“Empire” - my super F5

The last and possibly the best F5 ever. There was another F5 which also appeared to exceed the others with performance. It also had the Mundorf MLytic audio grade caps. In this build I increased the filter caps to 132,000uf and upped the power tranni to 300VA. Keeping the Cat5 solid core twisted pair for hookup wire and the standard compact enclosure. This build is very similar to the others with the filter caps well snubbed with larger and small poly caps. 

The BIG difference here is the use of 1W carbon film resistors. The Jim's kit comes with Fishey and Dale resistors which normally I would use. Not this time. Also this Jim's board, like the build before, uses his double weight brd. with two 100uf Elnas on board and other components. The sound is hyper 3D and incredibly transparent with extended deep bass and startling dynamics. The whole sound is one of earthiness and richness. The use of carbon film is a controversial one. All negative comments about the use of carbon film Rs come from those who have never used them in a build or/and have never heard them. I like to buck the trend especially when I know what I build will exceed what others can contemplate. And exceed in performance.

“Mimic-Magic” - MM phono stage

 

Yet another Mimic and this time combining all the components I thought have sounded good in other Mimics. That’s what makes it “Magic”. Another in these more hobby looking enclosures mainly because I had them on hand. 1/4W carbon film resistors, PIO output caps, MKP and poly caps and the same OPA2134 chip as in all Mimics. Smooth and warm sounding with my Garrett P77i. 

“Mundor/F5” - Pass F5 inspired with advanced boards

 

I was vey impressed with last F5 I built using Jim Audio boards. The amp sold before a I could start construction. The build was a big step up from the F5 before by upgrading the filter caps to 88,000uf of Mundorf MLytics and the toroid tranni upgrade from 160W to 300W. The total presentation of that amp was beguiling.

Here is my build based on what I thought maybe the best amp I have ever heard. Ounce more 88,000uf of Mundorf MLytics audio grade caps at over $300 for caps alone. Same upgraded Jims brds. and as before all Cat5 twisted pair hookup wire. This amp shines. Given the right music you are challenged to think something so compact and unassuming can generate such presentation. It’s a 25W Class A simple amp. Bass goes easy to 30Hz, mids are transparent and treble clean and controlled. Compact and astounding. 

“3D” - Three channel Class D amplifier

 

I completed a three channel Class D power amp for another SNA member. 1X 150W and 2X 180W Tripath amp modules, 500W PS with Mundorf MLytic caps - 2X 22,000uf and EVO oils on the input. I sent the amp off without taking any images and had to ask the new owner for a few picks.

"Shadow" - SRPP 12AX7WA Sovtek preamp

 

Just finished this compact tube preamp with Sovtek NOS NIB 7025 (12AX7WA). Again on a jiffy box - “Shadow” - this time is an ironstone epoxy enamel finish. All metal film Rs and PIO output caps with silver plated fine copper hookup wire. Two inputs. SRPP topology. External PS is a Radi0kit kit for 12V and  250V DC. The preamp is absolutely dead quiet. No snap, crackle or pop.

"Shu" - CV-181-Z and Golden Dragon preamp

 

For quite a number of tube preamp builds of late I have been using SS rectification. Coming across a new Golden Dragon 5U4 rec tube and new Shuguang CV-181-Z (6SN7) dual triode in my stash changed all that. Most of my builds of late have been SRPP but I started with single stage tube preamps. Time to revisit that and time to revisit tube rectification. You have to have a power tranni which will support a 5V filament at sufficient current for the rec tube and also have sufficient high voltage current support. The Hammond tranni I had hand on hand for many years (and this includes how long I have had the tubes) will do the job easy. In a big push through these many lockdowns to use up expensive parts in "da lab" and even having the cast Al chassis I knew I should go ahead.

Epoxy enameled sprayed cast Al enclosure with Hammond power tranni and heavy rubber feet makes a good start. Ceramic tubes sockets, silver plate fine copper wire in the signal path and a Pi X 4 filtration PS make the basis for a great tube preamp. I could have used some stock metalised poly output caps but I ordered Mundorf EVO oils for the output. Glad I did. The PS is CRCRCRC with the final cap a 4uf PIO. All filter caps are snubbed. 

Two selectable inputs and one out. Silver soldered signal path with fine silver plated wire and all carbon film resistors plus the excellent 50 Year Treasure ceramic based and gold pinned tube (CV-181-Z) make for real good music. Rich, smooth and soulful. 

"Priory" - tube Headphone amp

 

From the COVID lockdown last year I made a real push to use as many parts I had on hand as I could to build them into working pieces of sonic art as possible. Not just cheap passive parts but expensive tubes and transformers. I had two Hammond low power high voltage trannies, a Svetlana 6AS7 and cheapy 12AU7 plus a beautiful base and most other parts to build either a preamp or a tube headphone (HP)  amp. Take a look at what I decided.

This is the seventh tube HP amp I have built. This includes three Bottlehead amps for others from kits. This excellent build includes;- A beautiful Cypress base, Hammond power tranni, Svetlana 6AS7, Alps Blue Velvet pot and 4oz gold plated knob, very low noise SS rectification and 330uf of storage capacitance plus a 5H Hammond choke. Not only is the double Pi PS choked but has Ultra fast/Soft recovery diodes. All components in the PS are fully snubbed with poly caps. The amp is super quiet.

Of course all point-2-point wiring and no shielded wire or PCBs. All signal wire is solid core Cat5 copper. WBT silver solder used throughout. Only one capacitor in the whole signal path as the 12AU7 driver tube and the power tube are directly connected. To get that extra deep "full" sound I used 1W carbon film resistors. Every time I have used carbon Rs in any build I always get a richer warmer sound. Its the same here. 

This HP amp produces the most textural, deepest warm sound I have heard in my HP amps to date. Reverb just extends for ever. And to think the passive components are very basic. But there ae some tweaks - the 400uf output NP cap has a 0.1uf Russian PIO cap snubbing (or by-passing) it. Every electrolytic has a poly subbing it. The amp is dead quiet, only the music gets through. 

"Cadence" - SRPP 6SN7 Preamp

 

After building yet another SRPP 6SN7 preamp for another, who had his onw tubes, I build this one to used the spare Psvane Grant Fidelity 6SN7 Spheres I had. A few changes from the previous one but similarities to others. Big difference is the colour - Hammertone Copper. Other preamps I have used the same colour but not with the Hammond Wood chassis. 

Similar to others with with the Danish Jensen copper paper and oil output caps. Before discontinued they were quite expensive. Other similarities are the final filter cap in the preamp which is a Russian PIO 4uf with a Russian 0.1uf snubber. Fine silver plated hookup wire and Alps Blue Velvet pot round it off with the 4oz solid brass gold plated knob. This time resin tube sockets and not the usual ceramic. Cheeks are treated with a high grade finishing oil which dries to a hard glossy wax finish while lifting the grain. Nice.

Using an earlier PS which is choked and relies on an external 24VAC 1A wall wart I found the sound quite a jump up from all other preamps built with the same tubes. Also in this build I used 1W carbon film resistors except the grid resistor which is metal film. There is only three resistors in each channel and the two main Rs in the signal path are the carbon film. Ck is a low ESR type. Is this the carbon Rs the secret to the better sound or is the expensive caps? Whatever bass has a whole new depth and texture, mids crazily engaging and textured and treble super smooth and sweet.

This preamp was built to sell and move on the spheres. Not sure that is going to happen any more.

"Essence" - 6SN7 Preamp

 

Not the first of the 6SN7 preamps I have built but his one is not for me. And not the first in this hammertone blue. This is a commission job and the future owner has his own, fine, Psvane 6SN7s. Pictured here with my Psvane Grant Fidelity Spheres (expensive) for testing (and a lot of enjoyable listening). Two selectable inputs selected from the front switch and two outputs. One output for an active sub woofer. 

Under the bonnet are standard metal film resistors, a 24 step stepper attenuator, low ESR cathode bypass cap and my fav. 0.47uf Russian Military paper-in-oil output caps. The knob is 4oz of brass and gold plated. Combined with the stepper has a good solid feel. The heavy weight knob also helps with resonance control in the attenuator and chassis. From past builds you will recognize the Hammond wood cheek chassis. Paint is epoxy enamel with an acid etch primer. Always comes up well when the primer is used. 

The sound is what I have come to expect from similar builds with these tubes - balanced, clean and clear with detailed and warm midrange. Different tubes will have slightly different listening results but should stay very much in the enjoyable zone. PS is external with electronically filtered HT and regulated filament voltage. The preamp is absolutely dead quiet. The new owner will love this preamp. He should like the colour, he picked it. 

"Essence" - Pass inspired Class A enhanced amplifier

 

Being very impressed with my earlier F5 build (see previous post) I made a second but this time spent a lot more on a better, cleaner, more robust power supply. Same Jim's Audio amp boards but now with Mundorf MLytic audio grade filter caps. The caps are larger providing a total of 88,000uf of filtering. Again the filter caps are snubbed to ensure a dead quiet PS and an extremely pure midrange and treble. Only twisted pairs of Cat5 solid core wire used throughout for all hookups. No shielded wire for the signal path.

To bolster the PS even more a 300VAC transformer was used. Bigger caps and bigger tranni made for a tight fit in, once more, a compact pro enclosure. The enclosures got lost in transit and when finally arrived the front panel was scratched and gouged. To hide what I couldn't sand out a hammertone copper finish was applied. This has a nice textured finish and looks excellent.

All the audio and sonic qualities of the previous build were even more enhanced in this build. Hearing deeper into acoustic instruments and texture in voice were far more evident. 25W in my system is more than enough and this build has impressed me so much I am making two more with the intention of keeping one and selling the other. Such a simple design and inexpensive to build, I have to have one for myself. 

"Dolce" - Pass inspired Class A amplifier

 

After building a very expensive F5 Turbo for another I thought I would build my own. Using Jim's Audio F5 boards, a cool looking 200 X 300 X 100 enclosure a local 160VAC tranni and  4 X 10,000uf caps I built this. Looks cool sounds even better. 

I didn't push the bias current so the amp just runs warm and the sound is the same - "warm". The name "Dolce" really says it all. The upper bass is rich and fills the lower mids giving male voice extra weight and chest. The woofers bloom a bit more and bass goes down to 30hZ in my system. I like it and so does the new owner. 

"Ironstone" - MM phono preamp

 

For a change in colour and always a great sounding tube MM phono preamp I put together this kit from Radi0kit. I had the chassis and a spare kit and after a total external colour change to our house had a spray can of Ironstone leftover. As with my other tube phono preamps I chose the premium version of the Radi0kit kit. 

This build also uses an external PS and again I'm using the Radi0kit tube PS. Using a four pin power plug to bring in the DC heater and HT voltages. The PS can also be used on my later tube preamps having 12V regulated DC and electronically smooth 250V HT. 

Not only a great sounding tube phono stage but this time a more unusual looking low sheen blue/grey coloured preamp. All other builds of this kit have sold with the new owners saying how much they like the look and sound. This one is also up for sale. 

"Quiet Strom (take II)" - `100W Class D Tripath amplifier

 

This amp has been put together from most parts on hand. The enclosure once held SS amp and has a good PS including 20,000uf of smoothing caps. The T4 module has a further 10,000uf Nichicon filter cap onboard. This amp module is a T4 Tripath module and with an appropriate tranni will deliver 180Wpc. The PS will deliver 100W and with even low efficiency speakers will play loud.

The smart looking two tone enclosure is steel and Al. The IEC socket also has a RFI/EMI power filter. It is fused (internal) and earthed. Silver plated wire-warp wire is used in the signal path. The amp is dead silent with music off and is highly detailed. Bass is deep and extended and very well controlled. Very good use of parts which have been unused for so long. 

"Cello" - TDA7293, chip based 100W amp

 

Chips for power amps are continually improving. The TDA7293 is capable for 120W in my configuration this amp will produce 100W. The kit comes with all components, PCB, heat sink etc. The PS is onboard and all that is required is a 30-0-30V tranni. I used a 300VAC toroid because I had it on hand. 

The enclosure is two tone steel and Al and is very solid.  Solid brass gold plated speaker binding posts with quality RCAs. Hookup wire is all Cat5 twisted pair with no shielded wire. Not required. The enclosure is earthed and fused. The sound is extremely balanced and very engaging to listen to. Bass is very extended and well controlled. At low to medium volumes THD is 0.001%  

The overall sound is very dynamic and challengers my more powerful amps which cost three times the price. The amp module kit is $A15 delivered. Hard to beat. Of course the main cost is the tranni and enclosure. Very impressed.

Mimic - Custom, chip based MM RIAA phono preamp

 

Yet another chip (OPA2134) based phono stage. Most parts were on hand and in this build I used Russian PIO 4uf (snubbed) caps on the output. Metal film resistors here where in other builds I have used carbon. Other caps are a mix of MKT - for accuracy - and Polyester. Once more there is no PCB but a very small piece of vero-board. Differential PS in on board and two 9V batteries power the unit. Silver plated hookup wire (wire wrap) and WBT silver based solder is used. With quality batteries 50 hours of play can be expected. 

The metal enclosure is deadened in the lid and under the bottom with bituminized heavy Al. This adds weight to an otherwise light metal (Al and steel) enclosure and also dampens any resonances. There is  an earthing point and an external battery test point. The overall sound is very neural and dynamics are outstanding. The preamp is dead quiet with good gain. Simple and over-achieving.

Altec/FaitalPro and Ploycone woofer speakers

 

Initially I was asked to make an amp to work with some speakers. It turned out I made a whole system for the customer;- tube preamp, 300/500W SS amp, Xover and speakers. Boxes were supplied along with woofers (polycones) I recommended. Boxes are 170ltr, Dacron lined. The woofers are 95db efficient and the Faital compression drivers 109. I had to pad down the horns (Altec 511B) 14db. Xover at 1100hz and 3rd order on the horns and 2nd on the woofer. Owner to paint boxes.

The sound is a little forward but pleasantly so and the woofers are flat to 30Hz. Fs for this inexpensive efficient woofer is 25Hz. Bass is tight but with the speakers closer to the wall bass will lift a bit and sound even fuller. Very transparent sound driven by the Holton based amp.