Vaccum tube Equalizer schematic?

[32860]

Old thread but on topic.

This BBC AM1/11 equalizer looks a lot like the Blonder Tongue Audio Baton.

[kissabout2002]

Thank you EL504 looks very interesting project, all the best.....

[PRR]

> This BBC AM1/11 equalizer looks a lot like the Blonder Tongue Audio Baton.

It is nearly exactly the same except for "Pro" input and output interfaces (extra tube for pro output level) and minor addition in the power supply for the added output stage.

I wonder if it really IS a Blonder but modified in the UK for Pro use? (It was also used in US "Pro" work, but the BBC paper shows 8D3 output valve, which is not how we number that type.)

[kissabout2002]

I am at home for 30 days for this virus so lots of time, so I decide to give it a go to the Rickard Berglund design show here by Stellavox.

I already order most of the components moths ago, still waiting the power transformer from Antek and the 3U rack mount cabinet all bought in US so I really do not know when they will arrive here in Philippines with this crisis, so with all I have and using a power transformer used for a tube amp I start the project.

I finish the project on paper and assembling all components, this became also more complex because I add to the Berglund design a led display for every single frequencies so when finish I will have the exact idea of the equalisation.

I used 6N2P instead the 12AX7 but when finish I will replace with 6N2P-EV, also on the way, so I put all on a wooden board connect everything unfortunately with a not really good wire but is the only one available at the moment, so I was expected a not so good result or some not pleasant noise but with surprise when I put on the EQ all work very good and the sound is really amazing, no oscillation at all, just a little hum at the max vol of the amp, so I am extremely happy with the result so now looking forward to receive the missing component and cabinet for finalise this project, I still do not know how I will be able to do 100 perfect holes on the front panel of the cabinet but well will see :-).

The sound test was very good so next I will make some serious test with generator and scope and Rew, for the main time some pic of the EQ.

All the best to everyone and thanks to the useful information received from other members.

[32860]

Cool!

[Indigent Audio]

i would love to build a tube eq and or active crossover but alas I am no 300v pioneer more of a 300v dreamer, I would like a very simple 3-5 band eq (all bands above 120hz) with an active variable subwoofer crossover and output for below 120hz, if a lego master builder wants to design/test/produce a board I will take 2

[directdriver]

An EQ circuit in a guitar amp that might inspire some similar circuits for audio use.

[HeyBill]

@kissabout2002 What a nice prototype layout.

[kissabout2002]

Originally Posted by HeyBill

@kissabout2002 What a nice prototype layout.

Thank you

[kissabout2002]

Originally Posted by kissabout2002

I am at home for 30 days for this virus so lots of time, so I decide to give it a go to the Rickard Berglund design show here by Stellavox.

I already order most of the components moths ago, still waiting the power transformer from Antek and the 3U rack mount cabinet all bought in US so I really do not know when they will arrive here in Philippines with this crisis, so with all I have and using a power transformer used for a tube amp I start the project.

I finish the project on paper and assembling all components, this became also more complex because I add to the Berglund design a led display for every single frequencies so when finish I will have the exact idea of the equalisation.

I used 6N2P instead the 12AX7 but when finish I will replace with 6N2P-EV, also on the way, so I put all on a wooden board connect everything unfortunately with a not really good wire but is the only one available at the moment, so I was expected a not so good result or some not pleasant noise but with surprise when I put on the EQ all work very good and the sound is really amazing, no oscillation at all, just a little hum at the max vol of the amp, so I am extremely happy with the result so now looking forward to receive the missing component and cabinet for finalise this project, I still do not know how I will be able to do 100 perfect holes on the front panel of the cabinet but well will see :-).

The sound test was very good so next I will make some serious test with generator and scope and Rew, for the main time some pic of the EQ.

All the best to everyone and thanks to the useful information received from other members.

Unexpected arrival of shipping from US during lockdown of remaining parts necessary to finish this all tube graphics EQ by Rickard Berglund, then again extended quarantine until May 15 so perfect for give a finish to this project.

Big task has been find a way to avoid to much cable connections, so I made this kind of "guitar string" for connect the all 10 modules, this workout very well avoiding bundles of wires and unwanted oscillations.

I just tested musically and sound and work very very well, no oscillation whatsoever and even the little hum on the wooden board test is gone, max vol on amp and no noise at all.

I still need nice knobs and somehow some print for the front panel.

I will test now the EQ with generator, scope and Rew for see the real performance.....all the best