GroupDIY

Project Specific Discussions => Preamplifiers => Topic started by: Holger on November 22, 2017, 05:04:36 PM

Title: Modular Tube Preamp System
Post by: Holger on November 22, 2017, 05:04:36 PM
I've recently finished a system rack and one module of my 10 HP 3 RU system.
The module contains 2 mic pre amps based on the TLA Ian Thompson-Bell has designed.
The 10 HP design allows to stuff 16 pre amps into a 19" 3 U rack or, as seen in my first attempt, to put 8 pre amps plus PSU into a 19" "Baugruppenträger".
28 + 10 HP were used for the PSU, there is a remainder of 6 HP when stuffed with 4 modules HP. Non used space is currently filled with whatever I found...


(http://audiofor.tv/diy/2017/modular/modul%203.jpg)

Module:

(http://audiofor.tv/diy/2017/modular/modul%202.jpg)

Frequency response:

(http://audiofor.tv/diy/2017/modular/modul%20fr.png)

Noise floor:

(http://audiofor.tv/diy/2017/modular/modul%20nf.png)
Title: Re: Modular Tube Preamp System
Post by: bruno2000 on November 22, 2017, 05:18:05 PM
Nice!  B+ from PS or DC-DC converter on board?
Best,
Bruno2000
Title: Re: Modular Tube Preamp System
Post by: Holger on November 22, 2017, 05:52:59 PM
B+ old school from linear PSU.
Title: Re: Modular Tube Preamp System
Post by: ruffrecords on November 22, 2017, 06:15:40 PM
Very nice indeed Holger. These are the new 220mm deep modules?

Cheers

Ian
Title: Re: Modular Tube Preamp System
Post by: Tubetec on November 22, 2017, 06:27:07 PM
Nice work Holger ,
Any  links to music you have recorded with Ians system online ?
The story about the SSL owner turning pale when he heard the Krassmonster was classic ,stands to reason in alot of ways ,I'd imagine you have the equivalent of thousands of transistors for the signal to pass through in a big SSL
Title: Re: Modular Tube Preamp System
Post by: Holger on November 23, 2017, 06:36:40 AM
Very nice indeed Holger. These are the new 220mm deep modules?

Cheers

Ian

Ian, you're right.
Title: Re: Modular Tube Preamp System
Post by: Holger on November 23, 2017, 06:37:33 AM
Nice work Holger ,
Any  links to music you have recorded with Ians system online ?
The story about the SSL owner turning pale when he heard the Krassmonster was classic ,stands to reason in alot of ways ,I'd imagine you have the equivalent of thousands of transistors for the signal to pass through in a big SSL

This should be answered in another thread.
Title: Re: Modular Tube Preamp System
Post by: skal1 on November 23, 2017, 03:55:18 PM
Holger look's very pro , by the way, were did you get the screw's for the front panels, do you have a part number.

cheer

skal1
Title: Re: Modular Tube Preamp System
Post by: Holger on November 24, 2017, 02:51:32 AM
Look:

https://www.reichelt.de/Baugruppentraeger/BGT-HS-2/3/index.html?ACTION=3&GROUPID=7756&ARTICLE=67858&START=0&OFFSET=16&SID=95WhfK46wQAT8AAHDhqtgb890f251c008fdb15d7175e0dccda8ec&LANGUAGE=EN (https://www.reichelt.de/Baugruppentraeger/BGT-HS-2/3/index.html?ACTION=3&GROUPID=7756&ARTICLE=67858&START=0&OFFSET=16&SID=95WhfK46wQAT8AAHDhqtgb890f251c008fdb15d7175e0dccda8ec&LANGUAGE=EN)
Title: Re: Modular Tube Preamp System
Post by: ruffrecords on November 24, 2017, 03:52:06 AM
Holger look's very pro , by the way, were did you get the screw's for the front panels, do you have a part number.

cheer

skal1

Most of the sub-rack manufacturers supply these but usually only as part of a sub-rack kit. Surprisingly few seem to offer the screws separately. Fischer seems to be the exception.

Cheers

Ian
Title: Re: Modular Tube Preamp System
Post by: beatnik on November 24, 2017, 05:58:39 AM
very nice

how did you connect the back ? it seems there is a pcb backplane ?

do you use an off the shelf chassis system for the sub-modules ?
Title: Re: Modular Tube Preamp System
Post by: Holger on November 25, 2017, 03:54:53 AM
I`ve designed a new backplane PCB for the system since the "old" version is 14 HP wide.
You can buy some of the module stuff from stores like www.reichelt.de
but it is also possible to buy from the manufacturer directly.
Title: Re: Modular Tube Preamp System
Post by: Holger on October 16, 2019, 03:03:32 PM
I've recently finished a second unit, this time with pushbutton switches and different transformers. 

(http://audiofor.tv/diy/2019/min.jpg)
(http://audiofor.tv/diy/2019/m3.jpg)


Title: Re: Modular Tube Preamp System
Post by: ruffrecords on October 16, 2019, 06:54:07 PM
Are those the small MRK 12 way rotary switches?

Cheers

Ian
Title: Re: Modular Tube Preamp System
Post by: EmRR on October 16, 2019, 08:44:34 PM
Looks great!
Title: Re: Modular Tube Preamp System
Post by: Holger on October 17, 2019, 03:44:02 AM
Are those the small MRK 12 way rotary switches?

Cheers

Ian

Ian, that's Right.
Title: Re: Modular Tube Preamp System
Post by: Winston O'Boogie on October 17, 2019, 05:39:27 PM
That's a nice job you did getting it all packaged Holger, both of them  :)

Are you using individual pin sockets for each tube pin?  I can't see a ceramic or otherwise main body of a tube socket in the pics
Title: Re: Modular Tube Preamp System
Post by: Fuzz Face on October 17, 2019, 06:33:58 PM
Are you using individual pin sockets for each tube pin?  I can't see a ceramic or otherwise main body of a tube socket in the pics
Good catch! I didn’t notice that but it’s a great idea
Title: Re: Modular Tube Preamp System
Post by: Holger on October 18, 2019, 02:29:13 AM
...
Are you using individual pin sockets for each tube pin?
...
Yes, the pins are from Harwin, Mouser # 855-H3161-05
Title: Re: Modular Tube Preamp System
Post by: L´Andratté on October 18, 2019, 09:23:26 AM
Beautiful!
I feel local patriotism! ;D
Seriously, looks like something on par with the stuff from the broadcast studios of old...
Title: Re: Modular Tube Preamp System
Post by: Winston O'Boogie on October 18, 2019, 10:02:26 AM
Yes, the pins are from Harwin, Mouser # 855-H3161-05
Thank you sir.  Again, nice work
Title: Re: Modular Tube Preamp System
Post by: Holger on May 09, 2020, 02:31:32 PM
I've got the final front panel for the PSU today, so here are some more details:
I've designed two PCBs for the required voltages. Here is the HT PCB that bases on a schematic Michael Kingston published some time ago. It can supply up to 300V regulated. I've added a voltage divider for the elevated heaters I use in this project. The little toroid transformer is custom wound, it'a 28.8VA 240V transformer.

(http://audiofor.tv/diy/2020/mspsuht.jpg)

Next is the PCB that holds two SMPS, the large one is a MW LRS for the heaters, the small one is for 48V.
(http://audiofor.tv/diy/2020/mspsuhtr.jpg)

The two cards co into a large Fischer cassette that is able to hold several euro cards. Special rails for the cassette are required.
(http://audiofor.tv/diy/2020/mspsubc1.jpg)
Assembly
(http://audiofor.tv/diy/2020/mspsubc.jpg)
Assembled
(http://audiofor.tv/diy/2020/mspsu.jpg)
Complete
(http://audiofor.tv/diy/2020/msfront1.jpg)
Rear view
(http://audiofor.tv/diy/2020/msback.jpg)

Bottom
(http://audiofor.tv/diy/2020/msbottom.jpg)


I started in 2017. Still one module to build...



Title: Re: Modular Tube Preamp System
Post by: jensenmann on June 01, 2020, 06:26:08 AM
Wow, Hoger, I´m impressed. That´s a lot of parts crammed into little space. Does it heat up a lot?
In particular I´m interested if the heat transfer through these small tube pins to the PCB is a problem.
Title: Re: Modular Tube Preamp System
Post by: ruffrecords on June 01, 2020, 06:41:05 AM
Wow, Hoger, I´m impressed. That´s a lot of parts crammed into little space. Does it heat up a lot?
In particular I´m interested if the heat transfer through these small tube pins to the PCB is a problem.
Tubes get a bed press for producing a lot of heat, probably due the that fact that the power tubes in guitar amps do get very hot. But mic pres are completely different. One of Holgers modules will probably consume less than 10 watts.  Its front panels will probably rise about 5 degrees above ambient. 10 of these in a 19 inch space is 100 watts.

Cheers

Ian
Title: Re: Modular Tube Preamp System
Post by: Holger on June 02, 2020, 07:12:07 AM
I've measured the temperature in another 3 tube device
https://groupdiy.com/index.php?topic=72114.msg914634#msg914634 (https://groupdiy.com/index.php?topic=72114.msg914634#msg914634)
As mentioned there the temperature is at 39° C. So I think it will not go above 40/42°C, depending on the room temperature.Using the Harwin pins is safe. The entire Krässemaschine is build around them.