My take on Eric Johnson's Steel String Singer #005

[talbany]

I believe the added low end is mainly due to the Direct coupled cathode follower driver. By eliminating a capacitor feeding the grids,the result is wider bandwidth, deeper bass (Lower lows/higher highs)

Tony

[rootz]

I suspect a big part of the low end issue people have with this amp is going to be very low amount of NFB - therein lies the rub though, as you change the dynamic character of the amp. JM2C.

I think you are right. The impedance peak around the resonance frequency of the speaker will be pronounced. Less feedback -> more peak. That is also true for the high end. This explains why the 005 is scooped sounding too.

Also do not use a 500k bass pot. I think the photo of an early Amplified Nation SSS005 has the pot values right. They are written on the chassis of that amp.

Other than that, I use this amp with higher settings on the high filter. There are some demo’s of the AN 005 by RJ on YouTube. Look at his settings: high filter on 5, low filter off or on 1.

[beasleybodyshop]

I suspect a big part of the low end issue people have with this amp is going to be very low amount of NFB - therein lies the rub though, as you change the dynamic character of the amp. JM2C.

I think you are right. The impedance peak around the resonance frequency of the speaker will be pronounced. Less feedback -> more peak. That is also true for the high end. This explains why the 005 is scooped sounding too.

Also do not use a 500k bass pot. I think the photo of an early Amplified Nation SSS005 has the pot values right. They are written on the chassis of that amp.

Other than that, I use this amp with higher settings on the high filter. There are some demo’s of the AN 005 by RJ on YouTube. Look at his settings: high filter on 5, low filter off or on 1.

Are you using a 250KA pot?

[rootz]

Yes, I use typical classic tone stack values with 10n mid cap and 150k slope resistor. You can see those pot values in a picture a bit earlier in the thread.

I have this amp with 4x6V6. I corrected the gnfb accordingly and wired the 220k resistor to the 16r tap of the OT. Could have used the 8r with something like a 150k resistor for gnfb too.

Low end is under control now.

I sincerely thank everyone who contributed: without you my 005 would not even exist. Big thanks!

[beasleybodyshop]

Might be worth consolidating information (voltages, etc) and making a sticky?

Sure, it's not 100% accurate but seems like a growing number of folks are having successful builds. If anything my message inbox is a indicator of this haha!

[beasleybodyshop]

So I got curious and looked at the schematic for the Peavey Roadmaster - the iron of which allegedly went into SSS#5 or is similar. Interestingly enough it uses a 100K GNFB resistor and a post PI driver (albeit a different one):

Also the Peavey VT120 uses a similar setup albeit no CF driver. Just food for thought.

[Roe]

It's doubtful that the Peavey 120w transformers were used in 150w SSSs

[beasleybodyshop]

Then it would have to be the Roadmaster iron then - thats the only other thing Peavey made that could produce that kind of power. It does use a post PI driver circuit as well

[beasleybodyshop]

FWIW I can confirm 170-180vDC on the plates of V1. That seems to be correct.

[beasleybodyshop]

IMG_20220226_002703130.jpg

IMG_20220226_002724062.jpg

IMG_20220226_002747478.jpg

I've been making progress on this one if anyone was curious.

[Roe]

Then it would have to be the Roadmaster iron then - thats the only other thing Peavey made that could produce that kind of power. It does use a post PI driver circuit as well

It seems that the 150w models used Sunn/dynaco iron instead. Cf. https://ampgarage.com/forum/viewtopic.p ... co#p435423

[martin manning]

I've been making progress on this one if anyone was curious.

It's looking good! I was wondering what happened to this project. You must be getting close to applying power?

[beasleybodyshop]

I've been making progress on this one if anyone was curious.

It's looking good! I was wondering what happened to this project. You must be getting close to applying power?

I am Martin! Thanks for all your help along the way.

Also, I sent you a message on FB messenger. I dunno if you check that anymore.

[rootz]

The past months I've been working on and off on the 005. Every time I work on the amp, I get a bit closer to what I like to hear from the amp. One thing that puzzled me all this time, was the fact that people reviewing the Hi Plains Drifter state that the filters are pretty subtle. I do recognise that when it comes to the low filter. Subtle steps adding a bit of bass every notch you go higher. The high filter is a very different matter on my amp and does not seem to behave as expected: not subtle and get harsh in the mids/high mids from the 3 step up. Not at all like I hear from Steel String Sultan/SSS/HPD vids. Those amps all seem to behave well even with the high filter on the 4th or 5th notch.

Does anyone recognise that this amp 'need' a different cap selection for the high filter than e.g. SSS002?

The added simulation shows the effect of a more subtle high filter (green) compared to the values I use at present (red): no more enormous presence and high mid boost with lower values.

Even with an aggressive high filter, this amp is still a joy to play on lower filter settings. High end is very clear and present, low end is tight but big. Great amp for fans of big clean sounds if you ask me.

[Guy77]

The past months I've been working on and off on the 005. Every time I work on the amp, I get a bit closer to what I like to hear from the amp. One thing that puzzled me all this time, was the fact that people reviewing the Hi Plains Drifter state that the filters are pretty subtle. I do recognise that when it comes to the low filter. Subtle steps adding a bit of bass every notch you go higher. The high filter is a very different matter on my amp and does not seem to behave as expected: not subtle and get harsh in the mids/high mids from the 3 step up. Not at all like I hear from Steel String Sultan/SSS/HPD vids. Those amps all seem to behave well even with the high filter on the 4th or 5th notch.

Does anyone recognise that this amp 'need' a different cap selection for the high filter than e.g. SSS002?

The added simulation shows the effect of a more subtle high filter (green) compared to the values I use at present (red): no more enormous presence and high mid boost with lower values.

Even with an aggressive high filter, this amp is still a joy to play on lower filter settings. High end is very clear and present, low end is tight but big. Great amp for fans of big clean sounds if you ask me.

Hi Rootz. I will be building a similar amp this summer. I will let you know how the Hi Filters sound on my build.
To confirm you would have preferred that each step would have started with a lower value and not went as high as the 4700pf?
So instead of starting at 150pf it would be better to start at a lower value such as 68pf and increase each cap size in smaller increments?

Thanks

Guy