Description

Push-pull EL84's stereo amplifier, floating para-phase. $1500 or best offer. Selling off our ElectraPrint audio, past designed, working prototypes. This amplifier is one of the prototypes built (2018) to study the workings of floating para-phase, phase splitter, features related to not having to use matched tubes. Result was that it still needs matched output tubes when replacement is needed. This circuit type has been in the books for many years and appears no real explanation was given of how it works. It is hard to explain. We did find out and it appears one feature it has is the automatic phase splitting balance. But outputs must be matched pair. Output transformers are ElectraPrint 15K, 50% screen tap, to 8 ohms CCM (compound common mode) type winding arrangement. Original specs measured are: 8 watts clean to 10 watts max. BW -1db 28hz to 30khz THD at 3 watts, .4% IMD at 3 watts, 1.2% SMPTE .48 input volts to full output 8 ohm loading, suggested SPL 97db+ speakers. Uses two matched EL84's and one 12AT7 each channel. Uses no NFB, as others need to clean up their circuit flaws, so slew rate is very fast with high SPL speakers. Best on open baffle types. Built point to point as is the millions of other tube amplifiers since the 1930's, easy to trace and repair from those that have the proper equipment and knowledge. It is "stereo", meaning, one side's measurements can be used to find the problem in the non-working channel if a problem should happen. Easy for many. If you have no means to repair any problems that may happen you should have a local electrician. Shipping it back and such will probably ruin the amp physically and electrically, so do not buy this amp. Circuit is supplied with amp. Sold as is, working fine for weeks here before listing on eBay. Please contact us for more information needed.