807 vs. 1624 tetrode ?

[Miles Prower]

Originally posted by coresta
Yes, just add some OA2 or OB2 in screen, these are more sexy than zeners and look at AudioResarch or ... Western Electric schematics Happy listening

Here is what I built for a project.

[coresta]

Great !

[Jaap]

Would it be possible to have a 807 or 1624 PSE amp in pentode mode with local feedback and a mosfet regulated screensupply

driver is D3a in a IT

[Shoog]

This configuration works very well ala the RH807. It works so well infact, you can forget the screen regulation and simply strap it to the plate. You can also expect a lower output impedance than a triode strapped 807.

Shoog

[rcavictim]

Originally posted by Shoog
This configuration works very well ala the RH807. It works so well infact, you can forget the screen regulation and simply strap it to the plate. You can also expect a lower output impedance than a triode strapped 807.

Shoog,

I know what an 807 is but what is a RH807 ????

Sure wish had some of those 1624's to work with! I suspect they'd be a delicious sounding driver into an I.T. strapped as a triode with DC heat. I did this with a 1619 in my 809 A2 SET amp and it has real magic tone but the metal bottle doesn't have the same sex appeal of a glass ST bulb.

[korneluk]

Originally posted by rcavictim


I know what an 807 is but what is a RH807 ????

Follow the link:

http://www.tubeaudio.8m.com/807/807.html

[Bandersnatch]

hey-Hey!!!,
The 1624 is quite similar to type 1619. The 1619 is DH( at 2.0A/2.5V) and behaves more like a 6V6 than a 6L6. It has more plate dissipation, but since we can't see through the steel bottle, running it to its maximum ratings is not a good idea. I found the 1619 happiest at around 16W plate dissipation. The 1624 data also ref's the 1619 curves and they're quite different from a 6L6/807 set.
cheers,
Douglas

[rcavictim]

Originally posted by Bandersnatch
hey-Hey!!!,
The 1624 is quite similar to type 1619. The 1619 is DH( at 2.0A/2.5V) and behaves more like a 6V6 than a 6L6. It has more plate dissipation, but since we can't see through the steel bottle, running it to its maximum ratings is not a good idea. I found the 1619 happiest at around 16W plate dissipation. The 1624 data also ref's the 1619 curves and they're quite different from a 6L6/807 set.
cheers,
Douglas

As a driver I am running my 1619's easy and at only 200 volts, and also slightly starved filament as well. Steve Bench did some tests on this tube and discovered that the THD dropped to vanishing levels in starved filament mode. Finding non-microphonics out of my small batch of NOS was a challenge however. These were designed as a push-to-talk RF transmitter tube with cold filament between gabs to save the batteries.
I wanted all DHT in my SET amp adventure without spending money on boutique or mainstream DH triodes.

[Miles Prower]

Originally posted by Bandersnatch
The 1624 data also ref's the 1619 curves and they're quite different from a 6L6/807 set.

That's the whole point. The 1624 is not a DH 807, despite your seeing that claim all the time. As an audio final, the 1619/1624 doesn't work so swell in Class AB1. At Vpp= 600Vdc, Vsgsg= 300Vdc, the Vgk= 0 line hits the plate cuirrent at less than 100mA. Drawing a Class AB1 loadline, I got something like 10W of output, which is ridiculous for the operating voltages. Keeping that plate current down was desireable for a type that was probably going to be running in Class B or Class C since it can be cut off without excessive grid bias.

From the 1624 spec sheet:

Driver stage should be capable of supplying the grids of the Class AB2 stage with the specified peak grid voltage at low distortion. The effective resistance per grid should be below 500R and the highest effective impedance at the highest desired resonse frequency should not exceed 700R. [...]

With zero impredance driver and perfect regulation plate circuit distortion does not exceed 2.0%

This is obviously one of those RF types designed for a specific RF application that also happened to have decent linearity for audio. However, it only works as a Class AB2. Of course, zero drive impedance and perfect regulation is not exactly practical. This statement does, however, point the way: use a MOSFET source follower and you'll get closer than was ever possible back when this type was designed.

If you need the ~80W that this type and the Class AB2 807 can produce, it's not a bad way to go.

Besides, 1624s have that funky retro look, and the glowey bottle goodness.

[Tony]

Originally posted by Bandersnatch
hey-Hey!!!,
The 1624 is quite similar to type 1619. The 1619 is DH( at 2.0A/2.5V) and behaves more like a 6V6 than a 6L6. It has more plate dissipation, but since we can't see through the steel bottle, running it to its maximum ratings is not a good idea. I found the 1619 happiest at around 16W plate dissipation. The 1624 data also ref's the 1619 curves and they're quite different from a 6L6/807 set.
cheers,
Douglas

i thought no one would point this out...been watching this thread closely as i have sources of these tubes....


Hi Douglas,

the datasheet for the 1619 and 1624 shows operating points for class AB2, are these tried and tested?

Also, like in the case of 4D32, class AB2 seems to shows lower distortion percentage, any comments please....thanks...