Ampeg Style B-15 / B-15N Vacuum TubeBass Preamp Prototype
This bass preamp module contains thevintage preamp section from a 1968 Ampeq B15N. The preamp is allhand-wired on a vintage style turret board layout. It includes a HighVoltage Internal Power supply to give real tube sound.
This preamp was built to give theclassic Ampeg B15 sound that can be sent into a higher power solidstate amplifier (the original B-15 was only 20 Watts). It uses aminiature 9 pin preamp tube (12AX7 installed, 5751 matches B-15specs) to amplify the incoming signal by 36 dBu (63 times greaterthan the input).
This is a preamp module. It will NOTdrive speakers without a power amp!
One interested er asked me if this can be used as recording. I gave it a shot through some hobby equipmentEpiphone Les Paul Jr w/ GFS P90 pickup -> Ampeg B-15N preamp module -> Active D.I. Box w/ ground lift-> Fostex MR-8 MIC input and it gave really nice results.
Please see Disclaimers below forimportant usage and safety information.
Front Panel Features:
- Power Switch with on/off label
- Power Indicator Lamp
- Master Volume with mute switch
- Treble Control with Ultra switch
- Bass Control with Ultra switch
- Gain Control
- 1/4” Normal Input
- 1/4” -10dB Input for Active Basspickups ( with switch to enable “Bright“ mode )
Rear Panel Features:
- 5 foot 3-prong power cord for 120VACoperation
- 1/4” Preamp output jack
Component Features:
- Sovtek 7027/12AX7WA 9-pin miniaturepreamp tube
-Allied Electronics High Voltage PowerTransformer
-Xicon Round Amber Indicator Lamp
-Mallory 150 series poly film/foil andMicah Film coupling (signal) capacitors
-Alpha 24mm Potentiometers
-Black Chicken-head style set screwpointer knobs with white indicator line
-½ Watt Carbon film resistors inhigh-voltage preamp section
-Small-bat switches to prevent accidentswitching
-Neutrik 1/4” jacks with Chrome Bezel
-Hammond 13.5” x 2” x 5” AluminumChassis with Steel bottom plate
Disclaimer: I have tested this preampthrough a 200W 12” Active PA cabinet and it seems to work well withmy guitar (sorry don\'t own a bass!) I have not taken the time to testthis in every audio situation. Because of this, the preamp is beingsold “as is” with no warranties. Because this is essentially halfof a tube amplifier it would be best suited running straight into aVacuum tube power amplifier. I have found that running the preampinto a direct box w/ switchable ground lift helps tame any impedancemismatches with modern audio equipment, especially if there areground loop problems within the system (I have only tested an Activedirect box).
Disclaimer: This preamp contains highvoltages in excess of 300 Volts DC. This is to run the tube in itstrue operating mode. This preamp is only serviceable by techniciansqualified to work on such high voltage and is not user serviceable. Iknow its cool, but please don\'t open it to look at it and especially don\'t put your fingers in it!
Item is sold “As Is” with noWarranties. No Returns. Seller is not responsible for any harm causedby ignoring safety disclaimers and opening this module.
