Dyan 400's Huge Transformer vs. New Amps?

[Mike Gibson]

How about a little less I'm right/you're wrong and more open discussion in this thread please. Thanks folks.

Mike

 

[oldflame]

Thanks for the good answers and different valid points regarding audio reproduction.

That large power transformer probably allowed the Dyna 400 to be successfully used for professional sound reproduction, as were a few other "monster amps" of the day. In the Dyna's case, I think using only four Darlington's per side was a more limiting factor for continuous high-power use. A cooling fan was necessary even with its 8# heat sink.

 

[onanysunday]

The transformer on my Dynaco ST-410 was probably the biggest I've seen.

 

[Lavane]

if we're talking AB, yes. I was interpreting "modern" to mean things that aren't AB amps. Class D for example is a lot more efficient so less power supply is needed for the same output power.

Even if you did an AB amp with a switch mode supply the transformer would be an awful lot smaller even for the same power supply voltage and current capability. Higher frequency switching needs much less iron.

I have a Crown CDi-1000 pro power amp I use in my garage system. It's a hybrid. It has a SMPS powering a Class D type amplifier pushing a decrete output section with a big bank of TO-3 output transistors on a huge heat sink with a fan. I can pick the thing up easily with two fingers by the rack mounting ears. Its the smallest in the CDi series. 275wpc into 8 ohms, 500wpc into 4 ohms, and 700wpc into 2 ohms all at .5% distortion. Bridged into 4 ohms is 1,400 watts @ 1% distortion. The power supply and Class D type front end are very well filtered too. I had three of these. I set one up bridged into a 15" bass guitar speaker cab as a practice combo amp for a bass player. He really likes it and I've even seen him use it at a local club with one of the bands he plays in.
These are pretty ruggedly built too.

 

[Lavane]

The better modern built power amplifiers are more efficient compared to the vintage stuff. There is a some great sounding well built equipment being produced now. My only real gripe is modern equipment thats full of SMD's. It just makes the equipment more difficult to repair. There are brands that still use all or mostly decrete parts though. A modern Marantz power amp I borrowed for a bit only had one small very small PCB with with a few solder mask devices on it. The rest of the amp was all through hole descrete parts.

 

[curtisw99]

IIRC the old Dyna's power transformer had ~twice the capacity of many new high-end amplifiers of similar ratings. OTOH it's filter caps were small in comparison to newer amps. Yet again, many amplifiers don't double their power into 4 ohms as the Dynaco did (provided adequate ventilation).

Considering operating efficiency, maybe Dyna's 1360 watt transformer was right-sized for continuous output. Are modern solid state amps of 200wpc @ 8 ohms properly powered with 600 watt transformers?

Older transformers had to use paper for insulation. That made up a lot of the bulk.

 

[oldflame]

That's true and better wire insulation, laminating/metallurgy, and maybe improved winding techniques also should help new transformers to be smaller. I was actually referring to the rated watts though.