Why are Hammond SE OPTs dissed? Heavier than the competition... - diyAudio
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Old 13th July 2006, 09:17 PM   #1
awedio is offline awedio  United States
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Default Why are Hammond SE OPTs dissed? Heavier than the competition...

I have been shopping for cheap ($100-ish) SE output transformers; One Electron, MQ Robin Hood, Edcor, andddddd...... Hammond!
I have repeatedly read that the Hammonds are nothing special sonically, and I was looking to buy One Electrons. Then I began comparing actual weights, and the Hammonds are TWICE as heavy as the One Electrons. And I've always heard and assumed that more iron=better frequency response, esp. in the bass.

Angela is carrying a newish line of Hammond SEA series trafos, supposedly improved over the old SE series?

I have found very little info on the Magnequest RH series, but I get the impression they are small and don't support much bass. I'm a bass freak, y'all! No one seems to have tried the $75 Edcors.

Any wisdom from the group? The One Electrons seemed like a sure thing until I saw they were only 6lbs. each. Maybe you can't buy "sound by the pound", but I can't help wondering.
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Old 13th July 2006, 10:11 PM   #2
phn is offline phn  Sweden
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I'm out of my depth here. But I'll give it a go anyway. These quotes concern PP, but should still be valid.

"The high distortion with the Hammond transformer measured at low frequencies was not evident until I had the Edcor to compare it with. They gave a sound that seemed as good as the HF-50, although that was 40 years ago and memory of how something sounded is not reliable over that length of time."

And

"The best amplifier I have heard up to now was an Eico 50 watt monoblock using a pair of EL34s. [...] The Eicos had an excellent output transformer. I didn't have much test equipment at the time but I did have a lamp stabilized oscillator, home brew, and an oscilloscope good enough for audio. I loaded one of the amplifiers and looked at the lissajou figure on the scope. At 50 watts it held a perfect streight line from 20 to 20,000 cycles. The Hammonds don't come close to doing that well. I wish I could find a couple of those transformers or maybe the whole amplifiers."

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That people pay $1,000 or more for a single Western Electric SE OT has to do with more than scarcity and the name. Those trafos would probably cost $1,000 each if made today.

Edit: Second ethermion. SET fans tend to be FR fans. Unless you're into chamber music, you might end up paying very much for very little.
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Old 13th July 2006, 10:12 PM   #3
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Hammond may not be the cat's meow, but there are many fine amps built with Hammond transformers. Use them within their spec's and you will be fine. The only Hammond iron I dislike is the 2xx power xformers.

As for Edcor, you should use the search button on this forum. Also see http://www.angelfire.com/electronic/...es/index.html. Not an SE test, but a data point none the less.

As to MQ Robin Hoods, they were designed save you $$$, not deliver bass. RTFWS.

Maybe you should drop $75 on the Edcors and give us a report.

Frankly, if you wanted bass, you wouldn't be going SE in the first place in my humble opinion. Or, spend some real $$$ and visit Jack at electra-print. His CU5KB with a 304TL will probably be all the bass you need.

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Old 13th July 2006, 10:44 PM   #4
rdf is offline rdf  Canada
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A few reasons for me. Having worked around Hammond PS iron and line-level transformers for over twenty years iron the drop in finish quality is embarrasingly obvious. Flaking paint, missing washers and screws cut with side cutters for example. Of the recent HV power supply iron I've purchased not one transformer had filament windings close to spec under load. All were tube-roasting hot, typically around 6.8 VAC. Finally, deep into a project I discovered the 1628SE has a severe design flaw (don't know about the SEA.) The high frequency response nulls 4-5 dB around 13 kHz. Not a happy discovery after the chassis was cut.
To be fair Hammond's open frame stuff still seems alright, chokes and such. I'll buy more.
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Old 13th July 2006, 10:47 PM   #5
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This assessmnet may help you: http://www.meta-gizmo.com/tri/vtv-se.html

I have a pair of Hammond 1627 SE transformers and they sound too rolled off at the high frequency for me. I've not listened to any other SE transformer to compare so, perhaps that's normal for SE amps....

Kind Regards
Andrew
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Old 13th July 2006, 11:16 PM   #6
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They are quite good.... They got a bad rap due to a large lot
of the popular 5K plate load 1628SE having been manufactured
with a winding problem that resulted in the infamous 13kHz dip.
This appeared only on the 1628SE on the 8 ohm tap, the other impedance taps seemed to be flat from 20Hz out past 30kHz or so. I think you're best bet is to use the 1629SE, or, the newer
1628SEA.

Yes, you can find flaws with the big hammonds... They will provide
thunderous bass for a single ended amp, however, because they
are quite large, and thus are prone to the stray capacitances of
a big transformer, they might not present the ultra-low level detail that one can obtain from a parafeed output transformer with a nickel core.

My 1628SE found service as a plate load choke in another amp
using a parafeed transformer. Thus, you can recycle your investment if you desire.

As far as cosmetics, I was really happy... Paint job was clean with no bubbles. Further, the varnish on the laminations was uniform and even to the eye and the hands, so they look great on a chassis. You can also change out the bell bolts with your own hardware if you wish (i.e. brass or steel acorn nuts look nice)

-- Jim
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Old 14th July 2006, 12:34 AM   #7
Sherman is offline Sherman  United States
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You should also take a look at James. I used the 6123HS in a couple of monoblocks and they sound great. Sound aside, fit and finish is miles ahead of Hammond. The price is about the same as Hammonds 1628SE from Euphonia Audio.

The reason I purchased the James OPTs is because of that (in)famous 13KHz dip in the 1628SE. It was happening just at the time I was looking to purchase a 5K/ 8 Ohm SE OPT.

That said I also built an amp using Hammond 125ESEs which Hammond does not promote as a "hifi" OPT. They also sound very good.
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Old 14th July 2006, 03:06 AM   #8
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OK I may not be an expert, but, I am searching for just the right transformer to use in an amplifier kit that I am developing. It is an SE amplifier that runs 6L6GC's, KT-88's, 6550's and EL-34's in triode or UL (if the transformer has the tap). I have almost ALL of the mentioned SE transformers on my bench right now, with the big Edcors on order.

I ordered the Hammond 1628SE's from a major supplier. They shipped me some transformers that are TWO years old. I hooked them up and tested them. I was severely underwhelmed! Yes the bass is amazing. The lower 3db point is 14Hz at 8 watts. There is no saturation at 10 Hz and 8 watts. The distortion is the same at 20 Hz as it is at 1KHz. However the high frequency response is NOT flat to 20KHz - 1db as claimed. I find that the response is 3.4 db down at 20 KHz at any power level. I was using the 8 ohm connection. There is a notch that is 40 db down. It is at 35 KHz, which is OK, but I have never seen a notch this deep before. These are the most inneficient transformers that I have tested. The amp makes 5.5 watts in triode mode and 8.5 in UL with the Hammond. I get 8 watts in triode and 11 in UL with the $18 Edcor. It must take a lot of energy to magnetize all that metal. All testing is with an EL-34 at about 450 volts.

In listening tests the bass was the best that I have heard with my small speakers, but the sound lacked that "sparkle" that is evident on all of the mid sized transformers (One Electron, Electra-Print, and Transcendar). The bass on these transformers sounded as good as the Hammonds, but my speakers don't make any sound below 60 Hz. Some saturation was visible on the scope at full power and low frequencies.

I have the big ($75) Edcors on order, and I really want to test them. The little ($18) ones are anazing for their size and cost.

Some of the test data is on my web site, but that page was written before I got the Hammonds. I will update it (or start a new one) after I have finished the testing.

The One Electrons, and Transcendars that I tested were 3K ohms. I put a 13 ohm load on them for the testing to provide a 5K load to the tube. If a 3K ohm load is OK for your application, the Transcendars available on Ebay are a great deal. I bought 20 of them for 300B amps. They sound like the One Electrons for 1/2 the cost.

http://www.tubelab.com/BudgetOPT.htm
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Old 14th July 2006, 03:53 AM   #9
awedio is offline awedio  United States
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I had read the VTV transformer test results, and I was following Tubelab's assessment of the cheap little Edcors early on.

Tubelab, I didn't know about your Xformer test write-up, that was just what I was looking for. I was only interested in the bigger Edcors, that is until I saw your tests on those $18 suckers. Very impressive! I now am very eager to hear about the bigger Edcors when you get them... I might consider buying them even before any reports from your bench.

Looks like Hammond is out for me: I didn't know of the James OPTs, and now I see they are fully potted and encased in my choice of Champagne or Black! I am such a sucker for this look, it seems many Japanese Xformer companies are too, that I may just have to get these at $100 each.

My aural senses never quite eclipsed my visual sense, and even tho I typically want the best sounding choice, I always weigh how something looks, too. The James OPTs seem promising from a performance perspective anyway, and the potted cases will match my potted power tranny. (powered potty training?)
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Old 14th July 2006, 04:35 AM   #10
rdf is offline rdf  Canada
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In my application (EL84SE) the James 6123HS is about 2 dB down at 20 Hz and 4-5 up at 70 kHz. Well worth the money.
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