A 6N7 preamp with remote

The now converted 01a preamp is now a RCA - NOS NIB - 6N7. The tube is metal (No!) so not much of a glow and is a dual triode with single cathode. The tubes are wired as a single triode with grids and plates paralleled. 
 

This preamp was designed for me many years back and was originally built into a timber box as “Heavy Metal”. It had heat issues. In the better and classier chassis looks retro and business like. With Alps Blue Velvet remote pot. 
 

I required 0.68uf output caps but had none of that value. But did have four 0.33uf Sprague orange drops. Doubled them up for a near enough 0.66uf. Had them for decades, as the tubes, so time to use them. Most 1W carbon film resistors and some metal film and wire wound. Double Pi HT filtration - 300uf total. 
 

DC on heaters, 260V HT and 2.55V bias. All on point. Gain should be 20db with Rk un-bypassed. 

 

Tubes are run in but the rest new so some complete burn in time required. Sounding relaxed and midrangy with voice a standout from the sound stage. Dead quiet operation with retro-Zen EL34 amp but hummed with my latest EL34 amp. Very happy so far. 

“Perspective” - EL34 Single End Ultra-linear power amp

 

This amp is based on a pair of new Mullard reissue matched EL34s with a universal driver tube. Any 12A*7 can be used as a driver. OPTs are Asian 3.5K 10W with 4 and 8 ohm taps. I have used the 5W 5K versions in other amps with outstanding results. The OPTs and power trannies are shock mounted on split rubber grommets to reduce resonance.  The PS is external with over specced Hammond power tranni. A Sylvania 5U4GB handles rectification. 357uf of filter caps smooth and store 366V of HT. Further filtering feeds the driver tube with a 4uf PIO cap and 2.5K 2W resistor. The amp is very, very quiet. 

Filament current is rectified with a 10A bridge and single Pi filtering - 9400uf of filtration. HT and filament caps are snubbed with 0.1uf polies to reduce noise. The chassis is a Hammond wood cheek and is made of steel for strength. The finish is black stipple. The chassis for the PS is cast Al with a black epoxy enamel finish. The PS is fused and earthed. 

RCAs are Paladium plated and speaker posts solid brass with gold plate. Audio path wiring is fine silver plated copper wire. All wiring is point-2-point, no cct. brds. and no shielded wire. Not required. Sockets are ceramic and power is brought to the amp via three pin large XLR connection. The driver tube being used here is a Tung-Sol ECC803S gold pin. 6L6 and KT88 can be rolled here and any 12AX7 equiv. can also be rolled. 

Amp presents full bass and a complex warm soundstage with smooth highs. It is a pure Class A amp. Not only good looking but excellent sounding and definitely worth the weeks of work. The EL34s I’ve had for twenty years so now they get to entertain as they are designed to do. 

“retro-Zen” Decware inspired 6BQ5/EL84 triode strapped amp

 

A Decware inspired 6BQ5/EL84 (Zen) triode strapped amp with attenuator. Driver is 6N1P. And of course chicken beak knob with AWV 6BQ5.

OPTs are 5W Asian sourced which I and others have used and find excellent. They are shock mounted on split rubber grommets for HF/resonance suppression. Sockets are ceramic and gold plated with Visheys MKP interstage caps. Hookup wire is Cat5 solid core. 

External PS has a Sylvania 5U4GB and works with two other power amps saving me $400 each amp. But if I sell one ill have to make another PS. Power tranni is Hammond. Chassis is a cast Al with Epoxy Enamel paint. This is meant to be a fun amp, single input and just 2.5W. Good den amp or desktop amp. For good level music listening you need speakers with better the 90db sensitivity.

“Hegemony” - 6L6 monoblocks.

 

I was asked to build 6L6 monoblocks for a very keen tube collector. He would provide the tubes and I would build the amps. Monoblocks are almost double the work with two power trannies and filtering circuits. The requirements were also to use Silk OPTs from Thailand. I chose 20W models for a 5W amp. Interstage caps are Mundorf Evo oils. RCAs are Palladium.

These austere looking smart amps produce deep articulated bass, grounded detailed and rich midrange and crisp highs. Chassis are Hammond steel with wood cheeks and are difficult to drill but worth the effort. Hammond power trannies and 300uf of filtering in a double Pi config produce a very low noise (1.5mV) amp which plays plenty loud. Definitely one of my better and more expensive builds. You are rewarded, though, with an exceptional audio experience. 

“Rhetoric” - EAR834p MM phono stage

EAR834p MM phono stage in a Hammond wood cheek. External PS with Hammond tranni. DC on the heaters and the HT is electronically smoothed. Palladium and copper RCAs, and fine copper silver plated hookup wire. Im not supplying tubes but here Ratheon 12AU7 and two Mullard 12AX7 re-issues. 

“Elements” - 12AX7 SRPP preamp with remote

 

Built mainly from parts on hand including tubes (Gold Lion), enclosures, output caps and power tranni. The power tranni I got free because the filament windings were open. I had a 12V tranni on hand and was used here for heater voltage. 

Three inputs and Alps remote volume control with RFI/EMI filter in the external PS. Russian military metal clad output caps in a Hammond extruded anodised Al enclosure with a big gold knob make this a smart looking build. Brilliant sounding as well as smart looking, a great use for so many parts which had remained unused. 

“Aspire” - Psvane 6SN7 globe preamp

 

After checking the expensive tubes of one of my preamps I'd sold to another one came up bad. I purchased the one good tube and helped the owner acquire replacements. I had a few parts on hand including the enclosure, most passive parts, ceramic socket, remote control Alps pot and the power tranni. Inverting the enclosure made assembly much easier and after some masking I sprayed back and top for good visual effect. The front is a natural silver frost, untouched.  

A mix of carbon and metal film make the resistive compliment and 5W wire wounds on the 4XPi HT filter. Two 1A diodes rectify the HT then 350uf of high voltage caps do the smoothing and storage. Cathode bi-pass caps are NP types and are bi-passed by 0.1uf polies.  Output caps are high grade audio polies and always sound excellent. Three inputs can be switched from the front and the preamp is silent in operation. Hookup wire is fine silver plated copper wire and WBT silver solder is used in the signal path. As always with these retro looking sphere/globe 6SN7s the sound is full bodies and transparent. Yet another well performing simple tube preamp and a good used of parts I've had for way too long. 

"Clarity II" - LJM Class AB power amp

 

This was a slow burn build. I had completed the amp section but no PS. After completing two commission jobs I could finally complete the amp. The compact enclosure for the amp was built around two heatsinks I had had for years and the enclosure for the PS the same. Caps standing out of the top of the PS I was given years ago and are Nippon Chemi-com. Total capacitance is not large but is well snubbed and the amp is quiet.

Two fast diodes provide rectification and four 3.3uf polies snub the bigger caps which are 3900uf each. Tranni is 160VA so the amp is capable of 80Wpc. The LJM Class AB modules used are rate 120W and are all bipolars. I like the sound of bipolar transistors and these modules contain nothing else and are very inexpensive. 

A local metals provider cut the plates for the amp to my specs and after a lot of drilling and tapping came together well. Three large gold plated brass cones balance the amp and add to the looks and improves the sound. An umbilical cord connects PS and amp using a large XLR connection. DC offset for these modules does not require adjustment and is extremely low.

The sound is super clear, detailed and expansive. Bass extends just beyond 30Hz the limit of my speakers. Regardless of type of music played it comes through, clear and uncluttered. After hours of listening the amp is still cold. I believe the amp would have no problems driving low efficiency difficult speakers. Very pleased with both the looks and the sound. 

German made EL3N - “Puissance” - triode strapped amp

 This time with a German made EL3N NOS NIB, new Svetlana 6N1P and Sylvania 5U4GB NOS NIB.

Interstage caps are Mundorf Supremes which I have used in a number of amps. Big and expensive but sound good. Hammond power tranni and Asian OPTs. The OPTs were meant to have the UL tap but didn’t. This amp then is triode strapped. Base is heavy and of blonde fine grain timber. Top plate is 2mm Al.

The EL3N sockets are made in Japan and are CNCed from a block of teflon with phosphor bronze contacts. Again expensive. PS is double Pi with 247uf of caps and a 5H choke. Total current drain is low and just over 20mA. The sound is big and warm with lots of drive. Though triode strapped it sounds very similar to my French tube SE UL version

6N3 + TDA7294 integrated amp.

A completed tube and chip integrated. Fast and crisp. Absolutely dead, dead quiet thanks to CMRR. 80Wpc, 300VA power tranni, choked power cord, rodium RCAs, RFI/EMI power filter, heavy duty speaker binding posts and 2U 19” rack mount. At the members request a low filter switchable cut of 6db at 150hZ. Also a 24 step step attenuator.