Tri-Amping my TSCMs

[twistedcrankcammer]

I need a little help from everybody on suggestions for amplifiers for my aplication.

 

I already have my Nakamichi PA-7 Amplifiers and plan to use them on the Bass Bins of my TSCMs.

 

I need amplifier recomendations for the midranges, which are K-400 horns with 2 inch throats instead of 5/8 inch and have four K-55 drivers instead of one like a standard Klipschorn, so I need enough power to make 4 of these go to ear bleeding levels.

 

I need recomendations for a second amplifier to drive two K=77 compression drivers per horn lens.

 

I don't really have a preference for tubes or solid state, but will be going to an active crossover with time delays.

 

I plan to bend Roys ear on this if I can make it to the Pilgramige.

 

Let you oppinions fly and thanks in advance,  Roger

[Coytee]

If you are going to use an active, my guess is it will have XLR outputs.

 

I've been using Crown K2's with good luck (and good sound)

 

XLR input, gain controls on the front and....drumroll........  no fan noise!!

 

They do however, have a short power cord (literally, like 18 inches)  That is one reason I raised the outlets at each speaker to be just above the bass bin so I would not need an extension cord to plug them in at the traditional outlet height.  (I have them sitting on each bass bin)

 

Crown made the K1 and K2.  Both are available on ebay from time to time.

[John Warren]

22 hours ago, twistedcrankcammer said:

I need amplifier recomendations for the midranges, which are K-400 horns with 2 inch throats instead of 5/8 inch and have four K-55 drivers instead of one like a standard Klipschorn, so I need enough power to make 4 of these go to ear bleeding levels.

 

I need recomendations for a second amplifier to drive two K=77 compression drivers per horn lens.

 

Crown D45 or 75.  I picked up three D45s for $150.  Small, easy to manage, decent distortion numbers.  Some data here:

http://www.northreadingeng.com/Forums/viewtopic.php?f=8&t=9

http://www.northreadingeng.com/Forums/viewtopic.php?f=8&t=11

http://www.northreadingeng.com/Forums/viewtopic.php?f=8&t=16

[The Dude]

I second the Crown D45 and 75a. 

 

http://www.ebay.com/itm/Crown-D45-2-Channel-Stereo-Power-Amplifier-/182413079652?hash=item2a78aab464:g:CTQAAOSwie5XTLtw

 

http://www.ebay.com/itm/CROWN-D-75A-STEREO-POWER-AMP-EXCELLENT-PLEASE-READ-/222386828822?hash=item33c749b616:g:icYAAOSw5cNYY9Ug

[John Warren]

Looking at the D-series amplifier designs (and knowing something about how the amps are configured at the board level), it seems doable for example, to take a D45 (or 75) and, by modifying the error signal op amps to perform active filtering, one channel can provide the HF signal to the tweeter horn and the other channel can provide a MID signal to the midrange horn.  Level adjustments between the mid and HF units becomes a non-issue given each channel is on its on potentiometer.  Also D-series amps are compact packages and use balanced inputs which allows for the amplifier to be placed just about anywhere.   The bass horn can use it's own dedicated amplifier which needs to have some muscle anyway.

 

 

[John Warren]

Of the three D45s I bought, I use one for a headphone amp, the second I gave to my son and the third is going to be modified as follows.

 

Presuming one channel of the D45 is driving the tweeter and another driving the midrange of, say a Klipschorn, an active filter can be spliced between the front-end op-amp and the gain pot of each channel.   The front end op amp which performs the balanced to unbalanced signal function from the MC332079 package will act double duty as buffer for the input side of the filter. Both the HF and mid filter could be designed on a common PC board and be quite small.  There's enough room to get it in there too.  If I used  a pair of quad packages (AD713s?) it's straightforward to develop a tweeter high pass and midrange bandpass filters with 24dB/octave attenuation rates.  Since I already have a full SPICE model of the entire amplifier, integrating the quad amps is a piece of cake (takes about 15min to run on a Core I7 machine under Windows 10 Pro)  

 

So, from the simulator, the plot below is the output voltage of the D45 measured at the 7 Ohm load resistor across CH1 (pink) and 13 Ohm load resistor across CH2 (red).  The composite signal (green) assumes the drivers share a common acoustic center which, of course, is impossible but L needed to start somewhere.  The tweeter filter is a simple cascaded Sallen-Key which leaves two op-amps from the tweeter quad package free for other things.  The mid utilizes the entire second package and also uses cascaded Sallen-Keys for both the low and high pass sections of the filter.  I've selected the mid-tweeter crossover to be 4300Hz.    The filters are placed between the front end op amp and the gain pot with each pot set at max output (hence the 20dB output signals).  The source impedance is 500 Ohms. 

 

Need to design the board which should take a day or so.  I'll try to fit the whole thing on something the size of a business card.