Trying to decide on tube mic preamps

[GalenH]

There is no bass roll off in the two g9 units I put together (unless you engage the HPF, obviously) but these are not the 500 series variant which uses different transformers.

If you are not building these yourself then Jakob’s commercial units are very reasonably priced for the parts, labour and quality assurance. I think they sound very good.

Yes, I think for how well built they are they are priced very fairly! I have heard only good things. The diy 51x does seem to have issues that the big version doesn't, but I imagine as you are saying it is the different (smaller?) transformers made to fit in the modular units.
Do you know, if it might be possible to make a G9 that is 4 channels in 2 rack units, by moving the power supply to a separate unit? It would make this much more possible, as we are mobile and already 2 rack units is a lot of space for how light I'm trying to get a location recording rig.

 

[ruffrecords]

I don't know if I understand enough of the differences you are specifically referring to, to say.

What I was thinking was that most classic mic preamps like the REDD47 and V72 have no phantom power, phase switch or input pad. Also they have only rudimentary control over gain or none at all which is fine if you want colour but not if you are looking for a clean preamp with good headroom.

However I can say, something that uses parts that aren't going to disappear imminently, has low (for tube) self noise, and is built to be fairly clean, not intentionally creating distortion beyond that which is inherent in tubes and transformers is what I am looking for.
Modern designs and vintage designs could both work if they worked within those intentions.

I was going to suggest you might want to consider building something based on my Eurochannel PCB that was used in the EZTubeMixer project (which several members here have built into full blown all tube mixers). They will fit in a 2U rack and I think you should be able to fit four side by side as they are only 100mm wide. In the past I have built four of these in individually screened modules with power supply into a 3U rack mounting enclosure but that is taller than you asked for:

Custom Tube Consoles - Lunch Box

By the way the boards can use Sowter, Jensen or Cinemag input transformers and and external Carnhill output transformer and the gain is variable from 26dB to 60dB in 3dB steps.

Cheers

Ian

 

[GalenH]

What I was thinking was that most classic mic preamps like the REDD47 and V72 have no phantom power, phase switch or input pad. Also they have only rudimentary control over gain or none at all which is fine if you want colour but not if you are looking for a clean preamp with good headroom.

I was going to suggest you might want to consider building something based on my Eurochannel PCB that was used in the EZTubeMixer project (which several members here have built into full blown all tube mixers). They will fit in a 2U rack and I think you should be able to fit four side by side as they are only 100mm wide. In the past I have built four of these in individually screened modules with power supply into a 3U rack mounting enclosure but that is taller than you asked for:

Custom Tube Consoles - Lunch Box

By the way the boards can use Sowter, Jensen or Cinemag input transformers and and external Carnhill output transformer and the gain is variable from 26dB to 60dB in 3dB steps.

Cheers

Ian

Good options here! and yes in that case modern features are important.

what is the impedance on your designs?

Both of your suggestions, the eztube mixer design and the modular 3 unit tall design look possible. do you ever build them for people or know who might?

I know that this is a diy forum, but i know enough to know i shouldn’t try to build tube gear myself and would need to hire someone to build or buy something pre made

 

[GalenH]

What I was thinking was that most classic mic preamps like the REDD47 and V72 have no phantom power, phase switch or input pad. Also they have only rudimentary control over gain or none at all which is fine if you want colour but not if you are looking for a clean preamp with good headroom.

I was going to suggest you might want to consider building something based on my Eurochannel PCB that was used in the EZTubeMixer project (which several members here have built into full blown all tube mixers). They will fit in a 2U rack and I think you should be able to fit four side by side as they are only 100mm wide. In the past I have built four of these in individually screened modules with power supply into a 3U rack mounting enclosure but that is taller than you asked for:

Custom Tube Consoles - Lunch Box

By the way the boards can use Sowter, Jensen or Cinemag input transformers and and external Carnhill output transformer and the gain is variable from 26dB to 60dB in 3dB steps.

Cheers

Ian

also, do you know what you might charge to build either of the two you suggested of your designs, if you do such a thing for others?

i enjoy diving into the deep end of diy but i am not a big fan of the likely death from messing with high voltages as a newbie

 

[Murdock]

Oh! That looks interesting. It seems it is designed to distort but that it runs pretty cleanly? I didn't know that Jonte was doing stuff on here, his production preamp looks incredible. I wonder what the differences are between this and his preamps that he sells are. Do you have any insight on that?

No, I asked this myself. I think he uses other tubes in his production preamp. I don't know how much they differ soundwise. And I think the production preamp doesn't have all the options, like high pass filter, feedback or different output arrangements.
This preamp should be pretty versatile in regards to clean/distortion.
There was someone who designed a PCB for this. Maybe he is willing to share some with you if you don't want to go the P2P or turret board route.

 

[johnchantler]

Do you know, if it might be possible to make a G9 that is 4 channels in 2 rack units, by moving the power supply to a separate unit?

Not without making a different set of PCBs

 

[ruffrecords]

Good options here! and yes in that case modern features are important.

what is the impedance on your designs?

The input impedance of my designs is 1,5K

Both of your suggestions, the eztube mixer design and the modular 3 unit tall design look possible. do you ever build them for people or know who might?

Both the above suggestions use the EZTubeMixer board. The 3U modular design I have built several times for studios around the world. As such it is a kind of "standard" and it has a standard price of £4,000 plus shipping at cost. The 2U option I described would be a custom build and I don't do custom builds anymore - they just consume far too much design time that I would rather spend designing the things I am interested in.

I know that this is a diy forum, but i know enough to know i shouldn’t try to build tube gear myself and would need to hire someone to build or buy something pre made

I agree, tube builds are not for the beginner. I am happy to build you a 3U unit but please be aware I currently have two years worth of work on the books.

Several people have built themselves mic pres and even mixers based on my designs. Perhaps one of them will chime in and offer to do the build for you.

Cheers

Ian

 

[GalenH]

Not without making a different set of PCBs

got it, that makes sense, thank you.

 

[GalenH]

The input impedance of my designs is 1,5K

Both the above suggestions use the EZTubeMixer board. The 3U modular design I have built several times for studios around the world. As such it is a kind of "standard" and it has a standard price of £4,000 plus shipping at cost. The 2U option I described would be a custom build and I don't do custom builds anymore - they just consume far too much design time that I would rather spend designing the things I am interested in.

I agree, tube builds are not for the beginner. I am happy to build you a 3U unit but please be aware I currently have two years worth of work on the books.

Several people have built themselves mic pres and even mixers based on my designs. Perhaps one of them will chime in and offer to do the build for you.

Cheers

Ian

Thank you for your response, Ian.

I've been reading through your website and it seems like your designs might be perfect for what I am looking for, high gain, low distortion, low noise, 2 stages of tube with 20db pad, etc.

Selfishly speaking, I'm sad that you are booked out 2 years, but I understand how that would happen! I will take a look and see if someone would be willing to do the build. In case you are suddenly not booked out two years, I would be very interested.


Also I absolutely understand your reasons for not doing custom builds anymore! You've made your designs and your process is streamlined and you know they work well.

Have you ever used Lundahl Transformers? I see they're not on your options you listed.

 

[GalenH]

The input impedance of my designs is 1,5K

Both the above suggestions use the EZTubeMixer board. The 3U modular design I have built several times for studios around the world. As such it is a kind of "standard" and it has a standard price of £4,000 plus shipping at cost. The 2U option I described would be a custom build and I don't do custom builds anymore - they just consume far too much design time that I would rather spend designing the things I am interested in.

I agree, tube builds are not for the beginner. I am happy to build you a 3U unit but please be aware I currently have two years worth of work on the books.

Several people have built themselves mic pres and even mixers based on my designs. Perhaps one of them will chime in and offer to do the build for you.

Cheers

Ian

Also, one other thing, and I apologize if it is a dense bunch of questions, but I am wondering what the process would be for getting the necessary parts and information to have someone build a 4 channel lunchbox of your design, as you suggested could be an alternative to getting on your longer waiting list.

And thank you so much for your willingness to share your information and plans with the world here, I am amazed at what info you offer.

Would it be better to send you an email?
Is there a way I could order the parts from you and download plans and have someone put it together?

I hope these questions are not annoying, haha!

 

[ruffrecords]

Thank you for your response, Ian.

I've been reading through your website and it seems like your designs might be perfect for what I am looking for, high gain, low distortion, low noise, 2 stages of tube with 20db pad, etc.

THat was the aim!!

Selfishly speaking, I'm sad that you are booked out 2 years, but I understand how that would happen! I will take a look and see if someone would be willing to do the build. In case you are suddenly not booked out two years, I would be very interested.

You might try contacting Holger Classen. He has not only built a 12 channel EZTubeMixer but has developed his own mic pre modules based on my designs

Also I absolutely understand your reasons for not doing custom builds anymore! You've made your designs and your process is streamlined and you know they work well.

It is partly that but it is also that I want to spend time designing the Mark 3 mixer and the Poor Man's Tube Mixer

Have you ever used Lundahl Transformers? I see they're not on your options you listed.

I have never used Lundahl transformers mainly because they come in an odd sized package. The Sowter, Jensen and Cinemag mic input transformers are all very similar and I managed to design a single PCB footprint that accommodates all three. The Lundahl was incompatible with these so I did not include it and I never got round to creating a special board for it.

Cheers

Ian

 

[ruffrecords]

Also, one other thing, and I apologize if it is a dense bunch of questions, but I am wondering what the process would be for getting the necessary parts and information to have someone build a 4 channel lunchbox of your design, as you suggested could be an alternative to getting on your longer waiting list.

And thank you so much for your willingness to share your information and plans with the world here, I am amazed at what info you offer.

Would it be better to send you an email?
Is there a way I could order the parts from you and download plans and have someone put it together?

I hope these questions are not annoying, haha!

SRS in the UK have a standard enclosure kit for the lunchbox design. I can supply the mic pre PCBs and the backplane PCB that connects them all together plus drawings of the front and rear panels so you can have them made.. All the remaining parts are available from normal suppliers which I would assume whoever does the building would undertake. Assembly documentation and component lists are available on my website. I am happy to provide email support.

Cheers

Ian

 

[GalenH]

THat was the aim!!

You might try contacting Holger Classen. He has not only built a 12 channel EZTubeMixer but has developed his own mic pre modules based on my designs

It is partly that but it is also that I want to spend time designing the Mark 3 mixer and the Poor Man's Tube Mixer

I have never used Lundahl transformers mainly because they come in an odd sized package. The Sowter, Jensen and Cinemag mic input transformers are all very similar and I managed to design a single PCB footprint that accommodates all three. The Lundahl was incompatible with these so I did not include it and I never got round to creating a special board for it.

Cheers

Ian

That makes sense and thank you for your message! I may look into the lundahl possibilities... I like how they sound a lot...

 

[GalenH]

SRS in the UK have a standard enclosure kit for the lunchbox design. I can supply the mic pre PCBs and the backplane PCB that connects them all together plus drawings of the front and rear panels so you can have them made.. All the remaining parts are available from normal suppliers which I would assume whoever does the building would undertake. Assembly documentation and component lists are available on my website. I am happy to provide email support.

Cheers

Ian

Thank you so much for the support Ian!

 

[SIXTYNINER]

...
Does anyone know if it might be possible to fit 4 channels in a 2 RU case ..

Not diy stuff ,
Not Gyraf, Fearn, & co. ... ,

but old TL Audio Ivory 5001 is 4 ch tube preamp in 2 units rack case
probably "far" from what you are looking for ?

Could still be a starting point for the project you are looking for .
cheers