Why two amps from the same maker of the same model sound different

[myles_rose]

This was in response to a post that asked why two different amps from the same maker of the same model sounded different. This was my response.

 

It is much less likely today than in the past. Today, 5% resistors and precision caps are much more common and not as expensive as in the 50s and 60s. The amps of those eras had wide variations in parts. Look at the B+ voltage of 5 Marhall 100 watters of the 60s, and the voltage can range anywhere from the low 400' to 600 volts.

 

Today there is more consistancy, and whether or not you are a fan of PCBs (printed circuit boards), the fact remains that PCB's are more consistant, have trace runs that have been optimized for being quiet on CAD equipment, and they do not absorb moisture like tag board used in the 50s and 60s is prone to do.

 

A good circuit design implemented with proper mechanical design and assembly, will sound good and be reliable. Try to listen, for the most part, and don't get too caught up in dialogue.

 

Marhall and Fender both made amps of wide variation. That is why the same amps of the same model and year sound different. They did the best they could at the time, and stayed in business, which was their main concern (and there is no problem with that).

 

Today you have amps such as Carr Amps ... hand wired, point to point, with all the finest components available. They are fantastic amplifiers, frankly ... magic. Then you have amps such as Rivera and Bogner ... with mil grade epoxy PCBs .... great design and construction, and also wonderful amps. The comes along another thought ... Matchless ... a update of a timeless classic which exceeded the orignal in many ways, and you do not need to disassemble the entire amp to change tubes either. The Ashdown Pacemaker series of heads ... well, if you ever saw an original Hiwatt with its mil-spec constuction, Ashdown takes this even further, right to full British mil-spec for aircraft. Lets not forget THD ... with circuit boards made out of the best glass layup I have ever seen (and I used to build sailboats out of composite materials) ... his boards are four times thicker than need be ... his etch work is so thick that a grinder is needed to cut a trace, its all teflon wire and silver solder.

 

Those are some of the classics of today, but unlike their brothers of the past, they will sound the same when you pass them down to your grandkids, unlike the Fender and Marshall amps of my generation.

 

Regards

[strat0124]

I know exactly what you're talking about....there were some inconsistent amps back in the day, and alot of blue smoke I recall......in fact I think I blew up at least a half dozen amps before I turned 21. Think Texas...sweltering heat....and hot tube powered amps, peeling paint for the snuff queens and drunks.....

[myles_rose]

Originally posted by strat0124:

I know exactly what you're talking about....there were some inconsistent amps back in the day, and alot of blue smoke I recall......in fact I think I blew up at least a half dozen amps before I turned 21. Think Texas...sweltering heat....and hot tube powered amps, peeling paint for the snuff queens and drunks.....

 

I think the amps that I had the most trouble keeping up an running were Vox AC-30's back then. They produce HEAT HEAT HEAT, were not too big on venting and airflow, their output tubes are buried in the center of the amp, and being a class A amp, they run just as hot at idle as they do at full tilt.

 

There was also one paticular Marshall 1959 (100 watter), that had 580 volts on the plates that had to be shut down every 30 minutes or it would loose output tubes.

 

Regards