115 dB thing though. It gives you insight to why they call guitars "axes", at that level they cut right to your soul.
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Seattle, my home town, secured their position in the Super Bowl at home where we have the loudest fans in the league. I'm an acoustical engineer, so I may be the only person in Seattle who's not proud of that. I can guarantee that all 100,000 fans went home with some degree of permanent hearing damage.
Ear plugs are pretty common in there these days, though at those levels, I'd want muffs and plugs.
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At the last game, the guys on TV said that the record there was 135db :o...John
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So, now that we've cleared that up, how about folks' experience with push-pull amp kits or projects based on used amps? Any takers? What did you build or tweak, how much did you spend, was the result satisfying? How tweakable was it?
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Football is a brutal game. Seattle, my home town, secured their position in the Super Bowl at home where we have the loudest fans in the league. I'm an acoustical engineer, so I may be the only person in Seattle who's not proud of that. I can guarantee that all 100,000 fans went home with some degree of permanent hearing damage.
Loud fans + Century Link Field acoustical design (use link below) = loudest outdoor sporting event!
http://www.businessinsider.com/seattle-seahawks-stadium-loud-2014-1 (http://www.businessinsider.com/seattle-seahawks-stadium-loud-2014-1)
Gerry
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I started my valve journey with a K12-G kit, 8 Watt, PP pentode. Sounded great. Then bought a Dared I30, 16 Watt, PP 6L6. Sounded better. Neither sounded as good as the class A elekit 6L6 and the flea power zero feedback Stereomour sounds the best.
Someday, when I've run out of other things to do, I'll get a big push pull valve amp to try in the garage. Or not as the case may be - :)
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I started my valve journey with a K12-G kit, 8 Watt, PP pentode. Sounded great. Then bought a Dared I30, 16 Watt, PP 6L6. Sounded better. Neither sounded as good as the class A elekit 6L6 and the flea power zero feedback Stereomour sounds the best.
Someday, when I've run out of other things to do, I'll get a big push pull valve amp to try in the garage. Or not as the case may be - :)
Mike,
Yup, love my Stereomour w/the Orcas & a sub for small-group jazz, acoustic anything, vocals, etc. I was thinking tubes for a rock and roll amp b/c I'm just starting to get comfortable w/understanding vacuum tube audio circuits. But if tubes and rock 'n roll music is where I want to go, maybe I should be thinking Mainline and some new phones.
Mike
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I'm currently building Bob Latino's VTA ST120 which is like the ST70 but with bigger trannys in order to run KT88/6550/KT120 tubes.
I'm doing my own layout versus the classic Dynaco chassis which Bob seems to favor.
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Cool. That's the one I would use.
And drive the tweeters with the K12G.
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I'm currently building Bob Latino's VTA ST120 which is like the ST70 but with bigger trannys in order to run KT88/6550/KT120 tubes.
I'm doing my own layout versus the classic Dynaco chassis which Bob seems to favor.
How about some pics of that build as you go?
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I started my valve journey with a K12-G kit, 8 Watt, PP pentode. Sounded great. Then bought a Dared I30, 16 Watt, PP 6L6. Sounded better. Neither sounded as good as the class A elekit 6L6 and the flea power zero feedback Stereomour sounds the best.
Someday, when I've run out of other things to do, I'll get a big push pull valve amp to try in the garage. Or not as the case may be - :)
Mike,
Yup, love my Stereomour w/the Orcas & a sub for small-group jazz, acoustic anything, vocals, etc. I was thinking tubes for a rock and roll amp b/c I'm just starting to get comfortable w/understanding vacuum tube audio circuits. But if tubes and rock 'n roll music is where I want to go, maybe I should be thinking Mainline and some new phones.
Mike
Nevermind about getting a good rock 'n roll headphone/amp combo. Just tried my DT880/600's back from the warranty service shop & plugged 'em into my Crack/Speedball with the North Mississippi Allstars 'World Boogie is Coming' on the CD player. I won't be needing anything else headphone/amp wise.
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I built a triode-electronics ST-70, before I discovered Bottlehead. The build manual is nowhere near as good as those produced here. I was my first try at DIY, and I would not recommend it for a first timer. But I do have it working and it is a good amp. Mine is tuned down to 17 watts per channel (tirode mode not pentode). It sits like a trophy in my garage, not for being bad, but I found better. ;D
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I'm currently building Bob Latino's VTA ST120 which is like the ST70 but with bigger trannys in order to run KT88/6550/KT120 tubes.
I'm doing my own layout versus the classic Dynaco chassis which Bob seems to favor.
How about some pics of that build as you go?
You got it! http://www.bottlehead.com/smf/index.php/topic,5671.0.html (http://www.bottlehead.com/smf/index.php/topic,5671.0.html)
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Another option, just for kicks, is to pick up an actual original ST-70 and mod. OT's are wonderful. Put in a Triode Electronics power supply board to start just to be on the safe side and later replace the driver board with the flavor of your choice (I decided to put in a new board but one that used the original 7199 driver circuit in my original Dynaco ST-70). Can put in a new power transformer and tube sockets if you want, tube sockets eventually is a really good idea. Personally, I like refurbishing the old stuff when that is an option though the cost all in is probably about the same as a new kit when all is said and done. Anyway, just a thought.
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Another option, just for kicks, is to pick up an actual original ST-70 and mod. OT's are wonderful. Put in a Triode Electronics power supply board to start just to be on the safe side and later replace the driver board with the flavor of your choice (I decided to put in a new board but one that used the original 7199 driver circuit in my original Dynaco ST-70). Can put in a new power transformer and tube sockets if you want, tube sockets eventually is a really good idea. Personally, I like refurbishing the old stuff when that is an option though the cost all in is probably about the same as a new kit when all is said and done. Anyway, just a thought.
Yessir, absolutely. My preference, actually. More fun and probably a bunch more learning that way. I've taken to surfing all the area Craigslist sites for anyone who has an original ST70 for a decent price. Hard to find in the greater metro NYC/Philly area, tho'. Seems like the internet has everyone thinking that grandpa's old stuff is lost treasure.
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Well, if you are willing to risk an untested unit on ebay... they are really cheap. Saw one go for $200. Shipping is a royal pain, $50 on average I guess, but then you have one in your grubby paws and can get to work!
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Paully,
If I could find one for $200.00, I'd snatch it right up! Guess I'll keep looking on ebay & craigslist and see what I can see.
Mike
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I've said it before (maybe even here - apologize if I'm repeating myself) - a Dyna ST-70 is kind of like the Chevy Small Block of tube amps...lots of them out there, lots of aftermarket parts and pieces, and lots of tweak potential. You can generally sell them for as much (or sometimes more) than you paid for them, and they sound pretty good.
I had a Dyna ST-70 at the heart of my shop system for a long time, and was very happy with it.
If you can get one for $200, that is a steal - they tend to go for more than that.
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Might be a steal, but thus my preface that in that price range they are untested, so you take your chances. But they do show up in the 2-300 dollar range as a quick sold search on ebay will verify. My last Dynaco Grainger let me have (or sold to me so cheaply that it was the same thing) a Dynaco chassis. Everything after that was then my choice. Those can be had in the $75 range. Then buy either vintage output transformers or new (I used Magnequest) and you start off with the a new PT and power supply board. Anyway, there are enough Dynacos on ebay in various stages of undress that you can decide where you want to start and go from there. And all the Bottlehead preamps I have used mated extremely well with my Dynacos.
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FWIW, I placed a couple of ads for ST-70 road kill (AA Trader & US Audio Mart), and now I will wait.
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FWIW, I placed a couple of ads for ST-70 road kill (AA Trader & US Audio Mart), and now I will wait.
At one time I was into handmade antique carpets (on the cheap end of the scale!!) - we call them "noble wrecks". Sometimes you just have to make a cushion out of the good parts of a worn-out rug.
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I know this is the Bottlehead site, but since most of us here have a Bottlehead amp in addition to our Dynaco, for those who have one, so post your progress. I have built one from the chassis up and rebuilt another and that was my entry into tube audio before Bottlehead. So I will be very interested what direction you take as you go.
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FWIW, I placed a couple of ads for ST-70 road kill (AA Trader & US Audio Mart), and now I will wait.
At one time I was into handmade antique carpets (on the cheap end of the scale!!) - we call them "noble wrecks". Sometimes you just have to make a cushion out of the good parts of a worn-out rug.
I like that, Paul, altho' I had to stop for a minute and think it through. A cushion it will be, then.
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I know this is the Bottlehead site, but since most of us here have a Bottlehead amp in addition to our Dynaco, for those who have one, so post your progress. I have built one from the chassis up and rebuilt another and that was my entry into tube audio before Bottlehead. So I will be very interested what direction you take as you go.
Yup. I'm kinda doing this backwards. But better Nate than lever.
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Just paid $300 + shipping for a functional ST-70 sans tubes and cage. I missed out on a listing on DIY Audio for a Tektronix 2215. Maybe its time to look for another 'scope and some probes.
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Sweet! The upgrade process begins. Check your bank account. As always, the can cap is the first thing to deal with. Then the driver board, then the old tube sockets, maybe a new power transformer... Good luck!
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Sweet! The upgrade process begins. Check your bank account. As always, the can cap is the first thing to deal with. Then the driver board, then the old tube sockets, maybe a new power transformer... Good luck!
Selenium rectifier?
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Sweet! The upgrade process begins. Check your bank account. As always, the can cap is the first thing to deal with. Then the driver board, then the old tube sockets, maybe a new power transformer... Good luck!
Selenium rectifier?
How 'bout that stock GZ34 rectifier?
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"Selenium rectifier?
Its between the power transformer and the PCB, for the bias. Replace it with a diode first thing...John
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Sweet! The upgrade process begins. Check your bank account. As always, the can cap is the first thing to deal with. Then the driver board, then the old tube sockets, maybe a new power transformer... Good luck!
After I have a look under the hood, up close and personal-like, I was thinking about ditching the can cap. The Triode Electronics power supply capacitor board looks good. It mounts underneath one of the OT and has 500 uf of filtering. $77.
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"Selenium rectifier?
Its between the power transformer and the PCB, for the bias. Replace it with a diode first thing...John
Thanks, John. Had my first look at the schematic today (the 7199 pentode/triode was a head scratcher).
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The Curcio cap board replaces both the can cap and bias supply, Selenium rectifier. Paully put that in his first ST-70.
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Doesn't the Triod Electonics do the same? We put that one in the current Dynaco.
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Hey, guys. Where does the selenium rectifier appear in the schematic in the product manual?
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The Curcio cap board replaces both the can cap and bias supply, Selenium rectifier. Paully put that in his first ST-70.
I hadn't seen Curio's web pages before. As Werner Klemperer said, "very interesting." But it looks like their upgrades are for triode operation only. I'd like to get as much power out of the ST-70 as possible, and it looks like the sources for ultralinear upgrade boards and parts are at Triode Electronics and tubes4hifi.
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The triode power supply has the caps, you still use a rectifier tube.
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The triode power supply has the caps, you still use a rectifier tube.
Yup. And for $12 they also have this solid state rectifier package that plugs into the tube rectifier socket:
http://store.triodestore.com/ssr.html
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Actually Artie Johnson said "veeery interesting", on Laugh-In.
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Ooops. Dats right. (Great pic)
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The Selenium rectifier is the single diode (looks like it has heat sinks) for the bias supply. It is in the front left of the chassis, I don't remember where it is on the schematic.
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I hadn't seen Curio's web pages before. As Werner Klemperer said, "very interesting." But it looks like their upgrades are for triode operation only. I'd like to get as much power out of the ST-70 as possible, and it looks like the sources for ultralinear upgrade boards and parts are at Triode Electronics and tubes4hifi.
The Curio mods are the driver circuit and power supply. The output tubes can be wired pentode or triode as you wish. Joe has instructiions for triode conversion on the site.