So how does it sound, strapped?

[jusbe]

Really curious about the changes you've made and uprated parts used. How is is different form the Paramount?

[Paul Birkeland]

Really curious about the changes you've made and uprated parts used. How is is different form the Paramount?

This is really a question that's independent of your topic subject.  The bridged operation was something that Doc B. and PJ worked on several years ago to provide enough power for the low sensitivity midrange drivers in the big system. 

Apart from that, the Kaiju has both a larger plate choke and output transformer when compared to the Paramount.  The bigger plate choke assists the Kaiju in producing much deeper bass at its rated power.  The larger output transformer offers higher power handling and some other tweaks that PJ can go into more specifically.

Beyond that, Kaiju has a universal power transformer with several taps to keep the filament voltages nice and tight (+/- 5% for you EML users).  It also has enough voltage overhead for regulated DC filaments, which is a big improvement over Paramount. 

The added noise reduction from the regulated filaments required that the power supply be a bit quieter, so an extra power supply node has been added to accomplish this. 

[Paul Joppa]

Technically, the "strapping" is unusual. In normal parallel-output amps, the two tubes are wired in parallel, where one can take more than its share of signal current because the internal resistance is much lower than the load resistance. For Kaiju the two outputs are wired in series, which is only practical when you have output transformers. This is the best way to wire triode outputs, because the voltages add without interfering with each other. (Pentodes, in pentode mode, have high internal resistance, and can be paralleled without interfering with each other.)

[jusbe]

Thanks, both.

Got any shots of the amp under the hood? Curious to see how the iron looks and is laid out.

Lastly, any thoughts about using tubes such as the Elrog 300Bs in a strapped Kaiju? Anything to note for implementation?

(Sorry for all the questions - but a new amp from Bottlehead is an exciting event in my SET worldview).

[Paul Joppa]

I was intrigued by your post on the Asylum (about Elrogs in Kaiju). PB and I have some ideas; I just need to crunch some numbers to see what works. More later  :^)

[jusbe]

Thanks Paul. I've had 300Bs in the past (and then got sidetracked in vintage-land), and was considering a GM70, 211 or 845 for my next SET adventure but the new transmission-like Elrogs present a new opportunity. Combined with parafeed iron, a matching DHT preamp and suddenly the Bottlehead offering has a very distinct ultra-fi feeling to it.

[Paul Joppa]

Re: Elrog - looks like 5 watts per channel in Kaiju; the operatiing point needs no adjustment. We are still studying higher-power options...  :^)

[ebag4]

I just read this about the Elrog 300b's on another site:

"Talked to George Lenz about Elrog 300Bs with Lampizator DACs.  He is still not recommending them based on previous issues.  They believe the problem is the current at startup.  He is currently recommending only equipment that limits current to 1.2A at startup which is different from other recommendations that it could handle anything below 2A.  They are working on more resilient filament but no ETA."

Does the Kaiju limit the current at startup?

Thanks,
Ed

BTW, my Kaiju has been delivered, can't wait to get home!

[Doc B.]

I have said this a zillion times already over the years - if a tube manufacturer wants to make a tube and call it a 300B, it should work like a 300B. If a tube manufacturer who makes said 300B that does not really function just like a 300B wants us to make suggestions about its applicability in our 300B amp, he might want to consider sending us some tubes so we can put them in our amp and determine how they work. To offer information about whether some arbitrary current inrush limit or voltage regulation or whatever will work with a tube that has a completely different filament than a WE300B without actually testing it would be offering up a healthy scoop of irresponsible handwaving bullshit speculation on our part.

[ebag4]

Whoa Doc!!  No offense intended.  I had read this thread concerning using the Elrog 300b and wondered if it was reasonable to use it, if not that is fine too.  If someone is going to spend Elrog $$ best to check first, yes??

Best,
Ed

[Doc B.]

Sorry, not meant to be railing at you. Your point demonstrates exactly what I was trying to say, perhaps too emphatically... If Elrog loaned us a pair of tubes to try we could let you know if they work. Seems like that could be to their advantage, but what do I know about the tube business?

[patm]

Hello,

I tried the Elrog 300b,s in my Paramounts. They sound amazing, lot's of attack all over the leading edge. Powerful sounding. My first set lasted 60 hours and burned filaments. The second set lasted 200 hours. I still don't know if the Paramounts had a hand in the demise, I have had some issues with them but I think it was weak filaments. I had used EML mesh plates for the previous 4 years with no issues. I moved on to Takatsuki,s 300 b. Same leading edge magic with lots more air all in all a much more sofisicated presentation. I would definitely like to try the Elrog again if they solve the filament engineering issue.

Pat McSween

[Doc B.]

I still don't know if the Paramounts had a hand in the demise,

This new tube failure phenomenon is a very common issue. Shifting blame to amp manufacturers for the bugs that show up in early tube production is counterproductive. There are many, many Paramounts - fourteen in my own system alone - that have run for years and years with the same set of 300Bs. I think I just finally wore a pair of Svetlana 300Bs out that I have had in those amps for 7 years and maybe had a few years in another amp before that. To imply that the Paramount is the cause of the failure of a new, unproven tube that is getting bad press for its failure in not just your amps but other manufacturers' gear as well is misleading.

Believe me, I get that everyone lusts after the latest boutique hyped up tube. This has been going on as long as I have been doing this stuff. But one also needs to look at the track record of the various manufacturers who have brought these new tubes out over the past 20 years.

We have had an entire batch of new 2A3 mesh from AVVT that all blew after 100 or so hours. We've had a sample 45 from EML that didn't even make it to the third manufacturer who was on the sample list before failure. We've had newly released TJ45s go tits up to the first batch of customers and they were withdrawn for a while. There is the legend of an entire early production run full of Svetlana 300Bs that couldn't be sold because the filaments sagged and shorted. JJ small signal tubes pretty consistently have a reputation for excess noise when they come out. The Krons designed tubes that were so different than the 300B that they wouldn't work in any existing amps and eventually they had to make their own amps just to run them. Those 12AX7s  from the CRT manufacturer out of UK never even made it to market before they gave up on them.

Tube manufacture is a very difficult process, made even more difficult these days because some of the materials and processing that used to be used are so hazardous that they aren't even legal anymore. Most of these issues mentioned above eventually got shaken out and there are many great new tubes out there. Some like EH and Sovtek have been great out of the gate and continue to be super reliable. I'm grateful for all of them and I hope that Elrog ends up with a reliable design. But I'm not taking the rap if they failed to make the new tube meet spec and need to rework the design to function like the tube they are attempting to mimic or improve.


 

[patm]

I am sorry if I was misunderstood. I guess I could have said it better. I was referring to my abilities as a builder as a possibility and not BH equipment. Thomas Mayer at Vinal Savior did try and point to the statement on the EML site about the sparking. And the soft start ... After I explained that it was only on the direct coupled 2A3 version he understood and could see no reason for any concern with the voltage readings I sent him. At that point he wished to end the issue and offered me an 80% refund which I thought was fair.

[Doc B.]

Yes, that EML debacle has proven to be a good test of people's reading comprehension. Many bad assumptions have been made because of it, and I was inclined to avoid our endorsement of any one manufacturer's boutique tubes over another's after that.

Before I make this sound like a simple case of blaming all tube manufacturers for all audio issues, let me reiterate that New Sensor (i.e., EH, Sovtek) have been excellent to deal with over the years, and their power tubes are the most reliable I have seen. When you buy a few hundred power tubes every year it's reassuring to know that they simply work and sound good with no drama.