"PentaBoost" - 12 volt Pentode Booster using Submini 5672 tube

[frequencycentral]

Red Star Drive - what is that? Mate, you ain't tired of tubes yet?!  (hope you never will!!!)

Red Star Drive = You have to wait - not fully cooked yet!

[mth5044]

Theres going to be 5 mini tubes isnt there? I mean, it only makes sense... star has five points, five tubes, all glowing red. Oh man.

[sweetwilly]

A little bit of tinkering again today.  Clipped a battery in and put it in front of the English Muff'n with it's volume cranked and there is next to no noise whatsoever.  Actually sounds pretty sweet running of the 9v.  That pretty much leaves the PS as the culprit of my squealing.  I'll give that Maplin one a try Rick.

[sweetwilly]

Quick sound clip running off the battery is  on my Myspace.

http://www.myspace.com/therealsweetwilly

It's Gibson Firebird with minihumbuckers, bridge pu into Pentabeast (as mine is apltly named) then into EH English Muff'n - mixer - Cubase.  The Muff'n has a 12AT7 in gain stage and a 12AX7 output, the gain set about 9 o'clock and the level at 3 o'clock.  2 runs through the riff with just the Muff'n then kick the Pbeast into action.  Bearing in mind that this is at 9v instead of 12, it's pretty impressive.  With 12v the boost is more noticeable, but my PS issues meant a good sound clip was impossible.

[sweetwilly]

Here's the clip so you don't have to suffer my myspace!

http://www.aronnelson.com/DIYFiles/up/Pentaboost_Clip.mp3

[mth5044]

Sounds good man.

Can someone give me the measurements on the 5672 tube?

The diameter is really what I need the most, at the bottom, so I know what size hole to drill. Thanks!

[~arph]

It is not cilindrical. but more box shaped.   I'd say like 5x14mm, but that is a rough guess.

[frequencycentral]

Sounds good man.

Can someone give me the measurements on the 5672 tube?

The diameter is really what I need the most, at the bottom, so I know what size hole to drill. Thanks!

Datasheet:

http://frank.pocnet.net/sheets/127/5/5672.pdf

http://frank.pocnet.net/sheets/030/5/5672.pdf

http://frank.pocnet.net/sheets/138/5/5672.pdf

[frequencycentral]

Here's the clip so you don't have to suffer my myspace!

http://www.aronnelson.com/DIYFiles/up/Pentaboost_Clip.mp3

Hey Willy just had a listen to your soundclip - nice one! Sounds great - you can really hear when the boost kicks in!

[sweetwilly]

Thanks Rick, mine seems to fatten the signal when feeding other pedals, but is a pretty cleanish boost (breaking up a little with volume maxed) when at the end of the chain.

A really simple design that does exactly what it says it does.

Also, 9v sounds pretty good to my ear, but that's only with my home recording setup - into a good tube amp at volume and 12v might be better?

[pqt_bach]

Hi everyone,

Cool project, but I have one issue with it... these tubes are VERY micophonic in my pedal. Did any of you encounter such a problem?

[sweetwilly]

Yeah, led me to tear down my first build as I thought the tube was dead!  If you can reduce the vibration to the tube it pretty much eliminates any troubles.  My tube is board mounted and I've used double sided tape that overlaps the board and makes it fit snugly into the enclosure, but protects it from the mechanical clunk of the switch. 

[frequencycentral]

Hi everyone,

Cool project, but I have one issue with it... these tubes are VERY micophonic in my pedal. Did any of you encounter such a problem?

They do go 'ding' if I tap them with my fingernail though. In my PentaDriver I put foam padding round them.

[pqt_bach]

Cool.

And did those measures eliminate the all of the microphonics and "thouch sensitivity" ?

[sweetwilly]

Pretty much. 

[sweetwilly]

All (a)board layout!

[stereovoid]

hi rick, spoke to you on myspace a couple of weeks ago, thanks for the help there! got my build finished ant thought it was all good, when i plugged in power the valve glowed intensly and then all power stopped. pretty sure my hook up is all good. when i checked the power supply it was set to centre pos not neg. would this have caused this kinda problem do you think? sorry, pretty new to this! if it is just that i'll try a new valve in there, if not i'll rewire the lot!

sweet willy, are you going to be posting up your 'all on the board' layout again? it seems to have run away!

cheers and hello to all! this looks like a great forum for newbs to find people that know their stuff!

[sweetwilly]

there were some, er, school boy errors - fixed em now so here it is again.



Having looked at Rick's Red Star Drive pic, I'm sure there's a better way to lay it out! - http://www.diystompboxes.com/smfforum/index.php?topic=71350.0

I fried a tube (though salvaged it for a rather snazzy necklace for the missus!) with a short.  I had same as you - big time glow then nothing.  Check the voltages on the pins of the tube.  I was getting over 10v on pin 2 and (and possibly pin 1 from memory) with the fried tube. You might want to replace the electros as well. RG made a great post earlier this week on this very subject! - http://www.diystompboxes.com/smfforum/index.php?topic=55003.0

[frequencycentral]

hi rick, spoke to you on myspace a couple of weeks ago, thanks for the help there! got my build finished ant thought it was all good, when i plugged in power the valve glowed intensly and then all power stopped. pretty sure my hook up is all good. when i checked the power supply it was set to centre pos not neg. would this have caused this kinda problem do you think? sorry, pretty new to this! if it is just that i'll try a new valve in there, if not i'll rewire the lot!

sweet willy, are you going to be posting up your 'all on the board' layout again? it seems to have run away!

cheers and hello to all! this looks like a great forum for newbs to find people that know their stuff!

Definately replace the electro caps. These tube heaters are pretty hardy - though quite how hardy I'm not too sure. The LM317 might not have survived either. Shame! Just check out each bit at a time! Good luck!

[stereovoid]

thank you so much for the replies guys, it was my own fault. to eager to get it running...before walking! got some spare valves (and a whole load of spare time coming up!-thank the victorians for inventing holiday leave!) going to try your all on layout sweet willy. think the whole situation has just made me more determind to get it going! will keep you posted! thank you.



sorry about spelling and grammer.