Hi Anand,
The Deltic is a commercial amp and Hugh has requested that we keep the schematic close hold. I can tell you it is a BJT singleton input stage, there is a unique VAS with a MOSFET, the driver stage uses 2SA1837 and 2SC4795 (we could swap with TTA004 and TTC004), the outputs are BJT push pull.
The Deltic is a commercial amp and Hugh has requested that we keep the schematic close hold. I can tell you it is a BJT singleton input stage, there is a unique VAS with a MOSFET, the driver stage uses 2SA1837 and 2SC4795 (we could swap with TTA004 and TTC004), the outputs are BJT push pull.
On the bench today is Phono-01 pre-production sample has been verified and works beautifully. Sound is amazing. Superbly quiet. Dynamics and soundstage, clarity, transparent and detailed without being harsh - it’s all there.
I’m testing it using a Sumiko Blackbird MC cartridge with LSA TT, LSA Phono-01 preamp, LSA HyperDrive-2 preamp, VeraFi Audio A40 amp, 10F/RS225 FAST TL speakers.
First disc played is Dave Brubeck’s classic Timeout.
Gain set at 60dB, input impedance at 47k ohms.
I’m testing it using a Sumiko Blackbird MC cartridge with LSA TT, LSA Phono-01 preamp, LSA HyperDrive-2 preamp, VeraFi Audio A40 amp, 10F/RS225 FAST TL speakers.
First disc played is Dave Brubeck’s classic Timeout.
Gain set at 60dB, input impedance at 47k ohms.
My cat does that same standing paw thing when she wants treats or to sniff out a window.
That LSA turntable looks nice, relatively affordable too, maybe one day. I've been meaning to ask, what does the rumble filter do on your phono pre?
That LSA turntable looks nice, relatively affordable too, maybe one day. I've been meaning to ask, what does the rumble filter do on your phono pre?
Dave Brubeck's Time Out is what they used for a demo record at Sam Goody's in the 60s. I'm happy that it still holds up today. Joe Morello's drums were superbly recorded. I hung out in their stereo room many a day listening to that album through their best systems.
This is really surprising to me is how good music sounds when played from a TT to a headphone amp and good headphones. It’s a totally different experience. Something very organic and natural to the sound. I think it’s because there is no digital yet it is so close to our ears we can resolve all the little background noises recorded in the studio. Like someone shifting in their seat or shuffling music sheet paper sound, or literally something like a pin drop. I’m using HifiMan HE-400i’s with the HyperDrive-2 headphone amp.
In all my decades of working as a top-ranking audio/video service technician, I've never had to replace that many capacitors on one unit.
Some people are just obsessed and brainwashed with the internet-spread of the "re-capping" disease.
On my bench tonight.
I am working with an amplifier in SPICE.
Symmetrical with JFET input and MOSFET output.
Work is going very well.
I used the built in oscilloscope to know what filter caps I should put in the loop.
Simulation is fun 🙂
🙂 Stefan
I am working with an amplifier in SPICE.
Symmetrical with JFET input and MOSFET output.
Work is going very well.
I used the built in oscilloscope to know what filter caps I should put in the loop.
Simulation is fun 🙂
🙂 Stefan
The rumble filter adds a shelving filter below 100Hz to decrease the low bass noise (rumble). It appears to give maybe a -9dB improvement in noise at 20Hz.
Here is the measured background noise spectrum of the Phono-01 with 43dB gain and 47k impedance with the Sumiko Blackbird MC cartridge (high output designed for 47k). The 60Hz peak is totally from the cartridge wires acting as an antenna for mains EMI. When disconnected, it is not present. I am getting about -125dB noise at 1kHz and -110dB at 100Hz. This is quite good as phono stages go. The dynamic range it produces is very impressive.
A 1kHz 1.00Vrms sine wave function generator provides -7.1dB for reference.
Here is 60dB gain setting:
Last edited:
Sounds unique! Let me/us know if he changes his mind. Would love to build it…of course ;-)
Best,
Anand.
On the virtual bench is the Series One Preamplifier solid model high resolution renders:
Preamp will initially be offered to early adopters for $1295. Price will be $1595 once initial run is through.
On the bench is Deltic first power up and first sound since replacement of caps. I also took chance to add speaker protect SSRs. It all works and sounds great. Amp is superbly quiet. With music not playing and ear pressed to cone on speaker I cannot tell it is turned on. Running 120mA bias current. DC offset is stable around 1mV to 4mV.
I also redid the front panel with a 16mm pushbutton switch with LED ring light. This will activate the on/standby on the SFPP soft start with remote. Drilled out the volume pot hole for a standard Alps RK09 pot.
I also redid the front panel with a 16mm pushbutton switch with LED ring light. This will activate the on/standby on the SFPP soft start with remote. Drilled out the volume pot hole for a standard Alps RK09 pot.