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Author Topic: Vacuum Tubes Edward Jurich Master Film Handler Posts: 305 From: Las Vegas USA Registered: Jul 2003 posted 08-02-2003 01:47 PM                     Anyone else out there like vacuum tubes for audio besides me. I just restored a 1939 E.H. Scott console radio and it has a wonderful sound on AM. It uses 2 - 2A3's in push-pull for about 10 watts output driving a 12" electromagnet speaker. Besides restoring this radio, I've built new audio equipment with tubes.  |  IP: Logged Bobby Henderson "Ask me about Trajan." Posts: 10973 From: Lawton, OK, USA Registered: Apr 2001 posted 08-02-2003 01:59 PM                     I like the Groove Tube brand 6L6GC power tubes and 12AX7 pre-amp tubes in my Carvin stack. Transistors suck much ass for providing a good sounding "crunch."  |  IP: Logged Dan Lyons Jedi Master Film Handler Posts: 698 From: Seal Beach, CA Registered: Sep 2002 posted 08-02-2003 05:38 PM                     Me too!! Here is my Jolida 102b integrated amp from my hi-fi system. Got it about a year and a half ago. The tubes are EI brand 12ax7s and EL84s. It does keep the room warm when it's on. On the right is my Creek OBH-8 phono pre amp. Danny  |  IP: Logged David Stambaugh Film God Posts: 4021 From: Eugene, Oregon Registered: Jan 2002 posted 08-02-2003 06:24 PM                        The best-sounding audio electronics I ever had was all-tube. The preamp was a conrad-johnson, the power amp Audio Research. That system sounded so good!  |  IP: Logged Lindsay Morris Expert Film Handler Posts: 233 From: Darlington, WA, Australia Registered: Sep 2002 posted 08-02-2003 08:33 PM                     I much prefer Valves with the warmer richer sound and failures when trouble shooting are much less dramatic with valves compared to solid state devices. Sometimes just the simple slip of the multimeter probe sends a packet of expensive Mosfets to the bin but had that been a valve amp in most cases would have just been a big SPLAT. Am currently constructing a valve amp rack to cover the conversion to Stereo & Surround sound at the outdoor which over the past 7 seasons has run on mono sound from a Westrex valve amp type AE 307 with EL34's in the output and from the soundheads the signal was being collected by the original VERY OLD Photo Cells which have never missed a beat. Tested response was still quite good to 8khz but by 9k the signal had all but gone. The "newer" line up is a pair of the Westrex AE 307 amps (EL34's) at 35 watts RMS for Left & Right and a pair of RCA (National Theater Supplies) A161 with KT66's at around 50 watts RMS for Centre & Surround. Just quick and rough tests on the bench taking the signal from an Eprad Starlet processor has produced quite good results in the workshop which I am sure will translate to equally good sound outdoors for this coming summer season. I will have to resist the urge to wind it up a bit as it sounds so good right now. Don't have a drawing of the A161's but am in the process of sketching that out to work out just how it all hangs together and for future reference. Valves... I love 'em and no problems getting replacements either. Just repairing a friends Westrex Drive In amp (type AE 293)which has 4 X KT66's in output with 4 X 6SJ7's driving those. When fixed the final test I give these brutes is 24 hours on the bench delivering 70 watts RMS of steady tone into a dummy load which gets rather warm but the amp just cruises!. Only down side is the voltages that some of these units use... the raw HT in the Drive In amp is just over 700 volts so quite lethal and much care is needed. Lindsay  |  IP: Logged Jon Miller Jedi Master Film Handler Posts: 973 From: San Diego, CA, USA Registered: Sep 1999 posted 08-02-2003 10:02 PM                     Here's a workhorse Dynakit Stereo-70 I rebuilt and modded in 1993... About the only things left stock are the transformers, tube cage, and the basic EL-34-based output section. The amp received a Curcio mod featuring a regulated power supply section and a driver card with two 6922 triodes per channel and bias balancing for the output tubes. I replaced the cheap-o original connectors with gold-plated binding posts and RCA jacks, and built a capacitor farm to replace and improve upon the old quad-section filter capacitor. It may not be a single-ended amp with 2A3s, but that modded Dyna sure does sing! Gotta love those firebottles!  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 08-03-2003 12:44 AM                  I love tube stuff... I have tons of it... Radios, Ham radio receivers and transmitters, etc. I built my stereo system so I can select between FET & vacuum tube power amps. (McIntosh 240) Depending on what I'm listening to. In my workshop, I have a Heathkit FM-3A with a A-9C Amp that I built as a kid...both still work great! I love designing and restoring it. Favorite Power tubes are 6L6GC (of course!), 6550 (KT-88), 6146, 811, 813, 833A...& more. I still have my original Novice transmitter kit I built in Jr H.S. many moons ago. Johnson "Adventurer" and my receiver National NC-98. Yeah, I'm a tube junkie...BIG time! HAhahahah BTW: It always amazes me that the music amp manufacturers design special "distortion" circuits to make their transistor amps sound like tube amps. Seems like an oxymoron. >>> Phil  |  IP: Logged Ken Layton Phenomenal Film Handler Posts: 1452 From: Olympia, Wash. USA Registered: Sep 1999 posted 08-03-2003 12:57 AM                     Tubes are the only way to go! I keep a couple of old Bogen C60 public address amplifiers around for occasional use.  |  IP: Logged Bruce McGee Phenomenal Film Handler Posts: 1776 From: Asheville, NC USA... Nowhere in Particular. Registered: Aug 1999 posted 08-03-2003 08:51 AM                     I, too, have a Dynaco Stereo 70. Mine is all original with new electrolytics, and new tubes. It sounds great! (Still looking for that big surround system amp!) In my travels, I look for things with tubes. I have many clock-radios that work, and some that dont, but look good. I have several 35mm projector amps, and one real oddity from Simplex that uses 2A3's that works like a dream. For 16mm equipment, of the 20+ machines that I own, only 5 of them are not tube amps. I have a 1956 Zenith B/W TV with a working remote control, and a 1961 RCA color TV that needs caps, but runs decently. I thought that tube lovers were a minority until I got on the internet. Tubes rule! BIGGEST TUBE MISTAKE: I once owned 2 (TWO) McIntosh MI-200 power amps. I was 12-13 years old, and a friend of a friend of my dad gave them to me. The thing I remember most about them is the weight! I couldn't find the 8005 tubes anywhere, so they sat in the shed until we did a dump run. Recently, I found out how valuable these units are today. I know nobody here (in western NC) that has tube equipment anymore.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-03-2003 02:43 PM                     I love tubes as well, but they are no longer necessary in the audio amplifier world, unless of course its for the collectability aspect, or if you plain just happen to love them. There are still some very good pieces of vacuum tube based test gear out there though. For those that may be interested there are several modern solid state designs that are single ended and operate class "A" that will easily beat the socks of any tube amp I know of. These can be easily constructed at home and for little cost. These do require alot of static heatsinking, or built as a water cooled amplifier. I'm in the beginning stages of constructing a second pair of these that will be built with water cooled, solid copper heat sinks. Note that the audio path sees a mere two semiconductors!! Here is a link to one of the best of these amplifiers..... http://www.passlabs.com/pdf/aleph/a2srv0.pdf Please note that although this design is patented, the designer Nelson Pass, encourages people to build them as long as its a not for profit venture. Also check out www.diyaudio.com Mark  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 08-03-2003 03:27 PM                        We've always preferred today's modern tube equipment, here at our drive-in. This time-tested technology performs at an efficiency and quality-of-signal level which transistors can not hope to attain. Shown below is Transmitter Room "Abel", one of the three state-of-the-art, self-contained FM stereo broadcast systems we use to send our audio signal the 300-400 feet from our booth to our customers. We're very excited about these installations, as they are barely half the size of our original systems. Reclaiming that square footage has allowed us to add an additional 16 toilets to our restrooms! __________________________________________________ Shown below is a new final amplifier tube, undergoing performance and integrity verification measurements in our maintenance shop. We run through 3 or 4 of these tubes a year. However, the cost is well justified by the looks of satifaction we see on our customers' faces when we fire these babys up. Not shown is our new John Deere lawn tractor, just to the left of this view. ____________________________________________ We're especially grateful to our local power company for the new substation and bug zapper they installed for us last year. Centrally located in Field 1's playground (just in front of the swingsets), it's a sight to behold for young and old alike. On a practical level, it totally eliminated the voltage drops we experienced when turning on the filament, and eventually the high-voltage supplies to our transmitters. Thanks to this new equipment, we've taken out all of our oil lanterns. As shown, the new plant makes for a friendly and scenic attraction for our customers as they travel the well-worn driveway to the snack bar.  |  IP: Logged Aaron Sisemore Flaming Ribs beat Reeses Peanut Butter Cups any day! Posts: 3061 From: Rockwall TX USA Registered: Sep 1999 posted 08-03-2003 03:46 PM                     I too am a huge tube fiend... Some of what I have includes the following: Dynaco ST70: I have two of these, this one has Tesla EL34s, Sylvania 7199s and yes, that's a 5u4G filling in for the Sylvania 5AR4 that shorted out on me My other ST70 has GE Owensboro 6CA7s and a GE Owensboro 5AR4, and Sylvania 7199s. TruTest Stereo/5: This little baby is what powers my computer speakers!! From left to right: Telefunken smooth-plate 12AX7, 2 Fujitsu 35C5's, RCA 35W4 rectifier. Stuff not pictured, but fully functional: Altec 1570B: A pair of RCA 811A's, the other tubes are a mix of RCA's GE's and Sylvanias. I am looking for a second one of these, cheap (yeah, right!) Kenwood KW-55 Receiver: 2 GE 7189A's per channel on the outputs Precision (Grommes) PA amp: The only thing I have thats operational that uses 6L6's (RCA Blackplates, of course) Akai 1710W reel-to-reel tape deck 1969 GE Porta-Color 11" Color TV: Still works like a charm! I have a lot of stuff that is not operational (much of it probably never will be- I will probably use some of it for the trannies... -Several RCA theatre amps and preamps (including a pair of 2A3 PP power amps that I plan on restoring one of these days) -Several Japanese integrated amps (EL84 and 6GW8 power tubes mainly) -A Hewlett-Packard signal generator -Several small 'All-American Five' radio chassis I also have hundreds of tubes, both NOS/NIB and tested good used ones. Some of my favorites include: Preamp Tubes: Telefunken 12AX7/ECC83 Smooth plate RCA 12AU7/ECC82 Clear top Mullard 12A*7/ECC** Sylvania 7199 Telefunken 6267/EF86 RCA and GE 6C4 Power Amp Tubes: Any US-made 6L6GC, with a special fondness for RCA blackplates Tung-Sol 6550 GE 6550A Mullard/Philips/Amperex/Valvo EL34 Tesla EL34 GE Owensboro 6CA7 Sylvania/PhilipsECG (US made) 6CA7 GEC (Genelex) KT66 and KT88 Any US or Western European 6BQ5/EL84 Any US made 807 Any US made 6146 Any US made 7591A Rectifiers Mullard/Philips/Amperex/Valvo 5AR4/GZ34 GE Owensboro 5AR4 All US made 5U4G and GB All US made 5R4 varieties Tubes that SUCK: Most Russian (except Svetlana) and Chinese garbage -Aaron  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 08-03-2003 03:55 PM                     Vacuum tubes are great!  |  IP: Logged Gerard S. Cohen Jedi Master Film Handler Posts: 975 From: Forest Hills, NY, USA Registered: Sep 2001 posted 08-03-2003 08:16 PM                     Bravo, Jack! I loved your drive-in transmitter spoof which amplified my mirth from shot to shot! Thanks, Gerard  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 08-04-2003 12:19 AM                        Thanks, Gerard. Guess it proves I have too much time on my hands! The drive-in I grew up working at has FM now. However, they've maintained their original 1953 speaker system at a level very close to when it was originally installed. This is the theatre's sound rack. The only changes made to it since it was originally installed have been the removal of the original "S. F. Burns & Co." photocell preamps and the addition of an FM stereo system (the white unit at top). This box also houses preamps and switching for two projectors (which the drive-in had when I installed it), switching for music, film and microphone inputs and voltage-controlled amplifiers for level control. It also has a summing amplifier to drive the speaker systems. ________________________________________________________ This is one of the two amplifiers the drive-in uses to power its original speaker field. It was a common model that RCA used in its turnkey installations. The outputs are 807s. If I remembmber right, it uses a 6SJ7 (6SL7?) for phase inversion, two OD3 (VR150) voltage regulator tubes and a 5R4 (5Y3?, 5U4?) rectifier tube. Sorry about being a bit hazy on tube types. Been a while since I checked it out. Over the years, I've found two spare amplifiers of the same model for the place. One is fully tubed and ready to go. The other is fully functional, just needing a set of tubes to put it into operation. Each of these amplifiers could easily run a drive-in twice the size of the one that they're installed at. Still, the theatre runs both of them each night, splitting the field between them. It has the normal ramp switching matrix, including switching to put either amplifier to the full field, and monitoring for each amplifier individually. The theatre presently runs a Century DA, powered by a Motiograph sound head. A Century R3 is on-hand, upgraded with a Component Engineering reader for the onslaught of cyan tracks we all know is just around the corner! For anyone interested, here's a mini-tour of the place. Wheel-In Motor Movie, Port Townsend, Washington  |  IP: Logged

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