[mustang]

Quote:

Originally Posted by ble0t Perhaps a 'group buy' of a good transformer for this project is in order? Is there enough interest to get an order of 50? Would they do it for any lesser #, perhaps something like 25?

I think that'd be a good idea granted we get a consensus on what VA rating PS to buy.

 

[Turing]

Judging from the amount of people buying the boards, I'm sure there would be at least enough interest to make an order of 50.

The only problem would be getting people to agree on the optimum transformer to use.

I'd be down for at least one.

 

[stackofhay]

Based on my call -- a formal group buy is not required. If there is sufficient demand, they'll wind up some units for this application and probably include them in their standard products catalog.

The person with whom I spoke indicated that 50 is a minimum run for them, and they'd need "assurances" of the demand -- otherwise AND THAT THEY WOULD accept orders directly from individuals.

I suggest we run a poll somehow -- I'm no expert on HTML or this forum, so I'd appreciate some guidance, or for somone else to run the poll.

I believe the price for a 100VA unit is around $31 plus shipping -- with mounting hardware included.

There would be no NRE charge if we'd provide a confident assurance that we'd collectively take 50 of them.

Perhaps Mr. Gilmore could help us determine a definitive spec for a unit appropriate to single PS, dual AMP configuration?

MY SUGGESTION IS 100VA 33+33 WITH DUAL PRIMARY FOR 115/230 50/60Hz

(Edited -- deletes in silver and inserts in ALL CAPS)

 

[ble0t]

Yep, I saw that we don't need to do a traditional group buy...I put it in quotes because we need to at least get the # of people who want one down. As soon as we nail down the correct specs that everyone can live with, we can start up a poll/group interest thread to guage how many we would need.

Sound like a plan?

 

[stackofhay]

Exactly!

 

[intlplby]

i'd be down for 6, but i would want something with a higher VA rating so i could use the dynahi to power small efficient speakers as well.....


i don't know what the general concensus is on what VA rating is necessary to power small speakers

 

[Woody]

Quote:

Originally Posted by stackofhay MY SUGGESTION IS 100VA 33+33 WITH DUAL PRIMARY FOR 115/230 50/60Hz

If this gets the nod from everyone then it gets my vote. After my last post I've been finding out just how anything between 25+25 60VA and 55+55 100VA is rarer than hens teeth !

Not sure what the complications for me would be in the U.K. Presumably Avel would manufacture them in the states, so I'd have to check with them what the cost would be to ship to the U.K.

If there is anyone else interested from the U.K, let me know, we may have some options, either buying from the Avel U.K. branch as a "group" or buying from another U.K. company. I did find one company that could supply a 35+35 80VA toroidal for a min order qty of 10.

 

[stackofhay]

Quote:

Originally Posted by Woody If this gets the nod from everyone then it gets my vote. After my last post I've been finding out just how anything between 25+25 60VA and 55+55 100VA is rarer than hens teeth ! Not sure what the complications for me would be in the U.K. Presumably Avel would manufacture them in the states, so I'd have to check with them what the cost would be to ship to the U.K. If there is anyone else interested from the U.K, let me know, we may have some options, either buying from the Avel U.K. branch as a "group" or buying from another U.K. company. I did find one company that could supply a 35+35 80VA toroidal for a min order qty of 10.

The issue is creating a spec with which everyone can live. I'm trying to find something that will work for the single supply, 2 amp board folks. I'm figuring that if someone is going to go differential, then they'll use two of everything, and if they want to go dual mono with two PS boards, a single 100VA transformer should have sufficient headroom.

(I'm not sure about the folks who want to drive speakers though, as I would think that there would be work required to tweak up the power supply in many places to handle the increased output stage bias and the greater dynamic load presented by speakers.)

 

[ble0t]

I think 100VA per channel (assuming you would go dual mono) for an efficient speaker setup would be plenty, especially considering the fairly generous amount of capacitance in the power supply. I think that 100VA might be a good size for the headphone amp (assuming one PS board for both channels) because it is not excessive, but does provide for some headroom.

 

[amb]

Quote:

Originally Posted by ble0t I think 100VA per channel (assuming you would go dual mono) for an efficient speaker setup would be plenty, especially considering the fairly generous amount of capacitance in the power supply. I think that 100VA might be a good size for the headphone amp (assuming one PS board for both channels) because it is not excessive, but does provide for some headroom.

IMHO that's massive overkill. The regulator output is current limited to 3A. Even though the rail capacitors could provide some transient current bursts, they cannot do so in a sustained manner. Thus, all those extra VAs in the power transformer will go wasted.

 

[intlplby]

so is it basically not worth trying to drive efficient speakers with the dynahi and instead just build an amp specifically for speakers?


if that's the case then i can live with it and i'll go with whatever transformer everyone else is thinks works fine

 

[drubrew]

My Avel 30v + 30v 2.67A 160VA just arrived. I will let everyone know how it turns out. I have also designed a second power supply to also try that will run off the same transformer. The part number was Y236505 @ $35.26 and $8.50 shipping. I might be able to get a good deal on Quantity orders since I am a Dealer. Let me know if you guys want to pursue the option.
Drew

 

[ble0t]

After looking at things a bit closer, I think AMB is right. The Dynahi is around 30W (15W/channel) if I'm not mistaken. To provide a very stiff power supply, I've always used 2X the power rating, which would be approx 60VA. Looking at Avel's specs, they have a 63VA and 80VA range as well that might be more appropriate sizes. That is, if I'm thinking about this correctly

 

[dgardner]

Quote:

Originally Posted by dgardner Don't pay too much attention to the VA rating I put in the BOM listed above. It's overkill high for a channel setup. It was a place holder until there was a consensus on the transformer. Personally, I order the 160VA one a few weeks ago. They're due in a couple of weeks.

Actually, I mispoke here. I ordered this from Plitron:
037035201 TOROIDAL XFMR 2 X 38VAC @ 80VA

 

[ble0t]

I thought I'd drop in another place to possibly inquire about the transformers...

Victoria Magnetics

I've heard nothing but good things, and they are used to doing things in small quantities. I don't think their prices are bad either...possibly only a couple $ more per toroid.