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My Dynakit-70ST ain't stock anymore.

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Today fini and I made a visit to the home of audio maestro extraordinaire mdeneen. It is so cool that we all live within covenient visiting distance here in the Northern California wine country. After an audio tour of mdeneen's main system , an amazing ongoing development which is already top flight, and let me tell you those home made speaker cabinets of his are way more impressive than the posted photos would indicate, we went to the garage shop where I was instructed to start dismantling the old Dynakit -70.

After biting the bullet, and with total trust in the maestro's prospective alterations, I started snipping away and de-soldering. By the time I was finished, and learning about that solder vacuum cleaning thingy for the first time- something I do not remember from 50s ham radio days, there was virtually nothing left on this classic Dynakit-70 but the transformers and chassis, gulp!

At least the old 15.6 ohm extracted resistors, unique to this circuit are worth a couple of dollars on eBay. The rest of that old stuff under there was loosely referred to as "let's get all that crap out of there", yes, a good sign indeed, and affirmation that everything will be replaced with choice upgraded components and the wizard's mystery schematic. Now I will be able to polish up the old chrome chassis and wait for the next installment.

All and all my understanding of things electronic is making quantum leaps forward, as you would imagine, just hanging around mdeneen. Mr. fini and I now understand "the capacitor" along intuitive lines that few textbooks could make as clear. I am stoked and excited about the sonic results that will ultimately result from this Dynakit customization.

I'll keep you posted on future progress.

-stripped and de-soldered


This message has been edited by Clipped and Shorn on 02-27-2002 at 10:43 PM

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If you take some good shots and keep a record, I'll throw you up a website. There are so many messing with the Dynaco 70 that I am sure there will be interest, especially if going for a Class A Triode mod. Ned sells some great MagneQuest transformer upgrades if you do have problems there.

As for digital, I happen to use the Olympus Camedia C-2020z. The Olympus can be found for good deals. I believe the 2040 is on sale online. Almost any shot from me is either taken with the Olympus 2000 or 2020. A few shots to show you the resolution capable with this 2.1 megapixel camera:




Just a sampling. Digital is really a blast once you get used to it.

Yeah, that last shot is my wife's 98 VW Cabrio. Will somebody please buy the beast?!?


This message has been edited by mobile homeless on 02-27-2002 at 11:32 PM

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Mobile-The wife or the car?

I must say, I was mighty impressed with mdeneen's hospitality, and his willingness to freely share his knowledge with C&S and me. Thanks, Mark!


This message has been edited by fini on 02-28-2002 at 01:28 AM

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I hope someone actually tested the tubes...heh.

Should the words Dynaco ST-70 even be associated with this amp anymore? It appears as if this is going to be an entirely new amp/circuit using an old Dynaco chassis and transformers. Lordy Stripped, you could have almost sold the ST-70 for $350, added just a few more ducats and bought some new MagneQuest MQ-470-CL tranformers (actually better than original iron), a Hammond choke, a brass top plate and birdseye maple chassis and perhaps been in the same place with a better base! heh.... Stripped and Torn has lost his mind! Although, I have no doubt the result will be much better than the original - those damn input boards are gone, thank God! Look forward to seeing the new creation.

Anyone take a shot of the amp wiring AFTER the removal?

What's actually left? What's the new circuit?


ps- good one, fini.

This message has been edited by mobile homeless on 02-28-2002 at 07:22 AM

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I agree with you here 100% as well. Although mdeneen and I about come to blows on here half the time, I think he is a very valuable asset, especially to those in his area. As I said in the past, any time you can have someone knowledgable in the DIY sector of vintage tubes and circuits, it is a GREAT learning opportunity as you can learn more in an hour standing next to someone like that as they point out and explain, than 10 hours studing some text like Bruce Rozenblit's Beginners Guid to Tube Audio Design, which a one of the first texts that many tube novices procure hoping to step into the whole sordid affair.

If you are lucky, you could even find an old coot at a local TV/radio repair shop that might have some audio background. These guys can sometimes burn your ears up with knowledge and tips. Dont pass up on any offers to help from anyone fitting this bill. Do keep an open mind to new developments, however, as sometimes the old codgers can be rather staid and steadfast in what they DO know while neglecting what they dont. I have talked to my share of this type that wouldnt even know what to do with a computer.

The internet is an amazing resource as well. Lord, I think it actually is a major portion of the popularity of DIY tubes as the sharing of info and help is so great. Combining the real/practical with the text has never been so easy.


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The real inspiration for this project comes from that humble VW bug that just shut you down at the stop light because under the hood is a blown Chrysler V-8. This was a 50s hot rodder's fantasy and was behind countless modifications of otherwise innocuous looking street machines. We won't be throwing away the cage.

mdeneen, don't throw away that dustpan, it might come in handy again. BTW I want Von Dutch pin striping on those transformers and "flames" on the big capacitatortots.

-sparked and gapped

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Sounds like a hell of a project. Make sure the power trans is up to the task as well.

It appears to be a serious undertaking but one that can be very rewarding; I just hope ole Stripped and Torn can avoid Mr. Cold Solder Joint, something that plagues beginners like hitchhikers in a Southern field! Mdeneen will undoubtedly give you some fine tips here. You might want to practice on some broken down circuit board at home. It does take some getting used to. Hopefully, Mdeneen will do a good portion of the difficult soldering work as it can be a bit frustrating. He probably has an excellent iron which is halfway there! Don't skimp here! I made that mistake!

I am very interested in this project myself and would enjoy throwing together a page if you two tackle the text for the steps with some nice shots. Better get that amp chassis looking sweet! You can actually have it re-chromed for a price and if starting from scratch, this might be a good idea. Would really make you proud of the piece when looking at it after the hard work is done.

If you need a source for parts I might be able to help with a deal. Drop me a mail if interested.


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Last weekend I was rewiring, for the 10th or 12th time, the Heath W5Ms my wife gave me for Christmas a year ago. She said "Oh my, the gift that keeps on giving." I showed her the picture of the dustpan full of ST70 parts. Now I border on conservative.

What's this going to be? PP triode output? What will you do in front of that? I can't wait.

Clipped and Shorn, maybe you said, but I missed it. What are the lucky speakers?

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I believe mdeneen has a pp triode circuit up his sleeve and remember he believes the preamp is a serious project as well. We will be modifying a PAS 3 in keeping with the Dynakit vintage dynasty.

I was up at the local electronics parts store that also carries all kinds of surplus bargains. Even a new cheesy thin aluminum chassis could be $40-60 depending on size. Factoring in the actual price today of decent transformers and the fact that I can use the perfectly good old EL34s for my keyboard amp and I have pretty much recovered my $300 outlay for the old Dynakit, and hanging out with mdeneen and getting a crash course in DIY audio engineering, priceless.

As regards chrome plating the chassis: I did manage to find a bit of the old Amway Chrome and Glass cleaner lying around. Turns out they do not sell that anymore. {I wonder if there is NOS Amway and eBay}. The chassis polished up pretty nice but far from flawless. I gave it the time I wanted and after a point remembered that one of the themes of this project is Practicality. It is shiny enough! I cannot really justify the fetish finish aesthetic. This is a "deceptively menacing street machine", not a "powder puff show stopper". The attitude here is that if the first circuit does not do the trick, we will be willing to hack into it again until we learn what we need to get the most out of it sonically with the Cornwalls, eg. a work in progress if necessary.

I am as much curious about the Preamp upgrades now. After going through this whole process I will be seasoned for the next round of experiments which are inevitable.

-rooted and mean squared

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Thanks for the chassis info. Just the other day mdeneen said he wondered if anyone was making new chassis for Dynakit rebuild projects and here it is. I sent for their prices. However I am sure the information will mostly make me appreciate the value of the old chassis and certainly make me realize how much I have NOT actually lost by doing this rebuild, ergo, by not buying a new copper or stainless chassis and not buying new transformers I am saving at least $500, so given that I have $300 into the original Dynakit 70, I am ahead by at least $200 at the start of the remodel project. All because I do not feel particularly compromised by forfeiting every aspect of the fetish finish aesthetic.

Sometimes when you remodel a house you leave old wood that is still good. It would be embarrassing and silly not too.

This issue does bring forth an interesting question regarding the importance of the visual appeal of something that is essentially a tool, in this case an electronic tool for the production of simulated musical experience. If one is building a really high end house must one insist that the impeccably well dressed carpenters use beautiful polished hammers and chrome plated nails? {Actually I know tradesmen who have worked for the super Rich and things almost this insane do go on}.

I am too cynical here. Actually the idea of audio equipment as good looking furniture does go way back to the very beginning when Counsel Radios and Victrolas were almost visual works of art and craftsmanship. Corny yes and mostly Victorian or anything but the Modernist aesthetic of 'form follows function", at least until the late 20s and 30s -or was that the 40s and 50s, cannot quite remember.

I can just imagine high-end tube amplifiers today looking like they were designed by the builders of the hobbit's house in the Lord Of The Rings movie (rather than the Mad Max movies). Interesting why technology must pander to the tastes of those who do not ultimately embrace it, but then again, I can see the fun in all of this, take the new iMac for example, or generally the marketing attitude of Apple wanting to make the little bundle of technology look like a friendly cute thing not to be afraid of. The fear of "modernism" and the fear of math and science are related to this phenomenon, as is any utopian vision of the world in which the simple logic of technology would have sway over the weird stubborn superstitions and prejudices of us humans. Ever see that old old science fiction movie of H.G. Wells "Things To Come"? This whole trip I have just been on is the theme of that film.

Today "postmodernism" has replaced "modernism" precisely because the utopian vision of modernism (eg. technological logic solving the worlds painful and ultimately unneccesary contradictions) was rejected -mostly out of fear and the will of all those Blue Meanies.

Which is more important the contents or the container? The human or the "cause" etc.etc.{{{it's the oil stupid}}}}.............

"The Emperor's New Amplifier" by

-cryptic and cornered

PS. how about a tv show where audiophiles compete in building amplifiers like they do in Junkyard Wars. I can just see the teams scrounging around in old electronics junk piles looking for weird transformers and stuff to make speaker horns out of. Wow, this could really be a winner, at least for the folks in this forum. The final test would be a fight over whose sound system sounds better, and whose cables contribute the most to the sound. The participants will all need to have English accents.

-tripped and flipped

This message has been edited by Clipped and Shorn on 03-01-2002 at 03:57 AM

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Great post!

How about a show based on the show "Trading Spaces," where neighbors get to trade audio gear and do "upgrades." You know, a splash of paint on the turntable (using the tonearm to mix the paint), chenille slipcover for the subwoofer, moulding for the Crown (amp). Don't laugh: I know a guy who splatter painted his cars! Awesome!

Hmm...I wonder how that would look on a Dynaco chassis...


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Tripped and flipped is right... You are so far off the track here, you appear to be wallowing in bog of reactionary gobbledegook, confusing fashion with quality and the fuction of design/aesthetics.

Designed by little Hobbit elves? Perhaps you should not be near the keyboard at 3:47am, although I did chuckle a bit here with some additional head scratching.

Holy one of extremes, swaying wildly with mood. Aesthetics and function usually go together if looking for the ultimate. It is why a Ferrari 250 GT Berlinetta Lusso loaded with a perfectly tuned 12 cylinder V12 DOHC mechanicals is a beauty to the eyes, passion, and mind (too bad it is not a beauty to the pocketbook).

Were you not the one talking about a tripped out Bug with the fully loaded V8? (Bug = iMac...hummm)I would call this whimsy and a MESS as the weight of a V8 behind the axle of a VW Bug would be one of the most horrifying handling vehicles known to man, with oversteer so frightening, a lifting of throttle during a corner would send you catapaulting backwards into the Netherworld. Of course, the damn block would have to be in the back seat but still...

Ripped, we are talking about a fine chassis that is a pleasure to look at and aesthetically pleasing, something to MATCH the mechanicals, something that would BRIDGE FORM AND FUNCTION. We are simply talking about a chassis that is not a pitted mess.

At this stage, a 68 Bug with a 289 V8 seems logical...


This message has been edited by mobile homeless on 03-01-2002 at 08:54 AM

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