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DIY TUBE PREAMP HELP PLEASE

Califmike33 said:
I will wait until it arrives.
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Yeah, I'd wait. From what I've read you never know if kits like this ship with the parts shown or not.

At least some of the electrolytic caps pictured are labelled 105°. If any of them aren't, I suggest using caps rated at 105° for at least 8,000 to 10,000 hours. I generally use Nichicon, Panasonic, or United Chemi-Con but as long as you get them from a major supplier like Mouser or Digi-Key the brand is less important than the specs.

I usually use Digi-Key because they have a free shipping option:

http://www.audiokarma.org/forums/in...hipping-on-parts-orders.739513/#post-10018562

You'll want to spend some time figuring out how you want the finished preamp to look. Notice that the layout, with everything mounted as shown, is designed to have the tubes inside an enclosed chassis, just as the real Rogue 99 pic shows.

I think Lavane mentioned this earlier. If you want the tubes to be on top of the chassis and be visible, you'll need to mount the sockets on the other side of the board and attach the board to the top of your chassis. Or use long standoffs and only have the tops of the tubes protruding through holes in the top of the chassis.

Of course, you can build it inside an enclosed chassis if you don't care about seeing the tubes but the downside of this is that you need to open the chassis if you want to do any tube rolling.

Another option might be to order some chassis mount tube sockets, mount them on top of the chassis and connect their pins to the board with short wires. This would give you access to the tubes and also eliminate the possibility of damaging the board or solder joints when you pull and replace tubes. And given the variety of 6SN7s available it's likely you'll end up going down the tube rolling rabbit hole.

However you mount the tubes, you'll still need to have adequate ventilation. I don't know what mounts on those heatsinks (voltage regulators??) but if they need heatsinks there is a reason.

I remember buying a couple of tiny pre-made boards a while back that had voltage regulators on heatsinks. Those things got so hot it scared me and I set them aside. Perhaps it was just normal heat and I overreacted, I'm not used to using parts that require heatsinks, but I wasn't comfortable with the prospect of mounting them inside a chassis. They worked fine but I also wondered about reliability given their operating temperature. They seemed to be well made but I don't know enough about that type of circuit to know for sure.
 
Yeah there's a lot to think about about laying it all out. Not sure if I want the tubes inside or if I want the tubes on the outside most preamps I see the tubes are on the inside but I do like seeing the tubes. I will have to find a case that will work also.

There seems to be different versions of this floating around eBay and some other websites it's the same Rogue 99, some of them have upgraded parts they're using different film caps of better quality.

Think I'm going to build it get it all built while I'm building it start figuring out where I'm going to get a case I'm going to start looking around for a case figure out if I want the tubes on the top or inside more than likely I'll put them inside.

Now there is a version of it on eBay that's already built and in a case all wired up with the rear RCA jacks the front selector knob the front volume up it's basically a complete unit with tubes for $350. Thought about buying this and taking it apart and then upgrading all the parts that way I already have a case I already have the volume knob and everything else is already there in the long run it's probably much cheaper this way but then again it's not a complete DIY a lot to think about.
 
FlaCharlie said:
Yeah, I'd wait. From what I've read you never know if kits like this ship with the parts shown or not.

At least some of the electrolytic caps pictured are labelled 105°. If any of them aren't, I suggest using caps rated at 105° for at least 8,000 to 10,000 hours. I generally use Nichicon, Panasonic, or United Chemi-Con but as long as you get them from a major supplier like Mouser or Digi-Key the brand is less important than the specs.

I usually use Digi-Key because they have a free shipping option:

http://www.audiokarma.org/forums/in...hipping-on-parts-orders.739513/#post-10018562

You'll want to spend some time figuring out how you want the finished preamp to look. Notice that the layout, with everything mounted as shown, is designed to have the tubes inside an enclosed chassis, just as the real Rogue 99 pic shows.

I think Lavane mentioned this earlier. If you want the tubes to be on top of the chassis and be visible, you'll need to mount the sockets on the other side of the board and attach the board to the top of your chassis. Or use long standoffs and only have the tops of the tubes protruding through holes in the top of the chassis.

Of course, you can build it inside an enclosed chassis if you don't care about seeing the tubes but the downside of this is that you need to open the chassis if you want to do any tube rolling.

Another option might be to order some chassis mount tube sockets, mount them on top of the chassis and connect their pins to the board with short wires. This would give you access to the tubes and also eliminate the possibility of damaging the board or solder joints when you pull and replace tubes. And given the variety of 6SN7s available it's likely you'll end up going down the tube rolling rabbit hole.

However you mount the tubes, you'll still need to have adequate ventilation. I don't know what mounts on those heatsinks (voltage regulators??) but if they need heatsinks there is a reason.

I remember buying a couple of tiny pre-made boards a while back that had voltage regulators on heatsinks. Those things got so hot it scared me and I set them aside. Perhaps it was just normal heat and I overreacted, I'm not used to using parts that require heatsinks, but I wasn't comfortable with the prospect of mounting them inside a chassis. They worked fine but I also wondered about reliability given their operating temperature. They seemed to be well made but I don't know enough about that type of circuit to know for sure.
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I built a preamp once using a kit that used those flimsy connecting boards so the sockets and tubes mounted horizontally. I didn't like that, so I put sockets on the top of the chassis and ran wires to the board. It's not the easiest option for sure. My 300B SET amp has a 5v 5 amp dual regulator for the heaters. The regulator runs at the max rating. I didn't like that hot running thing mounted on the PCB with a big heavy heat sink. So I mounted the heat sink to the underside of the aluminum chassis plate and ran wires to the PCB. The regulator runs at a very exceptable temp now with the chassis plate adding to the heat dissipation.
 
I got another question for you DIY builders I showed you this headphone amp before it has wires that hook up to the top to the tubes but I'm wondering is that only on there for a particular type of tube? It does say that you can use multiple tubes so maybe their tubes you use you don't need those wires?

I think I figured it out it takes multiple types of tubes you do not have to use those wires for all tubes some of those tubes have a place where the wire can attach to the top but most of them don't.

Seller finally contacted me but he never answered my question about how much power does his headphone amplifier put out at 300 ohm headphones.

https://www.ebay.com/itm/2645080757...-qt1-8jQt2&var=&widget_ver=artemis&media=COPY
 
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Okay so it's a newer version it's not exactly identical. I'm really thinking I should buy the whole thing assembled and then just take it apart and reassemble it with better components. If I buy all that stuff separately it's probably going to end up costing about $500 versus the $350.
 
Califmike33 said:
I got another question for you DIY builders I showed you this headphone amp before it has wires that hook up to the top to the tubes but I'm wondering is that only on there for a particular type of tube? It does say that you can use multiple tubes so maybe their tubes you use you don't need those wires?

I think I figured it out it takes multiple types of tubes you do not have to use those wires for all tubes some of those tubes have a place where the wire can attach to the top but most of them don't.

Seller finally contacted me but he never answered my question about how much power does his headphone amplifier put out at 300 ohm headphones.

https://www.ebay.com/itm/2645080757...-qt1-8jQt2&var=&widget_ver=artemis&media=COPY
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It can probably be wired either way depending on the tube used.
If using the EL519, also known as a 6KG6A, there isn't an anode cap. There is probably a jumper on the PCB you would add to connect the anode pin on that tube, no need for the exposed cap wire.
 
Yeah because there are photos of it with the wires connected and with the wires taken off I was afraid you had to use the wires which I don't think that'd be very pleasing to look at so it does have options I may end up buying that also as a project to build.
 
Califmike33 said:
Okay so it's a newer version it's not exactly identical. I'm really thinking I should buy the whole thing assembled and then just take it apart and reassemble it with better components. If I buy all that stuff separately it's probably going to end up costing about $500 versus the $350.
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Honestly, just replacing the four film caps would be all you need to do. And there are plenty of decent 12AU7 tubes you can use. I use mostly JJ 12AU7's and 12AX7's when needed. They don't cost a lot and sound nice. I have them in several amplifiers, a headphone amp, and one preamp.
 
I may do that I might just replace the film caps. I think the one that's already made with the case even though I'm not crazy about the looks of the case at least I got everything I need all in one shot I can always change the case out later.
 
The case isn't bad. But I tend to like the industrial look. Maybe replace the knobs with black knobs you like to add some contrast.
 
You're right that case is not too bad changing the knobs could make a big difference. I don't like the way the lettering is on it I don't know how hard it would be to change the lettering around the volume knob and all that but the case is not bad that's a good idea changing the knobs can make a big difference.

I think what I'll do is I'll buy that and I'll just take it apart change the film caps out whatever else I decide to change check all the soldering check all the wiring update the wiring if the wiring is not good who knows maybe I'll even put the tubes to stick out the top it just seems like a much better deal.

If I order just the kit I'm going to have to order a case from China I'm going to have to get RCA's for the back I'm going to have to buy a bunch of stuff potentiometer and stuff it's going to end up costing me more money so this I think is the best way to go.
 
It will definitely be cheaper to buy the completed preamp and change parts as needed. Too bad they don't have a finished version that uses the 6SN7s, though. The 6SN7 is generally considered to be a better tube than the 12AU7. The better 9 pin miniature that's closest to the 6SN7 is the 6CG7. Unfortunately, they are not a drop in sub for the 12AU7. If the preamp was point to point you could re-wire it and use them instead.

What I would suggest, however, is that you wait until Stephe does her upcoming preamp shootout. The preamp that won the first one uses 6SN7s. I believe it is available as a kit and finished.
 
Okay maybe I'll wait and see her shoot out and see what goes on with that. You know what I want to do is I want to build that headphone amp that the links in this thread I really want to build that headphone amp.

It's too bad they don't have that preamp in the type of tube that you're saying I'd have to buy the DIY kit by the case separately by the RCA jacks by the potentiometer I have to buy everything separately.

I'm just going to take a reward for it that those are better tubes so I think I will wait for Steph shootout.

The seller contacted me on that headphone amp maybe I'll just buy the headphone amp kit and build that while I'm waiting for Steph shootout to get me something to build I'm itching the build something. It's $120 for that headphone amp with all the caps and I asked a guy and he listed the names of the Caps they're all quality parts. It list the chokes that I need it says I need two chokes but I'm not sure what transformer I need that's the part I need to figure out is what transformer to go with that kit. I'll build my own beautiful Walnut case for that headphone amp.
 
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Califmike33 said:
The seller contacted me on that headphone amp maybe I'll just buy the headphone amp kit and build that while I'm waiting for Steph shootout to get me something to build I'm itching the build something.
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I thought you said you didn't want to use tubes that have a top cap. All the ones they list as possibilities use top caps.
 
Charlie your killing me, i thought some of those tubes didnt used that that top cap. That being the case then im off that amp completely. The only way it would work is if you put it in a case where you cant see the tubes, then it wouldnt really matter. I know nothing about tubes that use top caps, never seen one amp with them and i have seen alot of amps.
 
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Califmike33 said:
I just saw your post all of those tubes use top caps?? . . . what exactly does that top cap do does it give it power?
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Yeah, not only that but most of them are also expensive ($65 each), at least from the dealer near me. The 6GB5 / EL500 is the only cheap one, which they list at $5. Who knows if they even have any of them in stock.

Here are the data sheets I was able to find:

https://tubedata.edebris.com/sheets/191/6/6GB5.pdf

https://tubedata.edebris.com/sheets/084/6/6KG6.pdf

https://tubedata.edebris.com/sheets/020/e/EL504.pdf

https://tubedata.edebris.com/sheets/010/e/EL519.pdf

https://tubedata.edebris.com/sheets/010/p/PL519.pdf

A top cap is just another way to connect to one of the internal parts of the tube, just like the pins on the bottom. Most top caps connect to the tube's plate / anode, which is a high voltage connection. Some tubes have top caps that connect to the grid. Some actually have both grid and plate connections via top caps. I have no problem using tubes with top caps but a lot of people don't like them.

If you already have an OTL headphone amp and you don't like it that much, why are you looking at other OTL headphone amps? I'm not saying its the topology that you don't like but it might be. I have no experience with OTLs, so . . . :dunno:

Why not try something with OTs? Or if you're itching to build something, why not Stephe's headphone box?
 
Ok well that amp is out, that is 65 per tube x4, pricey, that amp is outttttttttttttt. This amp were talking about is OTL ?. Im not saying OTL is bad, it just the one im using i dont like Xduoo TA-26, the sound is so so. I class A tube amp to try for headphones. Something like Little dot MK II, that is not OTL. The bottlehead Crack 1.1 is a good amp, not sure what type OTL ? i dont think it is, that is a DIY kit that some say is the best sounding tube amp you can pair with HD 650 headphones.

Like i said in the beginning i would love a tube pre with a class d amp that has a good headphone jack, or class a/b with a good headphone jack paired with tube pre amp. I think this is the best way to go, that why i have really been focused on a tube preamp. Since you told me that put together kit has less than stellar tubes, it has kinda ruled out that kit. Im not a big fan of that speaker box thing. When is Stephe shootout comming ? i may just wait and see what thats all about and go from there.
 
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