Dear Audio DIYers.

Stay safe, stay healthy, stay inside.

Perfect chance to build that project you always wanted to do.

I am going to finish my Beast Jr. The an tube Xover and let the lows go through the Beast Jr. and Highs to the 300B from Bruce his book.

Again stay all safe and healthy

Robber
Quote 0 0
Robbert
Should state Robbert at the end of the message. :-)

Robbert
Quote 0 0

Please keep this thread up to date and post pictures!

I need something to read other than BBC news.

Quote 0 0
Robbert
Finally done. Did not had as much time as I was thinking earlier. The negative of being an essential worker. 😁

The Beast JR. In my own case with voltage regulation by reg tubes for the two driver tubes. Still breaking in but happy so far.

This amp is feeding the woofer of my speaker system Tannoy GRF Corner DIY, while the 300B from Bruce his book with individual DC filament power supplys is feeding the tweeter.

The little speaker is my Fostex test speaker. Click image for larger version - Name: IMG_20200613_1256546.jpg, Views: 25, Size: 427.88 KB Click image for larger version - Name: IMG_20200613_1256546.jpg, Views: 23, Size: 429.74 KB Click image for larger version - Name: IMG_20200613_1636487.jpg, Views: 23, Size: 402.65 KB Click image for larger version - Name: IMG_20200607_1843182.jpg, Views: 23, Size: 314.02 KB
Quote 0 0
Anonymous
why torroid installed like these ?
Quote 0 0
Robbert
Its about surface space, I was running out of surphase but not height space. If the torroids are not run to warm it works without a problem. You can even wire the primarys in counter phase reducing stray fields even more.

All my amps except a 20 year ago build have the torroids like this.
Quote 0 0
Carson
Looks great, interesting project for sure.  How are you handling the difference in gain?

where are those octal cups from?
Quote 0 0
Robbert
The gain of an amp can be controlled with the feedback resistor.

The octal cups are from angela.com
Quote 0 0
Not the ideal way for changing gain as you change other things as well with the NFB resistor. The same amp sounds very different with different amounts of NFB! No resistor is 100% "neutral", not even the Vishay naked foil which are among the best I know. And because of this I use ALPS pots for adjusting the NFB as they "add" something very subtle but very tube-like in the mids while keeping the top end crisp and clean without sounding "clinical". As nothing is "neutral" anyway why not tweaking it to personal taste which is the only taste that really matters? And one can also find the CDF for the amp/speaker combo without measuring it (would need a DSO and a little circuit).
Quote 0 0
Robbert
Could not agree with you more Wolfgang.

What you state is just what I am doing. Tweaking to what I find pleasant sounding. A wonderfull audio journey.

Now next step is the active tube crossover.

Cheers
Quote 0 0
Deleting Attachment...