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Old 19th December 2008, 03:01 AM   #1
kmaier is offline kmaier  United States
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Default Hammond Gripe

Not sure how many have found Hammond iron to be grossly out of spec and very poor quality, but.... time to gripe about this junk.

I've been working on a small 45 amp... opted to use a 271X power transformer which is rated at 280-0-280 @ 60ma. With a 40ma load, the secondary is putting out a whopping 320-0-320! It also puts out a huge magnetic field and induces a huge hum output into the output tube. Just taking a flat piece of steel and holding between the power transformer and the output tube drops the hum level significantly.

My brother built a pair of 50-watt monoblocks and used Hammond iron.... the power transformers were so bad you could put a small screwdriver against the core and it held in place while buzzing away. He eventually had to dump them and replace with Dynaclone P782 units... and the amps went from humming to quiet. Hammond is also useless in helping to resolve issues with obviously defective components.

Seriously, Hammond quality varies so broadly I'm starting to think they have monkeys winding the stuff.... not much else can explain just how bad this stuff is. Oddly, I used an Allied transformer (yes, made by Hammond) on the previous amp... same identical layout, chassis size, parts, schematic, etc. and it was dead quiet.

I'm about to swear off anything Hammond... as it's a cr@p-shoot at best and a waste of time to design and build with it. I now have a useless amp due to the high hum level and am debating on building the second amp.

Regards, KM
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Old 19th December 2008, 03:22 AM   #2
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Edcor has a pdf up on their forum that has a list of all their previously engineered power transformers. You can certainly find a replacement for that. They made a set of custom power iron for a voltage doubler and the thing is dead quiet.Decent prices, great quality, and made in usa - what more can you ask for?
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Old 19th December 2008, 03:22 AM   #3
anatech is offline anatech  Canada
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Hi KM,
Too bad Hammond doesn't work for you. I have used Hammond transformers without trouble for over 30 years. I have even met the late Fred Hammond, I can say that quality is foremost with them.

When I was younger (early teens), I asked for some help with a few projects. I was able to talk to an engineer each time and they were very helpful on each occasion. This was basically Fred Hammond's personality.

Anyway, the Hammond plant is about an hour away from here by car. It is possible they have imported some of these instead of building them here. That might explain your issues. I have no idea if they build everything or import some.

Quote:
Hammond is also useless in helping to resolve issues with obviously defective components.
As with any complaint, this depends on how you approach them. An exchange has two sides and it only takes one to mess things up. I wasn't there, so I can't say anything except that your experiences are about opposite to mine.

Quote:
With a 40ma load, the secondary is putting out a whopping 320-0-320!
Did you measure your outlet voltage?

Quote:
Just taking a flat piece of steel and holding between the power transformer and the output tube drops the hum level significantly.
Often you have to rotate the transformer for the lowest radiated hum. If you place sensitive circuitry too near the power supply, you can expect some hum pickup. Placing a shield between the power supply and the circuits is common practice when the spacing is small.

In the end, what do you want us to say? To assist you, or be able to judge the situation, we need the specifics. Things like a complete schematic and pictures above and below the chassis would be expected so that the situation can be completely understood. Otherwise, your complaint has no basis in fact.

I would say the same thing about any complaint where no additional information was given. Just trying to hep you out for future posts for assistance or opinion.

-Chris
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Old 19th December 2008, 03:24 AM   #4
anatech is offline anatech  Canada
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Hi Boris,
Quote:
Decent prices, great quality, and made in usa - what more can you ask for?
Made in Canada?
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Old 19th December 2008, 03:30 AM   #5
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Quote:
Originally posted by anatech
Hi Boris,

Made in Canada?

lol

I do hear much better things with the 300 series Hammonds.
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Old 19th December 2008, 04:46 AM   #6
kmaier is offline kmaier  United States
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Chris,

Your points are well taken... I would agree that Hammond (many years ago) was good stuff in general, but that really doesn't apply to current products. I've used their filament transformers and chokes and these seem fine overall. Still, the small 271X has a much larger magnetic field radiating outward than the Allied unit (also made by Hammond), which was very quiet in the exact same application.

An update.... I Hooked the second 271X up and just put typical loads on the windings. The ratings are:

5.0 VAC @ 2 amps
6.3 VAC @ 2 amps
280-0-280 VAC @ 60ma.

Loads were:
5V4G - 2 amps filament on 5.0 VAC load
3C24 - 3 amps filament on 6.3VAC load (a full amp extra loading)
10K 50-watt resistor across plate winding

I also decided to use a variac to drive the 271X set at 115VAC... line voltage, like most things down here, wanders a bit in South Florida but mine usually hovers around 120VAC.

Even with a bit extra loading beyond the ratings the secondary was sitting at 590VAC. Overall I can live with a bit higher voltage, what escapes me is just how bad the magnetic field is compared to the Allied unit which is the identical size core, end bells, mounting orientation, etc. Here's a couple pics of the first amplifier using the Allied power transformer. It's very quiet compared to using the Hammond 271X.

Click the image to open in full size.
Click the image to open in full size.

Regards, KM

PS - my brother was using the 300 series power transformers.... one unit had massive magnetic fields... literally held a screwdriver in place... the other did not exhibit this problem in the identical setup. After replacing them all of his hum problems went away... nothing else was changed. Sorry, but I have to believe that these particular Hammond power transformers had problems.
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Old 19th December 2008, 03:24 PM   #7
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My experience with Hammond has been the same except that the Magnetic Field part I have not had issues with. But the 115 VAC primary wreaks havoc on the secondary voltages. The current Hammond transformer series needs to be re-labeled as the "Voltage Boost Series".

I had to variac down to 110 VAC a Hammond 278X before my amp blew-up. With Hammonds the bext thing is to under dimension the application and you are sure to get enough voltage and current. If you specify the Hammond in the normal way, somehow these transformers take 120-125 Volts to new height's making DIY an exercise in voltage control, not only B+ but also the tube filaments.

Drawing 4 amps from a 6 amp 6.3 VCT section makes for 7.5 VAC on my Mullard 5-20 amp. With the Variac at 110 VAC I get 6.3 VAC. Go figure....

Then I had a learning curve and was able to implement a Hammond 272JX on an Olson Amplifier design from the 40's with stellar results, and plenty of margin to play with.
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Old 19th December 2008, 07:27 PM   #8
anatech is offline anatech  Canada
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Hi Guys,
Good to know. Have any of you contacted the engineering department through their web site? It might be interesting to know what they say about this. It is entirely possible that their were QC problems and you might end up with free replacements. Can't hurt to go that route, you've nothing to lose. Keep one thing in mind, customer service is there to help you, but they need to be able to quantify what is going on. It's not that they are blocking you, just being cautious in this age litigation and "experts".

Hi kmaier,
Your amplifier really does look like the chassis is too small. Nothing I have is that compact, and that includes amps built by other people. I even have a nice amplifier that someone built in correspondence with Fred Hammond. It's a unit using 7581As that is rated about 20 wpc. Really good sounding amp. I'll try to post a picture of it.

The one thing that was stressed in the old days was to make sure your chassis was large enough. Distance is the best way to fight hum pickup - and lower operating temperatures. If you look at commercial amplifiers, you will see that most are spaced out larger than the one you have made there.

-Chris
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Old 19th December 2008, 09:36 PM   #9
anatech is offline anatech  Canada
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Hi,
Here is a home made amplifier made a long time ago, with Hammond iron and expertise. Notice the distance between components. The outputs are 7581A tubes.

-Chris
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File Type: jpg home made hammond.jpg (73.3 KB, 1171 views)
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Old 19th December 2008, 09:39 PM   #10
anatech is offline anatech  Canada
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Hi,
This one is a Leak Stereo 20. Again, there is a lot of room between components.

Sorry for the lack of quality. These are shot as they are on my shelves. I also have an Eico HF-87 that also shows a lot of room between components.

I guess we are all used to small things these days, but there are benefits to making a larger layout. This is probably even more true for a single ended amp. There is no cancellation happening with these at all.

-Chris
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File Type: jpg leak stereo 20.jpg (67.0 KB, 1076 views)
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