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dynaco_dan

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  1. 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

  2. On ‎25‎/‎04‎/‎2018 at 5:58 AM, Aadams said:

     

     

    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 

  3. On ‎28‎/‎04‎/‎2018 at 12:21 AM, dynaco_dan said:

     

    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

  4. 1 minute ago, dynaco_dan said:

    To add to the Dynaco ST-400 amp story.

    I have a vague memory of the resistors across the top of the relay plate that was also a choke-coil assembly.

    My memory cannot be relied on but I believe the coil wire was originally a red colour and a mod was instructed by Dynaco at that time.

    I quote from Audio Magazine May 1975 page 49, a review of the Dyna 400.

    This is a direct quote from Dynaco.

    "Dynaco informs us that a very recent change in the value of the resistor R305  to 1.8 ohms reducing the Q of the output inductor-resistor combination effects an improvement in high-end sound quality.

    This is easily made on existing St-400's by adding a 2.2 ohm resistor (2 watt minimum) in parallel with each output inductor (choke-coil assembly) on top of the relay mounting plate.

    This will also noticeably improve the square wave trace into a capacitive load, especially at low drive levels."

    This review was 3 years after it's introduction.

    If my memory  serves me correctly the colour of later kit coil wires was changed to black.

    If you should have black no mods are needed.

    The St-410 and 416 would also have black as they were designed later on.

    Vern

     

  5. On ‎06‎/‎04‎/‎2018 at 8:23 PM, dynaco_dan said:

    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.

    To add to this heading I was reading about a Pat-4 preamp that was noisy in only one channel.

    The writer replaced only one composition resistor that must be 40 years old.

    Noise disappeared.

    There is a need for replacing those old composition resistors with metal film or ?

     

  6. 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.

  7. 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.

  8. 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.

     

     

     

  9. 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.

    post-101040-0-51884100-1352743814_thumb.

    post-101040-0-40242400-1352743816_thumb.

    post-101040-0-21661600-1352743818_thumb.

  10. 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.

  11. 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.

  12. Q. re 'Stacked Advents' and new AV receiver...

    Just wondering if I need to manually wire the fronts in parallel to get the stacked effect, or if the Onkyo can do that for me if I just plug them all in... and can the bi-amp feature offered bt the 809 receiver help? I suppose this may be more a question about the receiver than the speakers. The receiver IS rated for 4, 6 or 8 ohm speakers.

    Many thanks for any expertise you can offer!

    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.

  13. I have a pair of Dynaco A25 loudspeakers that I use with an old Marantz 2230 receiver . Love the mellow sound this combo produces . It's music to my ears . Recently I passed up a pair of Dynaco A25 XL loudspeakers at the pawn shop . Went back to purchase them and they were sold . Now I'm wondering if I let a great pair of speakers pass me by . Has anyone ever done a listening comparison between the two speakers ? Mine has alnico drivers , the XL I believe has ceramic magnets . Is there a difference between the sound of the alnico speakers and the ceramic versions ? Comments appreciated .

    Hi there

    I recently went to our local Vancouver Public Library and copied a Dynaco A-25XL review.

    Next time I am here I will post it and make my comments, which I will have more than just a few.

    By the way, I've read several Epinion reviews done by Horsewhispr, nicely done.

  14. Hi,

    I have a pair of Wharfedale W90 speakers (sand-filled model).

    I'm desperately looking for someone who has a photograph of the crossover

    for these, or some know-how of the configuration.

    I've been attempting to repair them for a year and have had some techs playing around with bypassing the crossover (didn't work).

    Any help would be greatly appreciated, as I've almost given up. Wharfedale informed me that they lost this information when one of their facilities burnt several years ago.

    Finding someone with some know-how is my only hope.

    Kind thanks

    Hi there

    Do you have all the old crossover pieces?

    Can you post a good closeup of your crossover of both speakers, if both have not been altered?

  15. Hi there

    I never saw or even heard of Roy Cizek speakers until I came to this site.

    From the several writings previously it appears that Roy Cizek was not a very good businessman at all.

    He was a brilliant designer, as I read, but should have really worked with someone who could finance his operation.

    There was and is a lot of brilliant people with outstanding ideas and they need money for startup and ongoing expenses until the tide changes and there is a profit.

    Of the few writings from mostly Italian members, Paolo in particular, there is a great love of Roy's products and a super strong brand loyalty.

    Paolo, I believe, posted a photo of a small Cizek speaker, which to me looked like a high-end mini-monitor of today.

    The cabinetry is exquisite and even if it was a stock photo, I was drooling.

  16. I recently hooked up a Phase Linear 400 series two (running through the preamp of my Marantz 2285b) to my AR-10pi's and then to my AR-3a's - I instantly could hear a big difference.

    I would love to hear a pair of AR-LST's. I might have to save my pennies,sell off some other stuff, and buy a pair. Their shape is very interesting - I could make a really neat pair of speaker stands for them.

    Hi Darrell

    There is a great demand for LST'S in 100% mint original shape, which keeps the prices high.

    If 10 out of 10 they could still be not in 100% working condition.

    My ebuy experience is, sellers tend to lie or stretch the truth a bit.

    There could be one or more drivers dead and also their shipping, packaging and handling is very critical.

  17. Thanks Vern,

    Does the extra mids and tweeters of the LST make for a better balance with the woofer than with the 3a?

    Hi Darrel

    If you look at the five different graphs in the AR-LST manual, you will be able to read and see the repeatable outputs.

    There is at least one that is the same as the AR-3A speaker system.

    There is also one output, 2, that is about as flat as can be done by dynamic drivers.

    I've written previously about my in home demo against my AR-3A's.

    I felt that the LST's were worth twice the price of AR-3A's, they were and so was their powerful presentation.

    That was using my AR amplifier only, my other toy's came much further down the road.

    The AR-LST's were returned.

    The LST's like all speakers are not without their faults but also they have more than most speakers of what hifi is all about.

    You do need a stable, as in 4 ohm capable and even 2 ohms to be safe, medium clean power amplifier.

    There likely is no limit to the amplifier output size that can be used with them.

    They were not designed to be disco speakers but will handle 500 watt clean peaks or more.

    They are fused, it should be derated.

    A minimum of at least 30 watts per channel 20 - 20,000 hz.

    AR said 25 watts but that is really for only the better quality amplifier outputs.

    I am certain that many an amplifier of poor quality died a painful death due to the speakers variable demands.

    In addition, the AR-3A's were outstanding with my AR amplifier.

    Later a loaner Crown DC-300 and IC-150 was tested with the AR-3A's.

    It took less than 30 seconds to feel the powerful gut massaging bass that may have been there before but to a much lesser degree.

    I think I still smile thinking of that one time experience.

    Due to poor WAF and potential for divorce, the Crown equipment was sadly returned, also.

  18. A few questions on the AR-LST please…

    I have always assumed it is sort of an upgrade from the 3a? -- better handles the mids and highs?

    Does the AR-LST2 relate to the AR-LST sort of like the AR-5 relates to the AR-3a?

    What does LST stand for?

    If I were looking to buy a pair of LST’s is there anything I should know/ look for?

    thanks

    Hi there

    The AR-LST or laboratory standard transducer, is much more than just an upgrade from the AR-3A speaker system.

    The similarities are they use the same drivers, as in the later AR-3A production, just 3 more mids and tweeters.

    The cabinets internal volume is the same.

    The power handling capabilities is likely quadrupled for the mids and highs.

    They used a ceramic magnet for the woofer and foam surrounds.

    A switched autotransformer was used to alter their output, as per owners manual posted in the library.

    I posted an original scanned AR blueprint into the library que section, un-labled, sorry.

    The copy is poor but does also show the bypass resistor.

    There is not much documented here, as yet, in what variations were serial numbered and dated.

    There is the earliest crossover board, rear mounted, and the later mounted through the woofer opening and internally mounted.

    A large capacitance change, resistor bypass, and switch source changes are not documented nor do we, at present at least, have no

    serial number or time period when each was performed.

    The added power output and angling the drivers off of axis gave the speakers a wow factor when used with good equipment.

    Outstanding reproduction by most standards, not everyone will agree with this comment.

    Needed healthy amounts of clean amplifier wattage to show their stuff.

    A pair in mint condition may fetch $2,000.00 or more depending on condition, supply and demand.

    I've only given a general idea of their worth to us owners.

    The AR-LST 2 is basicly a parallel system but using less drivers same as the AR-5's.

    Tom Tyson will likely write a more thorough and romantic description of one or both speaker systems.

    The differences between the 2 systems is quite audible but both can be very satisfying to their owner.

    Some may never miss the lesser LST 2's sound characteristics same as an AR-5 and AR-3A comparison.

    The drivers have not been available new for well over 25 years now.

    Current new production goods are different in construction and sound characteristics if they are needed to be replaced.

    Packing and shipping them requires special packaging techniques as they are about 100+ pounds packaged for shipping.

  19. The guy who wants to repair it seems to think bypassing the switch helps a great deal but i forgot the technical terms he used, maybe i should just ask him not to replace the entire thing and just put it on the spot one above normal so the switch is still active ?

    Hi there

    Typically replacing the cap usually is a highly recommended step, with any brand of speaker and can at times, provide a slightly audible improvement.

    If there is no output from just the tweeter, this would be suspect.

    Bypassing the switch has not been a recorded step as yet, and unless it's broken, best leave it alone.

    It certainly have not been a problem historically.

    Think about how many times we adjust the tweeter level controls in our lifetime, not many for most everyone.

    Most listeners probably set it and forget it.

    Can you imagine someone getting up from their chair and adjusting the tweeter level for each cut of each and every cd.

    It is a simple switch with no dead spots and each setting is more precisely repeatable, unlike a pot or L-pad.

    Obviously if one of the resistors is burnt it will need to be replaced, extremely rare though with Dynaco, I've not heard of one, yet.

    Dynaco A-25 speakers are about as close to being trouble free as is possible, barring burning out the woofer, their main weakness.

    A recommended 1 amp or smaller fast blow glass fuse, in a open style fuseholder, will help lessen this event happening.

    A reasonably compact, well veneered, fairly neutral sounding speaker with some limitations at a very attractive retail price when new.

    They were voted quite often as a best buy speaker.

    I have enjoyed several of their models with all their warts.

    Remember, spending money will bring you most often, little or no improvement but we all justify it.

    updated 20110714 10:02 AM

  20. Hi Craig

    I see in the last photo the two pairs of A-25's.

    The photo is fuzzy but it appears in the other photos that you have all Seas drivers.

    I see metal staples in a different position than I am used to seeing on the vents.

    Could you please take new photos and re-post of the vent openings, please.

    The mirror image pair, tweeter on the left of center, are less common than right of center.

    Never read or heard why they were ever made in that format.

    I can understand that you might want and need mirror image pairs for mini-monitors, etc.

    This may have been Dynaco's thought, but, you would need to identify the shipping carton, left and right and keep

    them matched from the factory, to the dealer, and to the customer, for well under $100.00 each, not worth that much work.

    Doubtfull you or anyone else can hear the resistors being replaced and the switch being eliminated.

    The capacitor is another story.

    Much has been written here and elsewhere about suitable replacement caps and which type, model and brand to use.

    Some have raved about reasonable priced caps and others about the super deluxe and expensive caps.

    Most younger listeners might appreciate spending $100.00 per cap per $79.00 speaker but Solen may be a better buy.

    There is subtle differences and you may not be able to decide which is the best and most reasonable.

    Replacing the internal speaker wire will net you no improvement.

    Sometimes we can hear the un-hearable when we spend money.

  21. Hi i have a few questions about restoration.

    Q... What happens if you had a A25 woofer that was abused to the point woofer was pretty frayed/ ripped but went in for a repair ( van l speakerworks chicago) does this mean the roll over is not as good on it?

    A... Look on ebuy or similar for an identical model number used woofer, confirm whether it be a Scan or Seas model, round or horned but verify it is also a 10" version, 8

    ohms and not 4 or 15 ohm impedance.

    Q... Is a woofer compromised due to repair if other one is in mint condition ?

    A... From my own personal experience there is no repairs with this particular woofer nor should you pay to have someone else tinker with it.

    A... Your money is better spent on buying a used woofer and not reconing even, usually about $25.00+/- for buying a used woofer.

    A... The paper voice coil former gets pretty hot and ends up charring, also the damage is cumulative and non-healing.

    Q... What happens if you replace just the resister on the crossover of an A25 ?

    A... There is no reason to replace any of the resistors unless they are burnt or out of spec significantly, possibly the capacitor though.

    A... Solen makes a fairly nice PP capacitor replacement.

    Q.... How come dynaco A25s sound slightly different from one another ?

    A... The Scan and Seas are different drivers.

    A... There is more of a major difference between an A-25 and a A-25-XL speaker as well.

    Q... I think i have the scan and the seas version, the scan version seems a little deeper on the bass response. but i could be wrong.

    A... Two different speaker systems, I've never read or personaly done an A - B test to see what sound differences may be audible, there may be

    an audible difference across the band.

    A... Any chance of a photo of each of your speakers front baffle board without the grille cloths on?

    Q.... Last question, can you find modern dynaco A25 woofer replacements?

    A... The newly manufactured replacement drivers of today are different sounding, not a good thing.

    Q.... If so how do they compare to the original sound wise and how much do they cost ? ( i looked but they were out of stock)

    A... Used is your best bet for replacement drivers.

  22. This seems, on the face of it, to be a closely guarded secret. OTOH, there probably isn't a clear, well defined list all of the historians can agree on?.

    Hi there

    Part of the reason, I believe, that the serial numbers are not too well recorded was to keep production and sales numbers from other manufacturers.

    We assume that the serial numbers are like license plates, they may not all be.

    It would be kind of intimidating thinking that the competitor is outselling you based on serial numbers, when in fact they may be selling less.

    One manufacturer may jump thousands of numbers after starting out in the thousand or tens of thousands serial numbers.

    A while ago I suggested here when the AR chronological list was being redone, I had mentioned something quite difficult to implement and maintain.

    I also don't think my idea was well received at all.

    I had suggested that for each AR speaker model that had factory mods, without changing model numbers, be separately listed and possibly sub-identified.

    An example, AR-2AX's were modified several times in components, yet were never re-labeled.

    Another example, the famous AR-LST with several variations.

    If someone here was to take on the task of, collecting and sorting, serial numbers with known components and serial numbers still intact a partial

    serial number database could be started.

    The problem of this is, as each member posts their specific information and serial numbers the list would need to be adjusted.

    This may be daily, weekly or monthly to keep it accurate.

    After a long period of time a pattern range would form for all of us to see.

    I don't see Mark or Gene having such free time available.

    This information would be invaluable to anyone buying or selling or just owning a pair of AR speakers.

    At least a range of speakers serial numbers with similar components would be established.

    Just a thought for today.

    update 20110627 3:40 pm

    Another thought is, documenting the date from their drivers when removed.

  23. Mark,

    I'm new to the classic speaker pages. I have a few brochures and marketing brochures for the AR5 and AR9 series. I haven't seen them in the library and was wondering if I should send them directly to you for posting (if interested). You have done a GREAT job from what I have seen so far.

    Regards,

    xpat

    Hi there

    If possible please scan and upload the photos to the library que forum, it's the safest method of seeing them posted.

    Mailing unavailable literature today can be lost or damaged forever in transit.

  24. I wrote this review of the A-10s a few years ago (for Epinions, a site not exclusively for audio nuts) and I still think it's accurate. A-25s usually go for somewhat more than A-10s on eBay (I always watch Dynaco speakers), but really minty A-10s can go for around $200/pr. I've had about 10 pairs of A-10s pass through here and all had the same complement of SEAS drivers. Don't know if there were ever any Scanspeak A-10s.

    http://www99.epinions.com/content_278745878148

    Hi there

    I thank you for correcting my Scan driver comment.

    A few moments ago I re-visited a scanned SR review that I have and on closer inspection, I

    see that I was aware of the 4 screws, and missed the other 4 screw holes.

    I know that the Scan have 3 screws.

    My scan is inferior to Wally's original copy, which I have already returned to him.

    It took a blowup of my best scan to see where I went wrong.

    I guess I was tired and didn't pay close enough attention to details on my scanned copy.

    I was quick to draw a conclusion because of the many photos I have seen of A-25 and A-50 Scan and Seas versions, sorry.

    Thank you very much again.

    I've enjoyed a number of speaker write-ups you've done at that site, very well done.

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