6SL7 question
Jon Yaeger
Thanks in advance,
Jon
John Byrns
Jon Yaeger <jon...@bellsouth.net> wrote:
> What 9 pin tube is most like a 6SL7 in electrical characteristics? A 12AT7?
The plate resistance of the 12AT7 is way too low to be remotely like a
6SL7, I would say that the 12AX7, 7025, ECC83 family is a closer match
for the 6SL7.
Regards,
John Byrns
--
Surf my web pages at, http://fmamradios.com/
RS McCown
12AT7?
I believe 5751
Patrick Turner
not 12AT7.
12AY7 is very similar.
Patrick Turner.
Jon Yaeger
With that in mind, your suggestion about a 5751 ought to be spot on.
Jon
In article byrnsj-B4EC5E....@newsclstr03.news.prodigy.net, John
Byrns at byr...@sbcglobal.net wrote on 4/5/08 5:14 PM:
Jon Yaeger
in...@turneraudio.com.au wrote on 4/5/08 5:28 PM:
Thank you, Patrick!
Andre Jute
> In article <C41D6034.B9B70%jon...@bellsouth.net>,
> Jon Yaeger <jon...@bellsouth.net> wrote:
>
> > What 9 pin tube is most like a 6SL7 in electrical characteristics? A 12AT7?
12AT7 has a super precision sound but 12AT7 is a dumb sub for the
6SL7: totally different, much drier sound; 12AT is a sonic sub for the
6SN7. Always presuming that Yaeger has the discrimination to
understand that one uses the 12SL7 for its warmth and liquidity.
> The plate resistance of the 12AT7 is way too low to be remotely like a
> 6SL7, I would say that the 12AX7, 7025, ECC83 family is a closer match
> for the 6SL7.
>
> Regards,
>
> John Byrns
>
> --
> Surf my web pages at, http://fmamradios.com/
Nah, 12AX7/ECC83 will sound awful and probably need extra NFB to wash
off the 50% more gain, which aggravates the problem.
Sonically, in a quality amp the right 9-pin to sub for 6SL7 is 6072
but whether there are any 6072 that haven't yet migrated Eastwards is
another story. 12AY7 is a more common possibility, except that I don't
think it ever was all that common; super sound though. I built the
front end of a 211 with 12AY7 and was tres mucho impressed.
Of the 12xx7, the good-sounding ones are the 12AT7 and the 12AY7 --
and the 6CG7 (yeah, I know, it's a 6xx7), of which the first and the
last are 6SN7 sonic subs, and the 12AY7 is the only 9-pin 6SL7 sub
known to mankind. The 12AX7 is best left to guitar amps.
Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review
Alex
"John Byrns" <byr...@sbcglobal.net> wrote in message
news:byrnsj-B4EC5E....@newsclstr03.news.prodigy.net...
> In article <C41D6034.B9B70%jon...@bellsouth.net>,
> Jon Yaeger <jon...@bellsouth.net> wrote:
>
> > What 9 pin tube is most like a 6SL7 in electrical characteristics? A
12AT7?
>
> The plate resistance of the 12AT7 is way too low to be remotely like a
> 6SL7, I would say that the 12AX7, 7025, ECC83 family is a closer match
> for the 6SL7.
Also a Russian 6N2P. It has mu=100, as ECC83, but can not be wired for 12,6V
heater supply. The only pinout difference is that its 6.3V heater is
connected only to pins 4 and 5. Pin 9 is connected to an internal screen
separating the two triodes. This screen is a good feature to minimise
cross-talk, if the triodes are used in left and right channels respectively.
Regards,
Alex
West
"John Byrns" <byr...@sbcglobal.net> wrote in message
news:byrnsj-B4EC5E....@newsclstr03.news.prodigy.net...
IMHO 12AX7s sound soft and fat. The 12AT7s are better if you must have a
high mu min. tube. All 12AU, AY, AV, & AZ7s should be sent to the ham radio
guys. The SN7s, BL7s, & BX7s are some of the best driver tubes that do not
need negative feedback for the most part. If you have to have a high mu dual
triode, go for 6SL7GT. Single? 6K5GT. Got turned in this direction, a while
back from the Boss' suggestions, after I built a preamp using 3 12AX7s, CF
and was not totally satisfied with the sound.
Cordially,
west
Patrick Turner
Andre Jute wrote:
>
> On Apr 5, 10:14 pm, John Byrns <byr...@sbcglobal.net> wrote:
> > In article <C41D6034.B9B70%jon...@bellsouth.net>,
> > Jon Yaeger <jon...@bellsouth.net> wrote:
> >
> > > What 9 pin tube is most like a 6SL7 in electrical characteristics? A 12AT7?
>
> 12AT7 has a super precision sound but 12AT7 is a dumb sub for the
> 6SL7: totally different, much drier sound; 12AT is a sonic sub for the
> 6SN7. Always presuming that Yaeger has the discrimination to
> understand that one uses the 12SL7 for its warmth and liquidity.
>
> > The plate resistance of the 12AT7 is way too low to be remotely like a
> > 6SL7, I would say that the 12AX7, 7025, ECC83 family is a closer match
> > for the 6SL7.
> >
> > Regards,
> >
> > John Byrns
> >
> > --
> > Surf my web pages at, http://fmamradios.com/
>
> Nah, 12AX7/ECC83 will sound awful and probably need extra NFB to wash
> off the 50% more gain, which aggravates the problem.
>
> Sonically, in a quality amp the right 9-pin to sub for 6SL7 is 6072
> but whether there are any 6072 that haven't yet migrated Eastwards is
> another story. 12AY7 is a more common possibility, except that I don't
> think it ever was all that common; super sound though. I built the
> front end of a 211 with 12AY7 and was tres mucho impressed.
The 12AY7 has similar gain when used in a circuit to 6SL7 which was why
I suggested it.
6SL7, or 12SL7 etc at Ia = 2.3mA gives Ra = 44k, µ = 70, Gm = 1.6mA/V
12AY7 at Ia = 3mA gives Ra = 23k, µ = 40, Gm = 1.75mA/V.
For 12AY7, the gm falls and Ra rises and µ stays about the same as Ia is
lowered to
typical values used with 6SL7.
The gain from each tube with about 100k RL would be similar.
12AY7 is a more linear tube than 12AT7.
Perhaps it sounds better.
>
> Of the 12xx7, the good-sounding ones are the 12AT7 and the 12AY7 --
> and the 6CG7 (yeah, I know, it's a 6xx7), of which the first and the
> last are 6SN7 sonic subs, and the 12AY7 is the only 9-pin 6SL7 sub
> known to mankind. The 12AX7 is best left to guitar amps.
6CG7 has µ only 20, and electronically the same as 6SN7, so gain is to
low where
one wants the higher gain of around 30 to 40 with 6SL7.
Patrick Turner.
Patrick Turner
West wrote:
>
> "John Byrns" <byr...@sbcglobal.net> wrote in message
> news:byrnsj-B4EC5E....@newsclstr03.news.prodigy.net...
> > In article <C41D6034.B9B70%jon...@bellsouth.net>,
> > Jon Yaeger <jon...@bellsouth.net> wrote:
> >
> > > What 9 pin tube is most like a 6SL7 in electrical characteristics? A
> 12AT7?
> >
> > The plate resistance of the 12AT7 is way too low to be remotely like a
> > 6SL7, I would say that the 12AX7, 7025, ECC83 family is a closer match
> > for the 6SL7.
> >
> >
> > Regards,
> >
> > John Byrns
> >
> > --
> > Surf my web pages at, http://fmamradios.com/
>
> IMHO 12AX7s sound soft and fat.
Well, just how they sound to you or anyone else depends the brand and
age and how they are used and where.
> The 12AT7s are better if you must have a
> high mu min. tube.
Again the jury is still out trying to make up its mind.
12AT7 are both loved and hated by many, so are 6DJ8 and many other
toooobs.
> All 12AU, AY, AV, & AZ7s should be sent to the ham radio
> guys.
They'd only waste them.
The 12AU7 is a fabulous audio tube. The AY7 also is, and was developed
for low noise,
meaning low hum. The AV7 and AZ7 can be used for audio, but ain't,
because they suit RF use better.
> The SN7s, BL7s, & BX7s are some of the best driver tubes that do not
> need negative feedback for the most part.
Drivers, inputs, line stage amps, you name it, these tubes are kings.
> If you have to have a high mu dual
> triode, go for 6SL7GT.
Yeah, not bad, but where I can I'll use a 6CG7 instead.
> Single? 6K5GT. Got turned in this direction, a while
> back from the Boss' suggestions, after I built a preamp using 3 12AX7s, CF
> and was not totally satisfied with the sound.
6K5 is OK, but if ever I was wanting to have a 6K5, there wouldn't be
one around,
so I'd parallel a 6SL7....
Patrick Turner.
>
> Cordially,
> west
keithr
"Patrick Turner" <in...@turneraudio.com.au> wrote in message
news:47F85D31...@turneraudio.com.au...
>
>
> Again the jury is still out trying to make up its mind.
> 12AT7 are both loved and hated by many, so are 6DJ8 and many other
> toooobs.
The 12AT7 must the most microphonic tube known to man, the 12AU7 is far
preferred by most people of my aquaintance.
Keith
Andre Jute
Heh-heh!. That's not much of a gift to the hams. The 12AV7 and 12AZ7
are radio tubes anyway -- they already have them!
But I never said a word against the 12AU; I merely reported that Eric
Barbour, he of the otherwise infallibly impeccable taste, inexplicably
cannot stand the 12AU7. In my opinion 12AU7 is a grand-sounding tube
that goes hand in hand with the 12AT7 as the 6SL7 goes with the 6SN7,
a warm tube balancing a very precise one. Veteran designers had a few
rules of thumb that we could do well to resurrect, and one of the most
important was that you didn't use the same tube in two stages of your
amp because that would to multiply whatever it did badly until you
could hear it, and multiply whatever it did well until it became too
much of a good thing, which is also a betrayal of the music.
Another 9-pin tube I like is the 7044, which is a computer tube with a
good sound and dirt cheap (I got some of mine free by the ziplock-
bagful). Of course, it is no electrical sub for the 6SL7, but it is a
super low-voltage high-current tube, useful for drivers or even for a
microwatt amp in the same class as my T68bis 417A potato amp but
cheaper to build with as many parallel 7044 as you need to drive
sensitive speakers.
But these days I rarely use any 9-pin except the wonderful 417A. Last
amp I designed, to drive Stax electrostatic headphones to a 600V
differential, I automatically reached for the 6SL7/6SN7 combo and
never even considered anything else.
Mind you, I have five letters in my private mailbox twitting me more
or less gently for kicking the bejesus out of the "poor little" 12AX7
and reminding me that I often say my best design ever is the T113
Class A PP EL34 -- of which the conventional front end is 12AX7 input,
12AX7 splitter and 12AU7 driver... My excuse is that it was a
commercial design from the beginning, and it had to be designed with
what was available out of the RS catalogue. But bugger that for a
lark: I don't need an excuse. We'll just say a genius can design a
good amp with anything!
Patrick Turner
Microphony depends on the electrode rigidity in the tube.
A newly made one might be excellent, but an old one
that's done 10,000 hours in a guitar amp could be terrible.
Same exactly can be said of 12AU7 and many tubes.
A guy sent me a batch of about mainly used 60 x 12AU7 with an option to
buy for $3 each.
I tested every one, and 1/2 were either microphonic or too noisy, ie,
gassy,
or spluttery, or both, and I sent these all back to the guy. but I
purchased all the gooduns.
I have used a lot of 12AT7 and found them very good, ditto 12AU7.
The AT7 makes a good input tube for a power amp where gain is wanted,
and also for the second stage of a phono amp, because of the gain.
For the input of an MM phono, AT7 is OK also, but I do prefer fets these
days for
any phono input.
Patrick Turner.
>
> Keith
Patrick Turner
Well, now all you have to do is translate that to a formula
that predicts the distortions and it'll make sense to engineers.
There are a million conflicting descriptions about "The Sound" by those
who
rarely calculate anything or build anything.
Its pot luck whether they are right or not I have found.
>
> Another 9-pin tube I like is the 7044, which is a computer tube with a
> good sound and dirt cheap (I got some of mine free by the ziplock-
> bagful).
Manley Labs used those a bit.
These are a good tube, but sometimes just plugged into a circuit
where a better triode would have worked much better with the values
chosen.
So I don't like the 7044 because I never see them and you have to pay
lots for them.
I would prefer the 12BH7 or 6CG7 any day in most amps. If you try
running 7044 at
low Ia like the BH7 or CG7, they just don't go very well.
Of course, it is no electrical sub for the 6SL7, but it is a
> super low-voltage high-current tube, useful for drivers or even for a
> microwatt amp in the same class as my T68bis 417A potato amp but
> cheaper to build with as many parallel 7044 as you need to drive
> sensitive speakers.
Indeed the 7044 could be used as a power tube...
>
> But these days I rarely use any 9-pin except the wonderful 417A. Last
> amp I designed, to drive Stax electrostatic headphones to a 600V
> differential, I automatically reached for the 6SL7/6SN7 combo and
> never even considered anything else.
>
> Mind you, I have five letters in my private mailbox twitting me more
> or less gently for kicking the bejesus out of the "poor little" 12AX7
> and reminding me that I often say my best design ever is the T113
> Class A PP EL34 -- of which the conventional front end is 12AX7 input,
> 12AX7 splitter and 12AU7 driver... My excuse is that it was a
> commercial design from the beginning, and it had to be designed with
> what was available out of the RS catalogue. But bugger that for a
> lark: I don't need an excuse. We'll just say a genius can design a
> good amp with anything!
It ain't what ya got but how ya use it!
I prefer trioded EL84 to drive output tubes.
One EL84 in triode at 25mA is like 5 halves of a 6SN7 in parallel.
Same gain for 1/5 of the load value, and every bit as linear.
Ra about 2k.
Patrick Turner.
John Byrns
Patrick Turner <in...@turneraudio.com.au> wrote:
> It ain't what ya got but how ya use it!
>
> I prefer trioded EL84 to drive output tubes.
>
> One EL84 in triode at 25mA is like 5 halves of a 6SN7 in parallel.
>
> Same gain for 1/5 of the load value, and every bit as linear.
>
> Ra about 2k.
And only half the heater current!
legg
wrote:
>What 9 pin tube is most like a 6SL7 in electrical characteristics? A 12AT7?
>
>Thanks in advance,
>
According to K.A.Pullen you should be looking at:
5891
6113
6SU7
ECC35
12SL7
7F7
14F7
but that was in 1959.
Check out the manual for actual curves.
html
http://www.magma.ca/~legg/CCDM/CCDMp000iii.html
pdf (11M)
http://www.pmillett.com/Books/Pullen_Conductance.pdf
RL
Nick Gorham
> On Sat, 05 Apr 2008 16:58:28 -0400, Jon Yaeger <jon...@bellsouth.net>
> wrote:
>
>
>>What 9 pin tube is most like a 6SL7 in electrical characteristics? A 12AT7?
>>
>>Thanks in advance,
>>
>
>
> According to K.A.Pullen you should be looking at:
>
> 5891
> 6113
> 6SU7
> ECC35
> 12SL7
> 7F7
> 14F7
>
> but that was in 1959.
>
> Check out the manual for actual curves.
>
> html
> http://www.magma.ca/~legg/CCDM/CCDMp000iii.html
>
>
Err, I think they are all octal, not 9 pin.
--
Nick
keithr
>
>
> keithr wrote:
>>
>> "Patrick Turner" <in...@turneraudio.com.au> wrote in message
>> news:47F85D31...@turneraudio.com.au...
>> >
>> >
>> > Again the jury is still out trying to make up its mind.
>> > 12AT7 are both loved and hated by many, so are 6DJ8 and many other
>> > toooobs.
>>
>> The 12AT7 must the most microphonic tube known to man, the 12AU7 is far
>> preferred by most people of my aquaintance.
>
> Microphony depends on the electrode rigidity in the tube.
Exactly
> A newly made one might be excellent, but an old one
> that's done 10,000 hours in a guitar amp could be terrible.
Unless you either overdrive them like hell or physically kick them around
there is no reason why a tube should become microphonic with age. Old tubes
lose gain as their cathodes get used up, the harder you drive them the
faster it happens, but that should be all.
> Same exactly can be said of 12AU7 and many tubes.
>
> A guy sent me a batch of about mainly used 60 x 12AU7 with an option to
> buy for $3 each.
> I tested every one, and 1/2 were either microphonic or too noisy, ie,
> gassy,
> or spluttery, or both, and I sent these all back to the guy. but I
> purchased all the gooduns.
Gassy tubes are easy to tell fom the getter magnesium deposits losing their
metallic sheen and turning white.
> I have used a lot of 12AT7 and found them very good, ditto 12AU7.
>
> The AT7 makes a good input tube for a power amp where gain is wanted,
> and also for the second stage of a phono amp, because of the gain.
>
> For the input of an MM phono, AT7 is OK also, but I do prefer fets these
> days for
> any phono input.
Yech I wouldn't use a 12AT7 in any position where there is a lot of gain
involved either in that stage or after it. 12AT7s used to make good flip
flops back in the days before we used transistors for the job back in the
days before we used ICs for the job.
keith
Patrick Turner
John Byrns wrote:
>
> In article <47FA2565...@turneraudio.com.au>,
> Patrick Turner <in...@turneraudio.com.au> wrote:
>
> > It ain't what ya got but how ya use it!
> >
> > I prefer trioded EL84 to drive output tubes.
> >
> > One EL84 in triode at 25mA is like 5 halves of a 6SN7 in parallel.
> >
> > Same gain for 1/5 of the load value, and every bit as linear.
> >
> > Ra about 2k.
>
> And only half the heater current!
Bean counters in 1955 would be horrified with using a 6BQ5 instead of
say 1/2 6CG7. It cost several beans more.
The bean counter would see my plans as ruinously extravagant.
Two 6BQ5 for an LTP need 1.6 amps of heater power
and 50mA of anode current, an SS CCS at the cathode, and expnsive choke
loading with resistances
at the anode.
But who gives a shit for the limitational designs of 1955?
I don't.
I use what sounds well.
Today, a 6BQ5 costs about the same as 1/2 a hamburger with the lot,
or about 1/2 an hours worth of work by someone on AWE.
In 1955, it may have cost a day's pay, or 16 times as much in real
terms.
Then they brought out transistors, and after awhile you couldn't buy a
6BQ5.
The 6CG7 was nearly as expensive. The makers knew you were getting
value; two devices for the
price of one.
Now you can buy a PC processor chip with thousands of bjts within,
for the same real price as the 1955 6BQ5.
Patrick Turner.
Patrick Turner
Indeed we should be looking at the 1959 equivalents.
But I have never seen 5891, 6113, military numbered triodes,
6SU7, 7F7, or 14F7.
The only one I have seen around is the ECC35, the european number equal
to 6SL7.
If I want 6SL7 ype of gain and linearity, I might try the 12AY7,
made now in Russia.
Patrick Turner.
Bruce Seifried
<in...@turneraudio.com.au> wrote:
The 6SU7 is essentially a 6SL7 selected for service in DC coupled diff
amps, where the two halves need to be fairly well matched. Here in the
states you can still find them new for about $12 each. I believe this
applies to the 6188 as well. I haven't used them, but they probably
sound fine.
The 12AY7/6072 is one of my absolute favorite dual triodes. It is
unfortunate that they are no longer available, with the exception of
the Russian version, which is, in my opinion, dreck. The last batch of
twenty or so that I bought had a reject rate of over 60 percent,
primarily for excess gaussian noise, and wildly drifting bias point. I
wish someone else would take up the challenge of producing these, like,
maybe JJ??
-bruce seifried
Patrick Turner
keithr wrote:
>
> "Patrick Turner" <in...@turneraudio.com.au> wrote in message
> news:47FA2223...@turneraudio.com.au...
> >
> >
> > keithr wrote:
> >>
> >> "Patrick Turner" <in...@turneraudio.com.au> wrote in message
> >> news:47F85D31...@turneraudio.com.au...
> >> >
> >> >
> >> > Again the jury is still out trying to make up its mind.
> >> > 12AT7 are both loved and hated by many, so are 6DJ8 and many other
> >> > toooobs.
> >>
> >> The 12AT7 must the most microphonic tube known to man, the 12AU7 is far
> >> preferred by most people of my aquaintance.
> >
> > Microphony depends on the electrode rigidity in the tube.
>
> Exactly
>
> > A newly made one might be excellent, but an old one
> > that's done 10,000 hours in a guitar amp could be terrible.
>
> Unless you either overdrive them like hell or physically kick them around
> there is no reason why a tube should become microphonic with age. Old tubes
> lose gain as their cathodes get used up, the harder you drive them the
> faster it happens, but that should be all.
You are not quite right again. Repeated on-off cycles gradually loosens
up the
mica washers used to hold the elements of anode, grid, cathode all
tightly,
so they begin to rattle or sway around in the bottle.
Sure old tubes can sustain eventual decline in emission, and hence lower
gM,
but many suffer gassiness and loose electrode support before the cathode
looses emission.
>
> > Same exactly can be said of 12AU7 and many tubes.
> >
> > A guy sent me a batch of about mainly used 60 x 12AU7 with an option to
> > buy for $3 each.
> > I tested every one, and 1/2 were either microphonic or too noisy, ie,
> > gassy,
> > or spluttery, or both, and I sent these all back to the guy. but I
> > purchased all the gooduns.
>
> Gassy tubes are easy to tell fom the getter magnesium deposits losing their
> metallic sheen and turning white.
They only turn white when air is allowed into the tube.
But gettering in old tubes gradually combines with gas to form brown
dull edges
to the silvering, not whitness, which is the result of a sudden large
oxygen ingress through
cracked glass.
>
> > I have used a lot of 12AT7 and found them very good, ditto 12AU7.
> >
> > The AT7 makes a good input tube for a power amp where gain is wanted,
> > and also for the second stage of a phono amp, because of the gain.
> >
> > For the input of an MM phono, AT7 is OK also, but I do prefer fets these
> > days for
> > any phono input.
>
> Yech I wouldn't use a 12AT7 in any position where there is a lot of gain
> involved either in that stage or after it. 12AT7s used to make good flip
> flops back in the days before we used transistors for the job back in the
> days before we used ICs for the job.
That may be the case, but well chosen 12AT7 like many other tubes well
chosen
are fine for general audio use.
A batch of 6J6 I have were all very micophonic and despite the high gm
and theoretical suitability for an MC front end, they could not be used.
Patrick Turner.
>
> keith
West
Professor, I know that you do not use a tube tester, so could you tell
again how you determine the quality of 60 tubes without the use of this
venerated test instrument? Thanks.
west
>
>
>
>
> >
> > Keith
Patrick Turner
I do it very easily in a little test common cathode gain circuit
and with a following amp with gain = 1,000 and noise, microphony
and gain can all be measured simply, and as I have explained here about
5 times
during the last 4 years I suspect.
I did a heap of 6CG7 as well, but all those were nearly all quite new
and unused
and very much worth what I paid.
Patrick Turner.
>
> west
> >
> >
> >
> >
> > >
> > > Keith
Alex
"Patrick Turner" wrote:
> For the input of an MM phono, AT7 is OK also, but I do prefer fets these
> days for any phono input.
At some stage, for fun, I used "grounded source - grounded grid" cascode
configuration for the first stage of a MM pick-up. Fets were similar to
2N4416, matched by Vgscutoff and Io. 56ohm degenaration resistors were
connected in series with the sources. On top of them were grounded grid
medium-mu triodes, russian 6N6P. Voltage developed on the cathodes, about
+8V, was quite adequte for the FETs operation at 8mA. RIAA correction was
just a passive RC circuit from the anodes to ground. Power supply rail was
regulated and RC filtered. The circuit developed 200mV on the output.
Regards,
Alex