Feeler: an "Eee-Zzz" christmas present...ez1073 and ez1073-500

[lorcan]

Very nice ! Colin, you can count me in for a PCB for the 1U version too.
One little question about cosmetics: the vertical offset between the rotary switches and pots looks ... how should I put it ... creative
Is this going to be the final layout ?

I received a Carnhill 9045 transfo from you and built a Bo Hansen DI with it, it sounds awesome
I'll put up my custom pcb design for it here in a few days

Cheers,
Lorcan

 

[kante1603]

Congratulations!

Best regards,

Udo.

 

[Slenderchap]

One little question about cosmetics: the vertical offset between the rotary switches and pots looks ... how should I put it ... creative
Is this going to be the final layout ?

I received a Carnhill 9045 transfo from you and built a Bo Hansen DI with it, it sounds awesome
I'll put up my custom pcb design for it here in a few days

The vertical difference is simply due to the height of the pots and switches from the PCB... that cannot be changed... so yes it will be like that.

I have in the past used a pair of VTB9046's wired up to create a 16:1 step down for a DI input to a mic..... that sounds good (albeit a somewhat expensive solution).

Great photos Dalma.... glad you got it together with no problems.

Colin
www.audiomaintenance.com

 

[lorcan]

The vertical difference is simply due to the height of the pots and switches from the PCB... that cannot be changed... so yes it will be like that.

I have in the past used a pair of VTB9046's wired up to create a 16:1 step down for a DI input to a mic..... that sounds good (albeit a somewhat expensive solution).
Colin
www.audiomaintenance.com

Yes, I understand. I'll try to see if I can find some equivalent offboard pots when the details are available ..
The DI files are here http://www.groupdiy.com/index.php?topic=36569.msg562181#msg562181

 

[pietro_moog]

hi. any news on the 1U?

a couple of questions regarding the colourbook:
-why you didn't mark the tantalum caps? (i think all the 10uF and all the 22uF except two of them are tantalum)
-why a lot of caps are rated for higher voltages?

just curious..

 

[Slenderchap]

-hi. any news on the 1U?
-why you didn't mark the tantalum caps? (i think all the 10uF and all the 22uF except two of them are tantalum)
-why a lot of caps are rated for higher voltages?

PCB's should be here later this week.
We don't use Tants.... (we use electrolytics which we have specially manufactured)..... you can fit anything you wish... it is your project.
The higher voltage is simply because they are parts we stock....

Colin
www.audiomaintenance.com

 

[pietro_moog]

cool.
why you don't use tantalums?
why your electrolytics are special?

 

[pietro_moog]

really awesome work.
so, (2) single gang 1 pole and (2) single gang 2 poles and (1) triple gang gain switch. am i right?

then, which inductors?
9043; 9044; 9050 ?

can i use the VTB1148 as output trafo?
what's the board dimensions?
is (1) power toroid you have in the shop enough to power 2  boards?  i'd like to build 2 preamp in a 2U-3U chassis

 

[Slenderchap]

so, (2) single gang 1 pole and (2) single gang 2 poles and (1) triple gang gain switch. am i right?
then, which inductors?
9043; 9044; 9050 ?
can i use the VTB1148 as output trafo?
what's the board dimensions?
is (1) power toroid you have in the shop enough to power 2  boards?  i'd like to build 2 preamp in a 2U-3U chassis

Yes for the switches and inductors and VTB1148. Main PCB is 407 x 161 mm. Power tx is not yet available (tomorrow)... it should be enough for 2 PCB's.

A lot of your questions will be answered by the colourbook... it is nearly finished.

Colin
www.audiomaintenance.com

 

[domi62]

HI colin

is it possible to insert a comp between preamp and EQ ?

 

[pietro_moog]

hi Colin.
you told me about the resistors, all 0.6w.
i happen to have tons of 1/4w resistors, can i use some of them somewhere?
i was thinking that maybe just the 6k8s and the resistors in the power regulators and power supply ought to be at least 0.6w
am i right? that would be a good saving for me

 

[Slenderchap]

is it possible to insert a comp between preamp and EQ ?

Don't see why not.... unless you want to go out of the box in which case you would need an output driver and input return.

i happen to have tons of 1/4w resistors, can i use some of them somewhere?
i was thinking that maybe just the 6k8s and the resistors in the power regulators and power supply ought to be at least 0.6w

I expect that the originals had 0.25w resistors anyway apart from the 47R in the output circuit and the power feeds.... the only reason for 0.6W metal film is they are about the most common type of resistor nowadays.

The 6k81's for the phantom should be as closely matched as possible (0.1% is the usual method but you can simply measure and hand select resistors from a batch).... being identical values is more important than their actual value.

Some more info is now in the colourbook.
http://www.audiomaintenance.com/downloads/ez1073_colourbook.pdf

Colin
www.audiomaintenance.com

 

[Slenderchap]

The schaeffer faceplate file is here:
www.audiomaintenance.com/downloads/ez1073_1u_front_panel.fpd

Added some more mechanical and parts list info to the colourbook;
http://www.audiomaintenance.com/downloads/ez1073_colourbook.pdf

Colin
www.audiomaintenance.com

 

[rob_gould]

Hi Colin,

Just a couple of questions before I start ordering parts for this.  Please excuse the 'newbie' nature of these questions, but I don't want to cock this project up!

- Can you confirm for certain that ¼ watt resistors will work ok, except for the 3 watt resistor specified in the BOM? Like a previous poster I have a huge stash of ¼ watt and it'll save me some cash to not order 0.6 watt if they're not necessary.

- Do you recommend any particular electrolytic caps for the audio sections of the unit?  And does the quality of ceramic caps matter too?  I've read in other places that these are normally avoided in audio circuits as they tend to be noisy, hence my question about whether a specific type or manufacturer is recommended.

- Finally, the 600 ohm termination.  It's the first time I've come across this in a project, and I'm wondering if it affects the microphone that's connected to the input of the preamp, the line input or whether it is used for matching the input impedance of the device connected to the output?  I'm guessing it's not mic input as there's a separate hi / low z switch for this, but please can you just clarify when these pads should be jumpered just to ease my lack of understanding!

Cheers

Rob



Sent from my android device.

 

[chrispsound]

Thanks again Colin,  the ez1073 PCB is very nice!  Wonderful layout, colorbook, FPE file and partial kit, not to mention all the electrolytics are availiable on your AML site.  A true learning experience made very pleasant by your detailed work.  Many thanks and hopefully many more projects from you to come.  ChrisP

 

[Slenderchap]

1] Can you confirm for certain that ¼ watt resistors will work ok, except for the 3 watt resistor specified in the BOM? .......
2] Do you recommend any particular electrolytic caps for the audio sections of the unit?  And does the quality of ceramic caps matter too?  ..........
3] Finally, the 600 ohm termination.......

1] 0.25 watt will be fine for almost everything.... the ones in the power feeds are probably better as 0.6W
2] 1073's are inherrantly noisy and distorted anyway so it does not really matter what you put in there..... avoid capacitors sold as "audio" caps.... you will pay a lot of money for them because they have low distortion .... which is not what you want.
3] 600 Ohm termination is optional..... try it on and off and see which you prefer the sound of as it is application/load dependent ......

Don't "think too hard" about it.... just plow on and throw some components at it.... it is almost impossible to be dissatisfied with the results you will get regardless of brands.

Thanks again Colin,  the ez1073 PCB is very nice!  Wonderful layout, colorbook, FPE file and partial kit..........

Glad you like it.

Colin
www.audiomaintenance.com

 

[rob_gould]

1] Can you confirm for certain that ¼ watt resistors will work ok, except for the 3 watt resistor specified in the BOM? .......
2] Do you recommend any particular electrolytic caps for the audio sections of the unit?  And does the quality of ceramic caps matter too?  ..........
3] Finally, the 600 ohm termination.......

1] 0.25 watt will be fine for almost everything.... the ones in the power feeds are probably better as 0.6W
2] 1073's are inherrantly noisy and distorted anyway so it does not really matter what you put in there..... avoid capacitors sold as "audio" caps.... you will pay a lot of money for them because they have low distortion .... which is not what you want.
3] 600 Ohm termination is optional..... try it on and off and see which you prefer the sound of as it is application/load dependent ......

Don't "think too hard" about it.... just plow on and throw some components at it.... it is almost impossible to be dissatisfied with the results you will get regardless of brands.

Good stuff - thanks for the info.

Rob

 

[rob61]

Wow, thanks Colin. Already got my two ez1073-500 kits. Really excited about getting these built and trying them out.

I have one newbie question. Since the motherboard and daughter boards come as one piece, what is the best way to cut them apart, and do I need to trim off the connecting material between them?

Thanks for making this full kit available.

 

[Slenderchap]

We just cut them apart using a pair of wire cutters (the ones we use look like a pair of scissors) and then trim off the excess with end cutters.

You could use a cutting wheel but you end up with potentially health hazardous dust everywhere.

You can actually just snap them carefully across the edge of a desk.

Colin
www.audiomaintennace.com

 

[pietro_moog]

Hi Colin,i have a couple of questions too. (about the 1U)

- i need to fix the input trafo to the board. how do you do that?
i've seen angled stripes, but mouser wants TONs of money, and i'm not even sure they fit in the place.

- i've seen the rotary switches are a few mms from the border. so they are not designed to sustain the pcb. am i wrong?
how do you do that?