The Bob Carver RAM285 amp has arrived at the shop from the factory and is undergoing testing. So far so good. Mark and I are really proud of the team and their effort that has made this possible: JP, Tony, Darko, Jaclym, and Annie - thank you!
This is a huge milestone. The amp sings and is playing into Magnepans. Tested to make 126w into 8ohms while being spec’d for 85w is a nice way to ensure the amp delivers and has a long lifetime.
This is a huge milestone. The amp sings and is playing into Magnepans. Tested to make 126w into 8ohms while being spec’d for 85w is a nice way to ensure the amp delivers and has a long lifetime.
Bob Carver RAM 285
https://www.bobcarvercorp.com/ram-285
https://www.bobcarvercorp.com/ram-285-features
KT-120 tubes as supplied:
Stereo: 85 watts. 20 Hz to 20 KHz -1 dB. Less than .5% THD+N. 4/8 ohms
85 watts. 16Hz to 35KHz minus 3dB. Less than .5% THD+N.
100 watts. 18Hz to 35 KHz minus 3dB. Less than .5% THD+N for short periods of time (over 15 minutes).
https://www.bobcarvercorp.com/ram-285
https://www.bobcarvercorp.com/ram-285-features
KT-120 tubes as supplied:
Stereo: 85 watts. 20 Hz to 20 KHz -1 dB. Less than .5% THD+N. 4/8 ohms
85 watts. 16Hz to 35KHz minus 3dB. Less than .5% THD+N.
100 watts. 18Hz to 35 KHz minus 3dB. Less than .5% THD+N for short periods of time (over 15 minutes).
Yes, those are the specs as measured in the pre-production prototype. The ability to hit 126w confirms this.
On the bench is a slick little utilitarian single chip headphone amp that is integrated with a volume pot so that the whole thing can be panel mounted on any project needing a basic but high performing headphone out (monitor on a preamp or TT stage etc). This was designed by Jhofland for Redjr. And Redjr was kind enough to send me a sample. The HPA-01 as it is called uses a MAX97220 chip which provides up to 125mW into 32ohms and is capable of 0.0035% THD and 112dB SNR. It requires from a 2.5v to 5v (max) input PSU and has a built in charge pump to provide its own dual rail PSU so that the output is centered at 0v, negating the need for output coupling DC block capacitors. It also has built in anti-pop startup and shutdown. A lot of neat features in a tiny 3mm square chip. I connected it to a 3.7v LiPo battery pack which is perfect because batteries are about the quietest power sources there are. I used an iPhone dongle DAC for a test drive and paired with a Status Audio CB-1 32ohm cans. I was quite surprised by how good it sounds. It can get louder than I need and has a built in jumper to select 0/6/12dB gains. The jumpers can be wired to an external toggle switch for in the fly gain changes without pops. There is also a daughterboard to use an optional micromatch IDC cable for a remotely mounted volume pot.
All Molex KK connectors for power in, audio in, audio out. Micromatch 8 pin ribbon cable connector for double gang volume pot in Alps RK09 format.
I also tried driving it with a Hakuin SE class A preamp stage and let this amp be the “muscle of the Class A exoskeleton” and it sounded superb.
Anyhow, a big thanks to Jhofland and Redjr for this neat circuit.
All Molex KK connectors for power in, audio in, audio out. Micromatch 8 pin ribbon cable connector for double gang volume pot in Alps RK09 format.
I also tried driving it with a Hakuin SE class A preamp stage and let this amp be the “muscle of the Class A exoskeleton” and it sounded superb.
Anyhow, a big thanks to Jhofland and Redjr for this neat circuit.
All that HV is safely tucked inside the nicely grounded (to protective earth) heavy all metal chassis. It’s quite safe if you don’t open it up.
We have a couple of new products under development. These are in the power conditioning arena.
Infinity Fuse is a solid state relay programmable fuse with solid state soft start relay for audio products. Think of it as a low impedance fuse and soft start solution in one.
Programmable (hardware - no software or micro controllers) for 1A to 15A and slow or fast blow.
We also have another product called Snub Station Zero that provides DC block for mains, and high performance EMI filtering (Schurter filters on 2 and custom one for soft start enabled one) for up to 3 outlets.
These circuits are all based on real engineering and sound electrical design. No HiFi Phoolery here. 🙂
Infinity Fuse is a solid state relay programmable fuse with solid state soft start relay for audio products. Think of it as a low impedance fuse and soft start solution in one.
Programmable (hardware - no software or micro controllers) for 1A to 15A and slow or fast blow.
We also have another product called Snub Station Zero that provides DC block for mains, and high performance EMI filtering (Schurter filters on 2 and custom one for soft start enabled one) for up to 3 outlets.
These circuits are all based on real engineering and sound electrical design. No HiFi Phoolery here. 🙂
It is impossible for someone like me to never open cool looking amp
Hi X,
Snub Station Zero looks amazing
I love the idea of both these.
I have a DC blocker from ATL Hifi in between my wall outlet and APC H10 line conditioner, it works wonders. So well in fact that I put together a tiny DC blocker board based on the circuit in Bryston 4B SST schematics. In the future I plan to incorporate it into builds. Are you able to share just the DC blocking portion of your circuit? I'm always curious to better mine.
Is there any plan to release either as a diy friendly product in the future? I normally use just a Schaffner fused IEC inlet w/ EMI filter, but I am guessing your board is superior.
The DC blocker uses two sets of 3x 30A 600v fast recovery TO220 diodes (6 total) in series and each set in anti-parallel. The 4 DC blocking caps are 2200uF 16v with 6A ripple current rating at 120Hz. I can’t give out too much more than that but you can do search to see the typical circuits.
That lines up with some of the circuits I have seen. Thank you for sharing what information you can, I appreciate it.
On the bench and now the dresser, is a Khadas VIM3 single board computer paired with a Khadas Tone Board 1 DAC, running Volumio (on Linux). The Volumio app on my phone lets me control the music player in a headless mode. This DAC sounds amazing powering Hugh Dean’s Deltic Class AB amp and driving my TL speakers. @redjr was kind enough to assemble the hardware and load the software and got it all working for me. It’s a slick solution for streaming music from a network drive or USB thumb drive (my preferred method). I’m looking forward to trying out some DSD files.
The biggest thing I noticed is the total improvement in sound quality from using a small Amazon Alexa as a streamer (very handy and worked all these years but time for an upgrade for sound quality in the bedroom).
Here is a screenshot of the app interface:
The biggest thing I noticed is the total improvement in sound quality from using a small Amazon Alexa as a streamer (very handy and worked all these years but time for an upgrade for sound quality in the bedroom).
Here is a screenshot of the app interface:
Last edited:
Cool stuff X, I looked at the Khadas website for more info. So I take it that the output's of the dac are going straight to the speakers ?. The power available/8 ohms must be small, but adequate if driving your TL's.
Here is more info on the Deltic. The Khadas TB-1 is powered by 5v but has 8 internal DC/DC converters in board and I think the output feels like it’s from a +/-9v type opamp. Lots of swing.
https://www.diyaudio.com/community/threads/whats-on-the-bench-tonight-obt.372508/post-7315058
https://www.diyaudio.com/community/threads/whats-on-the-bench-tonight-obt.372508/post-7315058