Group Build: Dynafet

[Dreadhead]

If this is really the case and we are going with a one case design (or even a two for that matter.) I think we would be better off spending a little more for something that isn't going to cause problems down the road.

Agreed. I'm not a big fan of transformer hum.

[grawk]

I'm in for 2 pairs of the balancing transformers.

[Icarium]

with regards to Pars post in the business thread, I'd definitely go with the larger transformer and go with the same transformer for all builds. I'd recommend 160VA 2x30 VAC with universal primaries. Again, reference Plitron 057017201.

With regard to SumR, they are a bit of an unknown. The ones I have seem to have a bit of mechanical noise, but perform okay. Plitron is pretty much the industry standard in audio. I just wanted to throw this out to the crowd, and maybe those who have an opinion on this matter can give their $0.02. This is pretty much a no-compromise type of build and from what I've seen so far, this is the only already I'd consider a slight compromise, just because of the unknown-factor.

... gotta run for a bit, I'll comment more on the other thread later..

Hrm the SumRs you have are they shielded? I was basically operating under the assumption the shielded ones would not have a problem with hum.

I have no problem contacting plitron and figuring things out there as well. Someone mentioned that they might have a quantity requirement but if we can hit 10 pretty easily then that shouldn't be a problem.

I am leaning towards getting a 200-230VA one for my 4 board build, but I'm curious to see what values others want as well.

[Icarium]

I'm in for 2 pairs of the balancing transformers.

Okay cool I'll add that to the spreadsheet. I think I need 2 pairs as well for me and j4cbo.

[Icarium]

Updated. Starting to include sowter transformer info as well so if yall could start thinking about how many of those you want (Including 0) that works as well.

[vvs_75]

With regard to SumR, they are a bit of an unknown. The ones I have seem to have a bit of mechanical noise, but perform okay. Plitron is pretty much the industry standard in audio. I just wanted to throw this out to the crowd, and maybe those who have an opinion on this matter can give their $0.02. This is pretty much a no-compromise type of build and from what I've seen so far, this is the only already I'd consider a slight compromise, just because of the unknown-factor.

I am getting one custom shielded trafo very soon from sumR. This is my first trafo from them. SumR look good to me. But they probably not as ''big'' as Plitron. So we will see.

We definitely should check what the price will be for the same trafo from Plitron. In the end we will check all the transformers anyway, so if there a problem with some of them, regardless from whom we order, we just ship them back.

[vvs_75]

Updated. Starting to include sowter transformer info as well so if yall could start thinking about how many of those you want (Including 0) that works as well.

One pair of balancing trafos for Dreadhead team also.

[vvs_75]

Double post, sorry.

[Icarium]

Okay my brother and I have priced out the chassis work.

chassis pricing - Google Docs <- This is the spreadsheet as it stands right now. It is based on a rough preliminary version of the build I want which probably is more holes than most of you need.

Basically he is pricing his labor at 50 cents a minute (30 dollars an hr). If it ends up taking a little bit more time than is estimated... and we imagine it will especially for set up. That cost will be covered and not passed on to you guys.

He then gives a time estimate for each type of hole that I could think of.

Obviously if you only need 2 rca input holes and only enough holes to mount 2 boards versus my fairly tricked out build then you will save significantly.

If this needs to be updated with more types of holes then let me know.

But if you are interested in his services then I would need to know of your interest and what holes you need drilled.

Also he asks that we try and keep on/off switches to those of a circular shape.

One time costs will be fairly distributed across all those interested. I priced this out to 10 chassis, but I imagine we'll either get less or more so cost will go down or up depending on those interested.

I think he ideally would like to cap this out based on time. I think he is at most willing to dedicate ~20 estimated hrs to this thing.

If any costs seem unreasonable to you we can discuss it further. He is flexible and isn't particularly trying to make money, but it is a fairly tedious effort and some sort of basic compensation would be nice (Which is kinda how we tried to price it).

Also if time estimates based on your guys' experiences are inaccurate in some way perhaps you can offer feedback as well and we can calibrate it further to that.

We probably will want to get at least 1 extra chassis just for him to calibrate and test things out. That will probably be a distributed cost as well.

If it ends up taking a LOT less time or a LOT more time then costs may be adjusted... but you will be informed of this as soon as possible. Like if it ends up taking 10-30 percent more time either way then he'll probably just suck it up.. but if we are talking about like 2x or half as much time as estimated then some renegotiation may occur if that seems reasonable.

Now besides holes.. laser engraving is a possibility as well. He estimates it would take ~15 hrs to engrave everything. He is not particularly willing to do 15 hrs on top of 20 hrs.

Since laser engraving is mostly a set up and let it run type activity... if we can parallelize things then it may not be significantly more cost... but it largely is dependent on machine availability as he doesnt have dedicated access to all these machines (Other people will be using them and in fact it may be pretty busy on weekends). It may make sense for either me or j4cbo if this goes down while he is in town to also get access to help out.

Like my brother says if he's looking at 10 hrs of labor for chassis hole making then he will be more interested and willing to explore laser engraving. He basically isn't really willing to spend 35 hrs on chassis stuff as that's like probably 3 weekends mostly dedicated to this.

By the way you might see a class cost listed on the spreadsheet. Yeah he knows his stuff so it's not like that class is for him to learn how to use the machines... it is a shop requirement for him to be able to use the machines. It's a 2 hr class. If we do laser engraving he will be forced to take a 2 hr class for that as well.

Anyways any feedback is of course appreciated Everything is negotiable to some degree.

[luvdunhill]

Hrm the SumRs you have are they shielded? I was basically operating under the assumption the shielded ones would not have a problem with hum.

It's a slight mechanical hum, not EMI. Doesn't effect sound really that I can tell.

[Icarium]

Ah okay. Well I am of course not opposed to spending a bit more money on transformers to get the best shizzy. Really more the will of the group.

[luvdunhill]

Updated. Starting to include sowter transformer info as well so if yall could start thinking about how many of those you want (Including 0) that works as well.

So, latest cost on these is right around $150 a pair. If we get up to 12.5 pairs, it goes down by a whopping 5%. I'm in for 2 pair.

[Icarium]

K updating for you. Looks like we are already at 14 sowters.. what's the next price break lul.

[naamanf]

So I am reading the machining cost at $31.5 per person? Who is going to do the all the layouts for heat sink holes/board mounting/front panel/back panel?

I also think most people would want some sort of lettering on the front/back panels be it engraved or laser etched.

I also think that if j4cbo is going to be designing the super I/O board it should have PCB mounted connectors and the back panel to match.

[Icarium]

The machine costs would be 99 dollars per person if they want as many holes as I plan on getting and we get 10 people interested.

The actual machining cost per chassis is (If you want the number of holes I want) is 67.50. If you want less holes then it is cheaper. Basically use the conventions for estimated time per hole * 0.50 cents a minute to estimate how much cost your particular config of holes will be.

The additional 31.50 is to cover cost of membership/gas/drill bits and other consumed tool bits/the 2 hrs of his time he has to spend taking the class to use the workshop.

All those costs add up to 315 dollars so that will be distributed across all the people interested in this. If its only 5 people then it will be 63 dollars per person. If it's more than 10 then it iwll be cheaper than 31.50 per person.

He is going to do that without any charge since I already am in the process of pirating CAD/Wildfire(?) for him and he doesnt mind doing it from the comfort of his home. Yeah given that j4cbo will be local and is doing my build I'll be coordinating with him very closely with regards to his I/O board and stuff.

Moreover if etching/drilling holes can be done for cheaper by anyone else or a service that someone knows of I don't think either of us have a problem with going with them I am not knowledgable at all about this kind of thing so I don't know what's reasonable or what isn't. He knows more than me and thinks this is reasonable, but I doubt he knows really what's out there as far as DIY chassis work.

He could use the cash, but he likes his social life too (He just got a job making 60k at my dad's company, and shortly thereafter the company announced that everyone needs to eat a 20 percent pay cut due to the economy).

P.S. Yeah I really want laser etching too or whatever. I'll try and work with him to get it done. He said he might be more willing to do it like a month after he does all this stuff so he can recoop a bit but it would necessitate a second membership fee... and all that. It really is just a matter of time and money I guess.

[luvdunhill]

K updating for you. Looks like we are already at 14 sowters.. what's the next price break lul.

14 pairs, so 28 transformers? The price breaks are:

1-11 = 0%

12-24 = 10%

25+ = 15%

50+ = 20%

100+ = 25% (Maximum discount)

[Icarium]

Nah 14 period

[naamanf]

I just looked up the price for the panels I used for my B22 and it was $92 and that included the material and engraving for lettering. That's with a purchase of 10-19 of each panel. So I think the price will be similar with the advantage of FPE in that we know we can get lettering and it's of know quality (not saying he would do a bad job). I think CamXpert (Nate?) might also be another option.

We would also need the heatsinks/angle mounts machined or drilled and tapped.

[Pars]

with regards to Pars post in the business thread, I'd definitely go with the larger transformer and go with the same transformer for all builds. I'd recommend 160VA 2x30 VAC with universal primaries. Again, reference Plitron 057017201.

With regard to SumR, they are a bit of an unknown. The ones I have seem to have a bit of mechanical noise, but perform okay. Plitron is pretty much the industry standard in audio. I just wanted to throw this out to the crowd, and maybe those who have an opinion on this matter can give their $0.02. This is pretty much a no-compromise type of build and from what I've seen so far, this is the only already I'd consider a slight compromise, just because of the unknown-factor.

... gotta run for a bit, I'll comment more on the other thread later..

Nate (n_maher) has never mentioned anything about transformer hum with the one he got. These are potted as well as shielded, so maybe that's the difference?

Plitron charges extra for electrostatic screening and shielding (http://www.plitron.com/standard_spec.asp) and I could not find potting listed, although I see some transformers on their site that are in cans. I already have a transformer (well, it isn't here yet), so I don't have a horse in this race. Just wanted to point out that extra charges will apply particularly for a single chassis build.

[Icarium]

I just looked up the price for the panels I used for my B22 and it was $92 and that included the material and engraving for lettering. That's with a purchase of 10-19 of each panel. So I think the price will be similar with the advantage of FPE in that we know we can get lettering and it's of know quality (not saying he would do a bad job). I think CamXpert (Nate?) might also be another option.

We would also need the heatsinks/angle mounts machined or drilled and tapped.

Ah that's pretty reasonable re: your guy. Maybe we'll do that. What about the holes for board mounting inside the chassis?

Also with FPE do all panels have to be the same or can he accommodate for instance differences in types and number of inputs and outputs?

I was looking at the hifi2000 cases and they have the heatsink on the side of the chassis already. Are there different heatsinks besides those and the ones on pcbs? Also what are angle mounts? And what does "tapped" mean?

[n_maher]

I think CamXpert (Nate?) might also be another option.

In my opinion CamExpert would be the place to use for this. Having an individual hand machine the chassis seems insane to me when their are automated systems to handle stuff like this. Not to mention the advantages of the software, engraving, etc.

And I don't think any of the SumR trafos I've gotten have had any mechanical hum. I've got another one on the way now so I'll check that but I also have one downstairs that I'll try and fire up tomorrow to check (it's a fully potted and shielded unit). Plitron is not without its faults as well, I seem to remember having a conversation with a manufacturer about them and learning that under full load they tend to sag and consequently you have to guess and overspec them to get the desired output. I can't help but feel like they have some good marketing people who've gotten them a good rep and now feel free to charge a premium for their goods.

[luvdunhill]

Jacob et al.

One thing to think with regard to the attenuator will be the input transformer. The input transformer has needs to help inform the circuit, or it will turn out to be a problem. That being said, I don't think a Joshua Tree type attenuator is a good choice, due to varying impedance. The choice of RC loading the secondary, plus the impedance of the volume control mechanism after the transformer will have to be chosen carefully. These interact with the input capacitance of the amp, as well as any input filter or feedback capacitance. My experience with input transformers is mostly with the Jensens. Does anyone else have an opinion on this?

[Icarium]

Hrm I'll have to check out CamExpert. Do you guys have a link to CamExpert and naamanf's place?

Well I'll get some quotes from Plitron. It seems like transformers can be ordered further down the line so no hurry. But definitely try and move towards a consensus after the quotes are in.

It sounds like dynafet boards will be ready to get a prototype made in not too long... what do people generally like for pcb makers. j4cbo says he's had good results with pcbfabexpress.

[luvdunhill]

I can't help but feel like they have some good marketing people who've gotten them a good rep and now feel free to charge a premium for their goods.

if that's the case, here's a good quote from their marketing department:

diyAudio Forums - F4 power amplifier - Page 24

one other point is Richard's own claim about noise with increasing VA. Nate, how large dounts have you used from SumR? I've used 1000VA units from Plitron that were dead quiet. I think the concern is with increasing current capacity. I just think we should consider a prototype or two before going all in.

Edited February 22, 2009 by luvdunhill

[Icarium]

Sure I don't mind. I of course dont have the capability to test it. Do you want to distribute cost across the group for the prototypes? Another thought is looser101 is close by so shipping costs (Or pickup) for him would be considerably cheaper if we are going to do multiple orders. Ideally that or another DIYer who might use transformers of this type in the future just buying it for themselves.