Tube pre into a solid state - Page 2

Jules01983 · 23rd August 2012, 10:58 PM

The reason for sticking with the components I have mentioned is that:
A, I have them all
B, The marshall transformer gives me 6 volts for the heaters, 35 volts + and - for the SS amp cicuit and 190 volts for the valve.
I am trying to produce a better circuit diagram with more/clearer value data on it. I don't need 200w of output and hope that by not overdriving the SS amp, I can avoid adding SS distortion just a little something from the valve. The SE5a I built sounds sweet but is not quite loud enough for the gigs I play. And I do like to tinker

Printer2 · 24th August 2012, 12:23 AM

I disagree with the previous post saying you need many times more watts from a SS amp than a tube amp. What you need is to limit the voltage going into the SS amp to keep it out of clipping.

I would think copying a Marshall preamp and then soft clipping before the power amp would be interesting.

cyclecamper · 25th August 2012, 12:16 AM

Quote:

Originally Posted by Printer2

I disagree with the previous post saying you need many times more watts from a SS amp than a tube amp. What you need is to limit the voltage going into the SS amp to keep it out of clipping.

I would think copying a Marshall preamp and then soft clipping before the power amp would be interesting.

That's partially true, partially not, I just didn't get into it at any depth. The right compressor or peak limiter can indeed keep a SS out of trouble and make it behave more like a tube amp. But if you want the full capabilities of a tube preamp to be reproduced by a ss power amp that's a requirement the tube amp sidesteps. A tube power amp is a compressor/peak limiter but will also still operate farther outside its linear range...so in general I'd still stand by the recomendation that a ss power amp for guitar have a much higher power rating than a more conventional tube power amp for comparable usable output. That's partly because the ratings are based on some 'clean' distortion spec, and the tube amp is usable far beyond that, but the ss amp is not. Then again, the tube guitar amp "rating" may be so unflated it's unrelated to any reality...

Printer2 · 25th August 2012, 12:36 AM

Quote:

Originally Posted by cyclecamper

That's partially true, partially not, I just didn't get into it at any depth. The right compressor or peak limiter can indeed keep a SS out of trouble and make it behave more like a tube amp. But if you want the full capabilities of a tube preamp to be reproduced by a ss power amp that's a requirement the tube amp sidesteps. A tube power amp is a compressor/peak limiter but will also still operate farther outside its linear range...so in general I'd still stand by the recomendation that a ss power amp for guitar have a much higher power rating than a more conventional tube power amp for comparable usable output. That's partly because the ratings are based on some 'clean' distortion spec, and the tube amp is usable far beyond that, but the ss amp is not. Then again, the tube guitar amp "rating" may be so unflated it's unrelated to any reality...

And I would agree and yet disagree. Depending on the NFB and design of the amp the tube amp can keep clean up until clipping and no increase in voltage happens and the signal just gets more square. On the SS end I have a Lil Tiger amp that had no global NFB and it gave more distorted power than if spec'd for some arbitrary distortion figure.

nigelwright7557 · 25th August 2012, 12:56 AM

Quote:

Originally Posted by tinitus

no doubt a tube could give you tube sound, but not automaticly

An amp really needs multiple stages of tubes to get the true tube sound.

I have designed power amps with tube front ends but they sounded too clean.

Jules01983 · 25th August 2012, 09:40 AM

So, are we saying that I should put 2 tubes in the pre-amp to get my tube amp sound? The SS amp circuit is 200w rms but I only want volume levels equivalent to about 30 to 40 watts SS (like my sons Marshall MG30DFX). So that fits with Printer2s suggestion that I need more SS power to equate to Tube power (My 5w tube amp has a similar volume output to my Vox supertwin 20w SS amp). As I said in my first post, I don't expect this to sound great, but maybe it can with a bit of thought? If anyone is interested in making this work rather than debating the merits/demerits of the principal, do come on board. below are links to the circuits I am using as a starting point and my first draught design.
1. Marshal VS100 tube HT circuit, top right corner. http://www.drtube.com/schematics/mar...v100-60-02.pdf
2. Marshal VS100 power supply, lower right corner. http://www.drtube.com/schematics/mar...v100-61-02.pdf
3. SE5a tube amp pre-amp circuit. http://www.ampmaker.com/images/ak01kit/ak01sc2.jpg
4. Velleman K8060 SS poweramp stage
http://www.sayalhobbies.com/images_d/K8060D.gif
5. My design. see thumb nail on thread item #6

A final thought, how about using an old PC tower case to put it all in? maybe glue some sort of material on the inside to dampen the metal from vibrating?

Printer2 · 25th August 2012, 01:13 PM

Quote:

Originally Posted by Jules01983

So, are we saying that I should put 2 tubes in the pre-amp to get my tube amp sound? The SS amp circuit is 200w rms but I only want volume levels equivalent to about 30 to 40 watts SS (like my sons Marshall MG30DFX). So that fits with Printer2s suggestion that I need more SS power to equate to Tube power (My 5w tube amp has a similar volume output to my Vox supertwin 20w SS amp). As I said in my first post, I don't expect this to sound great, but maybe it can with a bit of thought? If anyone is interested in making this work rather than debating the merits/demerits of the principal, do come on board. below are links to the circuits I am using as a starting point and my first draught design.
1. Marshal VS100 tube HT circuit, top right corner. http://www.drtube.com/schematics/mar...v100-60-02.pdf
2. Marshal VS100 power supply, lower right corner. http://www.drtube.com/schematics/mar...v100-61-02.pdf
3. SE5a tube amp pre-amp circuit. http://www.ampmaker.com/images/ak01kit/ak01sc2.jpg
4. Velleman K8060 SS poweramp stage
http://www.sayalhobbies.com/images_d/K8060D.gif
5. My design. see thumb nail on thread item #6

A final thought, how about using an old PC tower case to put it all in? maybe glue some sort of material on the inside to dampen the metal from vibrating?

No, actually I was saying you might only need a bit more power and to keep the amp out of clipping. Say you take your 5W tube amp and run it to its sweet spot. Take the signal off the output and feed it into a SS amp and you would get appreciatively more output coming off a higher rated SS amp given that the ratings are accurate and you are driving the same speaker.

I would get a transformer something like this and run one of the 120V windings as input power and the other as the high voltage winding and then use a voltage doubler on it. You could probably find a lower VA rating one to use that is cheaper.

229C12 - Hammond - datasheet

Or you could use a back to back transformer arrangement to step up the voltage from your amplifier power transformer.

I would consider something like this.

The Free Information Society - Marshall 2204 Preamp Electronic Circuit Schematic

Jules01983 · 26th August 2012, 04:34 PM

OK, So, the marshall preamp schem looks like two valves in series? I'm up for that. The transformer part is giving me trouble, we have 240 volts in the UK for a start, or am I using the Valve HT feed like the output tran for the SE5a? then feed the SS amp instead of a speaker?

Printer2 · 26th August 2012, 05:48 PM

Quote:

Originally Posted by Jules01983

OK, So, the marshall preamp schem looks like two valves in series? I'm up for that. The transformer part is giving me trouble, we have 240 volts in the UK for a start, or am I using the Valve HT feed like the output tran for the SE5a? then feed the SS amp instead of a speaker?

Sorry, forgot you already had a HV winding.. Just rectify it and use it as is. The reason I suggest the two valve circuit is that preamp distortion with a couple more gain stages is suppose to be more pleasing than getting it all in one stage.

Jules01983 · 26th August 2012, 06:11 PM

Printer2, did you look at my schematic on post #6? with a 2 valve preamp, will I need to run the output through an output transformer before feeding the SS amp or can I feed it through a volume pot into the SS amp. this would let me reduce the input into the SS to reduce transistor clipping. I'm still lost as to what your plan was for the hammond bobbin.

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23rd August 2012, 10:58 PM	#11
Jules01983 diyAudio Member Join Date: Dec 2010 Location: Isle of Wight, UK	The reason for sticking with the components I have mentioned is that: A, I have them all B, The marshall transformer gives me 6 volts for the heaters, 35 volts + and - for the SS amp cicuit and 190 volts for the valve. I am trying to produce a better circuit diagram with more/clearer value data on it. I don't need 200w of output and hope that by not overdriving the SS amp, I can avoid adding SS distortion just a little something from the valve. The SE5a I built sounds sweet but is not quite loud enough for the gigs I play. And I do like to tinker

24th August 2012, 12:23 AM	#12
Printer2 diyAudio Member Join Date: Apr 2010	I disagree with the previous post saying you need many times more watts from a SS amp than a tube amp. What you need is to limit the voltage going into the SS amp to keep it out of clipping. I would think copying a Marshall preamp and then soft clipping before the power amp would be interesting.

25th August 2012, 09:40 AM	#16
Jules01983 diyAudio Member Join Date: Dec 2010 Location: Isle of Wight, UK	So, are we saying that I should put 2 tubes in the pre-amp to get my tube amp sound? The SS amp circuit is 200w rms but I only want volume levels equivalent to about 30 to 40 watts SS (like my sons Marshall MG30DFX). So that fits with Printer2s suggestion that I need more SS power to equate to Tube power (My 5w tube amp has a similar volume output to my Vox supertwin 20w SS amp). As I said in my first post, I don't expect this to sound great, but maybe it can with a bit of thought? If anyone is interested in making this work rather than debating the merits/demerits of the principal, do come on board. below are links to the circuits I am using as a starting point and my first draught design. 1. Marshal VS100 tube HT circuit, top right corner. http://www.drtube.com/schematics/mar...v100-60-02.pdf 2. Marshal VS100 power supply, lower right corner. http://www.drtube.com/schematics/mar...v100-61-02.pdf 3. SE5a tube amp pre-amp circuit. http://www.ampmaker.com/images/ak01kit/ak01sc2.jpg 4. Velleman K8060 SS poweramp stage http://www.sayalhobbies.com/images_d/K8060D.gif 5. My design. see thumb nail on thread item #6 A final thought, how about using an old PC tower case to put it all in? maybe glue some sort of material on the inside to dampen the metal from vibrating?

26th August 2012, 04:34 PM	#18
Jules01983 diyAudio Member Join Date: Dec 2010 Location: Isle of Wight, UK	OK, So, the marshall preamp schem looks like two valves in series? I'm up for that. The transformer part is giving me trouble, we have 240 volts in the UK for a start, or am I using the Valve HT feed like the output tran for the SE5a? then feed the SS amp instead of a speaker?

26th August 2012, 06:11 PM	#20
Jules01983 diyAudio Member Join Date: Dec 2010 Location: Isle of Wight, UK	Printer2, did you look at my schematic on post #6? with a 2 valve preamp, will I need to run the output through an output transformer before feeding the SS amp or can I feed it through a volume pot into the SS amp. this would let me reduce the input into the SS to reduce transistor clipping. I'm still lost as to what your plan was for the hammond bobbin.