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VanArn

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About VanArn

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  • Birthday 25/07/1941

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  1. Without knowing the exact make and model of the tweeter Aaron have used and hence a lack of the appropriate data, it is difficult to assist with a suggested replacement. The tweeter Part No. does not show up in any of my searches and you may have to rely on finding someone who has knowledge of it. Some tweeters can be repaired economically providing the voice coils are intact and they are otherwise undamaged. For some models you can obtain replacement diaphragms.
  2. The ESS HEIL AMT is not an electrostatic speaker. It is related to planar speakers but distinct in the way that the pleated diaphragm provides an efficient performance with a wide dynamic range from a relatively small aperture. The dynamic range is where it outshines most ribbon and electrostatic tweeters. The impedance is basically a resistive four ohm and providing the crossover network is correctly designed a complete speaker design does not present a problem for any good amplifier. It does pay to use better quality bass speaker with the HEIL AMT rather than the ESS originals and that is what Garry Cawsey has done with his workshop test speakers and I agree with Ian McP that it is a worthwhile exercise to listen to them and also how a pure Class A solid state amplifier easily drives them.
  3. Is the problem actually mains hum or are you hearing tracking problems all the way through the vinyl records ? The latter could be caused by incorrect settings of VTF etc., or faulty arm bearings, a damaged or dirty stylus. The MM/MC setting has been already checked. If it is a hum problem then the RCA interconnection leads should be tested for continuity and make sure that an earth cable is fitted between the turntable and the amplifier. Also check that the cable clips at the rear of the Ortofon pickup cartridge are firmly fixed and fitted to the correct pins.. The turntable should not be sitting on top of an amplifier as the mains transformer can radiate a high EMI field into the pickup wiring if it is too close to it. Impedance loading is not a problem that will cause hum or distortion.
  4. The next step is to disclose the speaker model that you need the surrounds for, or the size of what is needed, i.e. the outer diameter, the finish diam. of the roll, the start diam. of the roll and the inner diam. of the surround. Also the inner section of the surround can be either angled or flat. Replacement surrounds can differ slightly in dimensions and still be suitable replacements. The difficult ones to find are those that are needed for a very narrow roll dimension.
  5. The supply of parts is excellent from QSR especially when you purchase through eBay. If you order via the catalogue then unless you are meeting or exceeding the minimum purchase quantity, then additional charges apply.
  6. They should not be used in any circumstances. A vile product of the early years of LP vinyl records that contained silicon as an anti static agent.
  7. Using the same parameters and using a 0.5mm Xmax as the limiting factor (Audax PM 170 MO ), a 107dB SPL level can be achieved. Since at 250 Hz , if this is to be crossover frequency, the level for both the bass unit and the mid-range with a third order Butterworth network would typically be - 3dB for each speaker and given a 'perfect' summation the level attainable would increase to 110 dB. That should be sufficient for any domestic sound system. The use of a flat foam surround is a better choice for a midrange driver rather than corrugated cloth or roll surrounds. The noise is less and edge diffraction is minimised. Although their lifetime can be short they are easily replaced.
  8. davewantsmore is correct with his quick calculation. The simple formula that I used for u ( peak amplitude ) = 1.93 x sq root Pa /f^2 D^2 , when using a calculator requires the numerator to be calculated first before attempting the division. I missed this step. The answer is 4.416mm.
  9. I do not see a problem with being able to produce adequate SPL,s with say, the Audax PR 170. To achieve a* 120 dB level at 250 Hz would require a cone movement of 0.147mm. This is well within the Xmax figure of 0.5mm shown on the manufacturer's data sheet. Granted, real world signals can be more demanding than that of a pure sine wave as harmonics , in the speakers passband, can add to the excursion requirements. *This calculation assumes radiation into half-space of a circular disc that is small compared with the wavelength of sound at this frequency.
  10. Audax manufacture some specialist midrange speakers such as the PR170 MO. These use a coated paper cone together with a flat foam edge surround, aluminium wire voice coil and importantly a high flux magnet.
  11. You could try sourcing a replacement price from The Speaker Exchange who act as KEF service agents for the USA. You should have the speaker inspected and tested first before you commit to buying a replacement as repair may still be an economic option.
  12. A supplier of bamboo plywood is Plyco https://plyco.com.au who will precision cut sheets to size , although this is limited to 90 degrees only. If you need special profiles to be cut, you could contact John Woodhead at Aranmar Acoustics info@aranmaracoustics.com.au John deals directly with Plyco so that may leave you with only the delivery from Melbourne to Adelaide to deal with ultimately.
  13. The Fisher mains transformer suits 50 or 60Hz mains frequency. What has to be considered is the height of the unit as there is a little available clearance when the case is fitted and a suitable off the shelf replacement would be a problem to find. Otherwise you may have to go for a custom built transformer and then you may just as well rewind the old one. Modern insulation and wire coatings are superior to materials used in the 1960s. The original output valves are more likely to be 7868 types which were unavailable for many years and these used a special Novar socket. Other replacement types such as the 6L6WGC ( Russian 6Pi3C-E ) are readily available providing an Octal valve socket is fitted.
  14. The procedure I would suggest, keeping in mind the age of the amplifier and needing to replace suspect component parts, is not to follow the path of the Variac and step down transformer additions. The amplifier uses a mains transformer that is rated 50 to 60 Hz and this can be rewound to suit the Australian standards. This is the neatest method of conversion and should cost about the same to implement as that of a stepdown transformer. If your Fisher model is the X100 and the output valves are the original 7189 A types, the Russian 6Pi14Pi can be used as a replacement although some small changes to the valve socket wiring may be needed.
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