I bought something I think is pretty cool this last weekend... A Crescent TR-673 reel-to-reel tape recorder. I'm pretty sure there is a part missing in the pinch roller mechanism (56)... Don't know if this is really worth a restoration or not. I haven't even plugged it in yet... There is no fuse to be found, we have been sick with the flu this week and I haven't really had the energy. If it turns out to be worth more than just the parts I would just sell it for that... More parts to make a rocket! That's what I really want... A Rocket!
Anyway... I wondered what you guys would suggest for turning this into a single ended Rocket. Here is a link to a pdf:
http://sportbil.com/other/Crescent%20TR-672,TR-673.pdf
Schematic is on page 15... This particular unit has a 6k6 in place of the 6v6gt. Don't know how well that will work.
Specs for the transformers are on page 11... If I do rebuild, I would use all new quality components but would like to try to use the original transformers. I will get a new chassis if needed but this one may work if patched and some of the useless items tossed... It is aluminum.
I'm just thinking it would be cool to have a 2 to 5 watt Rocket and not have to stick a lot of cash into it. I am up for the effort. One of those build-with-what-you-have projects... Maybe like Ken would do?
What do you guys think? Is it worth it? Any suggestions?
Btw... I paid $5 for it... I think it was worth that... Anyone have any idea how much its worth or how to figure that out? Anyway...if I get any bites, I will answer any questions and post my results when I test it out.
Tony
Ps: if the link above doesn't work, just look up the model# on this page:
http://sportsbil.com/other/
Low watt Rocket SE
Moderators: pompeiisneaks, Colossal
-
dorrisant
- Posts: 2790
- Joined: Tue Sep 21, 2010 1:27 pm
- Location: Somewhere between a river and a cornfield
- Contact:
Low watt Rocket SE
Last edited by dorrisant on Tue Apr 12, 2011 5:14 pm, edited 1 time in total.
Re: Low watt Rocket SE
In this case I would think about how much money, research and build time is available and whether this could be better invested in building a proper Rocket.
That PT mA rating is way too low for my taste. These kind of conversions can be real fun, full of entertainment and surprises, but can also take your eye off the ball.
If you really feel you need a low wattage version, I remember that RJ made some cool Rocket moves with some really skinny tubes about a year ago or so.
Best, tony
That PT mA rating is way too low for my taste. These kind of conversions can be real fun, full of entertainment and surprises, but can also take your eye off the ball.
If you really feel you need a low wattage version, I remember that RJ made some cool Rocket moves with some really skinny tubes about a year ago or so.
Best, tony
-
RJ Guitars
- Posts: 2663
- Joined: Tue Nov 14, 2006 3:49 am
- Location: Los Alamos, New Mexico
- Contact:
Re: Low watt Rocket SE
Yeah, kinda depends on what you want to accomplish. Rockets are not especially finicky about the circuit, that is to say that you can make a good sounding amp by getting close. Sounding exactly like a Rocket could be a different story but that's where your own expectations eventually meet reality.
Since your parts donor is using a 6K6, the trannies are probably in the voltage range you need. I always say give it a shot unless you are really attempting a true clone. Worst case is you'll be wiser when your done and more likely you'll have a cool little amp.
If your time is critically valuable and you want the short path proven by others - maybe this is interesting to you... https://tubeamparchive.com/viewtopic.php?t=9816 this does not sound exactly like a full sized Rocket either but it is very cool.
rj
Since your parts donor is using a 6K6, the trannies are probably in the voltage range you need. I always say give it a shot unless you are really attempting a true clone. Worst case is you'll be wiser when your done and more likely you'll have a cool little amp.
If your time is critically valuable and you want the short path proven by others - maybe this is interesting to you... https://tubeamparchive.com/viewtopic.php?t=9816 this does not sound exactly like a full sized Rocket either but it is very cool.
rj
Good, Fast, or Cheap -- Pick two...
http://www.rjguitars.net
http://www.rjaudioresearch.com/
http://diyguitaramps.prophpbb.com/
http://www.rjguitars.net
http://www.rjaudioresearch.com/
http://diyguitaramps.prophpbb.com/
-
dorrisant
- Posts: 2790
- Joined: Tue Sep 21, 2010 1:27 pm
- Location: Somewhere between a river and a cornfield
- Contact:
Re: Low watt Rocket SE
Finally got time to check it out... I checked the electrolytics with my esr meter and they look very bad. Not surprised. Not even going to put power to it. It will be parts. Still worth the $5 though.
I see what you guys are saying... and I understand. I would never expect this thing to have authentic rocket tone. As good as some of the clips are here at TAG, even the ones that are one offs, anything close to that would be good enough for me. I would love to have a true rocket preamp that could be tapped for feeding another amp if needed or just played through a small > 10 watt se power amp. I already have an express preamp in an old solid state amp chassis. It looks like a complete amp... But I usually just run directly into the effects return on other amps... Like a pedal. Case in point, a peavey classic 30. Not exactly an express sound, but it is the best I have ever heard from that amp... Period. When I am not using it as a preamp, I have a small hybrid amp that drives the combo speaker. It still sounds great like that, just not nearly as loud. Maybe I could do the same with this project... A very useful preamp with the added flavor of a small se power section at the disposal.
But now for the questions...
Would getting rid of the 6e5 allow a little more breathing room for the power transformer? It only needs to power a few watts.
Should the dropping resistor be changed to a choke in order to get closer to the proper voltages needed for the preamp? Without stressing the power tx of course.
I don't know if the output transformer will work... The speakers are connected in parallel to show a 2 ohm load. Not too worried if I have to buy another one.
You guys are very right though... There will be a lot of work to pull it off. This is the kind of work that drew me to this hobby in the first place. I love it! Not only would I have a cool little amp, but it would also be the kind of lesson of adaptation that seems to be the best way for me to learn. It is different than the same old components...things have to be changed to make it work and the theories behind those changes become solid. But, it is only possible with the support of the members here.
I guess what I want out of this is a useable rocket preamp (with a fake pi and master volume). If the power section has to be changed to accomodate the power transformer, then that is what I will have to do, even if it means it will be a preamp only. Maybe it could have reverb instead.
If I can get some time this weekend I will pull the tubes and check through it to make sure the transformers are in fact good. I will keep checking here for your advise until then.
Tony.
I see what you guys are saying... and I understand. I would never expect this thing to have authentic rocket tone. As good as some of the clips are here at TAG, even the ones that are one offs, anything close to that would be good enough for me. I would love to have a true rocket preamp that could be tapped for feeding another amp if needed or just played through a small > 10 watt se power amp. I already have an express preamp in an old solid state amp chassis. It looks like a complete amp... But I usually just run directly into the effects return on other amps... Like a pedal. Case in point, a peavey classic 30. Not exactly an express sound, but it is the best I have ever heard from that amp... Period. When I am not using it as a preamp, I have a small hybrid amp that drives the combo speaker. It still sounds great like that, just not nearly as loud. Maybe I could do the same with this project... A very useful preamp with the added flavor of a small se power section at the disposal.
But now for the questions...
Would getting rid of the 6e5 allow a little more breathing room for the power transformer? It only needs to power a few watts.
Should the dropping resistor be changed to a choke in order to get closer to the proper voltages needed for the preamp? Without stressing the power tx of course.
I don't know if the output transformer will work... The speakers are connected in parallel to show a 2 ohm load. Not too worried if I have to buy another one.
You guys are very right though... There will be a lot of work to pull it off. This is the kind of work that drew me to this hobby in the first place. I love it! Not only would I have a cool little amp, but it would also be the kind of lesson of adaptation that seems to be the best way for me to learn. It is different than the same old components...things have to be changed to make it work and the theories behind those changes become solid. But, it is only possible with the support of the members here.
I guess what I want out of this is a useable rocket preamp (with a fake pi and master volume). If the power section has to be changed to accomodate the power transformer, then that is what I will have to do, even if it means it will be a preamp only. Maybe it could have reverb instead.
If I can get some time this weekend I will pull the tubes and check through it to make sure the transformers are in fact good. I will keep checking here for your advise until then.
Tony.
-
dorrisant
- Posts: 2790
- Joined: Tue Sep 21, 2010 1:27 pm
- Location: Somewhere between a river and a cornfield
- Contact:
Re: Low watt Rocket SE
Almost forgot... I will build a full blown rocket before too long. This is just one of those things that is just screaming for my attention right now. It won't be my only rocket. Just a little one!
Tony.
Tony.
Re: Low watt Rocket SE
i couldnt get the link to work. I built a 6k6 amp using a smps and it probably does about 2.5 watts at 200 volts. i like the way it sounds with a tube boost infront of it. I havent built a rocket but i bet it wouls sound cool authentic or not. besides a 2 watt amp is loud enough to be obnoviouse but still very reaonable volum wise and score shigh in cool points for sure.my 2 cents. here is when i first bult it http://www.youtube.com/watch?v=YtFdINnPEeo and here is after i refined ( use word loosley ) it http://www.youtube.com/watch?v=pAc2FTzL ... re=related
-
dorrisant
- Posts: 2790
- Joined: Tue Sep 21, 2010 1:27 pm
- Location: Somewhere between a river and a cornfield
- Contact:
Re: Low watt Rocket SE
I don't know zambo... That its pretty refined... And sounds off the hook! I have seen quite a few of your projects and I'm always impressed with your innovation. Come on man... Who else could put a speaker in a flower pot and make every one forget that fact when the sound hits? Your projects and playing rock! I appreciate your input here. Do you have a schematic of what you did with the 6k6? I will try to post the info from my link posted above... Schematic and fact sheets. Did you use the fake pi? What components did you use around the power section?
If my project sounds anything like what yours does, I would be extremely happy.
I love it man... Something wonderful out of a bunch of parts, wires and a flower pot!
Tony.
If my project sounds anything like what yours does, I would be extremely happy.
I love it man... Something wonderful out of a bunch of parts, wires and a flower pot!
Tony.
-
RJ Guitars
- Posts: 2663
- Joined: Tue Nov 14, 2006 3:49 am
- Location: Los Alamos, New Mexico
- Contact:
Re: Low watt Rocket SE
what is a fake PI anyway?
Good, Fast, or Cheap -- Pick two...
http://www.rjguitars.net
http://www.rjaudioresearch.com/
http://diyguitaramps.prophpbb.com/
http://www.rjguitars.net
http://www.rjaudioresearch.com/
http://diyguitaramps.prophpbb.com/
-
dorrisant
- Posts: 2790
- Joined: Tue Sep 21, 2010 1:27 pm
- Location: Somewhere between a river and a cornfield
- Contact:
Re: Low watt Rocket SE
rj -
Fake pi - using only half of a normal phase inverter (long tailed pair), using half of a preamp tube. When implemented in a single ended amp, this replaces the normal pi of a push pull amp and acts as a slight gain stage. This works well with a preamp like the express which uses only three gain stages because it uses the unused half of v2. The term "fake" is somewhat misleading... as it is real. "Half pi" would probably cause less confusion, but it was not coined that way. Hope that helps.
Fake pi - using only half of a normal phase inverter (long tailed pair), using half of a preamp tube. When implemented in a single ended amp, this replaces the normal pi of a push pull amp and acts as a slight gain stage. This works well with a preamp like the express which uses only three gain stages because it uses the unused half of v2. The term "fake" is somewhat misleading... as it is real. "Half pi" would probably cause less confusion, but it was not coined that way. Hope that helps.
Last edited by dorrisant on Sat Apr 09, 2011 5:27 pm, edited 1 time in total.
Re: Low watt Rocket SE
i used this schematic as the basis for it http://mysite.du.edu/~etuttle/electron/ ... tm#Triodes
scroll down about three quarters of the way and its under power beam tetrodes on the left side. for B+ i use a 1363 smps from taylor edge electronics ( 13 bucks! ) and ran it straight to the anode and the screen at 200 volts. i had to tweak the bias resistor alot to get the thing to stop squealing although i think the use of a standard power supply would be way better. its pretty lopud for only using 200 volts though. i used a simple 12at7 dual gainstage preamp 1 tube job. standard setup of 100k and 1.5 although they are unbypassed. no reason for that other than it sounded ok and i didnt know any better. for the flower pot I choose walmart. Hand picked by magic mojo monkeys...
Thanks for the kind words btw. Good luck and let me know if i can help!
scroll down about three quarters of the way and its under power beam tetrodes on the left side. for B+ i use a 1363 smps from taylor edge electronics ( 13 bucks! ) and ran it straight to the anode and the screen at 200 volts. i had to tweak the bias resistor alot to get the thing to stop squealing although i think the use of a standard power supply would be way better. its pretty lopud for only using 200 volts though. i used a simple 12at7 dual gainstage preamp 1 tube job. standard setup of 100k and 1.5 although they are unbypassed. no reason for that other than it sounded ok and i didnt know any better. for the flower pot I choose walmart. Hand picked by magic mojo monkeys...
Thanks for the kind words btw. Good luck and let me know if i can help!-
dorrisant
- Posts: 2790
- Joined: Tue Sep 21, 2010 1:27 pm
- Location: Somewhere between a river and a cornfield
- Contact:
Re: Low watt Rocket SE
Overtone is absolutely right. I don't know how they ever powered a 6v6 and two preamp tubes with that pt. I think I'll hold on to the tubes for a single ended project with different transformers. Maybe I could use one preamp tube and keep the power at an acceptable level for this tx... Or just use it for a preamp only... I'll use it all for something. Thanks for taking a look at it guys. I still learned something so all is not lost.
As a side point a little off topic... Is a rocket so sensitive to electromagnetism that you must use an aluminum chassis? I know that an express is that picky but what about a rocket in an old steel chassis?
Tony
As a side point a little off topic... Is a rocket so sensitive to electromagnetism that you must use an aluminum chassis? I know that an express is that picky but what about a rocket in an old steel chassis?
Tony