Picture of my first project 300B

[Tomatito]

Hi all,

I'm new to the forum so go easy on me. I thougt I'd share a picture of one of my monoblocks with you. It's my first project and I'm pretty proud. It sounds terrific although I'm not too happy about the hum (5mV)

 

[Bas Horneman]

Very..very nice..never mind for a first time project..it is a fine example of diy ..period.

Did you use star earthing?

 

[Tomatito]

yes I did. I'm trying to rewire the whole thing now so it uses different nodes for the different stages but it doesn't seem to make much difference.

 

[Bas Horneman]

Mmm..looks like you know what you are doing...so I can hardly give any advice.. ;-(

Do you have a hum-pot on the filament of 300b? (AC/DC)..

Did you ground the outside of transformers/chokes/caps etc?

I use indirectly heated triodes..so I have very little hum even with AC filaments..

 

[Tomatito]

Yes, there's a hum-balance pot on the 300B heaters.
Grounding the outsides of the trannies ? Do you mean the steel cases they're in or the transformer itself ? I use a powertransformer with a static shield and that's grounded but maybe it's a good idea to ground the cases as well... Where's my soldering iron....The cases of the capacitors share a groundplane (see picture)

 

[Tomatito]

BTW, nice website...

 

[fdegrove]

300B

Hi Tomatito,

Lovely job!

Hup!Hup!Holland!

I see a handful of tantalum resistors (I think),GZ37,300B and what tube did you use as input?

BTW,I would leave the grounding as it is now.

Cheers,

 

[Tomatito]

Thanks, you're making me blush. The resistors are Riken Ohm. The input tube is a 6SN7GTB, but tomorrow my 5692 red bases arrive. Can't wait to hear !

 

[FrankDIY]

Very nice job

 

[fdegrove]

RED OCTALS

Tomatito,

5692 red bases arrive. Can't wait to hear !

You're spoiling yourself rotten.

Doei,

 

[Tomatito]

Yeah, I know, isn't it great ?

 

[Tomatito]

Actually, to make things worse, I got the 5692 for 50 dollars, a nos pair

 

[fdegrove]

RED OCTOBER

Hi,

At 50USD each that is not even all that expensive.
I've seen prices at quite a bit more than that.

Trouble with stuff like this is what you're going to pay in a couple of years.

So better start saving,you're never want to go back to the regular stuff after the Red Octobers!

Oh well,

 

[Ken L]

beautiful job

Truly slick.

Ken L

 

[Lisandro_P]

Beautiful, jealousy-inspiring amp I better finish my jlh....

 

[nunes]

very good

 

[TubeHound]

Hello Tomatito,

Very nice indeed. Thanks for the underside pic. I am the one who emailed you earlier this month about your meter you have installed in your amp. Glad you joined this board. There, as far as I know, are two of us who are currently working on the JE labs 300b amp, Ciscokid and myself. CK is alot further along than myself. Anyway, don't hesitate to chime in when I post a question, I will need a lot of serious, thoughtful, insightful and humorus help in the very near future.

 

[Tomatito]

Hi Paul,

I hope I will be able to help in any way. I 'm not much of an expert myself, although I've learned a lot during the process of building this amp.

Martin

 

[PedroPO]

Very good job!

I would put a copper plate over the chassis for the looks.
look at my amp.

Regarding the hum issue,do you have dc filament in the 300b?

I have a AudioNote kit one, and hum is there also. I think these babies can't live without some hum.

Is it audible when music is on? In my setup I can only hear it in the tweeters at total silence.

 

[Tomatito]

Thanks. The 300B heaters are AC. Only as a last resort would I try DC. First I want to try Steve Bench's trick : http://members.aol.com/sbench/humbal.html .Anyone try this ?

Martin