My F5 turbo v3 mono's have been running smooth for the last few months, but I need to make some small changes, adding a larger fan, upgrade some of the internal wiring, and put them in the new cases I have built for them.
I was planning on just using my existing K&K Audio upgraded ST-70 while the F5's were out of service. But then I saw Kevin @ K&K has recently released new Single-Ended and Push-Pull Amplifier kits and I thought if would be fun to build around using the KT-150's. Also my set-up is based on monoblocks. Seems several manufacturers are taking advantage of the higher output, but not to much out there in the DIY realm.
I started out planning on using what I could out the the ST-70, but I ended up just reusing the one mains transformer and the pair of output transformers. The mains transformers are K&K's SST-70's and the outputs are a pair of Lundahl LL1682/PP's. I bought transformer coupled design with the boards populated, tested, and close to final settings. Should be an easy build. The board is set to bias the KT-150's at 125mA.
Wire is Kimber TCSS 19AWG, signal wire is Neotech LE-20AWG, and the binding posts are Cardas CCRR (billet copper posts, rhodium over silver plate post).
I spent a few days sketching and working with David @ Landfall Systems for the chassis. The artistic squiggle (sine wave) on the front panel will be the power on indicator.
I was planning on just using my existing K&K Audio upgraded ST-70 while the F5's were out of service. But then I saw Kevin @ K&K has recently released new Single-Ended and Push-Pull Amplifier kits and I thought if would be fun to build around using the KT-150's. Also my set-up is based on monoblocks. Seems several manufacturers are taking advantage of the higher output, but not to much out there in the DIY realm.
I started out planning on using what I could out the the ST-70, but I ended up just reusing the one mains transformer and the pair of output transformers. The mains transformers are K&K's SST-70's and the outputs are a pair of Lundahl LL1682/PP's. I bought transformer coupled design with the boards populated, tested, and close to final settings. Should be an easy build. The board is set to bias the KT-150's at 125mA.
Wire is Kimber TCSS 19AWG, signal wire is Neotech LE-20AWG, and the binding posts are Cardas CCRR (billet copper posts, rhodium over silver plate post).
I spent a few days sketching and working with David @ Landfall Systems for the chassis. The artistic squiggle (sine wave) on the front panel will be the power on indicator.
I have been gathering parts for the last month or so. The chassis arrived today so I couldn't help but check to make sure everything would fit like I thought/drew on paper.
So far only a couple items I would change if I built another pair, but not enough to recut these.
I'll be posting as I build, let me know if I'm messing up!
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So far only a couple items I would change if I built another pair, but not enough to recut these.
I'll be posting as I build, let me know if I'm messing up!
Sent from my iPad using Tapatalk
As built specs
Over the last week and long weekend I have almost completed both Monoblocks. I realized I needed some additional parts Thursday that should arrive Monday and then I can fire them up.
But here is kind of a spec sheet so far;
Push-Pull - Two Stage - KT-150 pair Monoblocks
-K & K Audio design/boards
-Signal phase splitting is accomplished with an input transformer
-Russian 6J49P pentodes that are connected for operation as Class A triodes
-Interstage transformer coupled input stage
-K & K Audio SST-70 mains transformer, 850 VAC output
-Lundahl cobalt amorphous core transformers for input and interstage
-Lundahl PP output transformer
-Cathode CCS with outboard heat sink
-The heaters for the input and output tubes are AC
-Teflon tube sockets with collet style contact
-5vdc solid state relay switched "power on/off" controlled by preamp
-Power Supply has turn on delay and soft start
-B+ 575VDC
-Initial CCS set at 250mA, 125mA per KT-150
-Furutech IEC inlet w/fuse holder
-Furutech RCA input connector, rhodium-plated copper conductor
-Cardas binding posts, billet copper posts, rhodium over silver plate
-Internal wire is Kimber TCSS 19AWG
-Input signal wire is Neotech LE-20AWG
-Transparent Cable from output transformer to binding posts
-Landfall Systems custom brushed anodized aluminum chassis
-Gain: 38.4dB @1KHz
-Maximum Output Level: 187VRMS (525VP-P) @ 3%THD+N
-Frequency Response: -0.9dB @ 20Hz and -6dB @ 58KHz (reference 1KHz)
-11" x 9 1/4" x 14 1/2" (w/h/d, w/tubes)
-28.2 lbs each
More pics after I complete, but here is a view of the rear panel;
Over the last week and long weekend I have almost completed both Monoblocks. I realized I needed some additional parts Thursday that should arrive Monday and then I can fire them up.
But here is kind of a spec sheet so far;
Push-Pull - Two Stage - KT-150 pair Monoblocks
-K & K Audio design/boards
-Signal phase splitting is accomplished with an input transformer
-Russian 6J49P pentodes that are connected for operation as Class A triodes
-Interstage transformer coupled input stage
-K & K Audio SST-70 mains transformer, 850 VAC output
-Lundahl cobalt amorphous core transformers for input and interstage
-Lundahl PP output transformer
-Cathode CCS with outboard heat sink
-The heaters for the input and output tubes are AC
-Teflon tube sockets with collet style contact
-5vdc solid state relay switched "power on/off" controlled by preamp
-Power Supply has turn on delay and soft start
-B+ 575VDC
-Initial CCS set at 250mA, 125mA per KT-150
-Furutech IEC inlet w/fuse holder
-Furutech RCA input connector, rhodium-plated copper conductor
-Cardas binding posts, billet copper posts, rhodium over silver plate
-Internal wire is Kimber TCSS 19AWG
-Input signal wire is Neotech LE-20AWG
-Transparent Cable from output transformer to binding posts
-Landfall Systems custom brushed anodized aluminum chassis
-Gain: 38.4dB @1KHz
-Maximum Output Level: 187VRMS (525VP-P) @ 3%THD+N
-Frequency Response: -0.9dB @ 20Hz and -6dB @ 58KHz (reference 1KHz)
-11" x 9 1/4" x 14 1/2" (w/h/d, w/tubes)
-28.2 lbs each
More pics after I complete, but here is a view of the rear panel;
I had a good half day to myself to play amp builder!
The last straggling parts arrived and after compelting the first one, went through the start up process. Power up without tubes, check for smoke and proper voltages. I have an issue with the SS relay for power on/off control via preamp I'm using, blows the 3 amp fuse, so bypassed for now. Cycled twice, 2 minutes on each power up, power down. Still good. Installed tubes, powered up, no smoke!
There are two trim pots to adjust on the input stage board, one to adjust shunt regulator voltage (210VDC) and one to adjust the input stage supply current (34mVDC).
The output tube bias is currently set at 200mA (for pair), as I break it in I will move up to 250 mA, if it doesn't melt down first! The mains transformer at the initial setting is running at 127 degrees.
Connected into my system, with my F5 turbo v3 on the other channel. With the amp in "low gain" (board includes switch for high and low gain) and in Ultra Linear mode (can switch between Triode and Ultra Linear) this amp is very slightly louder. At this point hard to get a perspective on sound, but not sounding out of place with the F5 on the other channel.
I have a noticeable hum/hiss in Tiode mode that can be heard from about 2 feet away. I think I need to adjust some of my internal wiring. In Ultra Linear mode it is dead quiet with ear to drivers.
So while amp one is running I finished installing the last parts and went through the same start up sequence on amp two. Replaced the other F5 and powered up.
My first impressions are extremely positive. I only had a couple hours to listen. Comparing to my F5's the bass is more powerful, the overal presentation seems quicker and the soundstage wider. Cymbals and like instruments hit with precision and speed with natural decay and you can almost feel the texture on the drum head on one track. In terms of volume it played as loud as I have played the F5, without stress, at my typical volume level setting on the pre. I didn't have time to push further to top end yet.
I did play the trailer for the upcoming Batman/Superman movie and the presentation was dynamic, even with my subs disconnected.
It looks like I have my work cut out for me to get the F5 up to this level is my first impression. I will be needing some advice!
Here is an internal shot. I'll take some exterior shots tomorrow.
The last straggling parts arrived and after compelting the first one, went through the start up process. Power up without tubes, check for smoke and proper voltages. I have an issue with the SS relay for power on/off control via preamp I'm using, blows the 3 amp fuse, so bypassed for now. Cycled twice, 2 minutes on each power up, power down. Still good. Installed tubes, powered up, no smoke!
There are two trim pots to adjust on the input stage board, one to adjust shunt regulator voltage (210VDC) and one to adjust the input stage supply current (34mVDC).
The output tube bias is currently set at 200mA (for pair), as I break it in I will move up to 250 mA, if it doesn't melt down first! The mains transformer at the initial setting is running at 127 degrees.
Connected into my system, with my F5 turbo v3 on the other channel. With the amp in "low gain" (board includes switch for high and low gain) and in Ultra Linear mode (can switch between Triode and Ultra Linear) this amp is very slightly louder. At this point hard to get a perspective on sound, but not sounding out of place with the F5 on the other channel.
I have a noticeable hum/hiss in Tiode mode that can be heard from about 2 feet away. I think I need to adjust some of my internal wiring. In Ultra Linear mode it is dead quiet with ear to drivers.
So while amp one is running I finished installing the last parts and went through the same start up sequence on amp two. Replaced the other F5 and powered up.
My first impressions are extremely positive. I only had a couple hours to listen. Comparing to my F5's the bass is more powerful, the overal presentation seems quicker and the soundstage wider. Cymbals and like instruments hit with precision and speed with natural decay and you can almost feel the texture on the drum head on one track. In terms of volume it played as loud as I have played the F5, without stress, at my typical volume level setting on the pre. I didn't have time to push further to top end yet.
I did play the trailer for the upcoming Batman/Superman movie and the presentation was dynamic, even with my subs disconnected.
It looks like I have my work cut out for me to get the F5 up to this level is my first impression. I will be needing some advice!
Here is an internal shot. I'll take some exterior shots tomorrow.
I enjoyed an afternoon spinning records and streaming on Tidal, through my new SST-70's. I am really excited about the performance right from day one (well day two now).
Discovered the fault in Triode mode, grounding, fixed. The sound seems a wee bit fuller, but at a larger loss of soundstage, in Triode. For now, keeping in Ultra Linear.
Had some email conversations with Kevin @K&K, after I have crossed the 100 hour mark I can start to increase the bias, up to 150mA each. (Now set at 100mA each).
Here is a good overall pic of the mostly completed mono. Still have to finish the power on LED on the front panel.
Discovered the fault in Triode mode, grounding, fixed. The sound seems a wee bit fuller, but at a larger loss of soundstage, in Triode. For now, keeping in Ultra Linear.
Had some email conversations with Kevin @K&K, after I have crossed the 100 hour mark I can start to increase the bias, up to 150mA each. (Now set at 100mA each).
Here is a good overall pic of the mostly completed mono. Still have to finish the power on LED on the front panel.
Thanks much for the compliment! Still working on a couple non-sound items to complete.
I built these amps (and rebuilding my F5 turbo v3's) around the Power Control feature of my McIntosh C2300 pre. The pre sends out 5vdc via a 1/8" stereo mini phono jack outlet.
I incorrectly assumed that the jack put out enough amperage to operate two relay's. I started out with a pair of SS relays, not enough amperage to operate one. Then I ordered a pair of regular relay's, small in size, with contacts rated for 8 amps (the SST-70's fuse size is 3 amp). The jack would only operate one.
So after a little more research (which I should have done in the first place) I discovered that the McIntosh amps are built with one mono block amp connected to the Pre jack and the other mono block amp connected to the first mono block amp.
So I am assuming the first mono block amp must have a separate power supply/relay to operate the pair from the the signal coming from the Pre.
So I ordered some more parts! A couple more 5vdc relays and a small 6vdc transformer. I had a small diode bridge and 470uF cap left over from another project so I built a simple circuit to be able to power up both amps from the single low amperage signal from the Pre.
The 5vdc power from the Pre engages a 5vdc relay which completes the circuit to the 6vac transformer. Then through the diode bridge the 6vac is converted to 6vdc and completes the circuit on the power supply relay, both the first amp and then through the 1/8" mini jack to the second amps power supply relay.
Long story, but might help someone else in the future. But operation is so nice by being able to power up everything by the Pre's remote control!
Next up is to add in the "power on" LED behind the sine wave cutout in the faceplate. But at night the glow lets you know it's on!
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I incorrectly assumed that the jack put out enough amperage to operate two relay's. I started out with a pair of SS relays, not enough amperage to operate one. Then I ordered a pair of regular relay's, small in size, with contacts rated for 8 amps (the SST-70's fuse size is 3 amp). The jack would only operate one.
So after a little more research (which I should have done in the first place) I discovered that the McIntosh amps are built with one mono block amp connected to the Pre jack and the other mono block amp connected to the first mono block amp.
So I am assuming the first mono block amp must have a separate power supply/relay to operate the pair from the the signal coming from the Pre.
So I ordered some more parts! A couple more 5vdc relays and a small 6vdc transformer. I had a small diode bridge and 470uF cap left over from another project so I built a simple circuit to be able to power up both amps from the single low amperage signal from the Pre.
The 5vdc power from the Pre engages a 5vdc relay which completes the circuit to the 6vac transformer. Then through the diode bridge the 6vac is converted to 6vdc and completes the circuit on the power supply relay, both the first amp and then through the 1/8" mini jack to the second amps power supply relay.
Long story, but might help someone else in the future. But operation is so nice by being able to power up everything by the Pre's remote control!
Next up is to add in the "power on" LED behind the sine wave cutout in the faceplate. But at night the glow lets you know it's on!
Sent from my iPad using Tapatalk
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