straylight

I submitted a manual with pics for Root beer 180 Vacuum tube mono amps but can't seem to find it anymore and it's not under tube amps section for manuals. Submitted this through Dennis Miller a while ago. Anybody know if its still in database?

In the mid-2000s Bob was working on protoype vacuum tube amps and auctioning off several of his amps on ebay. During these auctions Bob sold off about six prototype pairs of rootbeer 180 mono amps but answered hundreds of questions submitted by ebay members. Every question was answered and it was a huge knowledge transfer to the audience of onlookers. It is great to hear a return to those exciting times. Bob has so much audio knowlegde and general wisdom to impart to the world that if we can tap even a mere fraction of a percent of that we will learn an amazing amount! Jim's expert audio build team also has been able to interact with Bob and bring his ideas to the light of day. There is a weath of inspiration and knowlege there too!

Very sorry to hear of your loss, may he rest in peace.

Do you think Tom Waits still passes the hat at his performances, or is it just a rumor? KILLER songwritter with a whiskey-soaked voice.

One last point regarding E288CC tubes. These are tall envelope tubes and therefore require at least 2 and 1/8 inch clearance. If the clearance in your preamp is less than this than they will not fit and should not be used. These require slightly more heater current than 6DJ8 /6922/7308 but pinout and all other specs are the same: 6DJ8 - filament current = (36 ma) E288CC - filament current = (47 ma) FYI...

I think part of what you said is true of the B&W look-alike build, he won't ever recoup the CNC manhours or metal costs on this, but the pride of building it must be off the charts. He didn't save any money on building it either...he didn't have to do it all in metal...but clearly it was a cost is no object obsession. At one point Krell made an all aluminum speaker cabinet but it was tiny compared to these.

I'm sure your ML's are going to be safe and secure under their covers at night! Regarding that custom aluminum-water-jet-cut-one-off speaker project...OMG!...this brings a whole new level of audio insanity to our party! With Focal drivers and Morel tweeters this may look like a B&W from the outside but I think that's about as far as the similarities go. Looks like a custom crossover too. The carbon fiber stretched over custom carved wood midrange enclosure and solid billet machined tweeter are the cherry on top. I think the price of the aluminum scrap alone would pay for a pair of my 800D's. Must be nice to have the software and jet lathe lying around to do such projects. Maybe this guy builds satellites during the day? Thanks so much for sharing...I never would have believed it if I hadn't seen it...WOW! ...and the cost of all the Audio Research electronics to power those speakers could probably buy a small cottage on a lake somewhere. Nice.

The 6DJ8, 6922, and 7308 all require exactly the same filament draw, so should not be different from one another. Differences are more in the realm of tube life, noise levels and quality of manufacturing. The E288C is spec'd as needing slightly more filament current than the three listed. That does not, however, mean there aren't minor current draw differences between all tube brands and batches with the same spec but they should be near to the spec value. Power supplies should always be designed or upgraded considering how many tubes are drawing current in the circuit.

I have 2 quads of 6922/7308 variants...these are used (but testing strong) E288CC...vintage (not modern) SIEMANS gold pin...MADE IN GERMANY very, very rare. You can check them out on the web or many of the European tube collectors sites. Pulled directly from a working Audio Research SP-10 preamp with separate power supply. They will easily do the work of a 6922 or any 7308 (exact same pinout) but they require slightly higher filament current than standard 6DJ8s. May not be an issue if you are running only one or two but I make no promises regarding suitability for any particular preamp. The SP-10 preamp ran 6 of these tubes in the phono section alone and the preamp had extremely low noise and was a solid performer. The weakness of this preamp was finding quiet enough tubes since there were so many in the circuit. These tubes measured up to the task. I had once thought that the white labeled Amperex from Holland were the absolute best with the lowest phono noise in circuit. These may be a bit better then the Hollands in all regards and certainly will be as low if not lower in noise on the most gain-intensive phono preamp circuits (like 30 db to 45 db). If you are using them for just line level preamp these would better perform even better. These E288CC test high but will be retested if sold. PM me if interested. These are special tubes.

I once talked to the guys at Martin Logan about a pair of Sequel IIs planars that didn't sound quite right (they sounded bass heavy). I bought them from a guy who lived in the wilderness and heated his cabin via woodstove. Turns out that woodstoves and Martin Logans are a very bad combination because the smoke particles adhere to the ML drivers over time and pollute the surface making it sound lifeless and dull. He told me about a solution...wash them...that's right you can wash em' down and restore that once vibrant sound! Well I lucked out with one of the speaker panels but the other panel did not clean up too well and I wound up buying new panels from the ML guys anyways. So I was curious about them and took the dead panel apart to see what was on the inside. I discovered something really odd. The connection wire on the INSIDE connecting the panels together and connecting it to the outside world and its crossover electronics was a very gently looped but also slightly twisted pair of copper wires...NOT soldered and NOT tightly twisted together. I thought this was a defect and somebody at the factory had not finished the job. When I queried the ML guys about this they said "Oh yes, we found out the the purist connection between panels and the rest of the system is copper to copper"...they swore to me they could HEAR the solder connection whenever it was present in any internal wiring. Fascinating finding and If I hadn't dissected that dead driver panel I would have never found this out. It seems that trade secrets abound in all these high end products...

I also had a hard time transitioning from Apogee Stage ribbons to any other box speaker on the planet. The Apogees were just more natural and open sounding in the midrange and the difference with box speakers was always some kind of annoying peak or resonance that interfered with the sound. The Apogees were my main reference speakers for over 25 years because no other box speaker could measure up. Here is a picture of them at Carverfest 2022. The cabin we had had excellent acoustics with no early reflections from walls or ceiling to negatively impacting the sound. The vaulted ceilings were well over 20 feet high. Incredible sound. I did finally find a box speaker that could measure up but as you can see it really doesn't look much like a box...but it is. The B&W 800D (D for diamond encrusted tweeter) were every bit as natural sounding with an even greater sense of air and ambience around the musicians and instruments. They are more dynamic and with the right amplification can play much louder with less compression than the ribbons. The electrostatic types also have compression even with competent amplification, so to me the compression gets greater at greater volume ( I can't seem to escape this impression no matter which stats I listen to). Not so with the B&W 800D. These speakers can reach sound pressure levels that I'm sure can damage hearing...so discretion is advised! They have 3 inch thick MFD internal bracing in a matrix lattice arrangement. Each of the modules...tweeter, midrange and woofers... are contained within independent modules that are isolated from one another. I think it works but there IS a downside. Each speaker weighs in at over 275 lbs. ! The cross-over components are isolated from any vibration by their presence in the aluminum base. You could use a subwoofer with these but it would probably be pointless, they have adequate bass output in any normal sized room down to about 25-30Hz.

Hi Ed, Russ and Kirk (and wives) plan to stay in cabin 11 and really look forward to seeing everyone again for CF 2023. We all had a blast last year and it was really great to meet everyone. We will most likely stay for most if not all of the scheduled dates but will let you know if that changes.

+1

Ouch!

Well, I guess all we can say is life is a vampire and full of surprises.