How do 1B's and 1C's compare?

halo71
halo71 Posts: 4,603
edited June 2013 in Vintage Speakers
Can someone tell me what the differences are? I did some searching and didn't really see much info comparing the two models. The SDA's my brother are giving me, I thought were 1C's. But after a pic he sent me they appear to be 1B's.
--Gary--
Onkyo Integra M504, Bottlehead Foreplay III, Denon SACD, Thiel CS2.3, NHT VT-2, VT-3 and Evolution T6, Infinity RSIIIa, SDA1C and a few dozen other speakers around the house I change in and out.
Post edited by halo71 on

Comments

  • Schurkey
    Schurkey Posts: 2,101
    edited June 2013
    1B and 1C Studio share the same particle-board cabinet design, and the same tweeters. The 1C (non-Studio) uses the newer-style cabinet; I've heard that it's better-built, stronger, sexier, etc, and may be MDF instead of chipboard.

    Crossover is different in both the HF and the LF sections between 1B and 1C. All 1Bs use two round crossover boards, one for LF and one for HF. Some 1Cs use two round boards (different components from 1B), but most 1Cs use a single rectangular board. Far as I know, the 1C dual-round-board version and the 1C single rectangular version are interchangeable in terms of components used.

    The 1B cannot be used with non-common-ground amplifiers, while the 1C can be used with non-common-ground amplifiers IF an isolation transformer in installed in the SDA interconnect cable (Polk AI-1, or similar, including the Dreadnaught style.)

    Some folks will say that certain 1Cs cannot use the AI-1. There is a serial number list showing the affected units. The "fix" is to figure out how to connect the "ground" cable of the AI-1 to the negative terminal of the speaker; there's a dozen ways to do it depending on what style of connector you want to use--binding post, Neutrik SpeakOn, Polk-style pin/blade, or other style of connector. For practical purposes this is a NON-ISSUE as long as the AI-1 is electrically connected to each negative post.

    http://www.polkaudio.com/forums/showthread.php?131691-2B-and-EARLY-1C-AI-1-modifications&

    The mid-woofers are 6509 (all positions) on the 1B, while the 1C uses half 6510 and half 6511 midwoofers.

    The 1B is a 4-ohm (nominal) speaker, while the 1C is 6-ohm nominal.
  • Schurkey
    Schurkey Posts: 2,101
    edited June 2013
    (As usual, too late to "edit" original post.)

    The 1Bs had brown woodgrain, the 1C Studio used black woodgrain. 1C (not Studio) had the wood top and bottom, with fabric front and side panels.