Echoplex EP-3 EP-4 serial numbers

[Tazin]

TIS58 because it is a JFET the drain and source can be interchanged
it is the gate or base that if hooked up wrong that would be an issue.

There are some obsolete electronic suppliers still sitting on stock of these transistors even though they are no longer being made.

**EDIT- I just checked mine, all 3 on that board are flat side facing left

Eric, from what you posted, you prefer the brighter sound EP3..correct??

Thanks T.J. I never knew the Drain and Source could be interchanged....I learn something new everyday.

[rgorke]

For giggles, I checked the date codes on the pots in my EP-3. The serial number is 146XX and the pot codes are 1377306. So, that would put my EP-3 at early to mid 1973, I think.

[Tone-Freak]

I have two EP3's the first one has a dark base plate and serial number 9872 pot code 1377134 which makes it 34th week of 71. My second one ser# 17910 pot code 1377335 which makes it 37th week of 73 and it has a much lighter base plate. The early one with the dark base plate sounds darker and much better.

[leadguy]

The EP-3 had a small "Maestro" badge from the early 1970s until 1977 and then the EP-3 badge was changed to a wider "Maestro Echoplex" badge which continued from 1977 until 1979 and then the EP-3 badge was changed to a small "Echoplex" badge which continued from 1979.

The EP-4 was introduced in 1977 and had the same wider "Maestro Echoplex" badge as the EP-3 did from 1977 until 1979.
The EP-4 was introduced with the wider "Maestro Echoplex" badge in early 1977 and the EP-3 badge was also changed at the same time of the EP-4 introduction to be in synchronisation with the EP-4 badge.

The EP-4 had a wider "Maestro Echoplex" badge which continued from early 1977 until 1979 and then the EP-4 badge was changed to a small "Echoplex" badge which continued from 1979.

The EP-3 and EP-4 were both offered for sale from 1977 onwards.
The EP-4 did not replace the EP-3.

The EP-3 and the EP-4 from early 1977 had a compressor board installed for a short time and then the compressor board on the EP-3 and EP-4 was discontinued.

[musicmomma]

I have a 1973-1974 Maestro Echoplex EP 3 with serial number 18258 for sale if anyone is interested. I had it at the music store this morning and checked out. Nice condition. Everything seems to be working properly.

[JimmyLZ]

Hi.
Does anybody have any idea about how the echoplex was wired in Jimmy Page gear on "The Song Remains The Same" stage ???

Thank you all in advance!