[FallenAngel]

If you're building a speaker amp, take a look at this beauty.
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[holland]

Quote:

Originally Posted by pinkfloyd4ever /img/forum/go_quote.gif Much better selection than Avel too. And to add to what holland said, you can see their loaded voltages by clicking on the red link to each model's datasheet.

Yes. The datasheets need to be checked and not assumed. It needs to be brought to the forefront, in most cases it is not an issue.

I buy all my toroids from Antek. I think they are a great value and will continue to use them. I usually buy about 5 at a time, and have at least 10 toroids of different values in my closet.

I have yet really have to fall back to a different brand, but the only real issue that would make me consider another is the size. They are a bit larger in diameter than most. They say it's because they use thicker wire, but who knows. Most of the time, I just use a larger case. It may not work for all people. Again, the datasheet shows the size.

 

[espressogeek]

Wish I had seen this Antek thing before I placed my order with Part Express. I went ahead and got the transformer mentioned on the spreadsheet. Not a bad deal but not as cheap as these guys. I'll have to remember them for future projects of which I am sure there will be many.

 

[holland]

to be fair, I had brought up the Antek during prototyping discussions and requested that it be added to the BOM. Upon further analysis and discussion, I had determined that it would be incapable of reaching the spec'd B+ and requested that it be removed. It was specifically the 0515 because due to the higher VA it would not dip as much in the voltage due to the lighter load in the default configuration. This was with the early HV multiplier/setup. While this would be OK for me, it would not be OK for a broad recommendation. In the default configuration with the standard load using the original HV setup, I was getting a B+ of about 58V (spec was a bit over 60V) which was about what I had calculated for loaded and about 59.x for unloaded which also matches what I had calculated.

I have not tested it, nor done the math, for the existing HV setup. I have not tested it and probably would not recommend it for the higher current load configuration unless you can live with not having the highest of possible B+ voltages. One will have to decide for themselves what is acceptable or not.

While this is not a big deal, and many probably won't even notice th voltages or not care, some will find it a big deal.

 

[runeight]

Although I understand the wish to use the Antek and Holland's point about the new HV supply not being quite as sensitive to the secondary voltage, MHO is that sticking with one of the two recommended (or same spec) trafos will minimize problems that you might encounter.

 

[espressogeek]

Holland, I appreciate the detailed explanation and history. I'm sure a lot of this will make more sense once I build this thing and try to digest the design and it's philosophy

. I am still in the technical weeds here.

Quote:

Originally Posted by holland /img/forum/go_quote.gif to be fair, I had brought up the Antek during prototyping discussions and requested that it be added to the BOM. Upon further analysis and discussion, I had determined that it would be incapable of reaching the spec'd B+ and requested that it be removed. It was specifically the 0515 because due to the higher VA it would not dip as much in the voltage due to the lighter load in the default configuration. This was with the early HV multiplier/setup. While this would be OK for me, it would not be OK for a broad recommendation. In the default configuration with the standard load using the original HV setup, I was getting a B+ of about 58V (spec was a bit over 60V) which was about what I had calculated for loaded and about 59.x for unloaded which also matches what I had calculated. I have not tested it, nor done the math, for the existing HV setup. I have not tested it and probably would not recommend it for the higher current load configuration unless you can live with not having the highest of possible B+ voltages. One will have to decide for themselves what is acceptable or not. While this is not a big deal, and many probably won't even notice th voltages or not care, some will find it a big deal.

 

[Uncle Bob]

Now that the 1st boards have been delivered (except here, but maybe tomorrow

), might it be a good idea to start a new topic Soha II builders blog?

whoops.. a few replies to this topic have gone missing? I posted a question about transformer specs earlier, but it's not showing now ???

 

[Ferrari]

Yes indeed, we are missing some posts. Also one of mine, in which I mentioned the need of a transformer that can properly fulfill the job in the SOHA II for all PS sections (in high current mode when desired): 6.3V heaters, ±15V section and the B+ HV section (~105V unregulated). From this point of view, the Antek AN-0515 will probably not suitable due to the lower output voltage, which can drop to 14VAC under heavy load (according to Antek spec).
The one I’m using in my amp (for my GF) is also a relative cheap one (50VA, 2x15V), but it does output ~18.3V unloaded.

As runeight noted in some posts back -to minimize possible problem- it’s better to use transformers with a similar spec as the ones recommended, either 30VA or 50VA type (Hammond, Avel Lindberg, Amveco, Talema Nuvotem…).

 

[holland]

Yes, agreed, minimize problems.

Also note, that you can do a wallwart build. Mine is. I am using an EI core. I can't recall if I'm using a Hammond or something else.

 

[espressogeek]

I would have never thought about doing a wall-wart. I have seen folks run copper shielding between the amp and the toroid. Is that effective? If so, where can I get some to shield this thing with?

 

[holland]

good question, I don't know.

I was just throwing it out there in case cost was an issue. For me, it was space, with the prototype HV perfboard going in I could no longer fit a toroidal transformer in my case without it sitting on top of signal lines.

I'm not sure about the shielding or where to get it. You may have to google. You can build a "box" with mu-metal. That's probably what I would do. I would actually take mu-metal and wrap the entire rear section (including IEC) in a big box. Drill some holes to run some wires out to the PCB side or attach a terminal strip to the box and run wires to/from it (still need holes).

During my proto build, I had the toroidal up against the PCB, moved it around and had no hum. I didn't measure anything, but it may or may not have been measurable. Runeight had some hum from eddy currents being generated in the case, but it went away and I forgot what he did. Nobody else had issues, but I don't think anything was measured, again.

 

[runeight]

I did have some hum issues at the start, but they went away during the final caseup. I just put the toroid in the far left back corner (viewed from front). I ran the wires away from the input shielded cable which is on the other side of the box.

The website (Cavalli Audio) shows diagrams of where to locate the components in the enclosure for best effect.

 

[meat01]

Quote:

Now that the 1st boards have been delivered (except here, but maybe tomorrow ), might it be a good idea to start a new topic Soha II builders blog?

I agree with this idea

 

[runeight]

I'm good with this too. I am happy to start that thread, but if one of you guys wants to do that just let me know so I can subscribe.

 

[kostalex]

I want to gift amp kit to my old friend. I've been waiting for SOHA II kit for a while. Just checked glassjaraudio and found that Bijou kit is available.

What would you recommend for D2000 - Bijou or Soha II?
What would you recommend for HD650 - Bijou or Soha II?