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dynaco_dan

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About dynaco_dan

  • Birthday 10/04/1946

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  1. Hi Dan 

    I just re-capped with Sonicap 5.0uF 200v my pair of Dynaco A-25's they may be a little cleaner I went inside to secure the binding posts. Do you have cabinet plans for the Dynaco A-50 I'd like to build a set but can't seam to find much about two chamber box.

  2. Hi there Just recently I came across more old paperwork. The TIP mod for the ST-120 amp is an 8 pages instruction and parts list. Gregg Dunn site has that TIP mod with a short list of parts with no instructions, which is all that he may have been given. My comment is not negative for Gregg's site which is very beautifully done, but without a forum. Also another 8 page mod to increase the ST-400 to a ST-416 watt amplifier output, referred to as "The Double Dyna", substantially doubling a ST-400's wattage output. Stereo Cost Cutters (SCC) Dec 1983 catalog of most of 13 pages of 24 pages 8 1/2 x 11 paper size remaining Dynaco inventory they had purchased on Dyna's closing, 40,000 pounds worth. The parts list of only 5 pages was done in such a small font, it may not even be scanable. US and Canadian Dynaco wholesale and retail price lists. The MBI-400 mod changes around parts, wires, etc to turn a 400, 410 and 416 into a 600 watt mono amps and this is to be considered non-reversible and very prone to hurt the user (hernia). This project is extensive and the possibility of expensive damage to the amp, if an error is made or serious personal injury, also 8 pages long, not for the rookie. The danger is so great that maybe that is why it was pulled from Greg Dunn's site. I will scan and post some as soon as I can. Errata: There was 60,000 pounds of parts and inventory. There is also 2 follow-up SCC hot sheets which mentions that they had a flyer, 20 pages, of just Dynaco. I'm only mentioning that fact, I don't have it, date unknown. Vern
  3. Hi there I thought I would jump in here. I have both speaker systems, AR-3A's first and LST's later. When the opportunity to demo a pair of LST's in my house came up in the mid '70's, I jumped at it. I had the 3A's for several years of ownership and almost constant usage, so I had in intimate opinion of their capabilities. To add another point here is that I also had a Crown DC-300A amp and IC-150 preamp on another weekend loaner and after only a few minutes of listening again, the 3A's were outstanding reproducers on their own. In this case the electronics made all the difference, and they also were returned. My feeling after only a few minutes of usage with an AR amp was that the LST's were at least double the 3A's or at least considerably better. This was a weekend test setup and I returned them after the weekend, no WAF. I am sure I pouted for many, many weeks until in the mid 1990's when I bought a used and abused pair of LST's. Still not having the money or brains to turn down yet another used pair, I bought another used pair a few years later. No, I haven't stacked them, or placed Microstatic array tweeters on top of them. If you keep your eyes open, try to find an original pair of LST's as mint as possible. In my opinion, if you were to build your own cabinets, and be given brand new drivers and use the AR-3A crossover you would likely be happy with them, even with them being audibly less than real LST's. The LST's are great reproducers but they are only speakers. Vern
  4. Hi again Here I am with some more trivia about the Dynaco 400, 410 and 416 amps. Today I found an article which I will write about another day and perhaps scan and post here. It is a more detailed story about the coil/resistor which I discussed earlier. The colours were correct but they used a black plastic sleeve over the coil. I also came across a copy of the MBI-400 super-charge mod which can increase the mono output to 600 watts This is one of several links that has disappeared from, home.indy.net/~gregdunn/dynaco/components. That site does not have a forum, sadly, because Gregg has done a beautiful job setting it up. Also I came across price lists both retail and wholesale which I need to scan first. To change the subject here, I see lot's of viewers but only a few get involved with this site. If everyone visiting could post an answer or a question it would be great, even if no one here can answer it. Especially me. Also if everyone could post a photo of an article or ad they have of old Dynaco. Vern
  5. Hi Joel Yes the original composition resistors were slightly under-rated and that chap, Kevin, takes us through the steps to get to and replace them. After completing those replacements we get a helping hand to reset the bias. Only listed tools, parts and a VOM are needed. Which caps did you replace and were the new ones 85' or 105'? Did you strip the amp right down to it's basic components? Great job for someone here to do, you must be highly skilled. I picked up a Dyna 400 with meters here because one channel was dead. It is really ugly as it was tinkered with and likely stored in a damp carport. Less than $50.00 though, another of my rescues. I went to the directory here and see over 80 viewers have seen some or all of this topic. I wish some of those viewers would leave a comment or? Nice to see this amount of interest in this topic.
  6. Hi Joel The site referral is a site without an active forum. The repair was written by Kevin Boales for PC-28 circuit boards. I can print out the St-400, etc, mod for my use but I do not know how to just save it. This mod is for usually one dead channel and it covers replacing a common cause of the one dead channel. I do not feel it is ok for me to print out that file and re-scan it and post it here.
  7. I have a few mods or tweeks information on Dynaco's ST-150, ST-400, ST-410, ST-416 amps also series 80 amps and ST-120. If there is sufficient interest I will follow up here in the near future. If I remember correctly there was a phase 2 Dynaco ST-400, I have no information on why there was this added model designation. It may have been an internal doc. Please post here if you are interested in following up on these issues. Remember there is a serious risk of shock if you are not experienced. There was a TIP mod well known for the ST-120 but there was also a similar TIP mod for the 80 series. The mod for the ST150 - ST-416 amps is on Greg Dunn's web site. It was posted there around 2002. You can print out the article. A set of 8 pages has been deleted there that would have created a 600 watt mono amplifier. No explanation posted. Perhaps liability issue. Vern I do not have an email address yet.
  8. Well, it's been a while, but one of my two amps died. My first thought, because I saw something glow red how in the case when I turned the unit on, was the unit suffered a cascade failure. AKA not cost effective to repair.

    Fall is here, my depression over the event has abated a bit and I decided to open the unit to see how bad the damage was before trashing. No burn marks, no scorched wires or melted or loose connections to be found. Checking further, both 5 amp fuses were blown in the right channel, the channel that failed.

    I decided to check the TO-3 transistors first, and found two that are a dead short between B-C-E. Each was part of a pair, it's matched transistor was good, er, acceptable given it's age.

    Checking further, I noticed whatever repair facility replaced 2 of the 4 NPN transistors in the channel, and used the wrong part number.
     

    The original part numbers are now obsolete (MJ15024 and MJ15025) but two substitutions are available. The better choices for the TO-3 NPN and PNP transistors is MJ21193G and MJ21196G. Mouses strongly recommended replacing all eight if going with these options. They have a slightly higher gain than the originals, supposedly better linearity and a high SOA.

     

    If this fixes the amp, this plus the new electrolytic caps should be a minor upgrade in performance and perhaps extend this old Heathkit AA-1800's life a few more decades.

     

  9. dynaco_dan

    Cizek KA-1

    Hi Kent You did a great cabinet restoring job. If Roy was alive he would be proud of you, I'm sure.
  10. dynaco_dan

    Cizek KA-1

    Hi there Just thought you might like to see a great example of a Cizek speaker. I believe Paolo is the photographer of these. When I first saw the cabinet solidity, dovetailing, I fell in love with it. The middle photo is the one I love the most. Kent, I love your first speaker top photo.
  11. Hi there I've been waiting for one main members opinion of speaker crossover caps. He has been involved in several classic speaker designs during his life. I value his input as, having been there, done that. The main man is of course is the well known and respected, Ken Kantor. Ken may too busy with large projects and his life enjoyments but his comments would be extremely valuable to everyone here. He has faced cost in designs and surely he will have some interesting feedback if he has time to write here.
  12. Hi there Last week there was a pair of nice looking A-10's on auction. I only saw it once and the price was around $60.00 for a pair located here in Vancouver BC. A location was requested by a bidder also here in Vancouver. I missed the finally as to the final price but one living so close would be able to bid higher. A few years ago I won a pair for under $100.00 in Ontario. No one seems to bid if in Canada, what a shame.
  13. Hi there To create the Double Advent system you place the cabinets vertically, raised above the floor about 12" or more. The cabinets are stacked one above the other with the tweeters close together. You may wish to use double sided tape or equal in between them so they do not slide off. You will also need to wire them in parallel. Be certain of the wire phasing. Fusing is also a good idea.
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