a superb, heavily modified high gain amp from rat electronics.
tri- rectifier, opr (power scaling),3 x bias, 2 x gain stages, standby,variable boost f/s, speaker emulated line out.
fitted with jj tubes and a philips nos rectifier
selling due to the unexpected (and heartily welcomed)arrival of a fender hot-rod deluxe.
The amp cost me 450 and is in A1 condition
Interested in guitar trades, tele, archtop or something else maybe
The following is taken from the rat electronics website
Before I can start any Hot Rod work, I have to clean up the Buzz and Hum Issues, which is not easy. Once that is done, the Amp is Superb, and Wide Open to some Great Modifications. The Addition of ‘OPR’ and ‘OPR-1+2’ Allows the Amp to be used in any environment, From your Bedroom to the Stage.
1. 'OPR' - Output Power Reduction. This is the Business and essential for an Amplifier used in the Home. I Have tried ALL of the other systems that claim to Reduce the Volume without changing the Tone - 'OPR' really works.
2. 'OPR-1+2 - - -This Dual Function Switch allows two Distinctly Different Sounds when the Main 'OPR' Control is in Use - 'OPR-1'....Maintains the High Harmonic Content in the Final Sound - 'OPR-2'....Is Much Softer and Cleaner Sounding. Most 'RAT' Amps are Fitted with ‘OPR-1+2’ as Standard.
3. 'TRI' Rectifiers - This Option uses a Three Position Switch and a 'GZ34' Valve Rectifier, It Integrates Seamlessly into the BH15H Circuit and offers 3 different types of Rectification. Position 1= Standard Silicon Diodes - Position 2= V1, 'GZ34' Valve Running at Half Power, This gives Maximum 'SAG' - Position 3=V2, 'GZ34' Valve running at Full Power, Offers Reduced 'SAG' but maintains the Classic Vintage Valve Rectifier 'Feel'.
4. The Gain Structure of the Amp has been Changed so that you can get some Nice 'Cleans' if that is what you want -or- Turn it all the Way up for a Real 'Gain Monster'. The Gain can be Switched to one of two Modes. (1) Normal Mode - This is Stock 'Slightly Hot' Gain. (2) High Gain - Sets the Preamp up for Maximum Gain and Turns the Amp into a Beast.
5.Because of the Hum and Buzz Problems, I have to Remove all of the Rotary Controls from the PCB. The Stock Controls (Pots) are OK Quality but just to be sure, I replace them with Bigger '24mm Alpha Parts', 'Orange Drop' and 'Silver Mica' Tone Capacitors, then 'Hand Wire' them back into the Amp Chassis. I Totally 'Re-Build' the Tone Stack - it can Completely Remove the 'Treble', 'Middle' or 'Bass' from the Signal (if required) - It Now Replicates a 'Fender Twin Reverb' in Operation.
6. Tone Bypass and Variable Boost Footswitch - A Switch on the Front Panel of the Amp enables the 'Tone Bypass'. This Gives the Amp 'Monster' Gain and Works in Conjunction with Footswitch. When the Footswitch is connected to the Rear Panel of the Amp, the Tone Bypass Switch is Disabled. The Footswitch has a Built-In Variable Gain Control. You can set just how much Gain you want with the Rotary Control located near the Push-Button On/Off Switch. It Works Great and Gives you that extra 'Kick' when Needed. A Red LED Illuminates when 'Boost' is Selected. There is a Trade-off when using the Variable Boost. The Higher the Boost is set - the Less Effective the Tone Controls Are. In Practice this is not a Problem because at 'Full Boost' the Tone Network is 'Flat' and allows the 'Mids' to Cut Through Nicely.
8. Line Out
9. 2 x Speaker Outputs and Impedance Select - The Output Transformer offers individual Speaker Outputs of 4, 8 and 16 Ohms. The Stock Speaker Outputs are Very Confusing and you can easily make a Mistake connecting your Speaker/s. The 'RAT' Setup is Simple and Straightforward to use - Connect a Speaker or Speakers and select the Correct Impedance - Done. Fitted to all ‘RAT’ Amps.
10. There are Several 'Other' Modifications that I do to All of my Amps that are Exclusive to me and both Enhance Performance and Help to Keep the Noise Levels Way Down.
The Background 'Noise' from the ‘BH15’ Amp is now so Low, you may not notice it is Switched on.
Last edited by wurzel; 26th October 2012 at 12:25 PM.