DeathTrap400™ : : A Pretty Damn Good 300B Amp

[Steven-H]

Nice ! I happen to have some 813's lying around....How are you driving the 813's ?

 

[Parafeed813]

Nice ! I happen to have some 813's lying around....How are you driving the 813's ?

Still working on that one.
Power supply almost finished but I'm still saving for the OPTs (or need to sell off some of my valves that are getting too valuable to actually use ).
I'm tempted to cannibalize one of my other amps that has usable OPTs. Put them back when I get the parafeed set. Who knows.

Years ago I experimented with a trioded 813 driven by a trioded 6G6G/EF184 mu stage and liked the way it worked out. That encouraged me to continue the 813 project.
However, I read good things about the 6E5P here. Low distortion, high output (and cheap). If it's good enough for driving an 833, it surely can drive an 813.

About the filament regs: it took me some tinkering to get them to work with those monstrous 50W lightbulb grade filaments. Extra heavy (SMD) diode, small heatsink on the IC and chassis cooling for the whole board. In contrast to the ones for 300B filaments that don't need a heatsink at all.

 

[Steven-H]

Thanks for the info. I have the opts, tubes, sockets, etc - just haven't found a driver circuit for it....Was thinking this board might work...

 

[tomchr]

Tom,
Are you aware of anyone using these boards to drive something other than a 300b ? Like...maybe an 811 or SV572 ?

I list a couple of output tube options here: Damn Good 300B SET driver circuit

I'm not aware of anyone using the DG300B driver board to drive anything other than a 300B, though. The 300B is tough to drive. It requires nearly 200 Vpp of clean signal swing. The input capacitance of the 300B is not friendly to drive either... I suspect that if my board can drive a 300B, it can drive just about anything. I'm sure looking over the common operating points for the tubes you mention will provide some answers.

~Tom

 

[Steven-H]

Thanks Tom - seems like it could be interesting. Looks like the driver board would work, and your PSU for the front end. I'd love to use the reg board; but unsure if I can fit higher voltage rated caps on it (I want to run my 813 at 900v or so).

So in summary:
Driver board (12BH7 version) driving a 45 interstage connected to 813
Your PSU and Reg for the front end....need to finalize the 900v supply

 

[tomchr]

You don't have to buy a full kit. I'll be happy to sell you a driver board and a supply board separately. They're available on their respective pages on my website:

Driver: http://www.neurochrome.com/audio/?page_id=549
Supply: http://www.neurochrome.com/audio/?page_id=546

~Tom

 

[Steven-H]

Thanks again Tom...I would need the full suite to get the 45's running...Was more a question of do I buy an additional reg board to handle the 900v B+.

 

[tomchr]

I don't have anything that can handle 900 V B+. My 21st Century Maida Regulator Rev. 2.0 can deliver up to 600 V out with up to 750 V in.

~Tom

 

[bekim]

21st Century Maida Regulator Rev. 2.0

1. Is the same current output like in previous version?
2. From your website, apparently are less components on the new version, what will be cost for parts per regulator, exclude heatsink & PCB?
3. On version 1.0; Is it possible to use LT3080 SOT-223 package instead 5-Lead DD-Pak?

thanks

 

[hpeter]

'Sceleratus' from Head-Fi.org was kind enough to share some pictures of his build. Polished bronze on burley maple with walnut corners. Bravely done! He's very pleased with the results of his efforts. He's using my 300B amp design to drive a pair of Audeze LCD2 magnetostat headphones.

~Tom

So nice

 

[tomchr]

Sorry, Bekim. My subscription to this thread must have lapsed, so I didn't see your questions about the 21st Century Maida Regulator until now. The best way to reach me is via email (Contact Us on my website).

1. Is the same current output like in previous version?

Yes.

2. From your website, apparently are less components on the new version, what will be cost for parts per regulator, exclude heatsink & PCB?

If I recall correctly, the 21st Century Maida Regulator requires about $20-25 worth of parts to build.

3. On version 1.0; Is it possible to use LT3080 SOT-223 package instead 5-Lead DD-Pak?

No. The SOT-223 will not fit the DD-Pak footprint.

So nice

It's a nice build! 'Sceleratus' is quite a woodworker. The metal bits were done professionally (water jet cutting of the bronze and professional polishing). I hear from him on occasion and he still loves the amp.

Tom

 

[bekim]

Sorry, Bekim. My subscription to this thread must have lapsed,

Don't worry questions were before I purchase 21st Century Maida Regulator version 2.0.
As always, brilliant design and par excellence products and support from you

Thanks

 

[howard99]

can I use 300B XLS instead of regular 300B ? Thanks

 

[tomchr]

As far as I can tell from the 300B XLS data, it should be perfectly possible to use it in the DG300B. You may have to change a resistor to hit the -100 V bias voltage. That's pretty easy to do.

Tom

 

[howard99]

xls

so just change a resistor? transformers that you recommend would be ok? Thanks

 

[tomchr]

Yep. The power transformer I specify provides 525 V DC at the nominal mains voltage. I regulate down to 400 V with the 21st Century Maida Regulator. You can easily design the regulator for 425-450 V if you desire. The transformer has no issue delivering the total of 225 mA required if you're using the XLS tubes.

Tom

 

[howard99]

thanks now I have to get up the courage to get this started. It would be my first build. seems like you really support this and I have some great local resources as well. Thanks again for all of your time

 

[tomchr]

Those who subscribe to my newsletter or follow Neurochrome on Facebook know already, but I thought I'd made it more widely known that I have decided to discontinue the DG300B once the current board stock runs out. I'm spread too thin and have decided to focus on my solid-state designs. I have 15 DG300B board sets left. You can find them here: Neurochrome DG300B Product Page.

Tom

 

[Moderation Team]

Thread moved to Vendor's Bazaar.

 

[tomchr]

Fair enough. This thread was actually started before I started my business. Time flies. By now it certainly belongs in the Vendor's Bazaar.

Thanks,

Tom