Optimal transformer for UCD700

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#21
Kevin Haskins said:
I'm going to order some custom units for mono blocks. I plan on doing mono-blocks so 800VA with dual 60V windings and the other small secondaries also. I like to account for 10% line swings so even with that we get 93V rails which is just under the maximum 95V listed in the data sheet.

I'll get them potted with the electrostatic shield between windings. It only cost a few dollars more.

If anyone is interested I'd be willing to offer them at a VERY discounted price so I can hit the minimum order of fifty units. I'll have to get a quote but I'm guessing they will cost around $60-$70 each after shipping and customs. They will take 6-7 weeks though because the only reasonable way of shipping them is via Ocean freight. Air cost a fortune.
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10% line swing of what voltage, 110V, 115V, 117V, or 120V? I've seen all of the above listed as standard line voltages. What voltage are you expecting on the primaries for the 60V output on the secondaries? When I've measured my actual voltage here, it's varied from a low of 119V to a high of 124V.

The transformers I had made last year were made in the northeastern part of the U.S., Connecticut if I remember correctly. It took about 1 week to work out the specs with the company to make sure they understood what I wanted, then about 1 week to make them, and about 1 week to ship them via ground across the country to me in California. So about 3 weeks from start to finish.
 
#22
Kevin Haskins said:
I'm going to order some custom units for mono blocks. I plan on doing mono-blocks so 800VA with dual 60V windings and the other small secondaries also. I like to account for 10% line swings so even with that we get 93V rails which is just under the maximum 95V listed in the data sheet.

I'll get them potted with the electrostatic shield between windings. It only cost a few dollars more.

If anyone is interested I'd be willing to offer them at a VERY discounted price so I can hit the minimum order of fifty units. I'll have to get a quote but I'm guessing they will cost around $60-$70 each after shipping and customs. They will take 6-7 weeks though because the only reasonable way of shipping them is via Ocean freight. Air cost a fortune.
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I take it you have the extra secondary windings needed for the UCD700s included? If yes, this is cheaper than the Avels at PartsExpress, which are $70, but have none of the extra windings.

Given I am building 4 true mono amps to biamp (2 at first, 2 more if they sound better than the amps I have now), I'd be in for 4 transformers. 800VA each seems "oversized enough" and given I have 4 of these on a 15amp circiut, I'd never get to the max ratings before tripping the mains breaker anyway 🙂

Potted and EMI shielded is great, and 60V secondaries is what will work best with our much higher than 115V AC around here.

Does anyone know where to buy small amounts of mu metal to shield the transformers? The only surces I find want to sell you large sheets for hundreds of dollars...Related Q: anyone ever put transformers on sorbothane pads?

The lead time would be ok for me - I'm in the middle of a preamp project for the next 6-8 weeks anyway, but if you need to get 50 units comitted, I bet you'll have to wait quite a while here before you can even place your order.

Peter
 
#23
Yes.... they will have the 13-0-13 & the 16V single, both 1A.

I've spec'ed the 60V secondaries at 6.5A each so the main secondaries will be 780VA, the smaller ones 26VA & 16VA for a total 822VA. If they have problems hittting the 6.5A on the nose I'll have them adjust upwards.

I'm also looking at just getting a stamped black round metal can with exits for the primary/secondary.

I'm basing my numbers on 115V as a standard. I've seen as high as 126V. Under load they should drop a little and if you have a line voltage as high as 130V that gets us to 95.6V on the rails. I'm sure Bruno has a little wiggle room in his numbers so I'm confident with 60V secondaries.

If you have 130V in the home something is wrong and you should be calling the power company anyway.

My line voltage is typically around 123V which will run me at about 90V per rail.

I'm going to order these whether there is enough people here interested or not so there is not going to be a long wait before the order is placed. I figure within the next week or two.
 
#25
Transformers;

The only importend thing is the maximum voltage of the module were the overvoltage protection starts. And that's 95VDC. Unther every condition you must stay below this level, otherwise the amps goes in protection.

So, now you have the maximum power line voltage in your house. In general you have to use a normal mains voltage +10% is your maximum.

So in the US use 115 (or 120), +10%. And you have the maximum voltage of the transformer. For the rest you have the load regulation of the transformer, small +/-6%, big +/-3%. And you have to calculate the AC voltage by 1.41 to DC voltage and reduce this with 0.7 diode voltage.

In a way is 60VAC a good voltage were in the most cases it will work very good.

VA rating:
Our demos were build with some 2x30VAC/160VA (!) stock transformers. Because we coudn't receive the custom made transformers on time. So we put two of these transformers in serie. Actually we have a double bridge rectifier on the power supply board, so every transformer goes to one bridge rectifier.

So even with a 320VA transformer the sonic performance was very impressing!

But it can be that the sonic performance will be even better with a huge transformer!

Cheers,

Jan-Peter
 
#26
Kevin Haskins said:
Yes.... they will have the 13-0-13 & the 16V single, both 1A.

I've spec'ed the 60V secondaries at 6.5A each so the main secondaries will be 780VA, the smaller ones 26VA & 16VA for a total 822VA. If they have problems hittting the 6.5A on the nose I'll have them adjust upwards.

I'm also looking at just getting a stamped black round metal can with exits for the primary/secondary.

I'm basing my numbers on 115V as a standard. I've seen as high as 126V. Under load they should drop a little and if you have a line voltage as high as 130V that gets us to 95.6V on the rails. I'm sure Bruno has a little wiggle room in his numbers so I'm confident with 60V secondaries.

If you have 130V in the home something is wrong and you should be calling the power company anyway.

My line voltage is typically around 123V which will run me at about 90V per rail.

I'm going to order these whether there is enough people here interested or not so there is not going to be a long wait before the order is placed. I figure within the next week or two.
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Based on Jan-Peter's reply, that sounds good. I was actually thinking of speccing the transformers at 63V with 120V on the primary, which works out to within a few tenths of a volt of your spec.

:up:
 
#27
Kevin Haskins said:
Yes.... they will have the 13-0-13 & the 16V single, both 1A.

I've spec'ed the 60V secondaries at 6.5A each so the main secondaries will be 780VA, the smaller ones 26VA & 16VA for a total 822VA. If they have problems hittting the 6.5A on the nose I'll have them adjust upwards.



I'm going to order these whether there is enough people here interested or not so there is not going to be a long wait before the order is placed. I figure within the next week or two.
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I think based on all the replies and my measured 121-124 wall voltage, I am in for four of these custom units. Need two for the first build, but I don't want to run the risk of not having matching parts for the second pair of amps.

Peter
 
#29
I've recieved one quote back and they are way high. Something like $98 each before shipping.

I'd count on 7" round by 3" high. I'd like to keep the dia at 6.5" but it depends upon their manf. process. I can vary my enclosure to any width I want so I'll probably go with whatever standard width they quote me on.

I'm waiting on two others quotes and I'll make the information known here when I recieve the final information.
 
#30
I too am looking to construct a UcD700 based amp (two actually for stereo).

From the above discussion, are you all saying that buying the UcD700 Amplifier Module, Supply UcD700, and TR501 transformer combination (all from Hypex) won't complete the parts necessary for each mono amp?

Thanks... I'm new to this.
Joe
 
#31
jdgonko said:
I too am looking to construct a UcD700 based amp (two actually for stereo).

From the above discussion, are you all saying that buying the UcD700 Amplifier Module, Supply UcD700, and TR501 transformer combination (all from Hypex) won't complete the parts necessary for each mono amp?

Thanks... I'm new to this.
Joe
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The TR501 is meant for the UCD400s - wrong voltage.

In addition to the right transformer, you may want a softstart module, a few wires, an enclosure, connectors such as IEC, RCA, XLR and mounting hardware, but that should complete it

Peter
 
#32
I'm sure Hypex will have a transformer available for the UCD700 also. The problem with transformers sourced from them would be the shipping cost. It would cost a small fortune to have small numbers of them delivered. The transformer I'm looking at is about 16.5lbs each. You will find that the shipping cost from Europe is very high for that kind of weight. It will be a significant percentage of the total price of the transformer.

My approach is that I source transformers or enclosures from local or Asian sources. Since I'm on the pacific coast, ocean freight containers from Asia are very affordable options for me. Either that or sourcing them from a US company (who has them built in China) is another option. I'm getting quotes on both.
 
#33
Ahhhh. I am very green to the DIY amp stuff but trying my best to learn as quickly as possible.

So you would get the two "important" parts from Hypex, namely the UcD700 Power Amplifier and UcD700 Power Supply, and then get the transformer (of correct output voltage) locally?

I did wonder if the TR501 would work because I saw 42V values on it and the UcD700 Power Supply uses something like 63V. But I assumed that their largest transformer was meant for their most demanding modules, heh.

Thank you both for the clarification.

BTW, Kevin, if you too are constructing the 700 version, please do share your parts and distributors list. I would greatly appreciate it!

Joe
 
#34
Followup: I have asked quite a few local (to me) transformer manufacturers with no luck of them matching Hypex's specs. So....

I may just wait until Hypex does offer a "perfectly matched" transformer for a very "green" person like myself to purchase. And, as you mentioned, I would be biting the bullet by paying the shipping charge. I'm all for saving money but more so for getting it right.

Regarding the mains voltage others comment about, I've measured anywhere from 109 to 117 depending on what is running on the circuit. The dual-Xeon PC consumes quite a bit and when the B&W laserjet kicks-in, that's when all hell breaks loose. Or, in other words, everything is pulled down into the world of undervoltage! Investing in a true-online UPS for my future Hypex amp will likely be a necessity (if only to be a kind operator to it, ya know?).

Speaking of which, Sander Sassen confirmed that his build of the UcD400 used a mains filter. I zoomed in on the image of his build and was able to match-up the part number on the net. The Hypex Ucd180 photo shows that they didn't use one...interesting.
 
#35
jdgonko said:
Followup: I have asked quite a few local (to me) transformer manufacturers with no luck of them matching Hypex's specs. So....

I may just wait until Hypex does offer a "perfectly matched" transformer for a very "green" person like myself to purchase. And, as you mentioned, I would be biting the bullet by paying the shipping charge. I'm all for saving money but more so for getting it right.
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here's what you can do, if you don't want to pay for shipping transformers from Denmark to the US (you really don't, I just paid $44 for the slowest way to ship the light modules over here, and based on the wait so far, they must be using a rowing boat)

I assume you will be building monoblocks, as that's the suggested "best sounding" implementation of the UCD700s.

Wait for Kevin's custom transformer to become available. Get one for each module. Done.

Or, if you can't wait, get two 800VA 60-0/60-0 volt Avel Lindberg transformer from PartsExpress http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=122-700
$70 each

and add two small transformers (one at 12-0-12 Volt and one at 18-0V from a place like Mouser or Digikey), which will cost you between $10 and $20 each. I could get you some part numbers if you really can't wait.

The shipping of these parts will be reasonable - PartsExpress ships UPS from Indiana, I think.

A "perfectly" matched transformer doesn't exist unless it is made for your wall voltage. However, that voltage keeps changing over the day. So you compromise, and you compromise to a level where it will be more or less guaranteed that the UCD module won't go into protection mode when your evening voltage gets just 0.1V too high for the whole rig to keep working.

It has been discussed here and in other threads that given 115-124V wall voltages in the US (measure again, run NOTHING on the circuit, and measure at 10pm at night, just to get a high value), a 60V secondary rating is going to be as close as you want to cut it. The good news is - 60V transformer secondaries are not that hard to find. Plitron has them in their regular line, Avel offers that voltage as a standard option as well, and I'm sure you'll find a few more options if you keep looking. The problem with those standard transformers is that you still need those two other voltages required by the UCD700 boards, which means either two more transformers, or a custom job.

In short - even at $98 a pop, Kevin's custom units are probably the best deal and offer a cleaner installation than trying to jam three separate transformers into one monoblock.

Peter
 
#36
pburke said:


here's what you can do, if you don't want to pay for shipping transformers from Denmark to the US (you really don't, I just paid $44 for the slowest way to ship the light modules over here, and based on the wait so far, they must be using a rowing boat)

I assume you will be building monoblocks, as that's the suggested "best sounding" implementation of the UCD700s.

Wait for Kevin's custom transformer to become available. Get one for each module. Done.

Or, if you can't wait, get two 800VA 60-0/60-0 volt Avel Lindberg transformer from PartsExpress http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=122-700
$70 each

and add two small transformers (one at 12-0-12 Volt and one at 18-0V from a place like Mouser or Digikey), which will cost you between $10 and $20 each. I could get you some part numbers if you really can't wait.

The shipping of these parts will be reasonable - PartsExpress ships UPS from Indiana, I think.

A "perfectly" matched transformer doesn't exist unless it is made for your wall voltage. However, that voltage keeps changing over the day. So you compromise, and you compromise to a level where it will be more or less guaranteed that the UCD module won't go into protection mode when your evening voltage gets just 0.1V too high for the whole rig to keep working.

It has been discussed here and in other threads that given 115-124V wall voltages in the US (measure again, run NOTHING on the circuit, and measure at 10pm at night, just to get a high value), a 60V secondary rating is going to be as close as you want to cut it. The good news is - 60V transformer secondaries are not that hard to find. Plitron has them in their regular line, Avel offers that voltage as a standard option as well, and I'm sure you'll find a few more options if you keep looking. The problem with those standard transformers is that you still need those two other voltages required by the UCD700 boards, which means either two more transformers, or a custom job.

In short - even at $98 a pop, Kevin's custom units are probably the best deal and offer a cleaner installation than trying to jam three separate transformers into one monoblock.

Peter
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Hi,

Let's discuss it from an optimal all out viewpoint. When your load starts to suck the juice down and really work the xformer, they're going to suck down /modulate those aux windings with them, aren't they?

I think the best all out implementation would be three transformers. Grand total of six transformers ..... makes me cry.
 
#37
Chris, you're right, separate transformers will reduce interactions for a better sound. So will shielding against line-borne noise, the more shielding the better. Toroids are presumably the worst type of transformer from this perspective as they are high bandwidth animals that faithfully pass all sorts of high frequency stuff from primary to secondary.
 
#38
A couple of quick thoughts.

I don't think multiple transformers are necessary. The auxiliary voltages are regulated on the Hypex power supply so a little sag shouldn't have much effect on them. Also, Jan-Peter recommended 13V and 16V for the 12V and 15V output to also prevent this from being a problem.

For the high frequency noise being passed through, that's why a static shield between the windings is a good idea.
 
#39
Greg, yes, every possible improvement comes down to a question of "how much" and whether the improvement is worth the extra time and expense. I suggest that one reason the 700 sounds better than previous UcD versions is that it uses separate power supplies, including separate transformer windings, for the low voltage supplies. "Separation" would be the key contributor to the betterment if that analysis is correct. Dual mono works on the same principle, suggesting, further, that any separation possible is better. Jan-Peter's recommendation implies this, don't you think?
 
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