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Need your take on this ST-70 rebuild on Ebay


Daddy Dee

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I would have to agree with Mark here and I bet the true reason the seller is getting rid of it is tube cost. Another thing I wonder about is the reliability of the Iron operating the 8417's ? Its almost insane to rewire a EL34 amp to use some other tube when EL-34 are the most widely available tube there is !

Craig

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this makes three thumbs down. while the input board seems nice I too did not like the SS rectifier (with photo flash caps! lol) or the change of output tubes, what was this guy thinking? EL34s rule! anyway the price is not bad but the hard to get output tubes, SS rectification and questionable parts choice in portions of the circuit would tell me stay away. reagrds, tony

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I think you want to stay away from amps using outmoded 8417 output tubes. They are the reason people often dump their old Quicksilver amps.

8417 Background Info

PS. In case some of you newcomers do not know about mdeneen, let me mention that he really (really) knows his way around tube gear. I am currently using an amp which I purchased from him, it is a beautiful ST-70 mod which he designed and built on a custom stainless chassis, with new driver board, complete bias controls, and Class A triode output. Basically a whole new amp using the Dynaco Iron. What can I say, it is a truly great sounding tube amplifier and I feel very confident about it in all respects. It is driven by a legendary vintage Paragon Preamp which was also a company mdeneen ran in years past. I was lucky to find one of these Paragon pre amps.

PSS, I also am running an Eico HF-81 in a secondary system which is one that Craig trouble-shot & upgraded. We are lucky to have both these guys around here to help with the process of either converting vintage tube bargains into useable gems, or custom designs which are informed by an extensive background in the case of what mdeneen might have up his sleeve. My recommendation is to take your time before jumping into those eBay temptations and run it by these guys on this board. In the long run you will end up happier with your system and ultimately save $$$.

C&S

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Clipped,

Thanks for the complements but without Mark I wouldn't know what I would do !! So it all starts with Mark ! He is a endless help to me. At times I can't believe he doesn't tell me to buzz off I bug him so much !

Mark is the man !

Craig

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Jim,

Maybe you missed it before, but my speaker project is finally finished. It is up and running, they are real and they are fantastic. Actually they are so good, I don't even notice them. The music just sounds natural, just like speakers I would hear back in the days when I could only dream of having those kinds of sounds. As you can see, they are big and tall. The paint covers over the struggle it took to assemble them, and now they just look so cool.

C&S

post-8419-13819248120036_thumb.jpg

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Thanks Guys,

Do I ever appreciate this forum! The 8417 tubes would be trouble and a disappointment. Also appreciated reading the posts evaluating Mark IV's also currently on Ebay. Look good, but not a good choice after considering the collective base of knowledge on this board.

Regards,

Dee

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Interesting comments about the 8417. The problem isn't just the expense -- but also finding the things.

The following is from Al K's site. The context is the impression left on Michael Klementovich after he put Al's Type A network in his K-horns. So, that is the context. However, there is an interesting comment specifically about the Mike Sanders' 8417 mono-blocks.

"Just let me say that between the 2 of us (my co-author Maureen Barrett and I) we have at our fingertips: The Quicksilver Mini Mites, Quicksilver 8417's (arguably the best amps ever made), Wright AU-15's PP 2A3's, Wright WPA 3.5 2A3 SET, and the terrific Prototype Quicksilver 300B's (with Western Electric Tubes) the best 300B's I have ever heard. We both run pure silver speaker cable, and DH Labs Revelation Pure Silver Interconnect. We have Quicksilver Preamps and Wright Pre Amps. Solid stuff to say the least, because our philosophy is to have a solid base of equipment, a well treated room, and the best to connect everything all together with. Michael Klementovich -- Co-Author: Paul Wilbur Klipsch: The Life... The Legend.

Mark, I find your comment about the 8417 odd, as I have never, ever heard one negative comment about that tube. In fact, any time I run across anything about it -- it's always in such a positive light. I've talked with Mike Sanders about a half dozen times, and in conversation, it's obvous he's very fond of it.

I'm not pointing any of this out in defense of the modded ST-70 -- just the 8417 in general.

Solid state rectification: Man, what a bunch of tube rectified bigots :) Some highly regarded, good sounding amps use it. Didn't Saul Marantz use it in the 8B? My Quicksilvers use it, and they produce a wonderfully wicked sound. Mark, I'm sure you would agree -- it's more about the whole circuit, the sum of the parts and implementation -- than any one thing. My Quicksilvers have all the "no no's"-- negative feedback, parallel push-pull, cathode self-biasing, etc. -- and my RF-7's love them.

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The style of the paint job I used on the speaker cabinet is sometimes called the "all over" design. It is related to the paint pouring drawing technique that was developed by the American painter Jackson Pollack, whose life was dramatized in a motion picture in recent years.

A few years ago I developed a method of executing this type of painting with the help of an air compressor to speed things up. The style of painting would normally be quite labor intensive since it requires at least 5 to 7 different colors in order to be effective, sometimes more. The general effect of a surface painted in this manner is, on the one hand, "expressive" and on the other "sedate". I find it interesting and fun and actually very practical since the busy-ness of the surface detracts from other minor imperfections in the surface. You hardly know that the paint job on the cabinet covers over hundreds of screws and bondo filler.

When I first developed this technique it was used for fine art in a serious attempt to find one last real innovation in late modernism which was thought to be a closed book. I combined the expressive jestural approach of Pollock with the reductive attitude of what had come to be called "minimalism". Whereas most "reductive" painters rendered the painting surface with flat monochrome, I choose to treat the same structures with surfaces painted in the "all over" approach. In order to make an equivalence between the flat monochrome surface and the "all over" expressive texture, I needed to detract from the inherent "figurative" nature of the "all over" by taking it out to the edge in a manner which suggested that the technique could potentially extend infinitely in all directions. This point was a definitive departure from Pollack's approach which remained in the realm of the figurative and pulled away from the edges. Belieive it or not. Now you know the Rest of the story.

C&S

post-8419-13819248120586_thumb.jpg

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dean, I didn't see anyone downtalk the sound of the 8417, we all mentioned however the expense and the rarity. it is true many people have dumped or modded their amps to move away from that tube.

I am sure it sounds (sounded) great but praticality issues lead me to not reccomend an amp with those output tubes.

re: SS versus tube rectification. I don't feel that any amp with SS rectification sounds bad, the amps I have heard with tube rec sounded better to me than the ones I heard with SS rec, so I pass that along.

combining the output tubes (first priority) with the SS rec and the high sale price led me to not recommend the purchase, better ST-70 units can be found for that money.

tony

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Hi Tony -- yes, I pretty much understood of all of this. I did say I wasn't defending the modded ST-70. I agree that there are much better ST-70's to be had than that thing. Most of my comments were directed towards Mark, who's always launching curve balls at me. :)

As far as SS rectification goes -- it's probably true that it's not the best choice for Heritage or other large horn systems that would benefit from the additional warmth tube rectification provides. In my system, I've found it's definitely good to have it in the preamp -- but I've found some advantages to having SS rectification in the amps -- most noteably in the areas of speed and dynamics.

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p3_8med.jpg

The House of Representatives chose Pennsylvania's Frederick A. Muhlenberg as its speaker. Muhlenberg's reputation as the impartial presiding officer of both the Pennsylvania Assembly and the Pennsylvania Ratifying Convention made him an ideal choice for the job. His selection probably also came about because of the desire to give this leadership position to a Pennsylvanian to balance the president from Virginia and vice president from Massachusetts.

fini

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Dean, I think that well implemented SS rectification works great in some amps. In the relatively few amps I have had in my system (k-horns!) the tube rectified amps always stole the show, but isolating the effect of tube versus SS rectification was, of course, nearly impossible. I have heard a few quicksilver products and they ALL sounded great...not a great as my 2A3 PP of course, but great! LOL! regards, tony

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