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

[AquaTarkus]

And I've always heard and assumed that more iron=better frequency response, esp. in the bass.

Yes, that's generally true for bass. For high frequencies, winding patterns are much more critical. With the more interleave the better, generally.

That said I also built an amp using Hammond 125ESEs which Hammond does not promote as a "hifi" OPT. They also sound very good.

I've used those very successfully in guitar amps with EL34, 6L6 or 6V6 power tubes, where they provide a big robust sound, but never thought of using them for hifi.

 

[tubemax]

Hi,

Old post but just discovered new data for 125ESE on Hammond site:

https://www.hammfg.com/files/parts/pdf/125ESE.pdf

Finally some official measurements from Hammond!

 

[Schmitz77]

To build a cheap and heavy output transformer is not the most difficult task.
Transformer core lamms in low quality are very cheap. That will give plenty of low freq. response but quality of design is to be taken in consideration.

 

[tubemax]

Hi Schmitz77,

You are right on all accounts, with budget transformers there is no expectation of supreme linearity, low distortion etc... but they are fine for what they cost.

My experience was love/hate with Hammond, I had a amp with Hammond 125D PP output - tiny transformer with respectable sound, good extension in highs - moderate lows but interesting - very acceptable mid-range quality. I could listen all day long - just musical.

later I upgraded the same amp to Hammond 1608 PP and while the bass was very extended I was truly disappointed with mid-high range - kind of plastic sounding and limited treble response.

Many years later also tried Edcor SE GSX-10Watt 5KOhm with EL84 and while good sounding output - still suffers from similar compromise just as better Hammond in my previous amp.

So, I foolishly sold both amps - kind of tired of "upgrades" within my budget limit.

 

[FullRangeMan]

Hi,

Old post but just discovered new data for 125ESE on Hammond site:

https://www.hammfg.com/files/parts/pdf/125ESE.pdf

Finally some official measurements from Hammond!

Thanks for posting it, very interesting.
These Hammond graphics goes only to 50kHz not the usual 100kHz, they are useful for hi-fi evaluation purposes ?

Why its not rec for hi-fi use by the manufacturer?
Designed for general purpose or replacement use (not Hi-Fi),

This trafo could be suited to Headphone amp use?
Primary impedance range from 2,500 to 10,000 Ohms.
Secondary impedance range from 4 to 32 Ohms.
(amp are EL34/KT66 SET to HifiMan 32 Ohms 90dB)

 

[Depanatoru]

Frequency response: 100 Hz. - 15 Khz at full rated power . Good for some AM radios restauration .
So low inductance and poor interleaving for high frequency .

And the graphs are misleading , 0dbm = 0,001W , useless to draw meaningful conclusions

 

[Schmitz77]

Good examples

 

[tubemax]

All true,

Measurement on that low level is not realistic, inductance on 1Khz is also not useful - I would say based on experience that is at least double that value on 100Hz - if not more.
Yet - it does not stop companies to use this transformer in their final product.

One example: Single Ended Stereo Amp Kit - Hi-Fi Tube Amps, Current Models - Specimen Audio

 

[audiowize]

Oof, a 6SL7 driving a triode strapped 6L6! So close to 30dB of gain for a 5W amp.

 

[mondogenerator]

Doesnt it say EL34?

EDIT:

BOM states EL34, schematic shows 6L6G.

 

[audiowize]

I looked at the schematic in the manual.

 

[w5jag]

I have a pair of 125ESE here - about a dozen years old.

I used one of those Mega 328 component tester things to look at the inductance, and got 11.5H on one, and 13H on the other. For whatever that is worth.

I measured the frequency response at one watt in an actual amplifier, and it seems like it was a bit better than spec at the low end, and on the high end began a gentle roll off at 6 KHz, and was down about -1 dB at 15 KHz. I thought they did pretty well on two tone SMPTE IMD. The measurements are on here somewhere, don't feel like searching for them.

I measured primary resistance at 91R on one, and 92R on the other.