[sortech]

I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
6V6's or 6BQ5's wired in parallel?

[Patrick Turner]

sortech wrote:

I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
6V6's or 6BQ5's wired in parallel?


Whenever you want to get data on a tube try one of the best sources at

http://tdsl.duncanamps.com/tubesearch.php

The 1625 is electronically the same as an 807, which is the same as a
6L6 and screen voltage rating is 300V, not 450v as it is for later
versions of 6L6GC.

The 1625 has 12.6V x 0.45A heaters.

You cannot use a pair of 6V6 or 6BQ5 with the same highish Ea used with
1625, 807, 6L6.

You could use a quad of 6V6 or 6BQ5 instead of a pair of 1625 etc with
the same load value, but with Ea max at about 300V and Eg2 at about
270V.

Load a-a for PP would be about 4k to 6k, and max class A PO will be
about 20W, with max class AB PO about 45W.

Patrick Turner.

[sortech]

Patrick Turner wrote:

sortech wrote:
I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
6V6's or 6BQ5's wired in parallel?


Whenever you want to get data on a tube try one of the best sources at

http://tdsl.duncanamps.com/tubesearch.php

The 1625 is electronically the same as an 807, which is the same as a
6L6 and screen voltage rating is 300V, not 450v as it is for later
versions of 6L6GC.

The 1625 has 12.6V x 0.45A heaters.

You cannot use a pair of 6V6 or 6BQ5 with the same highish Ea used with
1625, 807, 6L6.

You could use a quad of 6V6 or 6BQ5 instead of a pair of 1625 etc with
the same load value, but with Ea max at about 300V and Eg2 at about
270V.

Load a-a for PP would be about 4k to 6k, and max class A PO will be
about 20W, with max class AB PO about 45W.

Patrick Turner.
Thanks Patrick, so if I got you right I could use a pair of 1625 in
place of 4 6BQ5's plates 310V and screens 290V. The drivers are 12AX7
plate loaded. Do you think this will drive them ok its a AB1 amp.
Still hope someone can tell me the settings to test 1625 on the Hickok 539b.

[[email protected]]

On Jun 24, 7:00*am, sortech wrote:
Patrick Turner wrote:

sortech wrote:
I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
* 6V6's or 6BQ5's wired in parallel?

Whenever you want to get data on a tube try one of the best sources at

http://tdsl.duncanamps.com/tubesearch.php

The 1625 is electronically the same as an 807, which is the same as a
6L6 and screen voltage rating is 300V, not 450v as it is for later
versions of 6L6GC.

The 1625 has 12.6V x 0.45A heaters.

You cannot use a pair of 6V6 or 6BQ5 with the same highish Ea used with
1625, 807, 6L6.

You could use a quad of 6V6 or 6BQ5 instead of a pair of 1625 etc with
the same load value, but with Ea max at about 300V and Eg2 at about
270V.

Load a-a for PP would be about 4k to 6k, and max class A PO will be
about 20W, with max class AB PO about 45W.

Patrick Turner.

Thanks Patrick, so if I got you right I could use a pair of 1625 in
place of 4 6BQ5's plates 310V and screens 290V. The drivers are 12AX7
plate loaded. Do you think this will drive them ok its a AB1 amp.
Still hope someone can tell me the settings to test 1625 on the Hickok 539b.- Hide quoted text -

- Show quoted text -

E-mail me off-group. I have the 539B and the extra books that go with
it. I believe your tube is listed in one of them.

pfjw at aol dot com

Peter Wieck
Melrose Park, PA

[Patrick Turner]

sortech wrote:

Patrick Turner wrote:

sortech wrote:
I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
6V6's or 6BQ5's wired in parallel?


Whenever you want to get data on a tube try one of the best sources at

http://tdsl.duncanamps.com/tubesearch.php

The 1625 is electronically the same as an 807, which is the same as a
6L6 and screen voltage rating is 300V, not 450v as it is for later
versions of 6L6GC.

The 1625 has 12.6V x 0.45A heaters.

You cannot use a pair of 6V6 or 6BQ5 with the same highish Ea used with
1625, 807, 6L6.

You could use a quad of 6V6 or 6BQ5 instead of a pair of 1625 etc with
the same load value, but with Ea max at about 300V and Eg2 at about
270V.

Load a-a for PP would be about 4k to 6k, and max class A PO will be
about 20W, with max class AB PO about 45W.

Patrick Turner.
Thanks Patrick, so if I got you right I could use a pair of 1625 in
place of 4 6BQ5's plates 310V and screens 290V. The drivers are 12AX7
plate loaded. Do you think this will drive them ok its a AB1 amp.
Still hope someone can tell me the settings to test 1625 on the Hickok 539b.

The anode voltage supply can be higher with 1625 if you wish to replace
existing 6BQ5. But screens need to stay lower under 300V.
So you could have B+ at 400V. Bias each 1625 for about 40mA. I'm
assuming you have fixed bias.

Don't forget the heaters for 1625 are 12.6V, not 6.3V, so maybe you need
a filament tranny.
You can use 25.2V at 0.45A with the heaters in series for the pair of
1625. So if you find a cheap tranny with say 25 to 30V winding rated at
1A for total 30VA rating then that can be used OK.

I don't have a tube tester. I test tubes in real amp circuits, and Iam
quick with the volt meter to measure the Ia during biasing in case there
is a dud which conducts too much Ia, and then you have to turn off the
amp quick. With multiple OP tubes I always have a 10 ohms R rated for 5
W between cathode 0V or chassis so that bias current is safely checked.

If you already have 6BQ5, the grid voltage bias will have to be much
more negative for the 1625, so you will have to alter your bias circuit.

If ya change one thang, ya hafta change another, and becoz ya changed
that thang, ya hafta change anothar, and so on.

Patrick Turner.

[[email protected]]

On Jun 24, 7:00*am, sortech wrote:
Patrick Turner wrote:

sortech wrote:
I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
* 6V6's or 6BQ5's wired in parallel?

Whenever you want to get data on a tube try one of the best sources at

http://tdsl.duncanamps.com/tubesearch.php

The 1625 is electronically the same as an 807, which is the same as a
6L6 and screen voltage rating is 300V, not 450v as it is for later
versions of 6L6GC.

The 1625 has 12.6V x 0.45A heaters.

You cannot use a pair of 6V6 or 6BQ5 with the same highish Ea used with
1625, 807, 6L6.

You could use a quad of 6V6 or 6BQ5 instead of a pair of 1625 etc with
the same load value, but with Ea max at about 300V and Eg2 at about
270V.

Load a-a for PP would be about 4k to 6k, and max class A PO will be
about 20W, with max class AB PO about 45W.

Patrick Turner.

Thanks Patrick, so if I got you right I could use a pair of 1625 in
place of 4 6BQ5's plates 310V and screens 290V. The drivers are 12AX7
plate loaded. Do you think this will drive them ok its a AB1 amp.
Still hope someone can tell me the settings to test 1625 on the Hickok 539b.- Hide quoted text -

- Show quoted text -

Fil. Selectors Bias Shunt Press Range Min.
Notations
12.6 HR-4036-0 6.0 -- P4 D
2400 CAP = P.



Peter Wieck
Melrose Park, PA

[Bret L]

The 1625 is an 807 with a 12 volt heater and a seven pin base and may
be used exactly where any 807 may be used electrically.

If one uses ultralinear connection one may operate the screens at
plate voltage provided plate voltage is not over 450 or so and a
screen resistor of appropriate value is used. In straight triode
connection this is also essentially true, at a somewhat lower voltage.
I believe the Williamson ran them at roughly 400. When run as a
straight pentode one must adhere to the lower figure in the manuals,
but a B+ of over 600 volts is permissable. At this higher voltage a
higher load impedance is called for. In RF service many transmitters
and exciters ran the 807 at over 700 volts with little ill effect.

[sortech]

wrote:
On Jun 24, 7:00 am, sortech wrote:
Patrick Turner wrote:

sortech wrote:
I have a bunch of 1625 tubes I would like to use in audio amps. I tried
to test them with my Hickok 539b but found no listing on my chart. Does
anyone know the settings for this tube? Also is it true that this tube
is much the same as a 6L6 and can be used in the same circuits with a
different socket and heater voltage? Could I substitute it for a pair of
6V6's or 6BQ5's wired in parallel?
Whenever you want to get data on a tube try one of the best sources at
http://tdsl.duncanamps.com/tubesearch.php
The 1625 is electronically the same as an 807, which is the same as a
6L6 and screen voltage rating is 300V, not 450v as it is for later
versions of 6L6GC.
The 1625 has 12.6V x 0.45A heaters.
You cannot use a pair of 6V6 or 6BQ5 with the same highish Ea used with
1625, 807, 6L6.
You could use a quad of 6V6 or 6BQ5 instead of a pair of 1625 etc with
the same load value, but with Ea max at about 300V and Eg2 at about
270V.
Load a-a for PP would be about 4k to 6k, and max class A PO will be
about 20W, with max class AB PO about 45W.
Patrick Turner.
Thanks Patrick, so if I got you right I could use a pair of 1625 in
place of 4 6BQ5's plates 310V and screens 290V. The drivers are 12AX7
plate loaded. Do you think this will drive them ok its a AB1 amp.
Still hope someone can tell me the settings to test 1625 on the Hickok 539b.- Hide quoted text -

- Show quoted text -

Fil. Selectors Bias Shunt Press Range Min.
Notations
12.6 HR-4036-0 6.0 -- P4 D
2400 CAP = P.



Peter Wieck
Melrose Park, PA
Thanks for the info Peter.
I got the amp to work using my lab power supply for the heaters. The amp
has a 24VDC supply that was uses for some external unit it is from a
baldwin organ. I wonder how I can be sure it will handle the current. I
put a resistor load on it and it went from 27v no load to 24v with a .6
amp load. Does this show it can handle the current? also it takes about
2vac to drive the amp to full power and I amp debating if I should add a
gain stage in front of the phase splitter or two after the splitter
(12au7) this would mean changing the feed back resistors. Would this
mess up some magic and cause problems? I wonder if 12ax7 splitter that
drove the original 6bq5's has current to drive the 1625's.

[[email protected]]

On Jun 26, 2:28*am, sortech wrote:

I got the amp to work using my lab power supply for the heaters. The amp
has a 24VDC supply that was uses for some external unit it is from a
baldwin organ. I wonder how I can be sure it will handle the current. I
put a resistor load on it and it went from 27v no load to 24v with a .6
amp load.

And the 1625 requires 0.45A at 12.6V, so your supply will feed two (2)
tubes at the correct voltage - BUT - that does not mean it can handle
the current. Does it heat up under the dummy load? It will be very
marginal at best and you are asking for trouble down the line.

Does this show it can handle the current?

It also it takes about
2vac to drive the amp to full power and I amp debating if I should add a
gain stage in front of the phase splitter or two after the splitter
(12au7) this would mean changing the feed back resistors. Would this
mess up some magic and cause problems? I wonder if 12ax7 splitter that
drove the original 6bq5's has current to drive the 1625's.


Short answer is "Yes" on the 12AX7. Along those lines, look for a
Sylvania Mil.Spec. 5751 - as a rule, less microphonic and in my
opinion, a much cleaner-sounding tube. Also as there is no 'aura'
around that tube usually availble at a much lower price.

There is virtue in simplicity. Nor is there any magic in resistors
despite rumors to the contrary. You will solve the problems as you go
along should they arise.

Peter Wieck
Melrose Park, PA