YEAR END SPECIAL SALE PRICE Thank you for checking out my ad. A Christmas Special Sale for this outstanding sounding RH84, Single ended EL84 stereo amplifier. Have you seen what some companies are selling their version of the RH84? One company based in NYC is selling a fancy model for 1400! Sure it has a very nice wood cabinet but how much does that add to the sound quality? You can save 1000.00 and get a better quality amp by buying this one. Please read on. This stereo, 2 channel amp is built with a top quality power supply which is the secret to excellent sound. After all, it is the power supply which is required to have the flexibility and current capability to supply the valves with voltage and current so they can exactly modulate the input signal and amplify it to the sound that emanates from your speakers. It all starts with the power transformer in this amp a vintage Stancor unit.
CLC POWER SUPPLY
From this foundation I have added an CLC, film cap, inductor, film capacitor power supply filter. This CLC power supply results in negligible AC ripple in the DC voltages. The first capacitor is a Solen 22uf followed by a Stancor 8H choke, and finally 80uf of film capacitance. The use of all film capacitors while many times more expensive than generic electrolytic capacitor, makes for a extremely fast, uncolored, and dynamic sound.
TUBE ROLLERS DELIGHT! Tube rolling is fun and easy with just a total of 4 tubes to change. In a single ended amp with so few parts in the signal chain, the "audio finger print" of each component is readily evident. Thus, the effect of the tubes are most important and no power tube matching is necessary. I have tried Mullard and Telefunken input and output tubes. I prefer Telefunken for women's vocals and Mullard for Classic music. RCA black plates are just the ticket for rock and roll. The Russian 6p14p is no slouch and is a perfect all round performer.
For the input tube the classic Euro tubes are at the head of the class with the Mullard CV4024 milspec 12AT7 sounding excellent in an all Mullard tube line up.. I have also rolled the RCA 12AT7WA which holds its own against the Euros. SOUND QUALITY One of the important attributes of a single ended amplifier is coherency which is the overall balanced sound of the amp. All the instruments and voices have a very realistic quality and occupy their own space in the soundstage. This is the sound that all audio amps strive for and I believe this amp will get you very close to it without requiring a second mortgage. I have just sold another RH84 which is very similar to this unit except this model is made with better sounding film capacitors in the main power supply. POINT TO POINT WIRING This is not a quick and dirty build! More time consuming but more reliable and better sounding point to point wiring of all components is used. This construction method allows ease in maintenance and modifications when that is required.
ALL NEW COMPONENTS
To improve appearance and reliability the amp has been out fitted with all new input and output jacks, new AC power inlet, on/off switch and fuse. The resistors are metal film and coupling caps are expensive EFCON which was originally used in military equipment.
In this iteration, the all important power supply, CLC (capacitor, inductor, capacitor) uses expensive film capacitors. Another big plus for using film capacitors in the power supply is that they last a lifetime. No electrolytics in the power supply makes the amp faster and more dynamic. And besides this, all the brand new components in the amp are hardwired, point to point, and still breaking in.
CLASS A TUBE OPERATION The power tubes are operating in class A with cathode bias. The cathode bias is stabilized with CCS which results in improvement in the bass. This little amp has amazing sound quality equal to or better than other SE EL84 amps such as Decware at WAY LESS THAN HALF THE PRICE! Operating in Single Ended Pentode Class A with ultra short signal path for minimal alteration of the sound.
The output tube is a single EL84 per channel (brand new Russian 6p14p) with a 12AT7 driver tube. The circuit design is by Alex Kittic and has been copied by thousands of DIY'ers all over the world. The unique aspect of this design is the use of "local feedback" vs. "global negative feedback" that is used in almost all other audio amplifiers. The use of local fb bypasses many of the ills of "global negative feedback" which requires compensation networks to reduce phase problems. This and an excellent sounding tube combination makes for an superb sounding single ended amplifer. This is the seventh RH84 amp that I have built and they all sound excellent, but truthfully, the all film cap power supply makes this amp a notch above the rest. If you have not heard a Single Ended tube amp you are in for a treat. The only issue is the need for some efficient speakers like JBL or Altec Lansing, or Klipsch. For this build, a Zenith console amplifier from the 1960s with their superb quality output and power transformers were used. Only the chassis, power and output transformers are reused. All other parts are brand new top quality capacitors, resistors, wires, etc. Thank you for reading thru the entire text and do not hesitate to email me if you have any other questions.
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