Bravo Audio - funny looking little tube amps - Page 127

Quote:

Originally Posted by Judge Buff 


Make sure the meter is set for 20V range. VOLTS not ohms. If this doesn't work, check for an internal fuse blowing. It happens...
I try to set the bias ~11V - 13V on both 6/12 settings. I have never set both sides at the same exact bias because I don't have a perfectly balanced tube. I get the voltages very close to each other, then I listen to get the output levels ~ the same strength per my old fart ears. Typically for me this means the R side gets tweaked up/down after I know the L side is approx loud enough for the volume level the amp is on. When the R output is approx as strong sounding as the L and I like the result, I quit. The better the pots, the easier the tweak. The two sides may be several V different... Let me repeat that. There may be a large difference in each side's voltage level. I've got tubes that may be 4 or 5 volts apart. One side may be 12.4V and the other 16V+.

This is why it's important to buy tubes that are close to balanced in triode emissions. The age and application of these used valves can cause big discrepancies. That's why many folks put a premium on mil-spec tubes as they are designed/made more rugged and why NOS is claimed all the time. If one triode is dying much faster than the other, you don't want the tube.

Sorry for the long post...

Mr. Buff,

  I bought a siemens 6922 gold pin, popped it in my indeed G3 and the left bias tops out at 12.69V. The other side goes 16+. So I set them both close to 11.5 but my question is should I return this tube and find a better one? Bought them on the bay from a fairly reputable seller and test results were good. They sound FANTASTIC but will life be shortened? Sorry about the multiple posts but I'm a noob 

FWIW, I rolled six tubes, including a RCA cleartop a Blackplate and Mullhard that I bought on Ebay but all of them suffered of channel imbalance. In some the imbalance is subtle, in others is really marked. That's why I stayed with the stock tube. I prefer sound balance over sound flavor.

Quote:

Originally Posted by aroldan 

FWIW, I rolled six tubes, including a RCA cleartop a Blackplate and Mullhard that I bought on Ebay but all of them suffered of channel imbalance. In some the imbalance is subtle, in others is really marked. That's why I stayed with the stock tube. I prefer sound balance over sound flavor.

As JudgeBuff stated, when buying tubes, you need to make sure you're buying balanced and tested tubes, usually sellers will mention such things on the description, sometimes the buyer will need to consult with the seller for more information because testing tubes for shorts, gas leaks and life rating is different to testing it and then hearing it. I have in the past spent over $150 on various 12AU7's before I got my Psvanes and Sophia's that were NOS grade but had channel imbalance and very loud background hums that burn-in did not fix.

The 4 greatest 12AU7 improvements that you can drop into the Bravo, Indeed or Sunrise and be blown away by the sound I have tried are the expensive Telefunken diamond base with gold grids (very very expensive), the grade a Psvanes and Sophias (best of the modern day production tubes but superb sound quality for value), Amperex Budgle Boys from Holland manufacturing plants and the military grade triple mica O getter 1950's RCA's.

Quote:

Originally Posted by stupidmop 

Is mouser the best place to source my parts? What brand capacitors and resistors should i be looking for? Thanks for any help

I get mine from a few reputable sellers on ebay but also deal on diyaudio forums. The shipping prices from mouser is ridiculous unless you're playing one massively large order. RS-online is also a good source but don't expect to come across the boutique branded caps (Elna Silmics, Cerafine, Blackgate NX's, Nichicon Muse series and other NOS vintage Philips Roederstein/BC, Sprague brands etc.)

Thanks DefQon. My search begins...

I'm going on H-F hiatus and I just wanted to give y'all something to mull over for a while.

I've been scarfing-up 6dj8s out of the Bay and I saw a listing for a combo of "Two ECC88/6DJ8 Radio Tubes Tested Made in Germany & UK" This is the picture of the tubes that was posted. The only picture. I'm thinking, "That's great! An IEC branded Mullard and probably a Siemens, since I can see 'made in Germany' on it."

The only real problem I saw was the vendor wanted $40 inc shipping for the pair. The Mullard appeared to have excellent graphics but the other looked rather nondescript... Read "unknown origin" since I didn't recognize the sparse labeling. The posting had a Best Offer available, so I low-balled a $27 offer, fully expecting it to be declined or ignored. The vendor came back with a counter of $31, so I'm thinking I'm on the right track with a decent Mullard & an unbranded Siemens. I started to jump on the $31, but I threw back a $30 offer and the vendor accepted it. The posting said that both tested "100%" which I was skeptical of, but I took a chance. Shipped with a 25% discount, I was expecting the Mullard to be the highlight of my dickering with this excellent AR vendor.

The tubes came today... free 3 day shipping! Awesome! The Mully sounds like a GB Mully. Warm as a tweed jacket and mids that are honey sweet. Decent top end and decent bottom. A good $15 tube and a Mully! When I got the other tube out of its box, this is what I found

It's a Tele! I totally missed the diamond outline. Even blowing it up, I couldn't see the diamond. But it sounds heavenly. Incredible range and soundstage. Balanced and detailed without grainy trebles or bloated bass. Really tight bass that thumps your ears and trebles that are distinct and clear. Oh yeah, this is easily the best Tele I have (of 4). It may not come out of this amp for a while. Heck, I may even get some new components and tinker on my G2 some more. But for right now, I'm just listening... and watching golf.

Take a chance. You never really know what karma holds for you until you do. There is no growth without risk, you know. Later...

Nice any number etched to the base of the tube?

There's something between the pins, but I'm not going to hunt down a magnifying glass to see what it is.

   I have more tubes than I'll ever be able to use, but it'more of a collecting hobby for me  Starting on 6080 and it's variants because I just ordered a crack 

Got all my parts ordered for my v2 mods. Changed the mosfets...great improvement. I read back through this thread till I was cross-eyed but it was invaluable. I know I'm late to the modding of this amp but I like modding things :p Should I put in some bourn trim pots? I've got a bunch laying around but I kinda like not having to bias, guess I'm lazy  They are def going in my g3 when I get it back, I don't like those trim pots.

  Gonna miss your entertaining posts Mr. Buff, enjoy watching some golf! I'm hittin the course in a couple weeks. Where I live we still have a bit o snow on the ground but a guy can dream.

Quote:

Originally Posted by stupidmop 

   I have more tubes than I'll ever be able to use, but it'more of a collecting hobby for me  Starting on 6080 and it's variants because I just ordered a crack 

 

Got all my parts ordered for my v2 mods. Changed the mosfets...great improvement. I read back through this thread till I was cross-eyed but it was invaluable. I know I'm late to the modding of this amp but I like modding things :p Should I put in some bourn trim pots? I've got a bunch laying around but I kinda like not having to bias, guess I'm lazy  They are def going in my g3 when I get it back, I don't like those trim pots.

 

  Gonna miss your entertaining posts Mr. Buff, enjoy watching some golf! I'm hittin the course in a couple weeks. Where I live we still have a bit o snow on the ground but a guy can dream.

Back for a few minutes... Get the best pots that will fit. I'm getting up a Digi-Key order to start modding my unused, virgin G2. I'll be replacing the pots on my Frankenamp, too, as they have seen better days. 2 years old and decrepit... I appreciate the props, Mop. BTW, you need to get a new name. Stupid "anything" is just wrong to be called IMHO... I guess it's better than "Richard Head," though.

Quote:

Originally Posted by DefQon 

Nice any number etched to the base of the tube?

In the diamond, there is a 5 in one end of an apex. If you turn the diamond 180* to the other apex, it looks like there is a very thin P. The 5 is definite. The P might just be an aberration in the glass. There isn't an aberration in the sound, though. Angels use these for choir performances...

Quote:

Originally Posted by Judge Buff 

Back for a few minutes... Get the best pots that will fit. I'm getting up a Digi-Key order to start modding my unused, virgin G2. I'll be replacing the pots on my Frankenamp, too, as they have seen better days. 2 years old and decrepit... I appreciate the props, Mop. BTW, you need to get a new name. Stupid "anything" is just wrong to be called IMHO... I guess it's better than "Richard Head," though.

 

In the diamond, there is a 5 in one end of an apex. If you turn the diamond 180* to the other apex, it looks like there is a very thin P. The 5 is definite. The P might just be an aberration in the glass. There isn't an aberration in the sound, though. Angels use these for choir performances...

dang I'm jelous e.e, although the way you described the tubes it sounds like my Clear Tops [I've yet to listen to all 4 of them] but they hace NICE tight bass great sound stage and nice highs! I enjoy them very much :D, If I hadn't BLOWN $200 on some stupid mmo [which I'm tellin you about so I NEVER DO IT AGAIN] I'd have mo cash for well HELL a freaking Project Sunrise 2 AND new tubes q.q. Still I should learn my tubes <3

Quote:

Originally Posted by Judge Buff 

Back for a few minutes... Get the best pots that will fit. I'm getting up a Digi-Key order to start modding my unused, virgin G2. I'll be replacing the pots on my Frankenamp, too, as they have seen better days. 2 years old and decrepit... I appreciate the props, Mop. BTW, you need to get a new name. Stupid "anything" is just wrong to be called IMHO... I guess it's better than "Richard Head," though.

 

In the diamond, there is a 5 in one end of an apex. If you turn the diamond 180* to the other apex, it looks like there is a very thin P. The 5 is definite. The P might just be an aberration in the glass. There isn't an aberration in the sound, though. Angels use these for choir performances...

 Thanks, Nice score on the tube! Stupid Mop is a Pearl Jam song. It's an inside joke amongst my friends and it just stuck. They all call me Mop. I didn't choose the lame nickname, it chose me Maybe I'll change it to just Mop if they'll let me.

Best,

Mop