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Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?

69.228.195.226
Posted on October 31, 2009 at 12:53:38
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 Looks to have a plate resistance of about 2K plus a bit at 200V biased at about 9V.

Could one use a 9V NiCad on the cathode?

Got a bunch of Tung Sol black plates and am wondering.
RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on October 31, 2009 at 22:30:26
kurt s
Audiophile

Posts: 78
Joined: October 12, 2009
 I've done it. And I've done it through a SE-PP IT to a 45 PP amp. Other alternatives are several. Try 7119, the most smooth, natural and neutral tube i know. might be a little boring to some. ECC99 is nice but goes through some rough sounding spots when wearing in. 7119 is a special tube to me. So silky smooth, so non-euphonic, so listenable. But can be a bit dull in the wrong amp.

There are some very good russian high gm triodes here to do the job, and they have harmonic richness for that special tube sound in the mids that are special. when i get money again, i want to try some. some stepping up, maybe up to 1:1.5 can be tolerated with this crowd of tubes to the 45.

I don't know about batteries anymore. So unreliable in general. one loss of contact and you practically blast out the speakers.

-kurt

RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on November 1, 2009 at 12:50:00
JANDG
Audiophile

Posts: 1564
Location: Washington State
Joined: February 27, 2004
 Kurt,
Can you explain this..? I run NiMH on the cathode of most my amps drivers & 1st stages in general. I have even used them in the grid of outputs,namely cordless construction tool batteries. Ya got me scared about my speakers...
Joe
Wisdom for today.........
A GREAT tube amp or speakers will allways be GREAT & bieng relevant today is irrelevant.
RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on November 1, 2009 at 17:18:58
kurt s
Audiophile

Posts: 78
Joined: October 12, 2009
 Don't be worried. It won't destroy the speakers. The only that happens with an intermittent contact from batteries, and battery holders are notorious for doing it occasionally, is the voltage will go from its mid-bias point and shoot to B+ in a spike transient. As that goes down the chain or just on the final stage, then there's max POW! on the speaker terminals that your amp can produce. These are usually low power amps and the speakers can take it, and it is just one pulse. But it can really annoy your ears and make you jump when it happens.

I had it repeatedly happen to me with my first phono stage and into very sensitive and loud playing horn speakers. A block away that POW! could be heard when it did that. Imagine having an ear in the horn. Out went the batteries and those poor contacts in the holders.

If you have good results with solid sure contacts, it's not an issue then.

-Kurt

I use the "pack" NiCads that have the taps spot welded to the terminals..., posted on November 1, 2009 at 18:36:07
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 I solder to that so as not to have to use a battery holder.


great! never saw those myself. nt, posted on November 2, 2009 at 10:28:35
kurt s
Audiophile

Posts: 78
Joined: October 12, 2009

"a bit dull in the wrong amp...", posted on November 1, 2009 at 09:22:25
Jim Dowdy
Manufacturer

Posts: 1168
Location: western North Carolina
Joined: July 22, 2000
 Thanks for the nudge Kurt.
I'll give the 7119 another shot...I thought they sounded "dull" compared to the 7044, but I've only experimented with them on one occasion.

The best smooth headphone driver tube i know, though, posted on November 1, 2009 at 10:21:05
kurt s
Audiophile

Posts: 78
Joined: October 12, 2009
 headphones tend to expose all details and they need detail and very smooth sound to keep listening to. so the best application i have used them for is my headphone amp with headphone OPT.

-kurt

RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on November 1, 2009 at 07:09:00
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 Darn, years ago I had the chance to pick up dozens of Aperex 7119's for dirt cheap.

They are not cheap anymore.

Smooth is the order of the day for me, as I use JBL 2441's for the mid horns and if harshness in anywhere in the chain, they reproduce it!

I use a NiCad battery for bias on the cathode of the 6SL7 SRPP driver on my current 300B amps. Got to be 6-8 years old and I might be wise to think to change it.
RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on October 31, 2009 at 20:14:17
Sam.
 A 76 will sound so much better than those SLNPT. :)

:-) /n, posted on October 31, 2009 at 21:39:18
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 n


RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on October 31, 2009 at 13:40:40
Eli Duttman
Audiophile

Posts: 6157
Location: Plainsboro, NJ
Joined: March 31, 2000
 Perusing a data sheet indicates your thinking is correct. FWIW, I make gm at about 8 mA./V. and IB about 20 mA.

TS' black plate 5687 enjoys a fine reputation. The idea rates to work out well, as long as the NiCd stack can take the 20 mA "trickle".

Eli D.
RE: Anyone here tried a 5687 as a driver tube through an IT to say a 2A3 or 45?, posted on October 31, 2009 at 16:11:42
danlaudionut
Audiophile

Posts: 3564
Location: Upstate NY
Joined: June 6, 2002
 Recommend a 9V NiMh that is
rated at at least 200mAH
and the more the better.

DanL
NiMh or NiCad?, posted on November 1, 2009 at 09:10:47
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 I can't remember what I have now as cathode bias battery in the 6SL7 driver of my 300B SET amps.

But after all of this time, perhaps a change is in order?

NiMh or NiCad?

I have heard Lithium Ion is a no-no.


RE: NiMh or NiCad?, posted on November 1, 2009 at 20:56:00
casouza
Audiophile

Posts: 486
Joined: March 18, 2008
 Ivan, most 6Sl7s run with 1.5 to 3V cathode bias, so probably your cathode batteries are different from the ones discussed in this thread.
The best way to find out is to measure the bias voltage under power.
Any NiCad is fine, since at 1.5 mA typical for a 6SL7, your battery will certainly be within the trickle charge "zone".

Mine run at about 1.5V..., posted on November 1, 2009 at 21:03:12
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 with one NiCad on the cathode of the bottom tube of a 6SL7 SRPP driver.

I substituted the NiCad for the resistor/capacitor which originally provided the cathode bias. It's a DIY/Kit amp.

But that was 6-7 year ago.

How long would a NiCad be expected to function in such a circuit?
RE: Mine run at about 1.5V..., posted on November 1, 2009 at 21:45:16
casouza
Audiophile

Posts: 486
Joined: March 18, 2008
 Hi
Yes, 1.5 V is about the correct charging voltage for a 1.2Volt NiCad.

At trickle charge (1/20 to 1/50 of their mA rating) NiCad batteries last very long.
To be on the safe side, I use as a yardstick the shelf life printed on the battery minus one year.

Make sure that the NiCad batteries are not near any heat sources. Heat is a battery's worst enemy.
Good luck

RE: NiMh or NiCad?, posted on November 1, 2009 at 09:16:25
danlaudionut
Audiophile

Posts: 3564
Location: Upstate NY
Joined: June 6, 2002
 Ivan

The 6SL7 uses such low current that the
battery will probably last many years.
I have a 9V that is on the 12B4 cathode
at 15mA and is good after over 2 years.
The more current the shorter the life span.
Measure the cathode voltage to see
if it is over 1.2V per cell.

DanL
RE: "I have a 9V that is on the 12B4 cathode at 15mA and is good after over 2 years."..., posted on November 1, 2009 at 09:46:25
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001

One like this?

At 15ma?


RE: "I have a 9V that is on the 12B4 cathode at 15mA and is good after over 2 years."..., posted on November 1, 2009 at 16:07:08
danlaudionut
Audiophile

Posts: 3564
Location: Upstate NY
Joined: June 6, 2002
 Ivan

YUP it was rated at 230mAH IIRC.

DanL
Yeah, that little tube sucks a lot of current..., posted on October 31, 2009 at 16:51:50
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 Biased at 9V or a bit more with a battery it ought to draw about 20ma or so.
RE: Yeah, that little tube sucks a lot of current..., posted on November 1, 2009 at 09:37:10
Michael Koster
Industry Professional

Posts: 585
Location: Bridgeville, CA
Joined: October 24, 2007
 20ma continuous is too much for a 150-200 mAH NiCd or NiMH 9V battery, The 6SL7 would be OK at a couple of mA but not 5687 at 20mA.

I use a rule of thumb of C/100 (Capacity/100) for charging rate and try not to exceed C/50. C/10 will overheat and bulge the cells, leading to high resistance failure after a hundred hours or 2.

If you only play the amp for short periods you might get away with it but I like things to be OK if I leave them on continuously.

DanL's suggestion to monitor the voltage per cell is a good plan and 1.2V is good for NiMH.

Cheers,

Michael
RE: Yeah, that little tube sucks a lot of current..., posted on November 1, 2009 at 16:13:45
danlaudionut
Audiophile

Posts: 3564
Location: Upstate NY
Joined: June 6, 2002
 Michael

I have a 9V running at 15mA and it has been
running fine for over 2 years now.

DanL
RE: Yeah, that little tube sucks a lot of current..., posted on October 31, 2009 at 19:52:43
bfranchuk@jetnet.ab.ca
 Set or PP?
I have a separate supply to give about 120V as B+ for a bias of -4V @ 13 ma. The main reason for the low voltage is the interstage transformer
is rated for 250V DC max as well as I want to keep the bias current
through the PP interstage as low as possible.
SET..., posted on October 31, 2009 at 20:02:13
Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001
 200V on the 5687 and bias on 2A3 grid at -45V?

That's about 250V.

What IT are you using?

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