AudioCircle

Other Stuff => Archived Manufacturer Circles => Hagerman Technology => Topic started by: chris65 on 15 Jul 2013, 12:19 pm

Title: Monogram Build.
Post by: chris65 on 15 Jul 2013, 12:19 pm

Hi,
First post here, but have been reading the forum for a while. Been wanting to build a Monogram for some time & finally got the board from Jim.
I have a small collection of 78's, but wanted a tube based stage to provide variable Eq.
There doesn't seem to be many who have built this, so thought I would share:

(http://www.audiocircle.com/image.php?id=83555)

Upgraded some of the components from the parts list: Solen & Vishay caps in the signal path, Vishay & Holco resistors
Wiring is vintage Western Electric except on the power.

(http://www.audiocircle.com/image.php?id=83556)

Chassis is Hammond, powder coated in a nice vintage grey. Not quite complete yet, front panel & some other cosmetics to finish, but I was pretty pleased when when worked first time. Been tube rolling a little, with some NOS tubes to play with (Brimar, Mullard, RCA).

(http://www.audiocircle.com/image.php?id=83558)

(http://www.audiocircle.com/image.php?id=83559)

(http://www.audiocircle.com/image.php?id=83560)

I have a few questions, but I'll leave that for another time. Thanks to Jim for a great design & sharing his ideas.
Chris

Title: Re: Monogram Build.
Post by: david62 on 19 Jul 2013, 09:01 pm

Nice neat build.You do nice work! Enjoy.
Dave

Title: Re: Monogram Build.
Post by: Jaxn on 21 Jul 2013, 02:51 pm

Nice work.....enjoy!

Title: Re: Monogram Build.
Post by: chris65 on 9 Aug 2013, 12:32 pm

Thanks for the comments.
Fully finished now, here running Brimar CV4004, JAN Philips 6189's & Osram U50. Some more tube rolling planned.

(http://www.audiocircle.com/image.php?id=85041)

As I am using vintage GE RPX & Clement cartridges, the output from these can be as high as 30mV. So, I do find the gain a little too much.
Tried using a 5751 tube replacing the 12AX7, but not really any difference.
My question is, can a 12AT7 (mu of 60) or even a 12AY7 (mu of 45) be used to reduce some of the gain. The volume pot is 50k, maybe a 100k would also help?

Thanks, Chris