C2 speaker

[John R Simon]

are there any electronic concerns when replacing a 65 speaker with a current unit such as Pioneer? I know this should be a no brainer but I want to be sure.
Thank you, and thank you NCRS and members.

[Patrick H.]

Re: C2 speaker

The original speaker is a 10 ohm, and the Pioneer is likely a 4 ohm. This is not an issue if you're using a modern radio, but might be if you are still using the original radio.

If you are using the original radio and just want a better speaker, consider having your re-coned.

Patrick

[William C.]

Re: C2 speaker

As Patrick mentions the difference is in the speaker winding. I have been told by my radio repairman who has done great work for me, that this will result in diminished volume, and eventually in the destruction of one of the transistors in the radio, one that is made from a material known as "unobtainium" the stuff that drives obscene prices on ebay for obscure items.

[Jack H.]

More...

The late C1 and C2 radios used a 'First of the Mohicans' DS-501 germanium transistor to drive the speaker. To thwart EOS (electrical overstress) that would result in drive xsistor burn-out, a 'matching transformer' was used between the radio and the speaker.

In most radios of that era, there was sufficient space within the radio chassis to install this 'matching transformer'. But, in applications like Corvette (and a handful of other GM cars), there wasn't sufficient space inside the radio chassis for the transformer. So, in these cases, the transformer moved out of the chassis and onto the speaker....

Since designers KNEW there would be a matching transformer in the circuit AND that transformer acted as a filter in addition to its primary job of protecting the drive xsistor, the 'color' of the acoustic spectrum (bass/treble mix) the radio produced was intentionally skewed to 'take advantage' of the presense of the matching transformer.

If you replace the speaker in one of these systems with a conventional, off-the-shelf, speaker that lacks the matching transformer (REGARDLESS of price/quality or impedance rating) you'll get low-volume 'tiny/distorted' sound. If you run it for very long or at any appreciable volume, you WILL burn up the DS-501 drive transistor!

To my knowledge, there's only one mfgr today (NTE) that makes a service replacement for the DS-501 (dinosaur technology!), and he gets a whooping $25+ for his part! So, this is a place where part swapping without knowing/understanding the impact of what you're doing can/does result in damage.

Now, later era Corvettes (e.g. early C3) continued to use the DS-501 xsistor, BUT they mounted it inside the radio chassis rather than on the speaker. There, you CAN replace the factory original Delco speaker(s) with off-the-shelf substitutes and achieve good sound quality without the threat of damage. And, before you ask, YES it is possible to move the matching transformer from an original C1/C2 Corvette speaker over onto a generic replacement speaker and have your cake and eat it too!

[Gerard F.]

Don't do it.

John,

I burned the main transistor on my 67 AM-FM by putting in a heavier speaker without the transformer. It will work for a while and then it will cut out when it gets hot and then finally blow the transistor. You need the speaker with the transformer to make the C2 radio operate correctly. I found a replacement DS-501 from Radio Shack Online, and with a correct speaker, the radio now sounds like new. Hope you like to solder.

Jerry Fuccillo
#42179