Powerful bass

[Elso Kwak]

Hi DJK,
As I am a happy owner of a GAS ApzillaII too I am eager to respond.
What makes the good sound and bass slamm is <B>THE</B> subject of this forum.
I can add that the old Ampzilla of mine outbeats the latest Krell 700 with 1 square meter floor space. I say floor as I can't even lift <B>ONE</B> of these monsters. This was my experience at my friends house using Wilsons Grand Slamm. I am not quite sure what makes the difference. I suspect it has to do with ample drive to the outputtransistors. I added some 2x10000µF to the powersupply but that did not make much of a difference.
Some 20 years back I had a interesting experience after selling a pair of Klipsh Heresy spaekers and a amplifier. The customer had already overrun his budget by choosing the Klipsch and asked me if it was OK using his old two times 15 watt receiver as a FM-tuner. The only problem was the cheap receiver did not have recoutputs so we connected the speaker outputs to the tuner inputs of the amplfier (easy to do as the old receiver used cinch for speakeroutputs)
The customer and I me were stunned by the good audioquality from this configuration especially the power and bass-slamm.
Also there once excisted a Krell preamp KRS1 that used a outputstage that more looked like a small poweramp. Again the power level of the sound striked me in comparison with he MarkLevinson JC-2 I owned at the time....
Did you see my mods for the Ampzilla on
http://groups.yahoo.com/group/SAE_Talk/message/2660 ?
I was burned to the the bone by the designer Mr. James Bongiorno.

[djk]

So Bongo burned you at the stake, huh? No one could ever say James was unbalanced, he has a chip on each shoulder. James has always used polarized elecrolytics in the signal path, and inexpensive ceramics elsewhere. Doesn't seem to have a clue about servo 'feed through' either. I would like to continue this later, compare notes, right now I really need to get some sleep.

[BrianEno]

Originally posted by djk
" I should have mentioned that I add power supply bypass caps to every amplifier I get, and film bypass to all the coupling caps in the signal path. An Ampzilla/Dynaco 400/SAE 2400 with these mods will have tighter bass and more slam than an unmodified Mark Levinson ML3 with its 20 parallel TO3 outputs per channel. The ML3 after my mods had more control and slam than the Rowland 7, which has a regulated front end and 32 TO3. per channel.

and

The ML3 was another amp that totally changed in character from just a few 'trivial' cap upgrades.]

This is a reply from a very old thread.
I have two ML-3's (very old ones 0107 & 0324), one with a biascircuit in one channel which did not fire up when I switch the amplifier on. Discoverd that one of the drivertransistors: 2N3585 only worked well when heated or cooled down with coolingspray. I soldered it through and fastened the base and it works for now at least.
This oldest one has been upgraded from the 18.000 uF silver Callins to 56.000 uF blue Sprague powerlytics nad has been serviced/refurbished by Madrigal in 1995, all transistors etc.. complete bag full of components that were replaced. New relays and two black boxes connected with the line (white cables) connection with the AirPax rockerswitch attached to the frontplate. Are they linefilters? The Avel Lindbergh toroids hum anyway.

The other one smokes the Dale limiting inrushcurrent resistors. The white Guardian relay doesn't release it's connection so that the current keeps flowing through the resistors till it burns.
Could not solve that problem yet. Maybe a connected condensator?

Ordered 10 Dale's 15 ohm 50 watts, 2 Airpax rockerswitches and three Guardian relays probablt for nothing the last two items.

I'm interested in the mods you performed with your ML-3 if you still posses it. And maybe you can relate to some of my questions.

Thanks in advance

[Don S]

After reading all of this thread I think I have something to add. I have either had or listened to a lot of upper end amps, and my conclusions are as follows. Outputs that are not bridged have slightly more bass slam, control is about equal. Power supplies are the largest factor. My conclusion is the DC resistance is a major factor. You can lower the AC impedance with caps but the DC is controlled by the amperage capability (output resistance) of the transformer. Output stage capability is also important as is the driver stages ability to control the outputs. Possibly from a subjective viewpoint, how the amp is controlled or rolled of in the bass may be another large factor. Good reliable performance without servos seem's most consistent. Servos either control too much or too little most of the time.

Just remember there are exceptions to every rule!

However if you have a weak PS you are not going anywhere.

Don