Hello -

This is my first post to this site. I would say I am an advancing newbie at this point.

I recently acquired some 5676 directly heated submini triodes. Here is some basic info from the NJ7P site:

Plate Voltage ................................. 135 V
Grid No. 1 Voltage ............................ -5.0 V
Amplification Factor .......................... 15
Transconductance .............................. 1600 µ
Plate Current ................................. 4.0 mA

I would like to use these to make a preamp for use as a guitar pedal / treble boost. I would also like to try building a hybrid headphone amp perhaps maybe using the 5676 in the preamp with a LM386 (or other op amp) power stage. I am also open to a complete sub mini design as well.

Could anyone point me in the direction of getting this designed. This is my first "from scratch". thx.

I just looked at the datasheet and the description says that they should not be operated continuously as they only have a life about 100 hours. That does not seem like it will be a practical for a preamp.

Wow -- thx for the heads up!

No problem. Here is the link to the 5676 datasheet

Also, here is some sub-mini info that may help you:
- 6111 sub-mini Tube Amp
- 5678 sub mini tubes
- The BIC 6088 sub-mini class A hybrid

I am sending a warning about directly heated sub-mini tubes. They are extremely microphonic.
Look for 5703 or 5718 instead, for instance.

Thanks for the links Gio -

I have some 6088 so I was interested to see the link - however the schematics had all be removed. Are they somewhere else? thx again.

Hi moonbird, there was a bug in the forum software and some attachments were lost. I've emailed Rogers to see if he still has the information and if he does, I will get them posted. I see that the YouTube videos were also removed.
Hopefully we can get some of the info back.

EDIT - good news, I think most of the info for Rogers' project is here: 6088 subminiature tube Hybrid: The BIC revisited

I got a hold of Rogers and he sent me the original images. They are now up on the thread: The BIC 6088 sub-mini class A hybrid.

You may want to ask Rogers in that thread if the 6088 tube is microphonic which could be an issue for use in a pedal.
Cheers

Thanks ver much for your time and efforts on my behalf!! This material really gives me a jump start!!

Do you happen to know a good source for 6088 submini's? thanks much!!

They are easy to find as most tube stores seem to have them and they are often on eBay as well. Shop around as the price can be quite variable.