Feeler: Classic Solo

[ruffrecords]

Oh and if we install the toroid on the side wall and the output transformer on the opposite side walls is that ok? In case we used a rackmount type of chassis of course

That would probably be OK. Distance really helps a lot.

Cheers

Ian

 

[ruffrecords]

According to some experiments by DaveP somewhere in this forum I think as long as I mount the output transformer at 90 degrees from the power transformer I should be ok. That power transformer is a little over 4 inches wide so mounting it on the back or sides is out on a 2U enclosure. I will probably mount it on the bottom back corner and mount the output transformers on the opposite side wall. I think that should work. I think Ian was a little restricted with space with that enclosure. My guess is that a full 19" rack would probably help. If things get a little ugly I will just enclose the transformer in a metal transformer case.

The problem is you need to get both the output and input transformers at 90 degrees to the toroid. The hum in the output transformer was not very much and only really appeared when using the Carnhill output transformer. The cheap Edcors don't seem to have this problem. If you are building is a rack mount enclosure and you have to have the toroid mounted on the base then I would agree with the suggestion to enclose it in a steel box. Despite steel not being nearly as good a magnetic material as mu metal, I have found it is perfect for this job. I had a similar hum problem when building the Lunch Box prototype and I fixed it by enclosing the mains toroid in  a steel junction box I got on eBay for about £5.

Just to put it all into context, these hum levels are extremely small - it raises the noise floor at maximum gain by 2 or 3dB. In normal operation you would be hard pressed to hear it but as a designer I would rather it just was not there.

Cheers

Ian

Cheers

Ian

 

[Deepdark]

allright and HT is about what, 280-300v?

 

[ruffrecords]

allright and HT is about what, 280-300v?

Yes.

Cheers

Ian

 

[Deepdark]

I just sketched a single PSU to feed 2 board at about 290V B+ at 40ma (20ma per board). I keep the 220uf caps. For a general purpose psu, rule of thumb recall a first filter cap of about 1UF / ma, twice the value and Roundup generously  ;D So i got about 100uf + the 5 stages at 100uf, too. But I stressed out and decided to put 220uf everywhere  8)

Ian, let me know if there is some mistakes or you think it would work. All we would have to do is connecting B+ and heaters to their respectives place, after the onboard psu.

Quick one about Heaters, by the way. If one would use a big EI transformer, filament coil and HT are always center taped. Since we are bridged rectified, do we simply leave out the center tap?

 

[ruffrecords]

@Deepdark,

That PSU design looks good to me. It should have an excellent performance because it has 5 RC stages - ripple should be virtually non-existent.

Cheers

Ian

 

[Deepdark]

@Deepdark,

That PSU design looks good to me. It should have an excellent performance because it has 5 RC stages - ripple should be virtually non-existent.

Cheers

Ian

Thanks Ian. I'll make a litttle drawing showing where to connect B+ and heater on the board to bypass the onboard psu, so it would make it easier for people who would like to use a single psu to feed 2 boards

 

[ding]

There's always the HT250. I am going to make it work with my 250-250 since my idea was to use what I had at hand but if someone didn't want to vero board something Ian's HT250 would work. At this point though we are just perverting the idea of the classic solo.    I think for a two channel pre a couple of  classic V3 boards, a four toggle board, an HT250 and one of the phantom boards is probably the best way to go.

HT250:
https://drive.google.com/folderview?id=0B_n67A1hN3qtaUVYOGdtYVFBaEE&usp=drive_web&tid=0B_n67A1hN3qtfk5YYjY4WnlweUtwTFRMZ09GWTV4M0VlbXZnRkpHT1Ytdzk1LU96ZTZ4RU0

The Classic:
https://drive.google.com/folderview?id=0B_n67A1hN3qtfnZxd01iS0ZOTnZvb0VpdnVSVWdxb1pybTlXZkk0aTdoMThjOGtLbWJVakk&usp=drive_web&tid=0B_n67A1hN3qtfkxudEtmWjBUS2xPWE13ZlFBNEFwdjdyNWxqOW9nZENxQlJ4aVB1N05UV2c

I think that Ian enjoys seeing people push his designs. 

 

[ruffrecords]

I think that Ian enjoys seeing people push his designs. 

The really good thing about DIY is that you are not limited  to building the design exactly as intended. I use the two prototypes I built in my studio. One has phantom and the 4 toggles board and I use it just for mics - mostly condenser. The other has no phantom but does have a DI input. I use that with my vintage ribbon mic and also for guitar DI.  They sit on top of each other in my studio. I don't know why but it never occurred to me that people would want to put two of them in a 19 inch box becasue that would be ideal for me

I will look at how best to combine  the supplies of two boards and see if there is a simple mod or two that can be made to the PCB to do this and incorprate them in a V3 PCB.

Cheers

Isn

 

[ruffrecords]

I just had a look at the schematic and the PCB layout and I think it is possible to wire two boards together to make a single supply powered by a single transformer without cutting tracks.  I have put together  a short document describing the necessary modifications. I have not tried these mode but I am confident they will work. The file is called ClassicDuo.pdf and is in the Classic Solo folder of the DIY tab of my web site. Here is a direct link if you just want to down load it:

https://drive.google.com/file/d/0B_n67A1hN3qtQVgzQnZsRkFqcWM/view?usp=sharing

Cheers

Ian

 

[Deepdark]

I just had a look at the schematic and the PCB layout and I think it is possible to wire two boards together to make a single supply powered by a single transformer without cutting tracks.  I have put together  a short document describing the necessary modifications. I have not tried these mode but I am confident they will work. The file is called ClassicDuo.pdf and is in the Classic Solo folder of the DIY tab of my web site. Here is a direct link if you just want to down load it:

https://drive.google.com/file/d/0B_n67A1hN3qtQVgzQnZsRkFqcWM/view?usp=sharing

Cheers

Ian

I like how you mod the title  ;D

 

[ding]

I am not going to go this route since I have a 250-250 transformer I will probably use but just in case someone wants this I drew it up. It might be more confusing than what Ian drew up but some people might think this way.

BTW Ian, I got my mouser cart today and even though you clearly have it in the schematic I somehow missed it since it wasnt in the miscellaneous BOM table and didn't get the TL783 or the 1N4007s. Might want to include it for distracted people like me.

EDIT: See reply #223

 

[ruffrecords]

That is a brilliant drawing! I am hopeless at stuff like that. What software did you use for that? Would you mind if I used it in the document instead of my hand written scrawl??

I had not realised  I had missed out the TL783 and 1N4007 diodes. I will add them to the misc. BOM.

Cheers

Ian

 

[ding]

That is a brilliant drawing! I am hopeless at stuff like that. What software did you use for that? Would you mind if I used it in the document instead of my hand written scrawl??

I had not realised  I had missed out the TL783 and 1N4007 diodes. I will add them to the misc. BOM.

Cheers

Ian

I don't mind. I used photoshop. What I lack in sence I make up for in creativity 

 

[ding]

Here is a preliminary idea for a 11" deep chassis layout. It is missing the 50v toroid. By the looks of it I might need to go with a 14" deep chassis. That monster transformer is about 7" away from the nearest input and output transformer. Plus add the 48v transformer below that. I would hate to have such a deep chassis but maybe the extra 3" will help. Any thoughts? Am I over complicating things?

 

[Deepdark]

are you using a 3U? If yes, put the monster toiroid vertically on the side panel.

 

[Deepdark]

oh and install your output transformer on the side panel, not on the bottom, that way, if you install the toroid on the bottom panel, you will not pollute the OPT (and putting them on the side panel will widen the distance between OPT and the toroid)

 

[ding]

are you using a 3U? If yes, put the monster toiroid vertically on the side panel.

2U. What do you think about going deeper on the chassis? I was looking at this one from circuit specialists. Its 14" deep so 3 inches deeper than the one pictured.

https://www.circuitspecialists.com/rackmount-enclosure-et235b.html

 

[Deepdark]

looks good but is steel, I prefer Aluminium, but it's not cheap. I personnaly get my cases from Par-Metal now. Anyway, 14inch is sure better, bu you could go long way with a 3U, about 8inch deep and install the toroid vertically on a side panel, and the output transformer, could then be installed on the bottom panel, or even the opposite side pannel. As you wish

 

[ruffrecords]

I am not going to go this route since I have a 250-250 transformer I will probably use but just in case someone wants this I drew it up. It might be more confusing than what Ian drew up but some people might think this way.

BTW Ian, I got my mouser cart today and even though you clearly have it in the schematic I somehow missed it since it wasnt in the miscellaneous BOM table and didn't get the TL783 or the 1N4007s. Might want to include it for distracted people like me.

I just noticed a couple of errors.  R22 is not fitted but is not coloured red in your drawing. Also I forget to list R26 as not fitted which you DID colour in red!! So if you would just tweak your drawing to colour in R22 red I will incorporate it into the duo doc.

Cheers

Ian