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Je labs 300b DIY project for NG?

TubeHound

Member
2006-12-10 8:56 pm
Hello,

New here and lurking for a little while. Want to build my first amp. What about the JE labs 300b amp?

Would this be unrealistic for a first time project ? I will ask many questions in the near future, some not so brilliant, so forgive me in advance, Thanks.

Paul A.

I borrowed the parts list from Audio Illusions website,(thanks).

General Parts List
Quantities are for dual mono construction
· 1.....2 req - Angela Universal Power Transformer - 380-0-380V / 200mA
· 2.....2 req - Hammond 1627SE Output Transformer - 2k5/160mA/25W/4,8,16R
· 3.....2 req - Hammond 193J Enclosed Choke - 10mH/200mA/82R
· 4.....2 req - Angela Oil Cap 15uF/600VDC
· 5.....2 req - Angela Oil Cap30uF/600VDC
· 6.....2 req - Angela Oil Cap50uF/518VDC
· 7.....2 req - Angela 0.22uF/630V Paper in oil, Copper Foil
· 8.....2 req - Black Gate 100uF/100VDC bypass cap
· 9.....2 req - Black Gate 47uF/160VDC bypass cap
· 10...4 req - 100K /1W
· 11...4 req - 220K /1W
· 12...8 req - 47K / 1W
· 13...4 req - 1K /1W
· 14...2 req - 470ohm/1W
· 15...2 req - Angela 880ohm non-inductive 25W Cath Res
· 16...2 req - Dale 50K / 25W power supply bleed res
· 17...2 req - 3k3 /5W metal-oxide power supply res
· 18...2 req - Clarostat 75ohm/2W wirewound pot
· 19...2 req - General Electric 5U4GB ( or Mullard GZ37/GZ34) rectifier tube
· 20...2 req - General Electric 6SN7GTB
· 21...2 req - JJ/Tesla 300B Tubes
· 22...2 req - China Ceramic silver 300B Socket
· 23...2 req - Octal CeramicSocket for GZ37 tube
· 24...2 req - Octal Ceramic Socket for 6SN7WGTA tube
· 25...2 req - Power supply cables
· 26...2 req - Speaker Binding posts
· 27...2 req - 100K log Pots - Bourns





[IMGDEAD]http://users.starpower.net/je2a3/JELsc-300BDX.jpg[/IMGDEAD]


Thanks in advance
 
Good looking project

Keep one hand in your pocket and remember that tubes commonly run up to around 500 volts. Take your tiime, pay attention - be careful - ask questions when you need and you should be fine.

Until I started several other projects I was considering this as a first project. It came down to JE Labs 300B or one of the kits from any one of the sponsors on Audio Asylum.

I've had a good bit of grief from a nosiy Hammond transformer in one of my current projects. Several other amp builders have told me they had similar problems with Hammond. You might want to consider another brand.

OTOH, the best sounding amp I have ever heard, an 845 amp had a bunch of Hammond iron.

Hope this helps

:nod:

Ken L
 

TubeHound

Member
2006-12-10 8:56 pm
Thanks for the replys Folks,

I ordered svetlana's 300b's and they are on thier way, cool.


Now for the Questions:

I have a liitle more to spend on the output trannys, say in the $200-$300 range, any recommendations?

What about the power trannys? recommendations, things to watch for?

Which is the better rectifier tube and why? 5u4gb or gz37? both work with this amp, just curious.

The chokes are hammonds, any ideas in this area?

Which is the best ever 6sn7* type tube ever made and why?
( not wanting to start a big debate, just would like to know)

Thanks again everyone for your help, will post pics as this project progresses.

Paul A.
 

Brett

Member
2002-01-07 6:02 pm
<b>I have a liitle more to spend on the output trannys, say in the $200-$300 range, any recommendations?</b>

<a href="http://www.lundahl.se">Lundahl</a> LL1620/80mA SE. Based on the results I'm getting with the LL1620 in PP, it will exceed the Hammond in performance. There are also the One Electrons (www.one-electron.com, www.tubesandmore.com) Magnequests (www.bottlehead.com) and Electraprints. The Lundahls are possibly the best value.

<b>What about the power trannys? recommendations, things to watch for?</b>

Don't use a torroid, an EI core is better because it has a lower bandwidth, so doesn't let a lot of the junk on the mains into the amp. Better not to let it in than try to filter it out later. Cheaper and simpler too. For the same reason, it's worth the extra to get a power trans with an electrostatic shield. Buy the largest one you can afford. Your circuit needs ~110mA, so don't buy a 120mA trans. I like to go double or at least 50% more than the circuit draws at maximum not idle. They run cooler, don't vibrate or hum as much and last forever. The Angela should be OK, one per channel.

I personally prefer fullwave tube rectifiers off a +-0-+ wound transformer, choke loaded, or at least one stage of a Pi. If for whatever reason I decide to use a DC filament supply, I use a seperate filament transformer to stop coupling of the rectification spikes into the B+, and a Pi filter and Schottkeys. Hammond chokes will be fine in a Pi filter, and should also be rated for a choke input too. If in doubt email Hammond and ask.

Put the PS on a different chassis from the amps if possible, connected by an umbilical.

For rectifiers, I only use TV damper diodes now, 6CJ3/6D22S. Much better than all the others I've used and not stupid money (cheap!!) like some of the NOS Mullard GZ37 etc.

Avoid electro caps in the PSU. PP and PP in oil are MUCH better.
Remember, all an amp does is modulate the PSU, so have a junk PS and you get poor results.

<b>Which is the best ever 6sn7* type tube ever made and why?
</b>

Who knows? Colt45 is right but forgot to add tube snobbiness and exclusivity. Why are the best tubes usually the rarest?

It might be worth looking at the Chinese <a href="http://www.diyhifisupply.com/tube_supplies/china_nos_tubes.html">6N8P</a> from Brian at www.diyhifisupply.com. I haven't heard them as none of my gear uses 6SN7s, but I've read a lot of good reports on email groups about them. Plus they're cheap, tested and traced, and Brian is good to deal with. More than good enough to start with.

Cheers
Brett
 

fdegrove

diyAudio Senior Member
2002-08-21 1:20 am
Belgium
300B

Hi guys,

Seems to me you all were looking the other way when taking a glance at this circuit?
Have you seen the suggested tubes for the first stage?
For a diy project I would not design anything using those unless I had a dozen of them already.
If your preamp has the gain to drive the 6SN7,I would leave the input stage out.

Just my 2 cents of it,:)
 

Brett

Member
2002-01-07 6:02 pm
Re: 300B

fdegrove said:
Seems to me you all were looking the other way when taking a glance at this circuit?
Have you seen the suggested tubes for the first stage?
For a diy project I would not design anything using those unless I had a dozen of them already.
If your preamp has the gain to drive the 6SN7,I would leave the input stage out.
Frank,
I agree totally, it's not a practical tube for most people, but I'm amazed what people have sometimes. I presumed he had some, as no questions were asked about it, and it's not in the component list.

Personally, I wouldn't use either the 327/56/76 or the 6SN7 and would select the single drive stage so a preamp with sufficient gain and drive to swing 4V out, ie most of them would drive it to full gain. Almost every system I've ever seen has too much gain.

Cheers
 
Brett said:
It might be worth looking at the Chinese <a href="http://www.diyhifisupply.com/tube_supplies/china_nos_tubes.html">6N8P</a> from Brian at www.diyhifisupply.com. I haven't heard them as none of my gear uses 6SN7s, but I've read a lot of good reports on email groups about them. Plus they're cheap, tested and traced, and Brian is good to deal with. More than good enough to start with.

neat, chinese tubes with russian names..
6N8P is latin spelling, cyrillic spelling is 6H8C, if it matters to ya.
6N9P/6H9C is 6SL7, btw.

I've got some russian tubes coming from my friend in lithuania.. it will be neat to try them.

an intresting one is YO-186 (UO-186).
4pin DHT, 4v 1A heater. 250v plate @ ~50mA.. 15w Pa.

It will be intresting to try out..

also getting russian variants of the 807 (G807) & EL84 (6P14P)... I'll put up a site about them, when I try them out. If anyone is intrested, that is.. hehe :)
 

Brett

Member
2002-01-07 6:02 pm
Colt45 said:


neat, chinese tubes with russian names..
6N8P is latin spelling, cyrillic spelling is 6H8C, if it matters to ya.
6N9P/6H9C is 6SL7, btw.

I've got some russian tubes coming from my friend in lithuania.. it will be neat to try them.

an intresting one is YO-186 (UO-186).
4pin DHT, 4v 1A heater. 250v plate @ ~50mA.. 15w Pa.

It will be intresting to try out..

also getting russian variants of the 807 (G807) & EL84 (6P14P)... I'll put up a site about them, when I try them out. If anyone is intrested, that is.. hehe :)
Please post your findings. I'm interested in the EL84 as I use them, the 807 because I have dozens looking for a use, but especially the YO-186. All I could find via TDSL was the Russian CityRadio site with a pinout.
<img src=http://cityradio.narod.ru/spr/tubes/russian/short/pics/uo-186.gif>
Do you have any more info on it including prices? All DHTs are pretty linear, so it might make a nice 3W SET or 6W PP amp. The op point indicated there is similar to a 2A3/6B4G, with a bit less bias, so I'm (WA) guessing it has a bit higher u.

Cheers
Brett
 
All i could find out about it was what youve found :(

the YO-186 isnt available at the store he normally gets tubes from, but I assume some store out there carries them.

He found it in his box o' tubes, and I said I'd give it a shot. :)

807 is alot like a 6L6GC.. but It looks cooler, and it can handle RF better than 6L6.

I think I'll try the 807's in AB1, if I can round up the iron for them. (im not a rich man. not even close ;) ).

the EL84's are cheap as heck. about $2 USD. :bigeyes:
i think 807's run about $5.

I want to try the 6C33C in OTL, but theyre $10 a piece, and I dont really have that to spare at the moment..

heck, I still need to make my 6080/6AS7 OTL. I sure like putting things off. (and having ten projects going at once).:D
 

TubeHound

Member
2006-12-10 8:56 pm
Hello,

Wow, the response is really good! I might try the ElectraPrint transformers, ( waiting for e-mail response ) and was wondering if any one has used these in a project?

Also, I like the idea of seperating the power supply from the amplifier, but how is this done? I mean, what kind of connectors and cableling are required to achieve this?

Can copper plate be used for the top of the chassis, instead of aluminium? or does this introduce RF signals?

BTW, I have about 3000 vacuum tubes in my garage rafters. Just thought you'd like to know. Of course no 300b's and lot's of old tv tubes. Not cataloged, some good ones in there though. Maybe some day

Paul A.
 
maybeim said:
Also, I like the idea of seperating the power supply from the amplifier, but how is this done? I mean, what kind of connectors and cableling are required to achieve this?

Octal umbilical cord looks/works well.

basically have an octal socket on each chassis, and run a cord with an octal plug on each end between them.

Can copper plate be used for the top of the chassis, instead of aluminium? or does this introduce RF signals?

Don't think it will be a problem. I like the look of copper..
remember to varnish it or something, or it will go dull..

BTW, I have about 3000 vacuum tubes in my garage rafters. Just thought you'd like to know. Of course no 300b's and lot's of old tv tubes. Not cataloged, some good ones in there though. Maybe some day

Throw some my way :D

Most any tube can be semi-useful, depending on how bored you are ;)
 
Hi,

I am a newbie and have chosen this amp for my first real project. So far, I have acquired Hammond 1627se opt's, Angela mains, Hammond chokes, sockets, several sets of NOS 6SN7s and 5U4Gs, big can caps, signal caps, big resistors and a pair of Welbourn custom walnut and aluminum chassis. Should have the rest of the parts over the next few weeks. Am really looking forward to doing this build.

In the beginning, I contemplated a complete kit (ie Billie, Bottlehead). If I had, then I would probably be finished and listening by now. However, I have really enjoyed sourcing the parts. I lucked up and found the 1627s unused on eBay, as well as the chokes. Bought the chassis from www.welbornelabs.com. A couple of friends turned me onto the 6SN7s and the 5U4Gs. Bought the mains transformers and caps from www.angela.com. Various other parts from several other suppliers.

I am almost ready to cut metal and am using Visio to do my chassis layout. I ordered and received some Unibits for the hole cutting on a drill press. And am about to prep the walnut chassis.

My background consists of rebuilding my vintage Fisher equipment. That stuff is cool too…

Anyway, you can get most (if not all) of the parts from www.angela.com if you don’t what to source other places. They seem to have pretty good prices.

Btw, I stuck strictly to the circuit. If my ears tell me, I my mod later.. :)

Best of luck,

ck
 

fdegrove

diyAudio Senior Member
2002-08-21 1:20 am
Belgium
RUSSIAN TUBES

Brett,

My estimation on either stock of EL84/807 is roughly at 75.000 units each/year.
Pricing will depend on you being an individual or company but will always be more a matter of quantity ordered.
Any tube being manufactured to order has a minimum of 10.000 units/year.
I should know.;)

Rgds,