Toad Suck Tones Classic 50 .... Hiwatt from heaven

The Boogie Board

Help Support The Boogie Board:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
2

212Mavguy

Well-known member
Joined
Oct 5, 2007
Messages
754
Reaction score
0
Location
Park City, UT
Just got this in today. Check out ebay search 280352662220

Phenomenal machine. Could be considered a Hiwatt tribute amp with a couple of original twists. I can't post clips, but this is the second amp I have gotten from this custom builder using Bendix tubes. Big. bold, tight as can be, and the sonic detail is unreal, cleans sound like a Steinway piano! Even in class ab bias it puts out some amazing even order harmonics, which push pull amps have some difficulty doing normally, the output transformer is huge. Great tone stack, and not a one trick pony. Has bias and bias balance between each power tube adjustment pots.

Great silkscreened note on the back of the chassis: "This amp was designed to kick *** and take names but be warned that it contains lethal voltages that will ruin your day if you carelessly poke around in it!" "In memory of Dave Reeves and Harry Joyce, builders of some of the finest tone machines ever concieved." This amp IMHO takes their ideas to a new level by designing the output section around the 6384, a secret weapon amp tube if there ever was one. Bendix 6384's are designed to withstand 300g's, and last 10,000 hours. Their tones are simply amazing. Bendix tubes were designed for Cold War military weapons such as nuke missiles and B-52 bombers.

The other amp uses a pair of Bendix 6094's and it is biased to put out 18 watts, easily the stoutest sounding 18 watter I have ever heard. Also has bias and bias balance pots. Both are one of a kind customs that the builder made just for the love of the art of amp building. The builder used to work on Titan nuclear ICBM's and that type of overly stout cold war build exists in both examples. There are currently no pics on his site of the 6094 custom, top secret!

Great looking headshell, huh?
 
Hi Thom,

Thanks for the compliment and links! :) I read every one of the posts in both threads...nearly all were unfortunately not well informed. There are two common misconceptions about 6384's:

one, they are not a sub for kt88's, besides not being pin compatible, they don't have as much output power, they are simply a 6l6gc in output, nothing more,

and two, when specs say 325 volts on the screens, that IS the upper limit.

I ran both Bendix and later production Cetron 6384's in my Frank-en-champ, which presents 424 volts on the plates and only a few less on the screens, and also in my Siegmund Midnight Blues Breaker head having the lowest voltage main tranny option. In the Frank-en-champ, after only a half hour the cetron lost 10 ma of output draw, and there was a dark carbon-y residue on the ceramic spacers that was not there before, also, the current draw was too high for a cathode bias setting for 6v6's. In the Siegmund, tube rectified, as long as the bias was set into a 6l6-ish amount of curent draw at class A, the screens were below the limit. I briefly ran them at a lower bias setting, in a hot class ab, and they sounded even better at that lower bias, amazingly articulate with still plenty of very tight bottom end. However, the screen voltage was above limits at that setting. When I flipped the class a/ab switch to class A in the Siegmund, they ran too hot and began to redplate. I could have changed out the resistors between the plates and screens, but I was not comfortable with modding a masterpiece amp like that one. The tube dealer I got my 6384's from had used a pair of his in a hifi amp with screen voltage in excess of specs and they wore out quickly.

This TST amp was designed around the specs of the 6384, hence the use of a voltage regulator tube in the circuit and as a byproduct it happens to be the quietest amp I have ever owned. Stay below that spec and bias sensibly to get that 10,000 hour tube life, and in this tube's case, biasing no hotter than a hot class ab gives up the wonderful goods that this tube is known to contain.

Another anomaly is that 6384's take about an hour to quit drifting in current draw when paired in a push pull amp, so when biasing it's best to set them right away, walk away for an hour, and reset them. If they were within 1% at first, they would invariably drift further apart. That is why I requested for the seller to add a bias balance pot in addition to the main bias adjustment pot. He did so, for the cost of the parts only! The reason for the drift is that the heater for the huge cathode is a massive ceramic block inside that cathode with the heater wires threaded through that block.

These tubes were originally designed for pulse applications, short intense pulses of high voltage and current. That is the reason for the huge cathode. The ceramic block style cathode heater was for withstanding 300g's of shock. A byproduct of this type of tube is the crisp and tight lower end when used for audio and guitar amps. Some of the HIFI weenies have discovered pulse tubes to work excellent for audio. Guitar players haven't caught on to the pulse type tube secret weapon tone factor yet as a rule and probably won't in the future.

I am planning on yanking out the JJ preamp tubes, with which the amp sounds amazingly good despite the use of them, particularly in the brilliant channel. Will revoice starting from the phase inverter, am planning on going euro VOS for replacing the jj's for keeping and accentuating the British accent in the tones.

This amp builder has created some very unique amps, he delights in doing up one-off customs. Check out the amp porn pics of the custom amp he did for Nancy Wilson from Heart... 8)
 
212Mavguy said:
I read every one of the posts in both threads...nearly all were unfortunately not well informed.
Click to expand...
Yes, I am now able to recognize that, because of the information you've shared. I thought it was interesting, and timely, that anyone else is discussing those rare power tubes.

You make a very, very important point about the biasing of these tubes. Most guitar amps, as you know, are actually designed to exceed the power tubes' stated maximum ratings, and that turns out to be okay. Not the case with 6384, though, where the limit is the limit. Lesson noted!

I'd like to hear what small-bottle tubes you use, in which positions, as you dial this amp in.

Best,

- T
 
I started to do that today, took off the removable back from the headshell, but will have to entirely remove the chassis from the headshell to swap out pre's. Kept burning my wrists on the tops of the output tubes when reaching in...When ever you have a situation where high output is crammed into a small bottle, things get really, really hot, not only with the 6384, but with other small bottle 6l6 types such as vintage Tung Sol 5881 and Sylvania/JAN Philips 6l6wgb, the 6384 is similar in size but significantly more massive/heavier in weight, once they get hot it takes a lot of time to cool them down, ceramic bases and extra thick nonex glass envelopes can store a lot of heat! The builder was very smart to set up the chassis to socket the tubes right side up for better cooling and less cooking of the chassis. But that's what you get when you have a real rocket surgeon designing and building your guitar amps. The interior layout is impeccable.
 
212Mavguy said:
you have a real rocket surgeon designing and building your guitar amps.
Click to expand...
Rocket surgeon?? Surgical strikes?? I'm glad you don't play death metal - you're armed, and would be very dangerous. As it is, it seems as if this amp is a weapon of mass seduction :mrgreen:

- T
 
The power supply and output section of this amp would do death metal VERY well, there is a huge capacitance storage capacity in this amp unlike any 50 watt amp I have ever seen. 6384's have incredibly crisp and big bottom end due to their being originally designed as pulse tubes. The preamp has nowhere near enough gain, though. Easy enough to mod or get your own custom built, but I'm not going there. When dimed you do get an 80's roar out of it, but it is too loud without an attenuator through my 16 ohm semi closed back 2/12 cab with JBL g125's, driving my semi closed back 16 ohm 2/15 with JBL g135's it is a double d ta=ta rattler. :lol: It would make a more than decent small club bass amp as it is.

Based on the 6094 custom I had previously purchased from this builder, I was expecting JJ's in the 12ax7 slots. Well, I was dead wrong...the first two positions were Telefunken smoothplates! :shock: The ef86 was an Amperex mesh plate, :D the PI was a Sylvania triple mica mil spec 12au7. :D The only tube I subbed was the V1, I stuck in a nearly NOS Siemens 12ax7 longplate, that gave possibility of a slightly more crisp pick attack texture then the 'funken in both channels, and slightly more gain and mids overall, the Telefunken had big bass, slightly less gain and and less mids. No wonder it sounded so good out of the box!

In addition, every nut that held a transformer or tube socket in place was a stainless steel aircraft lock nut with nylon insert, mil spec sealed pots everywhere as well, very expensive parts. The metal chassis standoffs were held in place with Allen bolts. Cold war nuke missile type construction indeed! WOOOOOEEEEEE! :mrgreen:
 
With specs like that, the response must be like a flash bulb. I can't help but think that the PI might be subbed-up, to increase breakup (is it possible in that amp?). Let me know if there's a particular 12AU7 you're looking for - I've got a bunch of nice ones, from when I wen't through my 12AU7 in V1 of my tweed Bandmaster phase (back to 12AY7 now).

Speaking of V1 - those long-plate Siemens sound a lot like I would have imagined Telefunkens sounding, just based on available verbal descriptions. But the reality is, the Siemens is much more clear; I like it, better than the T-funk.

This sounds like THE amp to play at the Restaurant at the End of the Universe (ever heard of Disaster Area?)

- T
 
Just recieved a detailed note from the builder explaining quite a few things I did not know about the amp along with a schematic redone with ideas for some possible tweaks. How many boutique builders would pay that kind of attention and care to a customer?

YOW! :shock: :D
 

Latest posts

Back
Top