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FDP Forum / Guitar Mods, Repairs, and Projects / Peavey T40 / T60 SC to HB wiring....Anyone ever try it on another guitar?



Apr 19th, 2018 10:44 AM   Edit   Profile  

A few decades ago, the Peavey T40 bass and T60 guitar had an interesting wiring configuration.

They had humbucking pickups. Two pickups, two volume, two tone. However, the tone controls were wired in an interesting way. (They also had a phase switch, but we'll ignore that for now.)

With the tone at 10, the pickup(s) were single coil and used one coil. No noise cancelling.

With the tone at about 7, the other coil was brought in and the pickup then functioned as a humbucker with noise cancelling.

With the tone between 7 and 0, it acted as a standard treble roll off tone control.

Has anyone ever tried this with another guitar or bass?
How did it work?
You'd need a 4 wire pickup to do it.

I actually have an old T40 bass, and I use this all of the time. Mostly for recording to get rid of the noise.

And before someone comments: Yes, it is HEAVY.
How heavy?
If you mixed a batch of cement with some lead and built a guitar out of it, it still wouldn't be as heavy as the T40.

Search terms:
T 40
T 60

Moderator Emeritus
(with many stars)

NW Pennsylvania

Apr 19th, 2018 10:56 AM   Edit   Profile  

The search engine ignores anything 3 characters or less.

Back in the days when you could get Larry DiMarzio on the phone, he described such a circuit to me. I still have it in my notes here somewhere.

Contributing Member

Wichita, Kansas

Drums = pulse, Bass = heartbeat
Apr 19th, 2018 11:35 AM   Edit   Profile  

I was reading a thread on another bass forum. They were talking t-40's (I have one - my first decent bass, purchased new in 1979.

Someone mentioned that Chip Todd, the designer of the T-60/T-40, said that if he were to do it again, he would would not do the HB to single-coil fade and instead just use coil tap switches. His argument was that the way the circuit works, one can never get a full-treble, open tone control sound out of the pickup when run as a HB.

On the T-40 at least, this results in the HB sound always being a little muddy.

A number of T-40 owners have converted their basses to HB-only operation. I haven't tried it, but apparently it is as simple as snipping the coil tap wire that runs from the pickup to the tone pot, thus it is easily performed and easily undone if you don't like it. IIRC, it is the red wire on the pickup. Chip was even recommending the mod.

Contributing Member

Get ready for the

Buena Buena
Apr 19th, 2018 01:48 PM   Edit   Profile  

Peavey Engineering called that pot configuration a "spin-a-split," and it works pretty well.

I have a version of this on an early 70's aluminum-neck Kramer 450G guitar. It didn't come like this in stock configuration, but I added it when I removed the stock Kramer pickups and installed a pair of Dimarzio Super II humbuckers in 1984.

It does make for a very versatile guitar.

However, it is more useful to install a pull-on coil split (switched pot) because that scheme preserves the 'single coil with the tone rolled off' tone.

(This message was last edited by Peegoo at 03:49 PM, Apr 19th, 2018)

Contributing Member

Get ready for the

Buena Buena
Apr 19th, 2018 01:52 PM   Edit   Profile  

Here's a diagram, from Seymore's site.

Remember that on a Duncan 'bucker, the black wire is the hot lead, and the red and white leads are the separate coil feeds.


(This message was last edited by Peegoo at 02:11 AM, Apr 20th, 2018)

FDP Forum / Guitar Mods, Repairs, and Projects / Peavey T40 / T60 SC to HB wiring....Anyone ever try it on another guitar?

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