This is my latest single ended amp build. It has a circuit design by noted audiophile and inimitable solder slinger "Keggar" who tragically passed away and we will all miss his insightful contributions. His circuit is a riff of the RH Universal circuit, with some component changes to optimize the tube line up. Speaking of that this is a CUSTOM, HAND MADE and POINT TO POINT WIRED (no circuit boards) 6L6 powered with 6SL7 driver SINGLE ENDED stereo tube amplifier on a very nice chrome chassis. The sound from one of these single ended amps is truly amazing. Here is the latest testimonials from a buyer of another 6l6 SE RH amp.
Rudy from Texas wrote back; "did the quickest setup for me. am listening to youtube videos on roku. optical out from TV to teradak NOS dac to audionote one pre-amp to your amp. old audioquest emerald interconnects. clear day speaker wires (thin guage solid wire (silver, I think) to 1970's klipsch heritage speakers ( I have had for more than 10 years, don't think they have ever been opened)
the sound is amazing! the amp and speakers disappear. getting the same feeling I had when first listened to audionote meishu. I know my audio memory is fleeting but difficult to say what difference there is between these tubes and 300B. have heard push pull el 34 amps before but this is way different, and way better. acoustic piano and bass sound exceptional"
The PRICE INCLUDES;
2 USA 1950s 6L6 metal tubes that test like new, complemented with a classic RCA 6SL7GT, and a very reliable GE 5V4GA for the all important AC to DC vacuum tube rectification. The use of a 5v4ga allows a slow advance of the amplifier voltages which is a good thing. To make this an even better bargain i will include 2 USA made 6v6gt power tubes, PLUS 2 more 6sl7 and a 5Y3 rectifier to go with the 6V6 for a more enjoyable tube rolling experience. All together almost 200.00 in tubes when purchased seperately. That makes the cost of this custom made , point to point wired, amp and even better bargain at 650.00. If you are familiar with tube amplifiers you know that custom made amps cost in the thousands, not hundreds of dollars.
This amp is not a quick and dirty hack job. It has all new capacitors , resistors, wiring, sockets, input and output jacks and paint job. The only parts that have been reused and recycled (to save you money, but not quality!) is the power transformer and chokes and the chassis. The amp has modern convenience and safety features such as on/off switch, 2 amp fuse, safety capacitors on the AC input, and gold plated 5 way speaker binding posts and rca input jacks. So, essentially, the amp has been totally rebuilt with all new parts and is very much a new amp.
A short word about sound quality from a single ended amp. If I would have to give one word it would be INVOLVING. It has the ability to draw you into the music. Voices and instruments are suspended out from the speakers and seem to be playing a personal concert just for you. It is this ability that all high end amplifiers aspire to. What sets Single ended tube amps, whether they use very expensive triodes like a 300B or 845 or even a 2A3, or if they use classic pentodes like 6V6, EL84, 6L6, 6550, KT88, EL34, etc. is the uncanny ability to achieve a very realistic sound presentation. Voices, instruments, sound effects, have an uncanny you are there quality that can evoke a genuine emotional response to the music. This aspect of home audio is usually available only in big bucks audiophile systems. This amp has the ability to do this at a fraction of the price of the name brands. Please read on for more details about how this is accomplished.
The all important tube circuit is a design that was developed by Alex Kitic of the famed RH amp. I have just sold another similarly designed RH84 except this model is made with better sounding film capacitors in the main power supply. Indeed, I have built 10 RH type amps and have sold 7 of them to very happy listeners. In fact one buyer has bought 2 RH84 amps from me. This circuit design 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. I have made more than 10 RH type amps and they all sound excellent, but truthfully, the all film cap power supply makes this amp a notch above the rest.
Single Ended Tube Amplifiers explained. Very, very, briefly the signal goes into the 6sl7 is amplified, then goes into the power 6L6 tube which increases the signal to about 8 watts and then it passes into the output transformer which then turns the high voltage into high current for the speakers. This simple circuit therefore has minimal influence on adding or subtracting from the original signal source. The result is a much more dynamic and visceral, for a "you are there" audio experience.
In this iteration, the all important power supply, CLCLC ( capacitor, inductor, capacitor, inductor, capacitor) uses expensive film capacitors instead of cheap generic electrolytic capacitors. These are Panasonic DC Link (the rectangular box) and Solen film capacitors ( they are 3 black cylinders on the underside of the chassis pics). The yellow colored capacitors are also of the film type. The 2 inductors are vintage units made in the USA by Stancor and Chicago Transformer. Why use old school inductors? Simply because they are reliable, dependable and sound better. After all it is just a big spool of wire around a stack of steel plates.
A 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. Check the pics of the underside showing the meticulous, time consuming point to point wiring, and the high quality capacitors and resistors.
The power tubes are operating in class A with cathode bias for about 7 to 8 watts of super clean sound. The cathode bias is achieved with a 226 ohm wirewound resistor bypassed with an excellent sounding Panasonic capacitor, which is further bypassed with a film cap. This little amp has amazing sound quality equal to or better than other SE amps such as Decware at less than half the price! Operating in Single Ended Pentode Class A with ultra short signal path for minimal alteration of the sound.
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. This amp plays extremely loud on my Altec 19 speakers of 100db efficiency and sounds amazing on my JBL L112 speakers which are 91db efficient.
The amp is very quiet on the JBL with no extraneous sounds emanating from the speakers but just a little buzz on the Altecs. You have not heard audiophile sound until you have heard a single ended tube amp. These amps have the ability to transport you into the music. Your recordings will sound like they never have, with heretofore, unheard of elements coming to the fore. The kick drum is thumping in your gut, cymbals have that metallic bite and reverberation and the vocalist sounds like she is standing in your room for a personal concert! In other words each element in the sound track has its own space. Truly, audiophile quality amplification at a beer budget price.
Don't let its small size fool you as the saying goes, great things come in small packages Thank you, for reading the complete text and visiting my sale.
Please remember that this amp is sold strictly as is. Caution is required as tubes are hot and there is no bottom cover to the amplifier. Just remember if you are into headbanging, window rattling, neighbors phoning the police, loudness, this amp is definitely not your cup of tea. But if you are looking for a great sounding little amp for your den or bedroom this will make a Bose sound like pocket transistor radio in comparison and probably cost less and have a better resale value. Although this amp is built to extremely high standards and with the utmost of care it is sold strictly as is. Thank you very much for reading my ad.
TAGS; single ended triode, set, 2a3, western electric, 300b, altec lansing, jbl, mcintosh, dynaco, dyna, marantz, heathkit, heath, fisher, EICO, vacuum tube, tubed stereo, valves, fender, gibson, audiophile, 12ax7, 6L6, 6BQ5, EL84.