Echo Dek Tape Delay Preamp Section

[pete_g]

Hi dudes. With the successful help of extracting the preamp schematic from a Univox EC-80 tape delay and building it, I love the sound of the preamp on my 1970's Echo Dek Delay. Can you please circle the cut off point of this preamp? Or just let me know what end of the resistor and cap would go to a pot and out. All help is appreciated

[pete_g]

[antonis]

[pete_g]

Does it cut where the 3k and 10k resistor meet (at the top) as I don't need the power section and will run it on 9v? Thanks

[antonis]

Quite right..

You may need to recalculate 3k value for affordable voltage drop or even delete it (if you're sure about your power supply good regulation)

IMHO, a value of 100R should be OK..
(about 8Hz cut-off frequency with 200μF cap..)

Also, dependent on BJTs used, you might need to either raise Q2 Collector resistor by 50% or lower Q1 Collector resistor by the same anount or even raise feedback resistor by 50% (give or take..)
(e.g. 10k -> 15k or 150k -> 82k or 250k -> 390k )

Or any incremental combination of the above mentioned..
(e.g. 10k -> 12k + 150k -> 100k + 250k -> 270k, etc.)