GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Audio Discussions
In the Thread: Devid Berning amplifiers: the anti-trnsformers frenzy?

Post Subject: The Lamm and OPT core saturationPosted by morricab on: 10/2/2007

Merlin here is the Stereophile measurements on the Lamm ML2.1
http://stereophile.com/tubepoweramps/1004lamm/index4.html

As you can see the rise in distortion vs. frequency shows only a small rise in distortion even down to 10Hz. This is an indication that the transformer that Lamm selected is adequate for its job without saturation. To get a comparison of this look at this SET.

http://stereophile.com/tubepoweramps/304antique/index4.html

As you can see in Figures 9 and 10 the distortion in the bass is gross and will for sure lead to an opaque muddy mess in the bass. The Lamm is very similar to a SS amp in this regard.

Now look at a PP tube amp.

http://stereophile.com/tubepoweramps/807ar/index4.html

As you can see there is a marked increase in the bass distortion here as well, although it is still below 1% at the given power rating. This is a new PP tube amp design and has a marginally adequate OPT.

Here is another SET from Air Tight that has a good reputation but again somewhat flabby bass:
http://stereophile.com/tubepoweramps/687/index6.html

It is complicated to see but at 16 and 8 ohms the bass distortion rises dramatically at low freqs.

Now here is something quite different, a hybrid amp that measures like a good SET amp:
http://www.soundstagemagazine.com/measurements/monarchy_se160/

Finally a Lamm PP amp the ML1.1:
http://www.soundstagemagazine.com/measurements/lamm_ml11/
Note also that it has almost no distortion rise in the bass and it has very good bass control and definition.

Here is a KR Audio amp model VA340. It is a hybrid SET (tube output!!)
http://www.vi-fi.nl/assets/s2dmain.html?http://www.vi-fi.nl/xtrartikelen/testen/meetrapportkraudiova340/index.html

Note again only a slight rise in low freq distortion. This amp has bass control as good or better than top SS amps (more musical but very controlled). Note that the damping factor varies between about 5 and 7 and there is no neg feedback in this amp.

Rerurn to Romy the Cat's Site