Tube DI Box

[ccaudle]

Galaxy Maggiorato GX288 230 x 280 mm which is only 35 Euros

When I checked just now it is 49 Euros, plus another 29 Euros shipping to North America. The Hammond might be an OK deal for those in North or Central America. Frustrating sometimes how much of the project budget is taken up by relatively simple sheet metal.

 

[ruffrecords]

When I checked just now it is 49 Euros, plus another 29 Euros shipping to North America. The Hammond might be an OK deal for those in North or Central America. Frustrating sometimes how much of the project budget is taken up by relatively simple sheet metal.

I just checked and 49 Euros is the price for the 3U version. I use the 2U version which for some reason seems no longer to be listed.

Edit: Just realised I listed the wrong part number, it is the 283 not the 288 and it is still 32 Euros

Edit: Nope, that is still wrong. The 2U version which is 230 x 280 is indeed 35 Euros as I originally said:

https://modushop.biz/site/index.php?route=product/product&path=25_290&product_id=431

Looks awfully like they have identical part numbers for two different enclosures? Nope, just a weird search engine that does not return the 2U unit when you feed it "Galaxy Maggiorato GX288 230 x 280 mm"

Cheers

Ian

 

[IBarfoot]

I just checked and 49 Euros is the price for the 3U version. I use the 2U version which for some reason seems no longer to be listed.

Edit: Just realised I listed the wrong part number, it is the 283 not the 288 and it is still 32 Euros

Edit: Nope, that is still wrong. The 2U version which is 230 x 280 is indeed 35 Euros as I originally said:

https://modushop.biz/site/index.php?route=product/product&path=25_290&product_id=431

Looks awfully like they have identical part numbers for two different enclosures? Nope, just a weird search engine that does not return the 2U unit when you feed it "Galaxy Maggiorato GX288 230 x 280 mm"

Cheers

Ian

https://modushop.biz/site/index.php?route=product/product&path=33_286&product_id=240

The above looks rather smart if all required could be shoehorned inside, doesn't break the bank either. Might have to mount the valve horizontally but that is the only issue I can see. Glad you have mostly recoverd from the old Covid Ian, it definately isn't funny when you get it. Did you progress your PCB's for this project

 

[ruffrecords]

https://modushop.biz/site/index.php?route=product/product&path=33_286&product_id=240

The above looks rather smart if all required could be shoehorned inside, doesn't break the bank either. Might have to mount the valve horizontally but that is the only issue I can see. Glad you have mostly recoverd from the old Covid Ian, it definately isn't funny when you get it. Did you progress your PCB's for this project

The one you picked is only a couple of Euros cheaper that the one I suggested bt it is a lot smaller which is attractive in itself. Apart from the valve(s) the single biggest component is the output transformer. If we use something like a Carnhill VTB2291 which is about 72mm x 35mm x 58mm it will consume a goodly proportion of the available volume. What I will probably do is make a cardboard version of the enclosure and place the parts in it to see if and how they fit.

I have not looked at the PCB since I was ill but I think it was nearly complete.

Cheers

ian

 

[TimG]

Ian, these are the kind of things you can shop for on Alibaba…
This item is in your size, and I bet you can get it simpler and cheaper by talking about it with them. Seems custom length is easy once they sell a width.
https://m.alibaba.com/x/AxEEL0?ck=pdp

Or make an RFQ with an example of one that you like, and hungry people will make you an offer.

https://m.alibaba.com/x/AxEEfb?ck=pdp

 

[13engrsapper]

I think this is a perfect situation for a Nuvistor based project. Also, I listed a number of enclosures in the black market that may work for this ;-)

 

[ruffrecords]

@TimG:

Many thanks for the links. Some are a little confusing - one says $12 per unit for 10 off but for the same quantity shipping is $384??

I think I need to spend some more time exploring alibaba.

Cheers

ian

 

[Mondy]

Hi Ian, looking forward to your designs and glad to have you back fit and well!!

I have had good results using these enclosures for valve/tube gear...

RS pro Instrument case

They are steel based but with AL front and rear panels. Used them without problems with toroidal power transformers. Zero hum. Old school look and feel!!

 

[Wavelength]

All,
I look at this as two different projects. The one I built with the AC power using the Hammond 261D6 (115/230) power and then another one with more usable options for 9V operation. The AC powered one would be best for a studio. Yeah maybe a 1U rack thingy or a 1/2 rack or 2 up would be better.
https://www.hammfg.com/electronics/transformers/classic/261-262?referer=787

For real use on a pedal board with a tube you really need an FX loop, phase control, input Z and some kind of output volume control. $ wise since you don't have to provide the power, it's probably better to use some choke loaded idea rather than SRPP which requires a pretty high voltage. Cut the HV in half with a choke loaded. The other idea would be a hybrid folded cascode with a tube driving an PNP it would be pretty easy.
Never had good luck with a nuvistor. I think my 5703 is still hooked up and I probably have some PNP capable of the voltage.

Volume control is a bit tricky with a single stage, any ideas there.

I have a little more time to look at this now that the monster S/PDIF DAC is out the door.

Gordon

 

[MidnightArrakis]

That was a problem like 10 years ago. Now with 4mil traces and separation being the norm you can pretty much specify anything you want at no extra charge.

[Now with 4mil traces and separation being the norm] -- I have just started a new 18-layer PCB-layout design that requires 0.0035" ( 3.5mil ) tracks along with differential-pair routing on most of the nets. There is a mix of both 50-Ohm and 100-Ohm sets of differential-pair routing. I'm certain that this board will be "all sorts of fun" to route!!!

/

 

[ruffrecords]

I am still surveying enclosures. At the moment I quite fancy the vented version Hammond 1458 series. Built like a tank, looks nicely retro and it has aluminium front and back panels. Not too pricey either.

https://www.hammfg.com/part/1458VC4B?referer=1226

https://www.farnell.com/datasheets/2634194.pdf

Cheers

Ian

 

[IBarfoot]

I am still surveying enclosures. At the moment I quite fancy the vented version Hammond 1458 series. Built like a tank, looks nicely retro and it has aluminium front and back panels. Not too pricey either.

https://www.hammfg.com/part/1458VC4B?referer=1226

https://www.farnell.com/datasheets/2634194.pdf

Cheers

Ian

Certainly pretty chunky Ian, nearly a kilo without contents. Still better to be robust rather than fragile.

 

[elskardio]

I quite fancy the vented version Hammond 1458 series

I built a custom headphone amp using one of these and it's a really nice enclosure! Also the client told me it was dropped a bunch of times and it still looks brand new

 

[ruffrecords]

I built a custom headphone amp using one of these and it's a really nice enclosure! Also the client told me it was dropped a bunch of times and it still looks brand new

The only thing I am not sure about is whether the 6in by 6in by 4in version will be big enough for both a mains transformer and a Carhill output transformer and the tube PCB and the connectors and controls. I will probably make one out of cardboard and try real parts in it. I could do it in 3D CAD but I don't have enough lifetime left to get up the learning curve

Cheers

Ian

 

[Wavelength]

Ian,
How are you working the controls? Currently my board has input Z (100K, 500K, 1M), termination (600, NONE, 3k3) and pin 1 options.
BTW the custom outputs (corrected) are coming in this week from Cinemag. So I should have everything to build 2 of these up (only have 2 of the Hammond Enclosures and end custom end plates).

On the pedal version I punted on the tube. Really for it to work for me it needed a solo switch with variable level, volume, full FX loop, TS and TRS transformer output. It was just getting too crazy to also have a 9V->HV converter and filament supply. So I did a JFET->PNP folded cascode 2 stages put the solo & volume after the FXin and another folded cascode to retain the phase. Put a couple of switches on it for phase, pre gain (bypass first LSK189 or not), input Z, input pad. Power either phantom or 9V.

Gordon

 

[MidnightArrakis]

The only thing I am not sure about is whether the 6in by 6in by 4in version will be big enough for both a mains transformer and a Carhill output transformer and the tube PCB and the connectors and controls. I will probably make one out of cardboard and try real parts in it. I could do it in 3D CAD but I don't have enough lifetime left to get up the learning curve

Cheers

Ian

[I quite fancy the vented version Hammond 1458 series] -- See CAD-image below!!!

[I could do it in 3D CAD but I don't have enough lifetime left to get up the learning curve] -- You don't really have to!!!

[I don't have enough lifetime left[ -- I have slightly less "lifetime" than you do, but I still gotta keep up with all of this CAD stuff!!! Currently, a U.S. defense contractor is paying me quite well to work here-at-home to create both mechanical designs and PCB-layouts .....even on CAD-programs I have -- NEVER -- used before and I have to quickly learn and pick-up how to use or, using other CAD-programs that I haven't even used for the past 10-years!!! I gotta learn this stuff -- NOW -- or go broke!!! That's life!!!.....



/

 

[Wavelength]

Gang,
New CineMag corrected output came in today. CM-14801PC with pinestripped nickel/iron (M6). They performed really good on the Prism dScope III +/- 0.085dB from 20-20KHz, distortion with 4Vac rms in and 0.9892Vac rms out @ 20Hz is 0.05867%. Square wave performance looks good will build some up and see how it goes.

 

[Wavelength]

So far so good, tested all 11 outputs and had two cold solder joints. All fixed and working now. DC voltages are good, HV = 160V, 390/390 biasing for the 6922 = 2.03 = ~5ma, before the regulator and after the SS choke is 185V, Heater = 6.28VDC regulated. Will fire up and do some AC testing after lunch.
Thanks,
Gordon

 

[Wavelength]

Gang,
Ok first I think the switch for input impedance is going to be changed to input PAD.
This works well, SNR ~-120dB, frequency response is pretty much flat actually stupidly flat to below 10Hz and above 22Khz. I can't even get the damn thing to go below -3dB on the low end and well the dScope III can do it but it's way out on the top end as well. I will have to use a meter and do this with my function generator but it looked to be like -3dB above 80Khz.
Time to box it up and see how my crappy mechanical skills are
G.

 

[Wavelength]

All,
Well the back panel looks great and really no changes there other than maybe loosing the termination switch and changing the input Z to pad.
The back panel, well... not so good so for now that will need to stay off or the power transformer is probably going to short out
More soon, no big problems.
G.