View Full Version : getting the tube amp for sure!
06-09-2003, 04:46 AM
Well, my friend forgot the model# on Friday and I finally gave me the # today. The amp is a Dynakit stereo70. It is made by Dynaco. The amp is effin pretty.
Here's a pic: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3028372336&category=39783
I've been doing a lot of reading around the net and everyone who owns them love the sound. They have a switch for driving lower impedance speakers. The information I've gathered so far has been very posititve. The amp is not as good on details but produces a 3D soundstage that is better than the mega bucks SS amps of today. That's the opinion of several folks on audioasylum. I'll have to wait and see if this is true.
He says the amp is in perfect condition and didn't get much use. I should have it by this coming weekend. Oh man I can't wait.
06-09-2003, 05:20 AM
Congrats, I've been eyeing one of those myself, so let me know what you think. BTW, don't let any little fingers touch that circuit board in the center, it's got alot of juice flowing through it.
06-09-2003, 05:41 AM
Thanx F1. I will be replacing the entire circuit board. An assembled center circuit board using the same specs is selling for $112 on dynaco-doctor.com Once I get it, the amp will be as good as a new stock. Of course, I will try them the way they are first to see if it's still good. I will let you know how it sounds once I get it.
06-09-2003, 06:13 AM
Nice amp. I love mine. Most of the weight is the transformers. The rest is the frame. What brand tubes are you running?
Here's an info link if you need it. http://home.indy.net/~gregdunn/dynaco/
If you get a manual please let me know. I could use a copy.
06-09-2003, 06:30 AM
It's a keeper. Out of all the older tube amps I hear this is one of the most sought after. And to think you were debating whether you wanted it or not! :D
06-09-2003, 04:57 PM
The original instruction book can be downloaded here: www.dynaco-doctor.com It is one of the best written instruction book I've come across.
Thanx for the link, I didn't know they'd still be that popular today. What speakers are you using with your stereo70? How does it sound compared to other SS amps? Is your amp a modified version? I have no idea what brand tubes he has in them right now but I will probably replace them.
Thanks man, I seriously didn't want to get it but after reading your post on well designed tube amps and heating I changed my mind.
I just got off the phone with him and he's bringing it to work on Sunday for me. Yeah!!
06-09-2003, 07:56 PM
Congrats... Expect to see pics real soon. Before you read on, know that I'm still a novice here myself so what follows is about the limit of my current knowledge.
Couple things before you fire it up. Find out how long it has been idle. If it's been years, you best bring it up very slowly on a Variac to reform the caps. Pretty safe bet you don't have one lying around, so call around your area for a loaner or a tech that will do it for you. Tube test may be in order as well. Be sure a mutual conductance model, like most old Hickocks, is used.
I suggest you do give it a listen before you start modifying it. Unmodified ones are among the more highly sought after. There are more different tweaks and mod's for ST-70's than anything I've ever come across. If it sounds good and holds a steady bias, live with it a while before tweaking commences.
If yours has a switch for speaker impedance, it's already seen at least one mod because the originals have different speaker terminals (screws, not posts) for 4, 8 and 16-ohm loads. They do have a switch, but it's to select mono vs. stereo operation. Often this switch is bypassed to one operation or the other.
Dynakits are the preferred models vs. Dynaco. Same manufacturer, but kits tend to be older and have the preferred US made, hand wound power transformer than a later machine made Japanese. You can spot the difference a couple ways, but cloth insulated leads (US made) vs. plastic (Japan) is the easiest way. Kits are also preferred as the tube sockets and all are anchored with screws making tweaks easier. Factory built Dynaco ST-70's have such parts riveted in place.
May seem like a lot to go through, but very mellow mids and highs are in your future. Don't expect to be wowed by their bass though. It'll be adequate, but not jaw dropping. But you can also cook dinner on it. You are going to be amazed at how hot these little beauties run.
One last thing... when adjusting bias, be careful not to touch anything. ST-70's do bite.... ZAAAAAAAAAAAP... :D
06-09-2003, 08:00 PM
One more thing... If any or all of the 4 output tubes (EL34's) say Dynaco on them, don't let anyone talk you out of them... Worth big bucks all by their lonesome...
06-09-2003, 08:27 PM
I to want one of these amps, or the heathkit amps.. very cool and one of my petpeves (sp) in old stuff besides the glass we collect is Tube gear, I love it!! don't have any yet.. but love the crackle of hot tubes and the heat.. the orange glow.. have messed with some old tube linear amps for CB's and ham rigs.. and had a old tube console, heathkit mono amp and tube table top radio all when i was young and dumb, as i tossed them after i was tired of them :(
one of the things on my long list, tube amp, separete pre and cd.. with a nice set of small speaks.. ah yes that would be great!!!
06-09-2003, 10:38 PM
Thanks for the very informative post! I don't know much about tubes myself but have been doing plenty of research for the past week. Biasing the tubes won't be a problem because I have a multimeter that I use for my labs at school and dialing the knobs to get 1.56ohms sholdn't be too difficult. The last time she glowed was about a week ago when my friend tested it to make sure it's working fine.
Accordig to him, the amp has never been modified. I read about the impedance switch on a website. He replaced the tubes once but I will ask him if he still has the originals.
I'm not expecting it to perform as good as my NAD in the bass department but the magical midrange of tubes is what I'm really looking forward to. For the past few years my ears decided that natural mids and highs give more presence than bass =) I can't wait to hear how opera sounds on this amp. I have Madama Butterfly and some stuff by Bizet ordered and should be here soon. I'm not planning on doing any mods for it unless something breaks down and need replacement. Again, thanks for the great post!
Sorry to hear about that man. I'm sure the new gear you're getting will outperform the ones you used to have. Are you planning on buying used or new?
06-09-2003, 10:46 PM
used,all used... later after i get my HT all done, someday:)
just need my Sub replaced and rears, then its 2 channel bound..
06-09-2003, 10:52 PM
Good deal. Don't forget you can always bi-amp with SS on the low end. Not ideal with Polk's mid-woofers, as would lose the mid-range magic, but with other speakers a possibility.
Then again if you have a sub to handle all below 80 Hz or so... :)
One other thing I forgot earlier, it can't accept oversized IC inputs because the jacks are very close together.
Congrats on what appears to be an excellent purchase. LSi-9's on tubes....
I trust you will give us a detailed review of what you find once all is set to go.
06-10-2003, 03:10 AM
Mine is updated with teflon and silver wires and modified with 5-way posts. Currently running Westinghouse and RCA tubes. It was idle for a bit after purchase, but is now running a pair of Monitor Audio bookshelfs. I've tried this amp on a few speakers and this was just what I had available at the time. It really sounded great with my 4 watt full range speaks, but that was just for a trial on my HT rig. I just bought 16 more 4" full-range to do some line arrays in the distant future.
You get what you pay for usually. This amp is a rare exception. On some speakers it it my best amp, on other (usually bigger) speakers a good 200 w/ch MOSfet works best for some (but not all) music. Lots of flavors to be had.
Never power up without speakers attached
Never power up without double checking speaker attachments
Never do a review/trial without powering up for an hour or two. Power it up (with source) and walk away for a bit.
Never touch anything inside within 24hrs of power up
Never get rid of vintage tubes
Good luck. I hope they sound good together. If not let me know and I'll be a bi-amped tube having mo-fo.
06-10-2003, 03:27 AM
Good additions, gidrah...
Reminded me of one more. Kill the power to the amp with a source still feeding it. Very cool the way the sound spins down, fades away. And doing this discharges everything making the amp safe to handle as soon as it has cooled enough to do so.
06-10-2003, 07:28 PM
Originally posted by organ
I'm not expecting it to perform as good as my NAD in the bass department but the magical midrange of tubes is what I'm really looking forward to. For the past few years my ears decided that natural mids and highs give more presence than bass =)
Don't short change the bass yet. I personally prefer the "tube bass" sound. Kinda spongy and really cool. On acoustic bass it can't be beat. (depends a lot on which brand of tube used).
06-10-2003, 08:09 PM
Point taken, max...
Certain bass is nice on tubes, but they are not likely to punch you in the gut with a bass drum kick. Tighter SS amps tend to do better there.
06-11-2003, 05:26 AM
I heard a friend's Fi-X integrated 45 tube amp and the bass kicked! Tubes can rock too! When I switched out the Sovteks out of my Paramour SETs to RCA double black plates, the bass doubled. No where near the sound of my friends 45s(which rocked), but very noticable.
06-11-2003, 05:48 AM
Welcome to the forum, millerdog.
Was just looking at your SDA-1 thread... nice. You find the SDA IC’s? You'll likely need the SI-1 if you’re going to intro them to your tubes…
I thought Solveks were damn good… the RCA’s are that much better, huh? Were they NOS you found somewhere?
06-11-2003, 06:12 AM
thanks for the welcome! What's the SI-1?
The tubes actually came from the friend I mentioned with the Fi-X. He liked the 45s better than the 2A3 RCAs. From what I heard he was correct. Although there were different speakers and different listening rooms that factored in.
The Sovteks I found were very detailed, but compared to the RCAs lacking in bass. If you have a 2A3 SET, try some RCA blackplates. I am currently looking for another back up set on ebay or anywhere I can find em.
The Sovteks are kinda hifi, where the RCAs are a bit warmer in the mids and lower end. I did not miss any high end either.
I just thought the RCAs were more musical.
edit: oh by the way, those are RCA double blackplates...No one I know has tried the oh so expensive single blackplates:rolleyes:
06-11-2003, 06:27 AM
The SI-1 is the alternative SDA IC F1nut mentioned in your SDA-1 thread. He wrote that both it and the plain wire IC came with the 1C's, which you apparently own.
You must use the SI-1, if your amp is not a common ground design, which I was guessing your tube amp was not. It may be though.
06-11-2003, 06:34 AM
tour, can you get one of the mods or admins to move your post to my thread?
I am not sure what you are talking about, but assuming common ground vs. some type of virtual ground type?
Man, I am lost:(
06-11-2003, 06:46 AM
OK, see you over in your old thread... We are kind of hijacking this one at this point...
06-13-2003, 01:19 PM
So when do you get this beast? I'm anxious to hear what you think of it with Lsi9's. For my tastes the tubes didn't work out very well with the Lsi's, at least not compared to the SDA's. Different amp and different tubes though.
06-14-2003, 02:06 PM
I will be getting it tomorrow. I just hope it works with the 9's. If it doesn't, I will try bi-amping using the tubes for HF. And if that doesn't work, I'll keep the amp and power some horns which I will own one day.
06-14-2003, 11:57 PM
Let us know. Seriously. We are pulling for you. Also keep in mind that different tubes are good for different tastes. Some have tight powerful bass and some have spongy bass and a great midrange. It all depends on what you need.
06-15-2003, 02:59 AM
This keeps getting better man. Now he wants to throw in a vintage turntable with it. He doesn't know the brand but said that it is a belt-drive unit with a $150 cart. He doesn't want any $ for it. He just wants to trade for my Oink 575. The Oink hasn't been used since March. I love that receiver but I'll have to trade because he also loves his Dynaco and TT. We will both lose something we truly love but gain something else. I want to get into tubes and analog and he wants to get into HT, so the trade will be perfect.
I can't wait to play around with different tubes. I'll let you know this in advance...I will be asking you plenty of questions about which tubes to get LOL I will post my first impressions tomorrow and a review after a few weeks to a month.
06-15-2003, 11:49 AM
Sounds cool, I'm working a deal for a Rega P3 right now. I'm happy with my Thorens but a P3 came up on Ebay and I can get it for $570US. Comes with a shure V15VXMR cart. So, my Thorens may go up for sale.
Good luck on that TT.
06-15-2003, 01:42 PM
It's fun to watch the black circle spinning. I grew up with LP's and was happy to dump them when CD's came out. They were cool when I re-discovered them 25 years later. (Last year). I had totally forgotten what they were like and it seemed almost mysterious that good sound could come out of them. A good table, arm, cartridge and clean lp's gets rid of all the noise. I was amazed at this. My old turntable still sucks, I tried it again and was very disapointed. Crackle, pop, feedback... you name it. Even on a perfectly quiet lp! (compared with my new setup).
06-15-2003, 10:08 PM
The other day I was listening to Pearl Jam's Spin the Black Circle off of Vitalogy and the song took on a whole new meaning for me.
Spin...Spin...Spin...SPIN! The Black Circle.
06-16-2003, 11:07 AM
So in that song what are they refering to?
06-16-2003, 02:34 PM
Simply playing vinyl. Seeing that I was playing it on my first turntable, I never payed attention to the song beforehand. :)
06-16-2003, 11:53 PM
Is that lp worth having considering the audio quality? Sounds kind of interesting.
06-17-2003, 10:17 AM
If you like Pearl Jam, it's definitely worth getting. The audio quality is good too.
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