Tube amp idea (home theatre)

[Mudhiker]

I know that the bottlehead folks are knee deep in prototyping and trying to get the stereomour and the DAC and whatever else out the door...  I think it's about time for...

Tube 5.1+ home theatery stuff.  After all these years there has got to be a simple all-on-one-chip dolby decoding chip.  Or something that can be hacked to make work.  toslink or coax in... 5 or more quickie style channels out.  But with some kind of plug into the wall power supply instead of umpty million batteries.  Whenever someone asks about all tube 5.1(+) people shoot it down with "the audio in movies isn't that good anyway you won't notice the difference" but it's the principle of the thing.  I listen to about half a dozen different sources, some DIY tube, some sand, some fancy, some cheap, and ultimately I enjoy them all.  But... building my own gear is fun and tweaking (and noticing the audible changes) is what makes the DIY side of things fun.  Maybe it's audibly better, but I still don't know how to tell, just like I can't really tell what makes a $40 bottle of wine better than a $4 one.  Maybe I never will, but I enjoy movies, music, and wine.  And I enjoy hacking together a bunch of parts into a functioning piece of kit.

So... there oughtta be a 5.1 quickie or something.  Or a way to buy most of the relevant parts to do it.  Or of course even better would be a buy-it-now-able 5 channel SEX pile of parts.  I don't need the chassis bits, just the iron and the tubes and the schematic.  I wouldn't care if it wasn't supported either.

[Paul Joppa]

I'm liking the idea, at least in theory.

Here's my off the top of the head thoughts - please chime in with other ideas, this is a great way to brainstorm!

* Video (like audio) is in a big state of flux, clearly moving from DVDs to computer/web based sources. Not mature yet, and many unforseen directions will certainly appear over the next few years. We're probably not big enough to ride those waves.

* But nobody is playing with SETs and high efficiency speakers in the home video context. We could do that. I'm thinking a 5-channel SEX amp, maybe even without level control, for use with a video decoder/preamp - buy your favorite 0.1 channel subwoofer and you're there. Does anybody know a good video processor/preamp?

* A variant of the SEXy Speaker could do the job. Surround channels really only need 125-5000Hz, which can be obtained from single-driver systems without great expense. Sure, Bruce Willis can afford something bigger and better. But he's not (as far as I know) a Bottlehead customer anyhow. I use dumpster-rescue JBLs and a SEX amp with my 20" TV and it's a great improvement over the built-in speakers. Especially the SEX amp, the lifelike presence of SETs really does something for movies.

* No reason the Bottlehead monoblocks should not be available in a five-pack as well as a stereo pair, for those who want to go higher end.

Other ideas?

[Paul Birkeland]

I'm thinking you could use one of these and pair it with a 5 channel SEX amp. 
http://www.octavainc.com/HDMI%20switch%204x2_7_1audio.html
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.lektropacks.co.uk%2Fview_product_standard.php%3Fproduct%3D1001185%26amp%3Bsub1%3D%26amp%3Bshow%3D&hash=71b142b176b02f630f05262fa1c6d168f0ea5517)

I like the reminder that full frequency range really isn't desired.  Good performance could be had with SEX amps using Specos, and maybe a 6 channel SEX amp with the last channel being an uber low impedance subwoofer line driver would make sense...  Level controls to adjust each channel could be done via trim pots inserted between each stage with a 6 deck Goldpoint sitting at the front...

[tbbenton]

I disagree on the notion of limiting the range on the "surround" speakers for two main reasons:

1. There is digital 5.1 channel audio programming available that is full range, so it would be nice to be able to reproduce it.  While its true that plain old Dolby surround is band limited, not all formats are.

2. All 5 channels should to be tonally matched.  The easiest way to get there is to use the same speakers and amps for each channel.  Of course, this doesn't deal with financial or physical economics.

I do really like the sex amp.  While I'm not in the market for more amps (I like my home theater setup.)  Perhaps consider a monoblock sex amp.  This opens up the possibility for 5.1, 7.1 and might make some 1.0 (mono) listeners especially happy. 

[Paul Joppa]

No problem making amps fullrange - I just mentioned that I've been told surround speakers don't need the full range, making them cheaper. But Bottlehead has never found speaker making to be profitable, so they are not likely to be a product.

Monoblock SEX sounds interesting. It would cost more per channel - more chassis plates, more bases, more power supplies and transformers. At a pure guess, maybe 50% more. Would the flexibility be worth it?

[Grainger49]

Xcortes has to chime in here.  IIRC, Xavier has an all Bottlehead 5.1 system.  But of course not the decoder.

[tbbenton]

It would cost more per channel - more chassis plates, more bases, more power supplies and transformers. At a pure guess, maybe 50% more. Would the flexibility be worth it?

Don't know.  Maybe?  Of course, some of the items could be extras.   Given the configurability, you may not need single bases -- that could actually become a high-margin custom add on.  they don't neccessarily need volume controls, the power transformers will be simpler.  Perhaps true mono amps would justify a higher price too.  You may be selling more of these, so maybe the margin can be lower.  You may lose money on each one, but make it up in volume.

[Mudhiker]

A S.E.X. style monoblock iron & tubes kit would be fantastic.  Bring your own chassis, jacks, etc.  It would make a good simple, flexible base for all sorts of amplification projects, from home theatre to instrument amplification.  Sure, I'd love to have multi-channel paramounts, but I can't afford that.  A nice 19 inch wide chassis with a whole big row of tubes glowing across the top of it would look fantastic!

The decoding part can probably be left out... there are a few options out there for line level dolby stuff.

[xcortes]

Here you can see my five Paramour IIs with Magnequest EXO-050 Ni Opts, Exo-003 plate chokes, and RGC-06 ps chokes.

The system has five Pi Pro Four speakers with JBL pro woofers and JBL compression drivers.

I've alway thought that for good multichannel all five speakers and five amps should be identical.

An Onkyo Pro processor and Oppo BluRay. Subwoofer is a Revel B15.

No need to go out for movie watching. I've tried multichannel music but still like my two channel mo' better.

Now, biamping: that would be cool!

[Paul Joppa]

OK, I'm looking at some possibilities. A mono SEX might be practical with some changes in the total lineup - i.e. a new power transformer that would also serve for a new Seduction and new Foreplay. I'll talk to Doc B. This would be a long term development thing though - maybe a couple years?

[Mudhiker]

OK, I'm looking at some possibilities. A mono SEX might be practical with some changes in the total lineup - i.e. a new power transformer that would also serve for a new Seduction and new Foreplay. I'll talk to Doc B. This would be a long term development thing though - maybe a couple years?

Is this the sort of thing I can hack up a prototype on a breadboard with some off-the-shelf hammond iron?  Having built a S.E.X. I have the schematics, though I am of course mindful of intellectual property issues and all that and needing permission to use the design.  Once the fiddly cap and resistor details are dialed in the hard work would be winding some new transformers and the like, right?  I have a solid electronics assembly and troubleshooting background, a good scope, function generator, etc... but I am not an engineer.  I am very interested in a "hacker's" SET DIY kit and I think other folks would be too.  I remember a thread on the old forum in which Doc B. was wondering why hardly anybody has bothered to try creative new things with the current SEX.  I think a mono circuit would make fiddling easier for some of us.

[Doc B.]

I'll talk to Doc B. This would be a long term development thing though - maybe a couple years?

It's funny to me that we have been changing over to stereo amps because our customers asked for it, and now you guys want monoblocks. I think the amps are the easiest part of the equation. Use three SEX amps. change to two mono pots if you want to balance levels. Heck for the price, use five SEX amps set up as monoblocks - bridge the input signal and wire the output trans secondaries for 4 ohms and put them in series on a single 8 ohm speaker. It seems to me that the critical part is a 5.1 channel Foreplay. We could do six CFs with a six gang attenuator (which of course will be expensive).

This would not take two years. However it would take a commitment of at least two dozen orders.