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Old 17th Jul 2012, 12:20 pm   #4
Herald1360's Avatar
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 14,506
Default Re: Binatone Mustang

Sounds like a totem pole, then.

The following Wikipedia comment may be relevant:

"Totem-pole push-pull output stages:

Two matched transistors of the same polarity (or, less often, Vacuum tubes) can be arranged to supply opposite halves of each cycle without the need for an output transformer, although in doing so the driver circuit often is asymmetric and one transistor will be used in a Common-emitter configuration while the other is used as an Emitter follower. This arrangement is less used today than during the 1970s; it can be implemented with few transistors (not so important today) but is relatively difficult to balance and so keep to a low distortion (the highly non-linear TTL circuits such as the 7400 use this arrangement)."

It's a relatively simple circuit to reverse engineer but your distortion may be amenable to just trying different output transistors. Have you any way to check matching?

Depending on the bias arrangements, even silicon devices could be substituted.
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