Wish Soldano Hot Rod (schematics included)

[sixtystring]

I've been researching Silverchair's huge post-Frogstomp tone recently and found that they used Soldano Hot Rods. Not sure how different these are from the other Soldano models or other "hot rodded" amps for that matter.

There's also video from back in the day where Leon mentions the HR-50+ is one of his favorite amps...

Below are some schematics I found:

 

[sixtystring]

Not sure if it's helpful, but I also found some shots of a HR-100+ circuit board.

 

[Corinthian]

The HR is reported to have the same circuit as the SLO; the only difference being the DeYoung transformer in the SLO. That said I have a Hot Rod 50 and it's definitely a different sound.

 

[State of Epicicity]

+1

 

[normanaj]

I havent spent much time in the wish side of the forum but i must admit....there has been some great requests in the past few weeks.
+1 on this one.

 

[sixtystring]

The HR is reported to have the same circuit as the SLO; the only difference being the DeYoung transformer in the SLO. That said I have a Hot Rod 50 and it's definitely a different sound.

Do you know the transformer that the Hot Rod uses? And is there a way to approximate the differences using the XFORMER (or other) parameters in the amp block?

@2112 I believe still has a Hot Rod, so maybe he can chime in on whether or not this is "different" enough to warrant a new model vs. tweaking an existing.

 

[jaycal6]

+1

 

[Corinthian]

Do you know the transformer that the Hot Rod uses? And is there a way to approximate the differences using the XFORMER (or other) parameters in the amp block?

@2112 I believe still has a Hot Rod, so maybe he can chime in on whether or not this is "different" enough to warrant a new model vs. tweaking an existing.

It seems they have changed a few times. Mercury Magnetics at some point, O'netics too I think. I don't know how they differ from each other or the DeYoungs though.

 

[FractalAudio]

Transformers don't make that much difference (despite internet opinions and myths to the contrary), especially with amps that derive most of their distortion from the preamp (i.e. MV amps).

A different resistor value or pot taper makes a much bigger difference. Looking at the schematic I have (which is different than above) a couple things jump out:

• The input treble peaker is different. There's a 1M || 470p on the HR50. On an SLO100 it's 470K || 2.2n.
• On the HR50 the gain pot is 1M. On the SLO it's 500K. The bright caps are also different but their roughly the same from an impedance standpoint.
• The grid stopper on the second stage is 220K vs. 470K.

There's a few other values that are different as well.

These things change the voicing of the amp considerably and much more than a different transformer would. Modern transformers are very flat in their response and really don't make that much difference. This isn't to say they don't make any difference, it's just not all that pronounced.

However, the topology of the HR50 is pretty much the same and you should be able to tweak an SLO to get a very similar sound. Or try one of the X88 or X99 models.

 

[Dave Merrill]

@FractalAudio can you say what you'd do in advanced parameters to emulate the component differences you noted? My tube circuit knowledge is insufficient

 

[sixtystring]

Transformers don't make that much difference (despite internet opinions and myths to the contrary), especially with amps that derive most of their distortion from the preamp (i.e. MV amps).

A different resistor value or pot taper makes a much bigger difference. Looking at the schematic I have (which is different than above) a couple things jump out:

• The input treble peaker is different. There's a 1M || 470p on the HR50. On an SLO100 it's 470K || 2.2n.
• On the HR50 the gain pot is 1M. On the SLO it's 500K. The bright caps are also different but their roughly the same from an impedance standpoint.
• The grid stopper on the second stage is 220K vs. 470K.

There's a few other values that are different as well.

These things change the voicing of the amp considerably and much more than a different transformer would. Modern transformers are very flat in their response and really don't make that much difference. This isn't to say they don't make any difference, it's just not all that pronounced.

However, the topology of the HR50 is pretty much the same and you should be able to tweak an SLO to get a very similar sound. Or try one of the X88 or X99 models.

Appreciate the insight, thanks!