Crack;Bottlehead OTL

[crappyjones123]

hell if i know, will send an email to bottlehead and see what they say unless someone here can say that they are substitutes

[ironbut]

You should contact Bottlehead and they'll shoot a couple off to you if they think it's even necessary.

Like I said, post something on their forum and see what other folks think. Believe me, there's plenty of knuckleheads like you and me that have done much worse and since these CCS boards can be used on almost all their kits, you won't be the lone ranger.

The Bottlehead forum is there to troubleshoot and discuss upgrades and design. It's a fantastic resource but only if you use it!

[crappyjones123]

plugged in an rca 6080wc tube that i was given by the nice gentleman upstairs. the bass with the 650s is stupendous. downright silly amounts of bass. a little tightening up would help but waaaaaaaaaaaaaay nicer than the jan 6080wc that was supplied with the kit. i can feel the insides of my head rattling on "poem of chinese drums" by yim hok man.

still looking for a bit of mid range sparkle. nice and smooth but would like it to be more liquid. perhaps even a little bright. (coming from someone who hates anything bright)

[ironbut]

That's one of the things I really love about this amp. You can really hear what each tube brings to the table. Of course there are some that sound pretty close and you need to find the right combination for the particular headphones you're listening to.

I think you'll find that rolling the 12au7 will help just as much as the 6080.

[Nebby]

There are so many tubes to choose from!

[n_maher]

There are a few listed for sale on HF right now worth looking at, specifically someone has a 7236 for ~$40 which is a pretty reasonable price IMO.

[crappyjones123]

thanks for the tip nate. should we be looking in the amp area or the tweaks forum?

[luvdunhill]

Looking at the info, I wouldn't worry about remounting that transistor... You might cause more damage than it's worth in the removal process anyways.

[Nebby]

The ones I saw for sale were under the cables,speakers,tweaks, etc. forum.

Is it wrong that I haven't even built my amp yet and I'm already buying tubes to swap with?

[n_maher]

The ones I saw for sale were under the cables,speakers,tweaks, etc. forum.

Yup.

Is it wrong that I haven't even built my amp yet and I'm already buying tubes to swap with?

Nope.

[dsavitsk]

hell if i know, will send an email to bottlehead and see what they say unless someone here can say that they are substitutes

Basically, any small signal NPN transistor should work. The higher the Hfe of that part, the better the CCS is at being a CCS (i.e., the higher the impedance). The 2N2222 is kind of crappy in this regard. You could use a higher Hfe part, but if you do that, the LED bias current will probably need to be increased, particularly if the CCS runs at high currents.

As for it touching the board, so long as the case is not shorting anything, it should be fine. The part does not dissipate any real heat.

[ironbut]

There are so many tubes to choose from!

There are a few tube rolling posts on "that other site" and the Bottlehead forum.

Those big sprague lytics insert an unknown into the equation since I'm not sure what the sonic qualities of those might be. Most of the well documented experimentation has been with 100uF film caps or the stock Panasonics. It's still in the early stages of what works best IMHO.

I think a good place to start would be a nice Mullard 12au7 or a CBS/Hytron 5814a and a Tung-sol 5998. You just might find that you won't need to go any further (with the Speedball installed).

[crappyjones123]

The ones I saw for sale were under the cables,speakers,tweaks, etc. forum.

Is it wrong that I haven't even built my amp yet and I'm already buying tubes to swap with?

i wish i had your kind of patience.

[crappyjones123]

Basically, any small signal NPN transistor should work. The higher the Hfe of that part, the better the CCS is at being a CCS (i.e., the higher the impedance). The 2N2222 is kind of crappy in this regard. You could use a higher Hfe part, but if you do that, the LED bias current will probably need to be increased, particularly if the CCS runs at high currents.

As for it touching the board, so long as the case is not shorting anything, it should be fine. The part does not dissipate any real heat.

i wish i knew what all that meant.

[crappyjones123]

There are a few tube rolling posts on "that other site" and the Bottlehead forum.

Those big sprague lytics insert an unknown into the equation since I'm not sure what the sonic qualities of those might be. Most of the well documented experimentation has been with 100uF film caps or the stock Panasonics. It's still in the early stages of what works best IMHO.

I think a good place to start would be a nice Mullard 12au7 or a CBS/Hytron 5814a and a Tung-sol 5998. You just might find that you won't need to go any further (with the Speedball installed).

im planning on listening to it with the sprague caps for this next week and then putting the stock ones back in to see what changes. however, the bass was virtually non existent with the original caps. at least to me. rather i was actually disappointed. put in the sprague caps - bass got nicer. changed the sylvania 6080wc to a rca 6080wc - bass got waaaaaaaaaaaaaaaaaaaaaaaay nicer. but along the way, the overall tonality got a little bloomy. changed the supplied 12au7 (dont even know what kind it is) to a raytheon 12au7 and midrange improved by a few notches. much more detailed. more liquidy. reminds me of my old extreme.

[digger945]

i wish i knew what all that meant.

You'll be fine just leaving evrything like you have it already soldered to the board, and hooking it up like you were gonna do anyways.

[crappyjones123]

steve, i actually found 2 mullard 12au7s with the square getter and marked as k61 b6h (supposedly the best ones) but one has some crazy hum and no sound in the left channel and the other has very marked channel imbalance in volume. nebby and i were getting super excited over it last night in chat. i was going to wait for the tube tester on monday but i just plugged them in to see how they were and was disappointed. the raytheon 12au7 seems to be ok.

[ironbut]

Having bad channel imbalance is pretty common with well used tubes now days. Lots of gear just uses one half of the twin triodes and so when that half is done, the whole tube is pretty much history. I do myself a favor and just toss tubes like that. Funny, I just pulled a Bugle Boy 6dj8 out of my preamp with the same issue and now I can't remember where I put it!

If you want to check out the sound with used tubes, be sure and buy them from a reputable dealer who has a stake in keeping his customers happy. Unless you have an eBay tube dealer that you trust, I'd stick with guys that have a web site. I don't think all of those guys that sell on "the bay" really do the testing they say they do. I've gotten some totally DOA tubes from ads with decent tests and lots of positive feedback.

[crappyjones123]

any comments on how to improve the build would be much appreciated.

[ATTACH=CONFIG]3599[/ATTACH][ATTACH=CONFIG]3600[/ATTACH][ATTACH=CONFIG]3601[/ATTACH][ATTACH=CONFIG]3602[/ATTACH][ATTACH=CONFIG]3603[/ATTACH][ATTACH=CONFIG]3604[/ATTACH]

[ironbut]

It's probably better if you wait till after the Speedball is installed. Heck, you never know,.. with a little tube rolling it could be perfect for your tastes!

[crappyjones123]

i meant the actual construction of the amp - soldering, wiring etc. what could i be doing better or different for that matter?

[Nebby]

If you have access to an IR thermometer, do you think you can measure the temperature of the transformer bell? I'm planning on painting it but want to make sure that it's not going to get too hot for the paint I'm going to use.

I don't have any advice for you as I haven't built mine yet >.> Most of the parts came in today though, so I should be able to get started once I find an anodizer/powdercoater to do the panel!

[ironbut]

Everything looks pretty tidy. It's really hard to see any particular solder joint without the ability to move the amp around to see it at different angles. As long as the solder flowed onto the different wires/terminals/components and the fillet is shiny and without any peaks, they should be fine.

You may have a little trouble fitting the CCS in between those output caps but where there's a will,..

With point to point connections, you may find that you have to move things around a little bit if you end up with some hum (from getting the signal wires from the RCA jacks to the pot too close to the filament wires) but that's something you have to experiment with yourself. It is worth taking the time to shift the signal wires around while you listen to to the amp with the volume maxed to find the best spot and use some cable holders to keep them there.

Once you install the Speedball, you should find a way to secure those caps since they do put a strain on their leads and the terminal strip they're connected to. And depending on how close the caps leads are to anything else, you might want to cover the leads with some tubing so they won't make any untoward connections. You can use the insulation from any spare wire you have.

[ironbut]

I don't have an IR thermometer but I just felt the bell on mine (which has been on for 10 hours) and it's not too hot. I used Rustoleum American Accents paint that I had lying around. As long as the paint can be used outdoors the temp should be no problem. I've put bare legs on lawn furniture that was way hotter than my bell is right now.

Just be sure and scuff up all the surfaces that will be painted with some sandpaper (that includes the edges) and put some good primer on it before you paint.

[crappyjones123]

i dont know if i am just a pansy but when i touch any part of the amp (the bell included) after its been on for ~1 hour (with music playing) i cant keep my fingers touching the metal for more than 3-4 seconds. anything potentially screwed up?