Most commercially manufactured home audio loudspeakers contain passive crossovers that have been assembled using inexpensive parts of dubious audio grade quality. In particular, vintage crossovers have components that have been improved upon in their designs over the years and they can benefit most by replacement with modern components. Certain key parts in the series signal path to the drivers could and should be replaced with audiophile grade parts. In most cases, replacement of older capacitors and resistors will result in much improved clarity and detail. Some vintage loudspeaker purists claim the ‘voicing’ of a vintage speaker intended by the initial design will be altered. This may or may not be true because this claim has yet to be proven conclusively. However, today’s modern digital-based music media contains a tremendous amount of detail that can go unheard with old parts in the signal path.
Acoustic Research
For those AR enthusiasts who are willing and capable of taking on a DIY upgrade, I offer AR2a, 2ax, 3, 3a and 4x kits. They contain all the parts and instructions needed to complete a worthwhile upgrade to vintage components*. Kits include very high quality 15 ohm rheostats – not cheap L-pads, metalized polypropylene capacitors and, if required as in the case of the 3a, cost effective high value electrolytics to replace those old, original Industrial Condenser Corp. components. Original air core inductors do not need replacing.
New rheostats are sometimes needed when cleaning of original, Aetna-Pollak units becomes a futile effort. I have selected very high quality, US made industrial grade rheostats for this application. Photos of these are available in the ‘project gallery’ section.
For tweeter and midrange circuits I typically select metalized polypropylene. Specific brands are chosen based on experience that strike an appropriate balance between cost and performance for vintage AR speakers.
Note that components are also available separately. E-mail or call for pricing.
PRICING (for a PAIR of speakers)
• AR2a, 2ax, 3 and 3a kits are $150 plus S&H.
• Without new rheostats - $20 plus S&H
• AR4x kits are $80 plus S&H.
• Without new rheostat - $15 plus S&H
* kits with rheostats do not include a cover to protect the exposed wiper. Plans to build a simple cover are included.
Advent
Kits are available for three versions of Large Advents and also for the New Large Advent model. Most contain new capacitors and resistors as well as instructions. Here again, inductors are not replaced unless burned out. Prices range from $50 to $70 plus S&H for 2 speakers. If you are interested in a Large Advent kit, please check the crossover components in your specific vintage before contacting me. New switches and/or inductors are extra. Below is a list of the 3 vintage variations.
- 16 uF/16 uF with a 4 ohm resistor – early 1971
- 16 uF/16 uF with a 3 ohm resistor – until mid 1975
- 16 uF/8 uF with a 3 ohm resistor – mid 1975 to end of prod. In 1977
UPGRADE SERVICES
Most crossovers in the 10-40 year old range contain parts that have either degraded over time or are of initial dubious quality. Non-polar electrolytic are known for their ageing characteristics. Both of their critical operating properties (uF and ESR) typically drift with age. This drifting phenomenon changes original crossover points and diminishes high frequency output. The “project gallery” contains photos of some of the crossover jobs I have done. Specific types and brands are selected which, I believe, are the most appropriate for the loudspeaker being upgraded. For example, I won’t select a Duelund capacitor for the tweeter circuit in a vintage AR or Advent speaker. Nor will I select a 49 cent NPE for a $3000 high end monitor speaker. I also provide capacitor test reports.Contact me with your upgrade questions.
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