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HH Scott 399 Output Tubes Help Please.

B

brud

Active Member
Hello all

I would please like to check what output tubes the HH Scott 399 Receiver was designed to use - is it the 7189 OR 7189A.

I have recently recapped / rebuilt a 399 and the output tubes in the unit - original I believe are marker HH Scott 7189. These tubes are not well matched and I think have seen lots of use . So I decided to replace them with "newer" ones.
I recently purchased some 7189 tubes - however I notice the connections inside the bottom of the tubes connecting to the pins are different from the originals. They work but are they either 7189 or 7189A's .

Is there an easy way to test the pins and identify where they connect ie : Grid, Plate, etc.

The Russian tubes i purchased as 7189A'sd have written on them 8810 ????

Any help here would be much appreciated - I am concerned I have been sent fakes !!!
 
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The only difference between the two is the "A" has pin 1 connected to pin 2 internally. The plain 7189 has pin #1 omitted.

If the amp called for just the 7189, there may be things connected to pin #1 which would be used as a tie point. If it originally used a 7189A, just make sure there is nothing connected to pin #1 at the socket.

You can also look up the data sheets to tubes by searching "tube data sheets".
 
8810 is probably the date code. Guessing they are actually a 6P14P-EV, which is generally considered equivalent to a 7189. Some pics would help here.
 
The best way to determine if pin 1 and 2 are connected in your 6bq5/7189 is to either use your eyes or your meter and check. I've had data sheets lie to me about this very matter.
There was probably an established convention at one time, but with everything that's happened since, all bets are off. It pays to check each one for continuity.

Then you've got your russian 6bq5 subs...
They are gaining popularity and people love em. I'm not about to learn to read Cyrillic, just so I can determine that the Soviet data sheets also contain errors. I'm going to use the eyes god gave me, and know in 5 seconds flat.

"They're just so transparent"

I have heard from Jim Mcshane that the 6bq5/7189 from any given manufacturer is exactly the same tube, only with a different number (INDUSTRIAL NOMENCLATURE) printed on the outside. On a piece of that caliber, I'd be sourcing matched pairs. The manufacturer of those matched pairs is less important than the fact that they match.
I'd also flip the unit over and see what's connected at pin 1&2 and determine if I can run any output tube I want. Personally I'd probably find a way to make it take either tube.
I tend to like to fix a problem in such a manner that it never is again...
Am I going to remember to peer into the glass every time? Am I going to be able to remember what to look for when I do?

Best solution is to fix it right once.
Congratulations on an outstanding amp.

In terms of affordability
If you simply have got to try a 7189 of a certain brand, but cant source a quad, matched, under about 4Benjamin's, search for the 6bq5 from the same manufacturer. It's the same tube, put it in and you will have an electrically equivalent match that was made by the same people on the same tools in the same factory on the same production run, at 1/3 the price. Now you know.
 
Last edited:
cademan said:
The only difference between the two is the "A" has pin 1 connected to pin 2 internally. The plain 7189 has pin #1 omitted.

If the amp called for just the 7189, there may be things connected to pin #1 which would be used as a tie point. If it originally used a 7189A, just make sure there is nothing connected to pin #1 at the socket.

You can also look up the data sheets to tubes by searching "tube data sheets".
Click to expand...
Thankyou
I have checked the original tubes that cane with the unit , they do have pins 2 and 2 connected ( checked with dvm).
On the output sockets there is NOTHING connected to this pin . All the other 7189 tubes i have do not have pins 1 and 2 connected - SO is it ok to use these tubes “plain 7189” in my HH Scott 399 .
 
Im
brud said:
Thankyou
I have checked the original tubes that cane with the unit , they do have pins 2 and 2 connected ( checked with dvm).
On the output sockets there is NOTHING connected to this pin . All the other 7189 tubes i have do not have pins 1 and 2 connected - SO is it ok to use these tubes “plain 7189” in my HH Scott 399 .
Click to expand...
sorry meant to say pins 1 and 2
 
brud said:
T

I also meant to say nothing connected to pin 1 of the output tube socket - i should have read it before i posted
Click to expand...
If there is nothing connected to Pin 1 on any of the output tube sockets you can use any of the various types.
 
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