10:2 Line Level Tube Mixer

Help Support GroupDIY:

Holger

Well-known member
Joined
Jun 11, 2006
Messages
855
Location
Hamburg, Germany
[font=arial, sans-serif]Here is my latest build, a 10:2 line level tube mixer in a 2 HU case.[/font]
m11.jpg


[font=arial, sans-serif]Each channel has a 10k:10k shielded input transformer. The debalanced signal goes to a channel PCB which has a volume pot, a mute switch and a pan pot. The stereo bus is done with a ribbon wire attached to all the channel PCBs.[/font]
[font=arial, sans-serif]The stereo signal passes a virtual earth amplifier, followed by a fader and a final voltage amplifier stage. The tube stages base on the design by Ian Tompson-Bell.[/font]
[font=arial, sans-serif]The nice little Simpson meters were buffered by Joe Malones VU meter buffer which I recommend again here.[/font]
[font=arial, sans-serif]The mixer has an external PSU.[/font]
[font=arial, sans-serif]And yes, the master knob is not final.[/font]

m22.jpg
 

Gold

Well-known member
Joined
Jun 23, 2004
Messages
2,743
Location
Brooklyn
Looks beautiful.  Did The project use Ian’s designs and PCB’s or did you lay out the PCB’s yourself?
 

Holger

Well-known member
Joined
Jun 11, 2006
Messages
855
Location
Hamburg, Germany
Thanks for liking, gentlemen
Paul, it's my PCB layout of Ian's TLA. I've used the same PCB for my modular tube pre amp. It's an 180mm euro card that can be used in multiple ways. Just add a mic front end and it's a mic preamp. 

min.jpg

 

Gold

Well-known member
Joined
Jun 23, 2004
Messages
2,743
Location
Brooklyn
Holger said:
Paul, it's my PCB layout of Ian's TLA. I've used the same PCB for my modular tube pre amp. It's an 180mm euro card that can be used in multiple ways. Just add a mic front end and it's a mic preamp. 

Ian's designs look so attractive. I'm not a tube guy but it looks like it sounds great. I never under estimate that. I'd love to build a line amp one day to check out.
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
13,755
Location
Norfolk - UK
Holger said:
I wasn't aware of that. Thanks CJ
The mixer works very good. I will do some measuremnts once it is finished.
Yes, I had a thread here about designing a low profile output transformer. CJ came up with a design, knocked one up and tested it. He posted the design details and I got Electro Mag here in the UK to make some. The rest you already know.

I will be interested to hear about your test results. I notice in the picture of a module you posted that you are using an OEP 187A15C mic input transformer. I am using one in the current Mark III design but recent tests have show it has poor  HF response when used with a 150 ohm source.

Cheers

Ian
 

Holger

Well-known member
Joined
Jun 11, 2006
Messages
855
Location
Hamburg, Germany
Ian, I never had the time to test the OEP stuffed modules as mic preamps, I just did functional test with line level signals. I will look at the issue once I'll have some time.
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
13,755
Location
Norfolk - UK
Holger said:
Ian, I never had the time to test the OEP stuffed modules as mic preamps, I just did functional test with line level signals. I will look at the issue once I'll have some time.

Thanks Holger. No rush.

Hope you and your family are OK.

Cheers

Ian
 

Sorr

Well-known member
Joined
Sep 16, 2005
Messages
250
Location
Australia
ruffrecords said:
Yes, I had a thread here about designing a low profile output transformer. CJ came up with a design, knocked one up and tested it. He posted the design details and I got Electro Mag here in the UK to make some. The rest you already know.

I will be interested to hear about your test results. I notice in the picture of a module you posted that you are using an OEP 187A15C mic input transformer. I am using one in the current Mark III design but recent tests have show it has poor  HF response when used with a 150 ohm source.

Cheers

Ian


Sorry Ian, I don't know the story. Could you let me know? Thanks
 

boji

Well-known member
Joined
Jan 6, 2010
Messages
2,129
Location
Maryland, USA
Great stuff.  Thanks again Ian for all your design sharing and Holger, your rack mixer is Soooooo clean!  Really nice job. Thanks for sharing picts.
 

ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
13,755
Location
Norfolk - UK
Rocinante said:
Holger or Ian, I love the design of the vertical tube pcb's! Is that part of the Ian tube preamp?

Yes and no.

The original EZTubeMixer version of this design had the tubes mounted directly at right angles to the PCB. That is why the modules had to be 2.8 inches wide.

Later, both Holger and I independently developed vertical tube PCBs so we could make narrower modules. Holger has extended the depth of his modules as well so as to be able to accommodate output transformers in a 3U module.

Cheers

Ian
 

echoplex

Well-known member
Joined
Jun 29, 2011
Messages
170
Location
Germany
Wow Holger and Ian.. I'm truly impressed. Amazing work and craftmanship.
This mixer looks like color for days  ;)
 

Latest posts

Top