Hello all,
I have a new project in slow motion and have a number of road blocks that I wanted to run by the group. If anyone has any thoughts, suggestions or criticisms, please share. All input is welcome. I want to get this as close to "right" the 1st time as possible.
The idea is to build 6 stereo amps and one mono to provide power for a Dolby Atmos 7.2.4 setup. After weighing class A vs B for this, I decided on B. I can work with crossover distortion better than unnecessary heat in the space this will be in.
F/L - F/R = KT66 pp stereo
M/L - M/R = KT66 pp stereo
R/L - R/R = KT66 pp stereo
Center = EL84 pp mono
F/Sub & R/Sub = KT88 pp stereo
F/L - F/R down fire = EL84 pp stereo
R/L - R/R down fire = EL84 pp stereo
That's a lot of tubes! 26 power tubes alone.
The big issue is Dolby Atmos processing. This is going to determine preamp purchase or design. I would prefer tube pre's, integrated simple design with a single Siemens e88cc at each pp amp. The rub is what is available for processing the Dolby Atmos signal. There are a few standard 5.1 decoders/splitters on the market, but that's not going to cut it here. Ideally, I would run a digital "receiver" unit that has line level outputs for each channel, but I don't think such a thing exists. Probably better than that would be just a surround/Atmos processor without integrated amplification, routed to my valve amps. Maybe something like this exists for theatres. I'm pretty sure some units exist that allow preamp output, but that kills my tube pres. I'm questioning my sanity.
I am not settled 100% on tube selections for the various roles, so no transformers or chokes have been purchased yet.
All of these amps will be built and installed in custom wood enclosures with trans and tubes top mounted.
Any and all thoughts, opinions or hate mail are welcome.
Thanks!
Chris
I have a new project in slow motion and have a number of road blocks that I wanted to run by the group. If anyone has any thoughts, suggestions or criticisms, please share. All input is welcome. I want to get this as close to "right" the 1st time as possible.
The idea is to build 6 stereo amps and one mono to provide power for a Dolby Atmos 7.2.4 setup. After weighing class A vs B for this, I decided on B. I can work with crossover distortion better than unnecessary heat in the space this will be in.
F/L - F/R = KT66 pp stereo
M/L - M/R = KT66 pp stereo
R/L - R/R = KT66 pp stereo
Center = EL84 pp mono
F/Sub & R/Sub = KT88 pp stereo
F/L - F/R down fire = EL84 pp stereo
R/L - R/R down fire = EL84 pp stereo
That's a lot of tubes! 26 power tubes alone.
The big issue is Dolby Atmos processing. This is going to determine preamp purchase or design. I would prefer tube pre's, integrated simple design with a single Siemens e88cc at each pp amp. The rub is what is available for processing the Dolby Atmos signal. There are a few standard 5.1 decoders/splitters on the market, but that's not going to cut it here. Ideally, I would run a digital "receiver" unit that has line level outputs for each channel, but I don't think such a thing exists. Probably better than that would be just a surround/Atmos processor without integrated amplification, routed to my valve amps. Maybe something like this exists for theatres. I'm pretty sure some units exist that allow preamp output, but that kills my tube pres. I'm questioning my sanity.
I am not settled 100% on tube selections for the various roles, so no transformers or chokes have been purchased yet.
All of these amps will be built and installed in custom wood enclosures with trans and tubes top mounted.
Any and all thoughts, opinions or hate mail are welcome.
Thanks!
Chris
Can you use Win 10 Creator or VLC for decoding? The decoded outputs can be handled by multi-channel soundcard followed by your tube preamps.
That's a good question. I will look into that now. Thanks!
I am looking at a NAD T 777 v3, but it's killing my tube pres.
Something that I can port HDMI devices through for switching to the TV is key. This will be for video/home theatre use, as will as just audio.
I am looking at a NAD T 777 v3, but it's killing my tube pres.
Something that I can port HDMI devices through for switching to the TV is key. This will be for video/home theatre use, as will as just audio.
Both technically, which I have no issue with the standard a/v. It's getting the HDMI Dolby Atmos encoded audio processed and delivered to the amps.
I wonder if getting something like the Pioneer VSX-1131, locating the preamp inputs on the PCB and separating all the amplification circuitry would be maddening....and if I would have a lot of fault detection to deal with. Could whip up a header with 1/8" trs jacks or something similar to inject the processed audio into the tube amp array...maybe. The connectivity would be awesome.
I wonder if getting something like the Pioneer VSX-1131, locating the preamp inputs on the PCB and separating all the amplification circuitry would be maddening....and if I would have a lot of fault detection to deal with. Could whip up a header with 1/8" trs jacks or something similar to inject the processed audio into the tube amp array...maybe. The connectivity would be awesome.
Check out MOTU HDX-SDI, some customization would be required as it only has 8 analog outputs (so 7.1 ok), to get more channels, you’ll need to use the AES outputs as well, but it should be doable.
Maybe spend the extra time/money/effort on the best receiver you can possibly afford, then use conventional tube amps on the 7.1 pre outs. I doubt there is any atmos content out there worth spending the huge amount of effort on doing that for
Best bet is a receiver with pre outs, as mentioned. Atmos seems difficult to do the signal processing in the analog domain for sure, even in solid state.
My best advice is to study the relevant patents until you understand them fully, and go from there.
Side note- Dolby pro logic was originally protyped by Jim using tubes, and the final circuitry was solid state. The patent shows the channel steering is done with opamp VCAs... I've been trying to engineer a way to do it with tubes, but haven't found a satisfying way to do it with a tube yet that would have acceptable quality., although the surround processing itself is quite simple and easy to implement.
My best advice is to study the relevant patents until you understand them fully, and go from there.
Side note- Dolby pro logic was originally protyped by Jim using tubes, and the final circuitry was solid state. The patent shows the channel steering is done with opamp VCAs... I've been trying to engineer a way to do it with tubes, but haven't found a satisfying way to do it with a tube yet that would have acceptable quality., although the surround processing itself is quite simple and easy to implement.
Pro logic was simple analog adding and subtracting, and didnt work that well. Atmos is full digital proccessing including lossless compression and decoding, not possible in analog. Not sure why anyone wuold want tube amps on every channel.
Good info here.
Dolby atmos decoder? | Audiokarma Home Audio Stereo Discussion Forums
Good info here.
Dolby atmos decoder? | Audiokarma Home Audio Stereo Discussion Forums
Most 5.1/7.1 content is properly mastered in so many channels and all you need to do is to replicate the speaker and room setup as intended, and you'll get the content as intented - no processing needed and it can sound fantastic
Atmos is object based surround, so sounds are 'objects' that have a position, distance, amplitude etc, and the processing gear works it out depending on the speaker layout, room etc. The consumer version is a gimped down and simplified version of this, but it really is meant for "bang" and "whoosh" type movie effects, and not fine audio
I had the oppertunity to experience the klipsch 24.10.10 demo at the melbourne hifi show last year and even with the 'ultimate' setup for it, it is still a very unrefined and loud experience. Move out of the sweet spot and it loses coherency pretty quickly
Atmos is object based surround, so sounds are 'objects' that have a position, distance, amplitude etc, and the processing gear works it out depending on the speaker layout, room etc. The consumer version is a gimped down and simplified version of this, but it really is meant for "bang" and "whoosh" type movie effects, and not fine audio
I had the oppertunity to experience the klipsch 24.10.10 demo at the melbourne hifi show last year and even with the 'ultimate' setup for it, it is still a very unrefined and loud experience. Move out of the sweet spot and it loses coherency pretty quickly
Because I can 🙂 I will check your link now. I did an experiment with a onkyo receiver tonight. I located the preamp inputs inside the amp and grabbed line level signal from there, then injected it into 5 mono blocks with 5.1 signal from the Blu-ray player and it sounded phenomenal. Get the processing from the unit. I am confident I can do the same with any other receiver now. More experimentation and research to come
Great thread. Very good info. Thanks for that!
Agreed. The only reason I am bent on Atmos is the constant chase for the ultimate film sound. Music listening, for me, is almost always stereo only.
After digging through the thread cbdb posted, I think this Denon receiver is the way to go. Build the amps as power only, nixing the tube preamp stage and using the pre-outs of the Denon. I have time to change my mind 209 more times. I'm not crazy about losing tube pre's or having redundant power amps in a receiver going unused... AVR-X6300H | Powerful 11 channel Network AV receiver with HEOS and 3D Sound | Denon
You bring up that you are chasing movie sound, not audio. Have you given some thought to why you want tubes? Movie sound is often exaggerated both in dynamic range and transients. It's not designed to be a musical experience. IMHO BIG SS amps will perform best in this type of application.
No, I'm going for both experiences. My current surround sound is 5.1 and I'm running 6 monoblocks. Decoding the signal to analog and out to the amps. Sounds incredible. I have also built these amps to have 0 sag. If these were guitar amps, it would be a different beast.
- Status
- Not open for further replies.