I wanted to ask how your Rocket proto is coming along,I have one in the works!!!!! 18 watts, off the schematic here....how's it coming?Should be done with it in a week or so.Any tips on this beast??
Thanks
Chris
Calling Mark Abbott!!!!
Moderators: pompeiisneaks, Colossal
Calling Mark Abbott!!!!
Hi Mark,
I wanted to ask how your Rocket proto is coming along,I have one in the works!!!!! 18 watts, off the schematic here....how's it coming?Should be done with it in a week or so.Any tips on this beast??
Thanks
Chris
I wanted to ask how your Rocket proto is coming along,I have one in the works!!!!! 18 watts, off the schematic here....how's it coming?Should be done with it in a week or so.Any tips on this beast??
Thanks
Chris
The Rocket thus far.
Dear Chris
I had been meaning to shoot off an email to you and Matt, but for some reason whenever I send messages to you they keep bouncing back to me.
At this point in time I'm building an 18 watt (mini bluesbreaker) Marshall. I've only heard good things about them and there is so much around in the way of information and parts, I thought why not. I'm also looking for a different reference tones too.
I'm also building a a SSL studio compressor for a friend's studio.
Now I have all my excuses aside, I'll talk about the Rocket prototype.
As I have stated in other posts, I like good AC-30's, I didn't know what to expect from this amp, but without being able to compare amps I'd say the clone sounds as good as any of the AC-30's that I really liked.
The clean tones are good, the distortion is wonderful with a Strat. I found the Express and the Liverpool clones I built didn't like a 12" open back cab and favour a 4 X 12" cab, the Rocket doesn't have any problems with a 12" open back cab, I am hoping to have a friend come around this Sunday with his 4 X 12" cab and see how it reacts to that.
I do recall someone saying that Rockets don't have a bright cap, so I made the cap switchable, I found that the effect of the 100pF bright cap adds chime to the amp, and makes the in between sounds of my Strat have more definition, so I'd keep the cap.
I haven't experimented with a second bypass cap across the second cathode resistor. I found the amp to have enough gain without it. Of course, I shall have to experiment with it at some stage, as I'm sure Trainwrecks are about doing things to excess.
I did try and experiment with the value of the first cathode resistor, once again I used a switch so I could easily compare 1.5K and 3.3K.
I didn't hear any real difference in tone at all. I was a little surprised by this as I had done similar experiments with cathode resistors with my Mesa Boogie and I could easily hear the difference between a 1.5K resistor and a 2.2K resistor.
I will have to experiment with this further, (hopefully this Sunday), but my theory is that the smaller cathode resistors made the amp sound fatter, and as the coupling cap to the volume control is so small (500pF), the increases in bass and midrange response aren't noticeable. Thus I will have to experiment with larger caps in this area. (The Callaham amp did appear to have a larger value than 500pF in it.)
I did decide to leave out the 220K resistor between the tone control and the P.I. stage. I will have to experiment with this resistor later. I read through some of Ken Fischers Fender mod comments in Gerald Weber's books and he recommends leaving this resistor out, (mind you, he does include it in the Komet.) Never say never eh!
I do want to experiment with substituting a 1K resistor in the power supply instead of the 18K resistor that I'm currently using. I will have to build up a small oscillator for my testing of this area as I do want to see how the rail voltage is affected when the amp is going flat out. I wonder what effect the Torres power supply diode would do for this amp?
As far as general thoughts on the amp go, it has nice chime and the bass response is good. I still believe that many Express builders who find the gain and brightness of the Express or Liverpool to be excessive would be happier with the Rocket/AC-30 design.
Sorry, I can't add too much to what you already know, hopefully, after this weekend I'll have a little more to say about it.
Chris, what sort of transformers will you be using?
Seeing your photo's did inspire me to be a bit more serious about building a Rocket clone. I have been comparing the Trainwreck circuit to Kevin O'Connors AC-30 circuit, they are a little different and in some place they agree with each other. (Large initial filter cap, K.F. uses 80uF, while K O'C uses a 100uF with Si diodes.)
I have been thinking that before I serious start building any Trainwreck clone amps, I'd like to have a 4 X 12" cab with speakers that resemble the sound of the pre Rola Celestions, perhaps I'll have to have another look at Scumbags amps and see what he can offer?
I think Mike B could the one to talk to in regard to this type of amp.
As always Chris, it's good talking to you.
I had been meaning to shoot off an email to you and Matt, but for some reason whenever I send messages to you they keep bouncing back to me.
At this point in time I'm building an 18 watt (mini bluesbreaker) Marshall. I've only heard good things about them and there is so much around in the way of information and parts, I thought why not. I'm also looking for a different reference tones too.
I'm also building a a SSL studio compressor for a friend's studio.
Now I have all my excuses aside, I'll talk about the Rocket prototype.
As I have stated in other posts, I like good AC-30's, I didn't know what to expect from this amp, but without being able to compare amps I'd say the clone sounds as good as any of the AC-30's that I really liked.
The clean tones are good, the distortion is wonderful with a Strat. I found the Express and the Liverpool clones I built didn't like a 12" open back cab and favour a 4 X 12" cab, the Rocket doesn't have any problems with a 12" open back cab, I am hoping to have a friend come around this Sunday with his 4 X 12" cab and see how it reacts to that.
I do recall someone saying that Rockets don't have a bright cap, so I made the cap switchable, I found that the effect of the 100pF bright cap adds chime to the amp, and makes the in between sounds of my Strat have more definition, so I'd keep the cap.
I haven't experimented with a second bypass cap across the second cathode resistor. I found the amp to have enough gain without it. Of course, I shall have to experiment with it at some stage, as I'm sure Trainwrecks are about doing things to excess.
I did try and experiment with the value of the first cathode resistor, once again I used a switch so I could easily compare 1.5K and 3.3K.
I didn't hear any real difference in tone at all. I was a little surprised by this as I had done similar experiments with cathode resistors with my Mesa Boogie and I could easily hear the difference between a 1.5K resistor and a 2.2K resistor.
I will have to experiment with this further, (hopefully this Sunday), but my theory is that the smaller cathode resistors made the amp sound fatter, and as the coupling cap to the volume control is so small (500pF), the increases in bass and midrange response aren't noticeable. Thus I will have to experiment with larger caps in this area. (The Callaham amp did appear to have a larger value than 500pF in it.)
I did decide to leave out the 220K resistor between the tone control and the P.I. stage. I will have to experiment with this resistor later. I read through some of Ken Fischers Fender mod comments in Gerald Weber's books and he recommends leaving this resistor out, (mind you, he does include it in the Komet.) Never say never eh!
I do want to experiment with substituting a 1K resistor in the power supply instead of the 18K resistor that I'm currently using. I will have to build up a small oscillator for my testing of this area as I do want to see how the rail voltage is affected when the amp is going flat out. I wonder what effect the Torres power supply diode would do for this amp?
As far as general thoughts on the amp go, it has nice chime and the bass response is good. I still believe that many Express builders who find the gain and brightness of the Express or Liverpool to be excessive would be happier with the Rocket/AC-30 design.
Sorry, I can't add too much to what you already know, hopefully, after this weekend I'll have a little more to say about it.
Chris, what sort of transformers will you be using?
Seeing your photo's did inspire me to be a bit more serious about building a Rocket clone. I have been comparing the Trainwreck circuit to Kevin O'Connors AC-30 circuit, they are a little different and in some place they agree with each other. (Large initial filter cap, K.F. uses 80uF, while K O'C uses a 100uF with Si diodes.)
I have been thinking that before I serious start building any Trainwreck clone amps, I'd like to have a 4 X 12" cab with speakers that resemble the sound of the pre Rola Celestions, perhaps I'll have to have another look at Scumbags amps and see what he can offer?
I think Mike B could the one to talk to in regard to this type of amp.
As always Chris, it's good talking to you.
Yours Sincerely
Mark Abbott
Mark Abbott
Re: Calling Mark Abbott!!!!
Hi Mark,
Thanks for the info,I should have this baby wired up by monday night!!
the trannies are an old stancor power/and the output is from an old German pa head.........I got alittle lucky as the output was originaly a through the chassis type mount ........but I found a set of bells to fit.
I think I'm gonna go with a 5v4 rectifier......insted of a 5y3 or a 5ar4......I've had this power trans in another amp and it sounded great!!
I will keep you posted !!!
Thank-you Mark!!
Chris
Thanks for the info,I should have this baby wired up by monday night!!
the trannies are an old stancor power/and the output is from an old German pa head.........I got alittle lucky as the output was originaly a through the chassis type mount ........but I found a set of bells to fit.
I think I'm gonna go with a 5v4 rectifier......insted of a 5y3 or a 5ar4......I've had this power trans in another amp and it sounded great!!
I will keep you posted !!!
Thank-you Mark!!
Chris
Re: Calling Mark Abbott!!!!
Mark,
I've started work on a 15-watt Rocket-ish amp. Your notes are a big help. I finished the metalwork and bolting on the iron and sockets. Using an OPT from a Harmon Kardon integrated amp.
I really like the AC-30, but it's too loud for any gig I'll ever play, so I opted for 15 watts.
-Neil
I've started work on a 15-watt Rocket-ish amp. Your notes are a big help. I finished the metalwork and bolting on the iron and sockets. Using an OPT from a Harmon Kardon integrated amp.
I really like the AC-30, but it's too loud for any gig I'll ever play, so I opted for 15 watts.
-Neil