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P.G.A.H. VOIGT: A Great Audio Inventor

Discussion in 'classic' started by eguth, Apr 8, 2010.

  1. Barniboy

    Barniboy Member

    Perhaps I can respond to your query, Eguth.
    Indeed it is a genuine Voigt field coil speaker.
    Easy to tell by the centering device that was visible in one of Robinhulmes pics.
    The unit has now come home, and I made this photoseries to those interested.

    http://www.flickr.com/photos/65583803@N03/sets/72157627525388096/

    In fact, it is quite similar to the Voigt units in Johns museum, not counting the outdoor versions of course (which are even more amazing).
     
  2. eguth

    eguth pfm Member

    Barniboy
    Splendid. This driver has ended up in a good home. I think Voigt would have been pleased that it is being cared for by a knowledgeable connoisseur of his work.

    Do you know when it was made?

    And do you have plans to restore it to working condition? If so, full report after listening, please!
     
  3. Barniboy

    Barniboy Member

    The front part w. diaphragm is definitely a "Light Coil Twin" first mentioned in the advert of Jan. 5th 1939 (your reference no. 58). A thorough review (by Voigt himself ?) is made in WW Mar. 9th 1939 p. 223 (which we both somehow missed, should be posted in your ref. as 61a). The large photo and schematic from the patent illustration shown in the review is very detailed.
    I think the "Item 3, new suspension cone" gives considerable reinforcement to the centering device, which is probably one of the reasons why the unit is still working.

    Yes , I do plan to get it working. I am currently looking for some (safe) 400V capacitors. Using it with a rectifier alone does give some ripple, or snare in the sound.
     
  4. eguth

    eguth pfm Member

    I have a drawer full of 1000V polypropelyne capacitors. If I have the value you need I will post it to you free of charge.


    Cheers
     
  5. Barniboy

    Barniboy Member

    That is indeed very kind of you. I'll send you a PM with my details.

    To all Interested: Allow me to make a reminder of the Audio Show at Whittlebury Hall this coming week-end !
    Mr. John Howes will be demonstrating the newly built Voigt Domestic horn as mentioned previously in this thread. This is the first original-build in over 70 years, and an excellent opportunity to have a listen to this rare speaker, the worlds first HI-Fi speaker, designed more than 30 years before the Hi-Fi norm was established.
    Perhaps we'll meet at the Monaco room, then.
     
  6. paskinn

    paskinn pfm Member

    Fascinating stuff..incredibly depth of research. I can possibly add a couple of points....firstly, the chance of building a proper pair of Voigts from 'guesswork' are pretty slim. Les Bartlet, who built the new pair is a highly skilled furniture maker. Even so he needed all five pages of A5 Voight drawings and then, had to take apart an original to see how theory and practice had drifted apart (they had, in small ways.)I have a pair of Voigts (provided by John Howes) but these originals were not terribly well built. The new pair are more rigid and substantial. The 1930s were a time of depression after all (not like now!).
    I also have a rebuilt pair of Voigt field coil units, rewired for 12volts and reconed by Lowther. It is interesting to compare them with a new state of the art design..the Voxativ field coils. The voxativs in the new Voigts are marvellous..although the room at Whittlebury was a touch 'boomy' and perhaps did not ideally suit the Voigts.Still sounded fine though. Manufacturers are rather at the mercy of demo rooms.
     
  7. eguth

    eguth pfm Member

    I have had the priviledge of being given a ‘sneak’ preview of Barniboy’s photos of his restoration of a pair of original Voigt DCH’s. They are a first rate introduction to how to do it. I have urged Barniboy to post these photos on this thread. Be prepared for a treat if he obliges!

    I am not a dedicated show goer, so cannot comment on what sounds good where. That said, I have sometimes wondered why very few (if any) demonstrators attempt to do some room treatment at shows. Demonstrators spend enormous efforts to show their item at its best, so why not make some room in the van for some sound treatment panels, carpets, soft furnishings or what have you?
    The Voigt DCH should not be boomy except in a very bright room with inadequate damping. It should sound better in a large room than in a small one. My own quarter wave pipe, used from 50Hz down to 22Hz (roll on and roll off below and above) does not usually sound boomy in my small, heavily furnished listening room, though it does ‘boom’ if the bass has been recorded as such. I think that the Basset, modified (a Voigt quarter wave pipe) would be an ideal partner for the DCM to extend its range downwards to 22 Hz.
     
  8. paskinn

    paskinn pfm Member

    Don't blame you for not attending hi fi shows...I only went to support John Howes and Les Barlett, who built the new cabinets. I have heard the Voigts in several rooms, and they have been fine. For some reason the bass was problematic at the show. They even work fine in my little room (about 13 foot by 11foot.) As for Voigt field coil drivers, I must get a new camera and post pictures of my pair. They are about to come out of the cabinets as I have raided the piggy bank for a pair of Voxativ field coils.They need to last a very long time to justify the cost! For restoration, those guys in Devises, who advertise in the back of hi fi news (sorry, the name has 'wireless in it) can rewind the coils for 12 volts if you don't fancy doing it. I don't know how Lowther feel about reconing them, but they did mine, so if you have problems ask John Howes for guidance.
     
  9. eguth

    eguth pfm Member

    Paskinn
    Re: the Voigt DCH you say:

    “…they have been fine…”
    This is hardly a careful or critical assessment.

    I said:
    “…why not make some room in the van for some sound treatment panels, carpets, soft furnishings or what have you?...”

    It is unclear whether you have missed my point or simply ignored it. Not that it matters, but in either case I think you need to consider whether the best form of advertisment is enthusiasm (or otherwise).
     
  10. paskinn

    paskinn pfm Member

    You misunderstand....I have nothing to sell, no commercial interest whatsoever in Voigt, or anything else audio for that matter.I made my living in other fields. When I said of the DCH 'they have been fine' that is what I intended to say; I am not offering a 'critical assesment' because the people reading this thread are more than capable of making their own.I bought a pair of dchs because they suit me.It is a personal response. This project was a great deal of hard work and expense for the enthusiasts concerned.....they aren't doing it to make money (fortunately!) In the end it is just a bit of fun, a hobby, and a bit of history. At least John has succeeded in reminding people of Voigt.That is a real achievement.And you can now hear a pair of DCHs in perfect condition. All to the good surely?
     
  11. paskinn

    paskinn pfm Member

    Have you seen 'adventures in hi fi audio' on the net? Excellent pictures of the Voigts at the Exhibition..you can even see how they have been waxed since the pics in hi fi news.
     
  12. eguth

    eguth pfm Member

    After Voigt’s death his wife, Ida, gave the original DCH plans to Dr. Bruce Edgar who passed them on to John Howes in 2010.

    John Howes engaged a cabinetmaker. He constructs the DCH to the original specs with minor modifications using 15mm birch ply instead of the original 1/2inch.

    Moulds for the concrete and plastic parts of the horn are apparently no longer available- the plans for these were, in any case, not included in what was to hand. New moulds were made (see Hi Fi News, Nov. 2011, p.18).

    John Howes produces an upgraded version of the DCH with Ines Adler’s Voxativ 12-18V field coil drivers.

    The original DCH sold for just over £32 in the 1930s. A pair would have cost £68.

    I understand that John Howes sells the recreated modified Howes DCH’s for about £28,000.
     
  13. amdismal

    amdismal pfm Member

    http://safalra.com/other/historical-uk-inflation-price-conversion/

    £68 in 1935 is £3,600 today. That was clearly a lot of money to spend on speakers in the middle of a depression. Exactly the same as now, in fact!
     
  14. Barniboy

    Barniboy Member

    Hello Amdismal and Eguth
    Interesting converter you found there, Amdismal.
    I asked the Bank Of England to make the conversion some years back and also found it to be reletively inexpensive wrt. modern buying power.
    So I figured then that something was wrong, and that there could be several converters for labour, income, tax, etc.
    But it seems the price of crafted goods has really gone up dramatically (due to higher wages and better wellfare).
    I would expect that to reflect in price-indexing too, though...
    But I am not an economist..

    In the 68£ price: Did you remember that the pricelists from back then listed the drive unit and the cabinet seperately ?
    One should count two drive units and two cabinets (for stereo).

    (Sorry for asking, I dont have my files handy.
    I sit in Pakistan, currently supervising erection of a 300 t/h cement mill.)
     
  15. eguth

    eguth pfm Member

    Barniboy

    The advertisement I looked at stated that the DCH was for sale for £32 and some further fraction of a pound. It did not list the drive unit cost separately, although some of the adverts may have done. I do not have any WW copies and all the ones I looked at have long since been returned to the British Library Boston Spa and cannot be consulted by me easily.

    Whether Voigt would have used two DCH’s for stereo is unknown. He is known to have pondered the question in Canada but could not obtain a second DCH to experiment with. The boat builder in Toronto he had hoped to commission to construct DCH cabinets never materialised.

    As a matter of speculation, one could imagine Voigt possibly, in the end, plumping for any of the following:
    1) would not use two DCH’s for stereo;
    2) would redesign the DCH so as to make the sound more directional and therefore, more suitable for stereo reproduction;
    3) would keep the DCH as is, use two of them, but bring them onto the diagonal into the room out of the corners and use a separate, larger quarter wave pipe enclosure to reproduce the bass instead of relying upon the corners of the room for this purpose;
    4) would have designed a totally new and original design for stereo reproduction.
    5) would have simply used two DCHs for stereo;.
    6) would have confirmed that one DCH should be used, and then only for mono.
    P.S. Have you tried mounting a driver in the cement mill for use as a subwoofer?
     
  16. paskinn

    paskinn pfm Member

    The cost is very high...but John is not doing this to make money, and frankly, he won't. The amount of preparation work was great....not least because the original plans are not accurate, by which I mean that if you follow them carefully, the speaker won't fit! Les had to dismantle another Voigt and use that as a model, along with the plans. Even then there were a series of changes over the years. The reflector took two weeks to build-up, because of the drying time of plaster of paris. You add up the wages, the materials, then factor in the cost of deming at Whittlebury, loads of leaflets, the charges any dealer or distributor will make...well, it is quite startling.Especially as they could only be produced in tiny numbers.
    This was never about making money. As for the field coils, the Voxativ field coils are a fair upgrade on refurbished Voigts (fitted with new Lowther cones and rewound for 12 volts). Better frequency response and a compete absense of the lowther 'shout '(which the Voigt cabinet seems to minimise anyway.) If anyone lives near the South East coast, and wants to hear original voigts fitted with Voxativ field coils, contact me. BTW, power supplies seem to be very critical. A battery seems the best bet for energising the coils...any noise on the line and you hear it.Fussy stuff.
     
  17. eguth

    eguth pfm Member

    Voigt Letter: Wireless World, 15 October 1939, p.390-392

    This is a long and masterly letter entitled ‘TRANSIENT RESPONSE’. It emphases, inter alia, the importance of phase and the (ideal) infinitely rigid, weightless material of the loud speaker designer’s dream. The letter contains a useful summary at the end. Point #8 states:

    “…in the absence of the phase/frequency curve (or equivalent) the response curve does not tell the whole story….”

    There is a great deal more in this letter. I cannot imagine how I missed it. Many thanks to Barniboy for adding it.
     
  18. bottleneck

    bottleneck pfm Member

    He won't make a lot of money?

    How many pairs of speakers at twenty eight thousand pounds do you think he'd have to sell before he DOES make a lot of money?

    What do you call a lot of money?
     
  19. paskinn

    paskinn pfm Member

    You obviously don't know John Howse.....he has run a Lowther/Voigt museum, at his own expense, for many many years.During that time he has given many hours of free advice to many many enthusiasts. Without him the whole Lowther/ thing would probably have disappeared. Certainly, he has been busy collecting cabinets to save them from the scrapheap. He has never sought to make any money . He won't make any money now....you try building a pair and marketing them. But somehow I rather suspect you prefer to criticise, not contribute. .
     
  20. eguth

    eguth pfm Member

    I have taken photos of Dulwich College, Voigt’s old public school.

    I have posted historical glass slide images of the Pender Electrical Engineering laboratory where Voigt carried out his studies at UCL.

    These images are now on p.1 of this thread.

    Acknowledgement for the historical images is given in the Acknowledgement section.
     

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