(Really Basic) Questions on Helios Mic Pre

Whoops said:

How is the restoration going on?

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Well, it has been a project of love, and many years collecting parts 

When I first wired it up, I used the effect send modules as an EQ for two channels and loved the sound! It was enough to play around with it. Eventually, I tacked on some transformers to be able to use mics with them.

Now I am pulling off all my hacks to the console, and will eventually have the EQs in the upper section again.

One thing that has made me curious is these WSW output transformers on the back, which,  is nice to have balanced outs. I have not compared the differences between the unbalanced and balanced outs on this yet. Surprisingly, the inductance measured lower than expected. Also, I have been surprised about these being there because it's been posted that the 15C1 is incapable of or shouldn't drive an output transformer.

Eventually, I will be posting some videos about the Helios and this restoration when I have some time.

thanks for the shared info.

it would be great is you dia a thread showing the photos and the progress.
Even if takes some years to finish it, you could also get the help of people in the thread

Thanks whoops for posting those Helios docs. At last it clears up one aspect that had been bugging me for some time - the correct schematic for the MMC card:

https://groupdiy.com/index.php?topic=58393.msg948068#msg948068

This clearly is a virtual earth mix amplifier.

Cheers

Ian

I'm glad the docs are useful Ian.

ruffrecords said:

Thanks whoops for posting those Helios docs. At last it clears up one aspect that had been bugging me for some time - the correct schematic for the MMC card:

https://groupdiy.com/index.php?topic=58393.msg948068#msg948068

This clearly is a virtual earth mix amplifier.

Cheers

Ian

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I could have sworn we talked about the MMC's virtual earth before via email. I currently have 4 different MMC cards, with a few different configurations. The MMC cards in Musicland were used in the subgroup bus, so the virtual earth makes sense. I think you mentioned in another thread that virtual earths were relatively new at the time.

Strat96 said:

I could have sworn we talked about the MMC's virtual earth before via email. I currently have 4 different MMC cards, with a few different configurations. The MMC cards in Musicland were used in the subgroup bus, so the virtual earth makes sense. I think you mentioned in another thread that virtual earths were relatively new at the time.

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I am sure we did talk about it. What has always confused the issue previously was the lack of an MMC schematic that makes sense. Now we have one that does.

Cheers

Ian

Whoops said:

thanks for the shared info.

it would be great is you dia a thread showing the photos and the progress.
Even if takes some years to finish it, you could also get the help of people in the thread

Click to expand...

I hope drawing board is the correct thread. Technically, it is a project...right?

Here it is:

https://groupdiy.com/index.php?topic=74900.0

Thank you @Whoops for encouraging me to start this. I really hope it is an enjoyable experience for everyone. It may actually help motivate me to work on this project more that I have.

Strat96 said:

I hope drawing board is the correct thread. Technically, it is a project...right?

Here it is:

https://groupdiy.com/index.php?topic=74900.0

Thank you @Whoops for encouraging me to start this. I really hope it is an enjoyable experience for everyone. It may actually help motivate me to work on this project more that I have.

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Sir, you have verified something that has plagued many of us. So thank you. This stuff is amazing.

Strat96 said:

I hope drawing board is the correct thread. Technically, it is a project...right?

Here it is:

https://groupdiy.com/index.php?topic=74900.0

Thank you @Whoops for encouraging me to start this. I really hope it is an enjoyable experience for everyone. It may actually help motivate me to work on this project more that I have.

Click to expand...

Great stuff,
thank you so much for that, will be great to follow your project If I can help just let me know.

I'm also sure the help of other around here can be quite positive for your restoration work.