Static electricity built up where? I had always thought (could be wrong) that pin 1 was connected to the can on the original metal 5U4's but connected to nothing on the later glass bottled versions.
Looking at a couple of samples that I have, it looks like the pin goes to the bottom mica, but no further....
Looking at a couple of samples that I have, it looks like the pin goes to the bottom mica, but no further....
the 6BQ6 is a great tube for P-P amps. ham radio operators have been using them for years in parallel P-P linear amps for many years. when i was growing up, there was a surplus of horizontal output tubes, and you could buy them for about a dollar each.
these tubes were designed primarily for pulse operation with a short duty cycle and high peak plate voltage. i have seen a few over the years that had melted funnels in the sides of the envelope, so even as horizontal pulse amplifiers, they could run into the red glow region (probably were run with grid leak bias, and the tube overheated when the horizontal oscillator quit).
these tubes were designed primarily for pulse operation with a short duty cycle and high peak plate voltage. i have seen a few over the years that had melted funnels in the sides of the envelope, so even as horizontal pulse amplifiers, they could run into the red glow region (probably were run with grid leak bias, and the tube overheated when the horizontal oscillator quit).
unclejed613 said:
Do tell. I figured they'd make a pretty good RF final, but never saw this done. It's always been the bigger HD VTs: 6KD6, 6LQ6, etc. that were used for RF finals. I did come across a couple of AM modulators that used 6BQ6s, but nothing Hi-Fi.
You still can.
However, based on how these sound, that may not last.Probably didn't include any hold-down bias. Lots of ham rigs were built like that too. Lose the master oscillator and
unclejed613 said:
I'm really interested on these tubes, just to build a guitar amp, not audio (nevermind some THD). I have seen 6DQ6 schematics, it seems they're similar to BQ's, as someone tolde me. Check out these schematics:
http://www.ozvalveamps.elands.com/playmaster/playmast_116.jpg
http://www.ozvalveamps.elands.com/goldentone/gt1755-1759cct.gif
http://www.ozvalveamps.elands.com/goldentone/1764_bassmasterhp.gif
could these tubes be a better alternative to well known audio output tubes as EL34's and 6L6's, for example?
slideman82 said:
The 6DQ6 has a higher Pd (18W v. 12W) than the 6BQ6, and likes a lower Rl. They are similar in that both types have a low Vsgk rating. You'll get more Po from the 6DQ6. (However, the nearly 40W that I get from the 6BQ6 serves my purposes just fine.)
My experience with 6BQ6s shows that these sound just as good as the 807/6L6 as Hi-Fi audio finals. For guitar amp use, the HD VTs would be better since horizontal deflection service is a good deal more demanding than audio amplification. They'd better stand the abuse that axemen frequently inflict on their amps.
it is strange...
I agree... I always thought it was odd what people pay for the 6V6 (especially before it went back into production outside the us) when the 6K6 can be had for pennies... and in most circuits will drop right in and run fine. In fact, many of you should take a look on ebay now if you want a great old stock tube that you can get 10 for $5 regularly... I have a ton of them I've picked up for little guitar amps - and as long as i have them, there's no way im paying current prices for 6V6's -- $20-40 New pair -- $40-60each NOS singles at tubedepot right now...
I agree... I always thought it was odd what people pay for the 6V6 (especially before it went back into production outside the us) when the 6K6 can be had for pennies... and in most circuits will drop right in and run fine. In fact, many of you should take a look on ebay now if you want a great old stock tube that you can get 10 for $5 regularly... I have a ton of them I've picked up for little guitar amps - and as long as i have them, there's no way im paying current prices for 6V6's -- $20-40 New pair -- $40-60each NOS singles at tubedepot right now...
Re: it is strange...
Welcome to the wonderful world of audiophoolery. The 6K6 is a bit thinner on the Pd, and has nominally higher THDs. However, you can work around that, if it matters in the first place. THD doesn't tell all. So you might be better off using these instead. There are also quite a few TV and RF tubes (small signal and large signal) that are overlooked, but would probably make great sounding amps.
It's just that they don't have that magical, audio voodoo, which is what those fat price premiums really buy you.
Cycline3 said:
Welcome to the wonderful world of audiophoolery.
The 6K6 is a bit thinner on the Pd, and has nominally higher THDs. However, you can work around that, if it matters in the first place. THD doesn't tell all. So you might be better off using these instead. There are also quite a few TV and RF tubes (small signal and large signal) that are overlooked, but would probably make great sounding amps.It's just that they don't have that magical, audio voodoo, which is what those fat price premiums really buy you.
Miles Prower said:
I know BQ's have lower rattings and transconductance tha DQ's, but I've read they have the same Ri, 20k... am ]I wrong? Your design looks interesting, but it hard to find those 6FQ7. i was looking for something similar, but using a more common TT, as a 12AX7 or T7, or even U7. If I could get how, I'll do the maths for an ECC189 (if this works right as a phase splitter), I've already found in a forum about calculing the gain depending on the triodes you have. I'm a rookie in all this about tubes, actually I' still a virgin! What I wanted to build is a guitar amp using ECC84 in the preamp section, and 6BQ6 as output.
By the way, I love Sonic 3! Full o' colours!
slideman82 said:
The 6CG7 is directly compatable with 6FQ7s. Electronically, the 6SN7 is identical, but comes in an octal format, not the nine pin mini bottle. The 12BH7A could also work, though its u-factor is somewhat lower, and will require a somewhat higher bias. You could also substitute a 12AU7 there. Since this is a follower, the poorer sonics of the 'AU7 shouldn't matter so much. (Although I can't say I recommend it) I would definitely avoid a 12AX7 for this since that type lacks the current handling capability of the other types.
I'm sure that there are more than one type that'll work with the same topology. It'll be a question of picking Q-Points.
Yep, sure is.
Better how? In one sense, these 6BQ6s are better than 6L6s. When run open loop, you don't get the same sort of harshness to the upper mids and highs. However, apply NFB and it doesn't matter since that eliminates the problem. All the types that can be run open loop seem to be either triodes or pseudotriodes. All pentodes need help from NFB (either local and/or global) in order to sound their best.
slideman82 said:
It's one of those areas where there doesn't seem to be any agreement. Some say that 12AU7s aren't very good for audio. Others say the opposite. Of course, the 12AU7 seems to have been used far more often for RF and quasi-digital circuits (multivibrators, R-S latches, Schmidt triggers, monostables) than for audio. Take that for what it's worth. As for 6FQ7/6CG7/6SN7, I've used these and they seem to work just fine for audio applications.
As for THD specs, the EL34 and 6L6 have the same THD= 1.8% in Class AB1. THD doesn't tell all. If that 1.8% is all high order harmonics for one type, and all low order for another, the one producing less high order harmonics is going to sound better before adding NFB. I haven't tried EL34s, but have tried the 6L6/807, and found that by adding NFB they work just great. Do the design work right, and it'll sound good.
