[BUILD] 1108 DIY project and PCB layout

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Neve 1290 (the preamp circuit on the 1073) uses +24v.
And there's a lot of modules based on this preamp  for the 500 series .

Check the schematics for those and see how they implemented the +16v to +24v

https://groupdiy.com/index.php?topic=41147.0

https://groupdiy.com/index.php?topic=33492.0


Saying this, there's much more simple projects to pursue for someone with your experience so chasing this one for the 500 series might be too much.
There's already a lot of amazing preamps for the 500 series, with pcbs already made and the project well documented
 
Thank a lot for those. I'll study them

I hear you man. I built an 1176 rev D a few years ago and love using it as a pre amp so I'm pretty set on the 1108 so I'll keep at it for some time.

Another question: My rack (Radial workhourse 8) has a TRS omni port on the back for each channel that corresponds to pin 7 and 9. Would it be possible to send 24 volts through the omni port via another power supply or is this insane?
 
So I studies the don classics nv73 converter circuit from the schematic. Given my limited knowledge  it looks exactly like what I need but am unsure after playing around in lt spice (for the first time). I would be willing to pay someone to help me figure this out. Hopefully this is an appropriate post... please remove if not.
 
coledingo said:
So I studies the don classics nv73 converter circuit from the schematic. Given my limited knowledge  it looks exactly like what I need but am unsure after playing around in lt spice (for the first time). I would be willing to pay someone to help me figure this out. Hopefully this is an appropriate post... please remove if not.

as this thread is for another 1108 project, not the one you're after, I think you will be better in doing a new thread for a 1108 project in the 500 series format, to gather some help and have the relevant info compiled there
 
Hello
Long time no see.
After reading the whole thread one doubt... J309 it's out of production... Beside eBay where can I get some?
Best regards
 
louder said:
Hello
Long time no see.
After reading the whole thread one doubt... J309 it's out of production... Beside eBay where can I get some?
Best regards

Mouser has J309 in stock:

https://www.mouser.com/ProductDetail/InterFET/J309?qs=OxRSArmBDfxFLq%252BlAKFMwA%3D%3D

Probably any of this would work well also as a replacement:

2SK170
LSK170
2SK370
2SK117
2SK369
2N5457
2N5486
BF862
 
I also have a few UTC A-10’s to try this:

Title: Re: UREI 1008 Mic Preamp Schematic
Post by: Bill Wilson on May 13, 2010, 01:14:51 PM

For the input transformer a UTC A-10 would do very nicely. It has a winding ratio of 1 to 10 & has the necessary taps on the primary. The secondary impedance is 50k ohms & will take +15dbm before the core saturates. The freq response is down only 1 db @ 30cps & .5db @ 20kcps,
(oop's hertz), forgive me but I cut my teeth on tubes back in 52.

The A-10 will work for the 1008 & 1108 as they are to single grid & single FET; it will not work for 1016 as it is a balanced circuit configuration & requires a split primary. A UTC HA-114 will work well as the output xfmr. for the 1016, it is 30k ohms split primary w multiple secondaries covering all the pro output impedances & will handle +23dbm. It is perfect for a 12AY7/6072 in push pull. Freq. response -1db 30hz to 40khz. Input trafo. for 1016 would be a UTC A-12, it has split windings on the secondary for push pull.
Have not take the time to look @ 1108 in detail so cannot give you anything but a guess on the output trafo's impedance but could be around 600 ohms.

I can guarantee the frequency response of the A-10 as I used them in a 6 input 3 channel mike muxer in 64; when I was doing on location mastering for a couple of small rcord co's.

Hope this helps.
Bill W.

P.S.: the dbm figures on the transformers are for the 600 ohm impedance.
 
Gain control - I used 1Meg audio pot in place of the LDR for level control. This worked great. If you are controlling them further away with a fader you might want a LDR, but in a single unit it's not necessary. This gives you control from off to max. You could easily build a stepped switch instead of a continuous pot if that were preferred.
The gain control on these is a two position switch that changes the amount of negative feedback. I've always used them on high and don't the switch is even necessary. You could probably make a stepped switch to change the gain in more steps, but I don't think you can get much more gain out of them than the 'hi' setting of the design.
And I put a pad on the front ahead of the input transformer.
These sound great. I used UTC O-1 / O-2 but any 1:10 mic transformer will work
 
I've read through about half this thread but not the last 50% yet. To keep this simple, short and to the point:

I want to build this. Lola and the Hairball blue stripe both went fabulously well in early 2018. I have another Lola and three more 1176 kits to build that were ordered five years ago but never put together. I've been studying electronics in my spare time and have learned a lot but have not yet been ready for a scratch build. But I want to build this.

In looking over the BOM, it has come to my attention to order the ICs (for the variable/phantom power supply board) now since they're "End Of Life" and will get harder to find. In researching what else I'll need....

The MNats PCB (for the main board) is "Out Of Stock" at Hairball and I wonder...."permanently?"

I see the layout at http://mnats.net/files/1108_V1.1a_DOC.pdf --- am I going to have to learn to make my own board in order to build this now or are boards ever becoming available again for sale?
 
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I've read through about half this thread but not the last 50% yet.

Read all the thread and copy paste the most relevant information to a word doc,
then you have a "Compilation" doc of the most important info for the build

In looking over the BOM, it has come to my attention to order the ICs (for the variable/phantom power supply board) now since they're "End Of Life" and will get harder to find. In researching what else I'll need....

What ICs are you talking about?

Remember, this preamp only needs a +24V supply and you need 48V for the phantom power,
there's many 2 rails or 3 rails PSU pcbs that could be used for this, you don't need to use the Mnats board.
You can use JLM PSU, or the old SSL 9K PSU, and in the White Market you have the Silent Arts PSUs,
the "POS48PSU" will work great:
https://groupdiy.com/threads/51xaudio-by-silent-arts.39570/


The MNats PCB (for the main board) is "Out Of Stock" at Hairball and I wonder...."permanently?"

I see the layout at http://mnats.net/files/1108_V1.1a_DOC.pdf --- am I going to have to learn to make my own board in order to build this now or are boards ever becoming available again for sale?

Contact both Mnats and Harball Audio to check if they will do another run.

If not the PCB is so simple it can easily be self etched at home,
if you don't know how to do it, maybe ask a friend?
Find someone locally that can help you out?
 
Thanks @Whoops. Without being corny about it, I do have a dream and want that dream to come true (even if it's only a dream because I saw this project in 2018 and didn't yet feel ready, so I derailed for another six years reading '50s tube literature and teaching myself about basic electronics via guitar amps).

Read all the thread and copy paste the most relevant information to a word doc,
then you have a "Compilation" doc of the most important info for the build

Great suggestion. Will do.

What ICs are you talking about?

Specifically, the voltage regulators for the Mnats power supply board. Even more specifically, the TL783. I realized this when looking on Mouser and then found this thread: https://groupdiy.com/threads/tl783-becoming-obsolete.85571/ -- I was advised to purchase a small handful while I still can but knowing that I wouldn't necessarily need to use the Mnats board is good information too.

Contact both Mnats and Harball Audio to check if they will do another run.

If not the PCB is so simple it can easily be self etched at home,
if you don't know how to do it, maybe ask a friend?
Find someone locally that can help you out?

I emailed Hairball this afternoon to ask. I assume the best way to get in touch with Mnats is on this forum? (no contact form on his website). I'm always reticent to send any unsolicited private messages and saw his profile says "Last seen Nov. 2023" so I haven't asked him yet.

I've never etched a PCB but am watching videos on how to and would like how to regardless. I live in Nashville....there's got to be someone here who can etch boards with all the studios in this town. But learning how to self-etch at home would be a good thing for me no matter what.
 
So get some TL783,
But any PSU board that has a positive Rail and a 48v rail will do.

You can contact any member by PM, that’s why that options exists, solicited on unsolicited doesn’t matter, member contact each other all the time

As for etching the first pcbs, it’s much easier if you do it the first time with someone more experienced, that’s what I did and my recommendation. Easier to learn that way and will yield a better result. But you do as you wish
 
I've never etched a PCB but am watching videos on how to and would like how to regardless. I live in Nashville....there's got to be someone here who can etch boards with all the studios in this town. But learning how to self-etch at home would be a good thing for me no matter what.
[I've never etched a PCB but am watching videos on how to and would like how to regardless] -- While there are those in this forum who somehow "get a kick" and/or "personal pleasure" out of etching their own PCB's, I have never personally gotten into it. My distaste for etching my own PCB's may arise from my aversion of having highly toxic and dangerous chemicals in my home and their odor that is strong enough to peel paint from your walls!!! You need to be extremely careful and cautious using these toxic chemicals while wearing aprons and gloves so you don't get any acid-solution on your skin or clothes, which it will then eat a hole through and/or turn your skin yellow/orange.

I would instead suggest that you download and learn how to use the KiCAD PCB-design program and then design your own PCB's. Once you are finished and you output the famous "GERBER" files, there are plenty of "low-volume / prototype" PCB-fabrication companies here in the U.S. and abroad.

Here is the KiCAD PCB download web-page. It's FREE!!!:

https://www.kicad.org/download/

Here is the PCB-fabrication shop that I have used for around 30-years:


https://www.4pcb.com

However, the DIY'ers on this forum tend to prefer this PCB-fabrication shop:

https://jlcpcb.com

Since you mentioned you are in Nashville, here is a short list of PCB-related companies located in Tennessee:

1708182974379.png

>> ORANGE-colored company names are "clickable":

1) American Manufacturers Agency, Inc.
Address: 603 Morning Rd., Dyersburg, TN 38024-1948 United States
Business Type: Service

2) Creswell Richardson
Address: 900 Appling St., Chattanooga, TN 37406 United States
Business Type: Distributor, Service

3) Kanson Electronics/ISSC
Address: 245 Forrest Avenue, Hohenwald, TN 38462 United States
Business Type: Manufacturer, Service
Description: Made in the USA | Woman-Owned and Veteran-Run Kanson Electronics develops innovation solutions for specific contract assembly problems. Over the years, our dedication, honesty, experience and one-on-one personalized service.

4) Kele Precision Manufacturing
Address: 2999 Brother Blvd., Memphis, TN 38133 United States
Business Type: Manufacturer, Service

5) KNS Associates, Inc.
Address: PO Box 11746, Memphis, TN United States
Business Type: Distributor, Service

6) Micron Corporation - TN
Address: 107 N. Porter St., Suite 6, Winchester, TN 37398 United States
Business Type: Manufacturer, Service

7) S/G Electronics, Inc.
Address: 9113 Macon Road, Cordova, TN 38016 United States
Business Type: Manufacturer, Service

[learning how to self-etch at home would be a good thing for me no matter what] -- You'll spend more time and money etching your own PCB's while stinking up your residence and burning holes in your clothes and skin, than you will learning how to design your own PCB's using the now worldwide "famous" -- FREE!!! -- PCB-design software program!!! But.....sure.....GO FOR IT!!!

>> SEE??? IT'S EASY TO DO!!!


1708186922255.png
/
 
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You can contact any member by PM, that’s why that options exists, solicited on unsolicited doesn’t matter, member contact each other all the time

Thanks again. Good to hear/know.

@MidnightArrakis - I really appreciate that reply! Thank you for attaching those PCB-related companies in TN and the other links too. I'd rather secure the board either from Mnats/Hairball or have someone else make it for me. That's my first choice. Etching would be a last-resort, although what I wrote earlier gave the impression I was more enthusiastic about learning to etch at home than I realistically am. It sounds like there are plenty of other ways to get the board even if I have to send off for it with the etch files provided on the Mnats page, so the links help a lot.

Last question, and I'm afraid to ask it because I'm insecure about embarrassing myself around smart people but I have to ask anyhow: as shown in posts #164, 175, and 199 I'll need a PCB board for the input transformer. When I zoomed in close on #175 I could see that particular photo revealed a CM-2511 mounted to a board that clearly said "Cinemag CM-2511 (c) 2011 mnats."

I used the Internet Archive to go back to 2011, 2012, and beyond into 2016 and never found any self-etch files or even old sales pages for that board. The only transformer board I see at all on the site is for the 1176 builds. I also did an archive search going back in time to the Hairball site too and then searched all of Group DIY but didn't pull up anything.

In post #175 I see how simple the board is. XLR into Primary - SW3 (impedance) on primary --> secondary to IN+/- of main board.

Is this a PCB I'm going to need to design with something like KiCAD or are transformer board etch files available anywhere??
 

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