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About Dchristie

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  1. Double Advent crossover

    Thanks Pete. Yes, I have revision 2 (later Original Large Advent crossovers) as per your baselaudiolab info. Dean
  2. Double Advent crossover

    Hi folks, over the years I have accumulated several pairs of Large Advent ( Original series not the New series) drivers including tweeters, bass drivers and of course the crossovers. As you all are aware, the Double Advent system was simply running a pair of Large Advents in parallel on each channel ( also referred to as stacked Advents) with each speaker sharing the crossover with the other speaker and the amp. I am currently building a Double Advent system from scratch and want to place the drivers for each channel in a single cabinet ( compensating for the correct volume for the doubled up bass drivers) but would like to have the appropriate crossover values for the dbl system (not separate crossovers for each single system in parallel as per the original design). I am going to rebuild the crossovers with better components eliminating the frequency switch so looking for some help on what the inductor, and cap values would be appropriate for such a system. I seem to recall that the single Large Advent had a 1.6 mh inductor in series with the bass driver ( 1st order slope) and a 16 uf cap in series with a 3 ohm resistor with a 0.45 mh shunt on the tweeter ( 2nd order slope). If I remember my basic speaker building principles, a change from an 8 ohm system to a 4 ohm system doubles the inductor value for a 1st order crossover ( in this case for the bass drivers) and halves the inductor and doubles the capacitior values for a 2nd order crossover ( tweeters). So, can anyone ( Pete or Carl, or?) give me some guidance - would simply applying the basic 8 to 4 ohm principles outlined above be appropriate for my Double Advent rebuild? And, if not can anyone supply the correct values for a single crossover in a Dbl Advent system? Thanks Dean
  3. Cloth surround sealer question

    Hi Roy, thanks for your reply and yes, I would like to respond to Larry so I would appreciate it if you would provide me with his email address. Thanks Dean
  4. I realize that there are a lot of topics regarding the proper sealer for cloth surrounds but I have a question regarding the restoration ( increasing the viscosity) of AR Vintage cloth sealer. I bought two samples from the AR Vintage Store on ebay and despite my best efforts to keep air from the containers, both samples have thickened to the point of being unusable. The AR Store indicates they should be good for a year or so but mine seem to have become too thick in a relatively short time ( 6 mos). So, I am wondering if Roy or Tom or (?) has any advice as to how I might thin the sealer so it is once again usable for sealing surrounds. Thanks Dean
  5. I recently received in a trade, a bunch of AR3a parts including crossover components and drivers ( except the woofer which was sold by the original owner and the 16 ohm potentiometers). I have a pair of spare KLH model 17 woofers so I am going to play around with using the 3a mid and tweeter with the KLH woofer. I am just in the experimental phase so just looking at options - I have not tried any combinations yet. I have a Marchand electronic crossover that I am going to actively biamp the woofer to the mid/treble drivers but use the stock 3a crossovers for frequency shaping for the mid and high units respectively. So, I will not need a low pass ( high cut) for the woofer or high pass ( low cut) for the mid as the Marchand will actively roll off the highs to the bass driver and also the lows to the midrange driver. I do want to use the standard passive 3a low pass and high pass crossovers for the midrange and tweeters, respectively. I would also like to play with the potentiometers in and out of the mid and high frequencies circuits since the marchand will allow flexibilty in level matching the bass with the mid/highs but I will still have to subjectively adjust levels between the mid and high frequency drivers to balance out the levels for the whole system. The reason for taking the potentiometers out of the mid and upper frequency crossovers is I also have 3 amps with level controls so another option would be to triamp each driver with the electronic crossover between the bass and mid ( levels can be adjusted for each of these with the electronic crossover) and the tweeter could be adjusted by the tweeter amp with the amp's level controls ( to balance the sound with the mid and low drivers). So my questions for Roy C. ( or anyone else) are as follows : When looking at the AR 3a crossover, it looks like there is a a 0.044 mH inductor in series with the 16 ohm potentiometer providing the high cut on the mid and a 6 uF cap on the tweeter also in series with the potentiometer for the low cut for the tweeter. Is this correct ? I assume the 0.88 mH inductor and 50 uF cap are providing the low cut for the mid in this circuit ? If the above is correct, would the same value ( 0.04 mH and 6.0 uF) d components be acceptable for rolling of the highs to the mid and the lows to the tweeters IF the 16 ohm potentiometers were removed from the circuits or are the potentiometers in circuit critical to the high cut and low cut values of the mid and tweeter respectively and would need to be recalculated without the potentiometers in the crosssovers ? As I indicated, I am just experimenting and I am sure my ignorance of cirduit designs is showing but I would appreciate any advice and clarification anyone can provide. Thanks ! Dean
  6. Bang and Olufsen and Dynaco Speakers

    Hi folks, in my current quest to try and find replacement drivers for my damaged A-25 XL speakers ( see buying and selling listings), I came upon some postings on Ebay where bass and tweeter components for Bang and Olufsen speakers are being advertised as being the same as used in some Dynaco models. When looking at the B&O drivers, they certainly apper to be very similar ( even the B&O woofer and tweeters in a couple of postings are listed as models 25F-EW and H-086, respectively - same as Dynaco A-25 XL). However, they are 4 ohm and not 8 ohm drivers so I don't think they are direct replacements for vintage Dynacos ( such as the XLs) . So my question is this - can anyone confirm that the 2 companies were both being sourced from the same supplier ( the above example would certainly appear to indicate that they were). Also, when you look at some of the B&O speakers ( such as the 2600 model) the bass and tweeters do look very much like Dynaco drivers. It is also interesting that B&O speakers are fairly well regarded for their sound qualities on the various internet WEBS and they appear to have more elaborate crossovers compared to the simple crossovers in the A-series Dynacos. While Dynaco was very successful in just using a single capacitor and a few resistors to adjust the high frequency 6 db rolloff in many of its most popular models, it appears that B&W also used inductors (even in their 2 way 2600 speaker) to provide an electrical rolloff on the bass driver as well. They also used midrange drivers more frequently so their speakers once again appear somewhat more complicated than the simple Dynacos. Dynaco was certainly very successful and seems to have almost universally good comments regarding sound quality so they obviously did something very right. I have never had the pleasure of hearing a B&O speaker so I am making the above comments based on limited 2nd hand knowledge only but I would like to hear from anyone who may have more in depth information. I am really wondering if you could use B&O drivers to replace damaged Dynaco drivers as long as you observed the polarity and model numbers. Dean
  7. WTB Dynaco A 25 XL drivers

    As another option to buying XL components for my damaged A-25 XL speakers, I would also like to throw out an offer to trade a pair of perfectly good functional Classic A-25 bass drivers and tweeters for the same XL components. I currently have an extra pair of the original A-25 speaker components that I am willing to trade for. So, if any of you are not happy with your XL speakers and would prefer to have the original version, please get in touch with me and perhaps we could just exchange drivers for drivers. I assume the cabinet volumes and driver cut outs are the same for both models although the crossovers would have to be modified to some extent to accomodate the different components.
  8. WTB Dynaco A 25 XL drivers

    Hi folks, I recently had an electrical misshap with my refurbished Dynaco A 25 XL speakers and unfortunately destroyed both tweeters and the bass drivers. As you all know, the XL series used different drivers than the original A 25 speakers so finding the separate bass and tweeter drivers has not been easy. I noticed a couple of pairs of 25 XL speakers available on Ebay, but I would have to buy the complete set of speakers and I do not need the cabinets ( not to mention that shipping the speaker with cabinets adds considerably to the expense). My cabinets are fine so components are all that I need. Anyway, thought I would check here first and inquire if anyone has any spare drivers they would be willing to sell to me before I consider plan B (Ebay). I can be reached at 509-443-7196 ( Spokane, WA) or my email is dean.christie@bayer.com Thanks Dean
  9. Bose 901 Grill Removal Details

    Carl, Simply Speakers has a You Tube presentation video where they walk you through the removal of the grills for the early 901 series models and also include info about the later series 5 and 6 models. It is quite informative so you might check it out. http://www.youtube.com/watch?v=dbGfFw650gQ I found it by googling Bose 901 Speaker Foam Edge Replacement and Repair.
  10. need help w/ AR5 crossover

    The large wax block is indeed 2 capacitors ( 24 and 72 uf) on a single chassis. The wire-wrapped block is providing the resistance as per the original crossover design so all of the parts are there as per Carl's schematic. Not sure how this was ever restored as the parts all appear original (old) but regardless, if you follow Carl's schematic you could update the caps with newer individual caps and maybe replace the wire-wrapped block with an audio grade noninductive resistor for a simple upgrade. If you follow the AR 3A restoration project on this Web Site youi can do a whole lot more to restore these classic speakers. Good Luck ! Dean
  11. Dynaco Crossover Capacitors

    Thanks Kent. The crossover in the A-35s is 1200 hz and for the A-25s it is 1500 hz so a larger cap in the A-35s makes sense. I am pretty sure that the 8.0 uf is correct for the A-35 model. Nothing else is changed between the two models - all resistors and combinations for tweeter adjustments are the same.
  12. Dynaco Crossover Capacitors

    Hi Vern , Just looking for some clarification regarding the caps in the A-35 and A-25 models respectively. I have seen a couple of threads where it was said that both models used a single 5.0 uf cap and also a couple of references which indicared a 5.0 uf cap for the A-25 and 8.0 uf for the A-35. Your posting above would support the 8.0 uf cap in the A-35. Does anyone know definitively what is the cap value in the A-35 speaker ? I am restoring a pair ( they have been modified with a more recent cap and it is a Solen 8.2 uf) so this would also lead me to believe 8.0 uf is correct for the A-35 but I would sure like to get some confirmation from the Dynaco experts. Thanks Dean
  13. EPI M100

    ra.ra I usually glue and screw a 1 X 1 inch brace cut to fit snuggly between the front and back baffels. It is probably overkill for most modifiers but the speaker experts do claim that it does help to reduce baffle breathing (movement) and I have added so many braces to modified speakers over the years, that I find it pretty easy to do but it does take time and patience. You can probably live without it as a lot of older speakers do not have this and they sound fine just as they are. With regards to treating the rubber surrounds, I would only do this if the rubber is stiff or shows some of the symptoms of aged rubber. My Marantz Imperial 5 speakers had a white powder-like exudate on them after years of sitting idle and treating them made them very pliable and softer as well as bringing out the black color. Same thing with my refurbished Dynaco A-25XLs. My ADS 810s are just fine after 35 years and needed nothing done to them. The rubber seems to be in good shape and they look the same as when I bought them in 1978. As to what to use, I searched extesively the various internet audiophile webs (AudioKarhma, AudioCircle, and Classic Speakers)and finally decided upon a product called 303 Aerospace Protectant. I bought mine at a NAPA auto store and it is made for specifically treating, protecting, and restoring rubber and a number of other synthetic materials. I have had no adverse effects from the treatments and it makes the rubber diaphragms look almost new. Many folks warn against using anything at all on the surrounds but this product has served me well but use at your own risk - I have treated several pairs of speakers with 303 over the past year and the diaphragms still look and work just fine so I am very comfortable using it. From my experience, EPI rubber surrounds usually don't need any treatment, but you must decide for yourself. Good luck! Dean
  14. EPI M100

    ra.ra I think you would be fine replacing the 8 uf with a 10 uf cap. For most of my EPI mods, I also replace the spring loaded speaker inputs with high quality binding posts ( as long as you are comfortable with soldering techniques). You could also purchase the whole thing from Huw Powell as he sells a complete xover replacement including the 10 uf caps, wires, and posts all on a new mounting plate but it is really pretty simple to do yourself. Also, unless you really like the ability to adjust the tweeter level, I would bypass the L pad as it really is not needed in EPI speakers as the woofer and tweeter levels match very well without it. If you keep it in the circuit, a little Deoxit cleaner may be needed to clean the internal contacts if it is scratchy from years of oxidation. I also add a cross brace between the front and back baffles and attach it in the area between the tweeter and the woofer. Also, you might recondition the rubber surround with a proper recoditioning product but this should be done only if the rubber seems to be somewhat stiff due to age. All of the above is what I usually do for a full mod, but just replacing the old cap with a good quality poly (as you indicated) and cleaning the L pad will get you a very nice sounding speaker for just a little effort. I have found all of the earlier EPI speaker models and their Epicure cousins to be very natural sounding and very enjoyable overall .
  15. EPI M100

    ra.ra I have looked at quite a few EPI speakers over the years and the 10 uf cap has been common, so your pair may have had a substitute cap at some time but I am by no means an authority on this subject. I have also not seen the gray, mortite- like putty on the speakers I have worked on (I assume it was used in your speakers to seal the holes where the binding posts enter the cabinet) so this also could be a clue to your speakers having been modified at some point. On the other hand, this brand went through a lot of changes over the years and being so simple in design (and cost efficient), it would not surprise me if the manufacturer had several variations during the model 100s' production run and different caps could have been used to keep costs down. Also, keep in mind that with the woofer running full range and just a 1st order xover on the tweeter, the difference between 8.0 uf and 10 uf caps is relatively minimal and many folks would not find it that much different without careful direct comparison. You might also contact Huw Powell at Human Speakers as Huw is most likely the best "expert" on this brand of speakers.