• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Why are Hammond SE OPTs dissed? Heavier than the competition...

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
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.
 
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."

Fun With Tubes

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.
 
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/funwithtubes/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.

-e
 
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.
 
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
 
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.
 
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
 
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?)
 
From what Iv'e heard,they are a great value for the money.
They also appear to rate them a little conservatively..

An example Dogzilla

Scroll 3/4 the way down to "(November, 2002) - Some updates"
Granted,that is for guitar use,not Hi-Fi. Still pretty impressive though.

The Edcor's look like a pretty good piece of iron for the money also.
I guess we'll see how they compare. So far Tubelab's (and others) experiments with them seem promising. ;)
 
When comparatively testing transformers the raw frequency response numbers can be misleading. Many of the small transformers (Edcor, and Hammond 125CSE) can post good frequency response down into the lower audio range (below 30 Hz) even at considerable audio power. This is because the analyzer does not measure distortion, only amplitude information. Most of the little guys will show signs of saturation below 100 Hz at full power. Transformer saturation sounds gross and even a small amount will make you turn down the volume.

All of the mid sized (One Electron, Transcendar, Electra-Print) are capable of 10 watt bass notes down in the 20 to 40 Hz region without saturating. In my case the amp clips before the transformer saturates. This is a far better sounding scenario.

I will test the saturation effects when I have all of the transformers. Still waiting on the Edcors.
 
Leben of Japan uses Hammond OT and power transformers. "A Special and high capacity power Transformer produced by HAMMOND(Canada)," it says on the website.

Maybe it's like one here said. Hammond has the competence but doesn't give a damn. Or, at least, not enough.
 
Hammond 1627 SE OPT

Hi Guys,

I am wondering why no one say any good about the 1627 SE OPT. My friend and I both built the 2A3 mono blocs with this OPT with good sounding.

We just love to listen the music with the amp.

BTW, I also have the 1628SE OPT that in the 45 tube amp. Even though there a dip at 13kHz, it sound very good indeed.

I have compared it with James 6123 and Plitron 3035 OPT's. The bass of Hammond is more strong and solid. Hammond only looses the extensions in the very high frequencies.

Lastly, I would say Hammond is really worth for the money you pay.


Johnny
 
Johnny,

I would love to hear more about your impressions of the Plitron 3035SE. I am very curious about these toroidal OPTs and I would love to try them when I can scrape up enough cash.

Right now, I am wary of Hammond because it seems that they are not very efficient. Here is a test that shows the Hammond has very high primary DCR (copper losses).

http://www.sacthailand.com/transformerTest1.html

That is enough to turn me off...
 
Remember there are a few more things than meet the eye,

1/ there are at least 2 lf points on an output tx,

the small signal, is the one they all quote, as its misleading, this is equal to the plate impedance in parallel with the tranny primary, you get around 600 ohms for a 300b.

Xl=2 x pi x f x L

where xl is the 600 ohms, for that all trannys go down to at least 12 hz

2/ the large signal, which is approx. the impedance of the primary, and gives around 50 hz for a poor transformer, this is for full power output.

you will also get less bass distortion.

3/ the ac saturation point, dependant upon freq, no. of turns, ac flux density, area of core, applied volts

4/ dc saturation, dependant on dc current, no of turns, area of core, magnetic path length.

more henries in the tranny gives

1/ less distortion (core saturation)
2/ less phase shift, this reaches well into 100 hz.
3/ lower freq. response.

look for at least 8 henries per 1000 ohms.

that's about 90% of what you need to know. It took me years to work that out with some help from the web.

I have had a good few transformers,

hammonds,
3 kinds of chinese, much of a muchness
silk, superb.
james, good, too.

Hammonds were excellent, great build quality, and sound? fine, really good, I woudln't think twice.

remember what is measured doesn't always correlate to what is heard, the hammonds were a good improvement, and lovely and heavy.

highly recommended. they were all acceptble: just judge them on the sound, and the hammonds are fine.

its snobbery, pure and simple

There are 3 or more components to a s e tranny

a/ iron core, is it EI, toroid, R core, C core....

b/ core geometry ie layers and configuration

fatter wire gives less resistance and losses, less heating, too. takes up more winding room

wire insulation, too. remember as secondaries carry more current, they have fatter guage wire.

c/ insulation, paper or plastics, polyester, mylar, all that, similar to capacitors really.

d/ air gap piece of paper.

Its all one big balancing act. fatter wire, less DCR, less copper loss, less room for turns which gives inducance, more inducance, more DCR, and turns, and lowers distortion, but more capacitance, bigger core needed raising capacitance....etc....

inductance is dependant on iron, coil, and gap. that's the low end

A very good way of judging is to see the care in the stacking, ie how well the lams. are put together, and of course, weight.

in the immortal words of langford-smith, bigger core always wins ( caveat, if they know what they are doing with coil and gap), having said that, the small cored 2kg chinese ones sounded ok to me.
 
I do understand the potential for "iron snobbery".

However, I think that folks would back up and support a company like Hammond if they were at least consistent. Like rooting for the Yankees or something... Hammond has been around forever and many of us would love to support a North American company.

Unfortunately, problems like the infamous 13kHz dip seem well documented, and fit&finish is apparently questionable or inconsisitent. So it is beginning to appear to me that Hammond is not getting rained on for no good reason, but is actually putting its own reputation at stake through its products.

I don't expect sonic perfection for $100. But nor do I expect 4-5dB dips in the frequency response anywhere NEAR the traditional 20-20kHz audio band. Even if they have fixed the problem, I am unwilling to find out for myself.

Between the Edcors, OneElectrons and James, I am leaning towards the James -- if only they too were made in the USA, I wouldn't even think twice.
 
Anyway, lt cdr data, thanks much for the groovy treatise on SE OPT specs and design considerations. As with nearly everything in audio, it's all about compromises.

One more reason I am currently enchanted with the James transformers is the multi-tap Primaries along with multi'tap secondaries. This would give me a lot of flexibility in (re-)using the OPTs for various tubes, projects. Not to mention some more tweaky foolin' around. As it stands, I am looking to try both a 5881 SET as well as a 300B design. I was going to go with a 5K primary, but it would be great to have the extra choices (plus a UL screen tap!) with the James.
 
lt cdr data said:

Hammonds were excellent, great build quality, and sound? fine, really good, I woudln't think twice.

remember what is measured doesn't always correlate to what is heard, the hammonds were a good improvement, and lovely and heavy.

highly recommended. they were all acceptble: just judge them on the sound, and the hammonds are fine.

At least as regards the 1628SE vs. 6123HS, the Hammond had far inferior finish, measured much worse up top and didn't sound as good as the James. I'll grant one thing, the HF notch appeared to tame the ubiqitous sibilance of some of my early circuits.


its snobbery, pure and simple

I'm as Canadian as Hammond and have worked with their product for near a quarter century now. In terms of quality control it's no longer the same company.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.