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PostPosted: Sat, Sep 15, 2018 12:16pm 
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Hack

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A meta question spawned from amp garage and honestly, I thought, why not ask the man himself?

Let's pretend for a moment that Friedman actually came out with a preamp from the JJ series, that was ripped straight out of the head. And then we took out the power amp section to turn it into a slave ala Marshall 9000 style.

If we go from the pre-amp out to the power-amp in, this is, to my understanding, not the same as the actual preamp and poweramp coupling as a head. And that "hitting the power amp up front" is part of what creates the sound and feel of a hotrodded head.

So the meta question is then, can a rack setup ever be as good as a head? Even if we use the actual pre and power sections?

E.g. The recto pre + a 2:100, what special requirements are there for this combo to bridge the gap between rack gear and a head in two parts?

Is a simple line level boost from an FX out\pre-out enough to hit the power amp properly to simulate the hot coupling of a head? Or is this already factored in and innate to rack gear (i.e. Preamps assume power amps want a hot signal that is slightly boosted over line)

I could be COMPLETELY off the mark here :lol: :LOL:


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PostPosted: Sun, Sep 16, 2018 12:40am 
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Just my opinion, but I think that separates can sound like a head. Just maybe not quite identical to a specific make/model/year of a specific head.

To get separates to sound like an exact head, both the pre-amp unit and the power amp unit would have to be identical to the head. The connection between the two must be at the same place in the circuit and at the same voltage level. It would be best if the power supply was also separated out to a third unit, primarily because there are fluctuations in the power supply due to load on one component reducing the available current to another component. At that point, the only difference would be the cabling required to connect everything, or basically, there'd be more of it just because it has to go farther between components than it does in a single head shell, as well as any differences that would bring into play (and there would be some differences there).

The other side is that, with separates, you can mix and match. Want a Boogie Mark pre with a Marshall power amp? Easy. Many, many, many combinations are possible using separates that are not available as a single head, outside of a completely custom build (and the possibility of infringement on multiple patents, where applicable). Of importance here is that some components are made to be just preamps or power amps. Some are made to be able to do your dishes and clean up after your cat. Some can be really good doing both, but my personal favorite preamps don't have a lot of bells and whistles. They're just a preamp. Same goes with power amps, but I haven't seen a lot of those that try to incorporate a full-fledged digital multi-effects processor as well (while I have seen a lot of preamps do this).

I look at them as different, but equally valid choices. YMMV, of course. For me, the bottom line is that, if it sounds good to me, if it inspires me to play beyond my normal boundaries, then it's good, regardless of what box or combination of boxes it happens to be in.

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PostPosted: Sun, Sep 16, 2018 8:19am 
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To me the difference is in the feel because voltage demands of the power amp don’t effect the preamp voltage. Seems that synergistic dynamic is the key.

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PostPosted: Sun, Sep 16, 2018 12:52pm 
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Well if identical it would be very close. The only difference is the sag the amp would have if pushed.. the preamp voltage would follow to some extent. Now if you are not playing really loud the amp will not sag at all so then it would be the same.

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PostPosted: Sun, Sep 16, 2018 5:44pm 
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Hack

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Ahh, so to avoid this issue you manually control the power amp level and preamp levels. So they can sound essentially identical but lack the "synergy" or essentially linear control that they have when paired. Got it. Thanks man!


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PostPosted: Mon, Sep 17, 2018 8:43am 
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Nickerz, Think of it this way. Take the JJ100 amp that you mentioned for example. The send from the loop IS the output from the preamp, The return from the loop IS the input to the power amp, this rings especially true because on the JJ the loop is always on (many amps you can bypass the loop)

You could physically split the amp pre, power sections, and provided you had a power supply for both sides, you would have a discrete preamp, and a power amp.

The only difference when you have the pre, and power section together in a head IS they share a power supply. There is a possible tonal phenomenon that occurs, and Dave pointed it out very well. If you have the power amp cranking it will/can introduce sag, drop in voltage on the dc B+ power, the preamp will see this sag, and it will sound, feel different.

Bare in mind too, this effect mitigated by some modern amps by adding more filter/reservoir capacitance, and beefier power transformers. So you'll have this effect mostly on vintage amps, and or modern amps that are based on vintage amps. Many of the amps Dave makes are based on vintage filtering.


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