68 Super Reverb with thin plastic insulated hookup wire

premiumplus · Post by **premiumplus** » 21 Jun 2008, 13:20

I've got a nice SFSR, a '68 or early '69 I think, wired with very thin, 22 or 24 gauge hookup wire. The only reference I've been able to find on the web is this quote from http://www.unclespot.com/AA763vsAB763.htm

"Fender’s sudden transition from cloth wire to thick PVC wire (in pastel greens, white & yellows) is well documented by anyone who has ever pulled a chassis. Sometime in late 1968, the cloth covered wire went away. However, several amps from the late ‘60s (non-reverb Princeton, Vibrolux Reverb, Bandmaster Reverb, and possibly a Deluxe Reverb) with oddball wire have been reported. The Princeton Amp was an early-mid 1969 model entirely wired (factory original & stock) with thinwall, 22awg irradiated PVC (IPVC) wiring. IPVC wiring is usually found in electronics like computers, not lo-fi amps. Keep your eyes peeled for wire with very thin, cream to yellow insulation. It’s likely IPVC."

It looks strange in there without the cloth covered wire but I don't notice any sonic problems. I heard that Fender went away from cloth covered wire in those years because amps that were in high humidity areas of the world developed a type of "Jungle rot" where the cloth insulation completely deteriorated and left bare wires and debris inside the amps.

Have any of you ever seen an amp with this type of hookup wire? Mine even uses it for wiring the 4 ten inch CTS speakers together. Although there is only a foot or so of wire involved, I have never changed it. The amp has been blackfaced and it sounds absolutely wonderful. I wonder if changing the speaker wire would have a benefit or not? After all, isn't it just a voltage drop that we're talking about with 24 gauge wire? The amp is plenty loud. Would there be a change in tone I wonder?
As for the innards, I have no plans of changing anything else. It's just a matter of curiosity to me about the thin hookup wire.
-Dave

soulsonic · Post by **soulsonic** » 24 Jun 2008, 08:51

I have a Super Bassman that's also wired with the oddball thin wire - it really surprised me when I first opened it up.

24 gauge is thin for speaker wire, but the Super Reverb isn't a very powerful amp, so the wire can probably carry the current no problem; if it couldn't, it probably would have melted by now. Since the wire is so short any added resistance from the small gauge would be negligible. If it's actually 22 gauge, then I wouldn't mess with it and just leave it be, but if it is 24 gauge, then I'd consider this a fine opportunity to upgrade to some nice Belden Teflon Silver-plated wire!

Fuzzer · Post by **Fuzzer** » 24 Jun 2008, 17:09

Super Bassman?, Changos, To me a Bassman was already 'super', that would be nice to see.

soulsonic · Post by **soulsonic** » 24 Jun 2008, 23:39

The Super Bassman was a 100 watt Bassman head. It had the standard setup of a "Bass" channel and a "Normal" channel. The Bass channel has Bass and Treble controls with a Deep switch, and the Normal channel has Bass, Middle, and Treble with a Bright switch. The circuit has many of the "CBS" features, including the added signal filtering and the "balancing" type Bias control. One thing that surprises me is that it has fairly low plate voltages on the power tubes; about 350 volts. It has a large output transformer (larger than a standard Twin or Showman) and it's designed to power a 2x15 4 ohm cabinet. I've used mine for years and it has always gotten me a good sound that I've been very happy with.
You can see a schematic of it here: http://www.schematicheaven.com/fenderam ... _schem.pdf

Cheese Bag · Post by **Cheese Bag** » 25 Jun 2008, 17:02

I have a '68 SFSR with that wiring as well. I had the amp balckface and have thought about changing the wire but I haven't got that far yet.

Hotrats · Post by **Hotrats** » 25 Jun 2008, 20:06

premiumplus wrote:I've got a nice SFSR, a '68 or early '69 I think, wired with very thin, 22 or 24 gauge hookup wire. The only reference I've been able to find on the web is this quote from http://www.unclespot.com/AA763vsAB763.htm]
After all, isn't it just a voltage drop that we're talking about with 24 gauge wire? The amp is plenty loud. Would there be a change in tone I wonder? As for the innards, I have no plans of changing anything else. It's just a matter of curiosity to me about the thin hookup wire.
-Dave

I don't think there's any/much difference in tone due to minutely increased wiring resistance - I've seen tragic results with people trying to replace the wiring ... the only thing about some of the '68 series SF amps is the B+ is a little lower then before, lying at around 440v on some Pro and Super Reverb's ... in '69 the B+ went back up to around 485v on those amps ...