From: info@turneraudio.com.au   
      
   Hi Patrick,   
   don't laugh - I deleted some lines about those old ampegs and the   
   Baxandall... Did I really delete them? =:o   
      
   the components I'd consider to measure and clone ain't the pots, but the   
   caps, the slope resistor and the cathode caps (them throughout the whole   
   amp). It's the whole system - not just the tone stack. Differnces might   
   be subtle. You are dealing with - humans - worse: artisans   
      
   For me the speakers themselves don't need to be "old". IMHO the   
   particular OEM-Emi in the DRRI is simply a piece of shit. It does not do   
   any justice to the capabiliies of the amp.   
   New speakers ain't generally bad. You've got a hunch of choices   
   nowadays. IMHO there are some Speakers to consider with a DR:   
   EMI RedFang,   
   Celestion Alnico Blue,   
   Jensen Electric Lightning,   
   the WGS Blackhawk,   
   Celestion G12-65;   
   EV-12L   
   et al   
      
   It's simply a matter of taste.... Myself, still opinionated, that   
   "better" is not always necessarily "BETTER"..... But I have to confess:   
   I'm a convinced player of an old 5E3 Deluxe Repro with an 12" Alnico   
   Blue RI - far away from technically perfect, but a real fun machine ;-)   
      
   regards   
      
   Jochen    
      
   Well, I guess I should leave all that you said alone because probably it makes   
   a lot of sense to the muso brigade.    
      
   BUT, I had a look at a few Ampeg pre-amps and they all have just bass and   
   treble and no mid to make a big dip at around 400Hz. The tone "stacks" are NOT   
   stacks as such but are stock standard Baxandal which give the widest possible   
   range of bass and    
   treble variation. Pots are 1M so network RL is all high enough ohm load to be   
   driven by piss-week 12AX7 anode power. I'm not going to put in 1M pots to   
   replace what's there but will stay with 260k pots and try for a Marshal type   
   of Mid dipper pot and C.    
   But I'll put a follower in to drive the tone network which will better   
   preserve gain, and give the wanted curves with highest possible slope.   
      
   I downloaded a Tina90-TLen program for simulations of R&C networks and much   
   more. It took an hour to learn how to use it, and its clumsy and slow and you   
   have to keep closing pages and re-opening and starting new ones to see what   
   changing C or R    
   properties does to response. But the response of what I measured yesterday   
   were exactly reproduced so I have faith that it works OK to simulate such   
   things.   
      
   BUT, Suppose I tried to draw a response line I wanted, then enter an order for   
   program to tell me what R&C to use, the program would be quite useless at   
   telling me what R&C I should use to get that specified response.   
   As soon as one expects the PC to act like a human, its fucked. Like, OK, we   
   want passive, no extra tubes or NFB & PFB loops, and we want it NOW, and no   
   more than 20dB insertion loss, and whatever it thinks up must be as close as   
   it can get to the wanted    
   curve. Hmm, I reckon I can guestimate faster than involving a dopey 3rd party.    
   Its not hard for humans to think up stuff that a PC cannot answer.   
           
      
   So, I have a bit more trial and error of pot values and C values to use to try   
   to create an adjustable 400Hz dip, so that the tone control can give the same   
   response as the good sounding amp - but with a lot more to play with.   
      
   Are the people on the nearest planet to us outside the Solar System purple,   
   with yellow stripes?    
   Nah, PC and Google is useless.   
      
   Patrick Turner.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)