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dynaco_dan

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About dynaco_dan

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    dynaco_dan
  • Birthday 10/04/1946

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  1. Should the AR-5 have been a 12" Speaker?

    Hi Frank It appears that you have all of the toy's and all in one room my friend. Vern
  2. Hi there Thank you for posting this information here. Vern
  3. AR Turntable Documents

    Hi there Thank you for posting this information here. Vern
  4. Dynaco A-25's & Subwoofer

    Hi there Just a small comment here. The original Dynaco A-25's were very well liked in their day. J. Gordon Holt of the original Stereophile Magazine fame went gaga over them in his first review. Very smooth and wide range, within their limits. I like them very much. Use caution with any bass boost, loudness controls or loud volume levels. You might download Dynacophil's "Dynaco Dynamax" paper from this site. It show's several options for multiple Dynaco speakers of the same brand and model. There is no reason the same cannot be used with most all 8 ohm speakers, at least to experiment with. For more bass, maybe if you have a friend with another pair of A-25's, try paralleling them together. Fusing them with a 3/4 or 1 amp fast blow fuse in an open style fuse-holder will help protect your investment at least. Just a thought. Vern
  5. HELP! Has anyone figured out KLH tweeters?

    Hi Kent I am certainly not an expert but the tweeter must have a totally enclosed metal frame so that the woofer back pressure does not pop out the tweeters cone material. I have seen some tweeters with holes stamped into the frames, but the correct version will not have any holes. The same with the mids. They had intentionally installed special sealed sub enclosures to prevent that type of accident. The satellite speakers with a single mid/fullrange driver would not have any issues in this regard. Vern
  6. Dynaco A-50 cabinet salvage

    Sorry for not posting photos. I took a lot of photos, but at too high a resolution to post here. Here it is 5 years later and I have still not posted them. There is photo editing software that I am trying to locate to allow me to post them. The photos of the work are too nice to not complete this article. The work that was done can be done to any walnut or other wood veneers. I may remove a woofer to photograph the inside of the enclosure and crossover network and even take some measurements. Originally I commented that the rear cabinets corners had the metal brackets for hanging on a wall and this wall not as Dynaco had advertised them, despite their light weight. Dynaco had several times advertised artists conceptions of their products and then altered the final product appearance, sometimes several times. Till next time. Vern
  7. KLH Twelve speaker info

    Hi Kent Thank you very much for your posting of photo. Vern
  8. KLH Twelve speaker info

    Hi there Is there a speaker review or schematic of this speaker system available?.
  9. 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.

     

  10. Improving The KLH Five - A New tweeter???

    Hi there Check out Ebuy for a used pair. The original tweeter was well regarded, not only in the Fives.
  11. KLH Twelve vs Five (drivers)--another piece of the puzzle

    Hi there Check your woofers cones for the black felt marked 25+/- or other numbers. This is the cone weight and depending how low the number was determined which model it was installed in. The opposite is also the the same.
  12. Dynaco A25 Vent Damping

    Hi there Put back the original piece of fiberglass.
  13. Dynaco A-25xl crossover network

    Hi there I need to scan and post the Audio Magazine review I have found of the A-25XL speaker system. I read it 3 or 4 times to try to digest it's contents. Will try to post it soon. The owner that gave them to me also found one broken coil wire. Strange!
  14. Bang and Olufsen and Dynaco Speakers

    Hi there Dynaco used both Scan and Seas drivers. B&O used some drivers that were made by Seas also. European speakers tended to be 4 ohms and North American 8 ohms. The original A-25 prototype was 4 ohms and Dynaco insisted that they be made in 8 ohms. You need to check the paper label for model numbers and if missing use a VOM to verify impedance. Whether swapping out both drivers in a Dynaco speaker with 4 ohm drivers or visa versa with B&O's would be up to experimenters to try. There may be an improvement or not in each case. I was recently given a pair of Dynaco A-25 XL's and the tweeters had been replaced with a brand of other manufacture. My hearing is poor so I cannot say if there is any difference in output between Seas and Scan drivers. Dynaco A-25's tweeter had a commented peak at about 9 - 11 kh in many reviews. I cannot comment on the A-25XL's tweeter reviews.. Even the Dynaco's woofer either had horned baskets or round baskets and were both were from Seas. These may or may not have performed exactly the same. I have not read the complete story of Dynaco's relationship with Seas and B&O, and the A-25 birth. While Scan drivers were used early on there was a switch to Seas. There was no fanfare or announcement to that fact that I've seen. There was tweeter on the right and left of center versions. Different grille cloth frames. There is no Dynaco internal information of any of their speaker systems. They may have experimented with a mirror image pair but found it difficult to keep paired in distribution. The A-25XL came out when I was transitioning and never saw them for sale. I own AR-LST's which are 4 ohm. Their tweeters tend to have a disintegration of the tweeter cavity padding. I bought 4 ohm versions of the Seas Dynaco/B&O tweeters for future replacement. They won't perform the same but will last longer than me. As long as you are happy with the xL's, enjoy.
  15. Too rough with 5 spot switch / A25 lost highs

    Hi there It is possible the switches stop is bent or broken. Only opening up the cabinet and inspecting the switch is there a possible solution available. A used switch is not much of a gamble in my experience. When I didn't have an original switch I bought a 5 position MBB or make before break stepped switch and have not had a problem with it. You may be able to buy a cheap used pair on Ebuy and if shipping is cheap go for it. Be carefull not to buy a BBM or break before make switch, as you lose the signal each break in the contact. Some surplus switches have adjustable adapters so that you can have 1 up to 10 positions (limit of some switches). Do check the stop post first.
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