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David Willard (the draftsman at Phase Linear) used to like sneaking in things like "Fudder Mudder" on circuit boards. Management wasn't too happy about this. Mike F. was Mike Frost. Mike worked in the engineering department at Phase Linear. Unfortunately, Mike passed away in 2016.

It has been a while since I last worked on a 3300. However, I seem to recall running into problems with at least one headphone jack before. "The SW outputs are turned off when a headphone is plugged in. This allows headphone listening without speaker background sound. The UNSW outputs are not...

Here is a little more history on the Triad Transformer Mfg. Company now Triad Magnetics. "Talking With Triad Magnetics: Demystifying the Science Behind Audio Transformers" by Frank Doris in PS Audio Copper magazine March 25, 2025 Issue 216...

Here is a link to my recent post on the Triad G-336 transformer: https://forums.phxaudiotape.com/threads/phase-linear-bridging-information-using-triad-g-336-transformer.12173/

Here is a link to my recent post on the Triad G-336 transformer: https://forums.phxaudiotape.com/threads/phase-linear-bridging-information-using-triad-g-336-transformer.12173/

I have gathered up some historical information concerning the Triad G-336 transformer. There were several Phase Linear service bulletins issued (one has been previously posted on this forum) as well as a couple Triad documents. Also included is a photo of a G-336 transformer I acquired a...

I don't know what the original intent for the Cerwin Vega A-2800 was. I am curious what the B+ and B- voltage rails were and if the amp was a bridge amp.

Ron, Here are some pictures of an Cerwin Vega A-2800 mono-block power amplifier I found on the internet. The amplifier used a total of (16) GM/Delco DTS-411 transistors. NOTE: Many are already aware that the GM/Delco DTS-411 transistors were also used by Phase Linear (in their 400's and 700...

The AI-sphere can't be trusted. The copy of the RCA410 datasheet from 11/1973 like the one you posted is the earliest one I can find so far in all the documents I have gone through. "Simultaneous and nearly independent developments by GM's Delco Radio division and Motorola led to the widely...

Most likely the "D" in DTS does stand for Delco. Therefore: DTS is Delco, Transistor, Silicon. Likewise DTG is Delco, Transistor, Germanium and DRS is Delco, Rectifier, Silicon. By the way, A number of other manufacturer's made a similar transistor to the Delco DTS411 (introduced in March...

I stayed in touch with Lee over the years and we talked occasionally by phone whenever he had a question for me. The last few years have been interesting. I've been very busy. I've sold many pieces of test equipment and bought a number of others. Along the way, I've learned so much more...

In the case of the Fairchild FPL909's, the (3) digit date code "722", the first number indicates the year 1977 and the 2nd and 3rd numbers indicate the 22nd week of that year. The FPL909 is a Fairchild FT411. Similar to Delco DTS411's (Phase Linear PL909's and XPL909's), Motorola MJ411's...

According to my old Phase Linear employee list his name name is Xich Bui.

I was on the phone a couple days ago with a gentlemen in the Seattle area who I knew about decades ago but never talked to previously. He said that the coffee can amplifier did exist. He stated that he had a repair shop in the late 60's and early 70's and Bob would stop by his shop because Bob...

At Lee’s request, I am providing this post. NOTE: I have been away from this forum for almost a year. I wonder who the Phase Linear employee was that built the amp? I know a Gary C, Gary K and there were several Charles (Chuck’s) at Phase Linear. Most likely it was built up from parts that...

Don, Most people have no idea how much grief I got from Dean over the 25+ years I worked with him when I replaced the XPL909's, FPL909's, etc with MJ15024 (and later MJ21196) output transistors in series 1 amplifiers. He hated dealing with the oscillations that they created and in some...

Glen, I was asked many years ago either on this forum or elsewhere to post some schematics for the fully comp 700 series two amplifier. I hesitated at that time because I knew there were some errors in the schematics and that some debate would follow. Most notably is the inclusion of the fly...

As you already know, the 200 series 1 service manual appears to be lacking some details in the meter sensitivity section. I will post it here for others to see. Step #20 Apply enough input signal (2K Hz) to the left channel so that the -12 dB LED comes on, with the meter sensitivity switch on...

The DC offset spec in the Phase Linear 700 service manual (for serial numbers 0 thru 773-200) stated: "using a voltmeter, adjust the offset controls so that the meter indicates 0 (zero) volts at the speaker terminals between hot and ground. The controls are readily adjusted simply by using the...

The Phase Linear 700 (Edmonds Washington version of the) owners manual states: INPUTS "... the Phase Linear 700 is equipped with direct coupled inputs as well as normal coupled inputs. For high fidelity reproduction, the "normal" coupled inputs are to be used. The normal inputs provided...