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 Post subject: Is an 7189 Tube Replaceable With an E84L Tube? **Correction*
PostPosted: Oct Tue 26, 2010 11:54 pm 
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Looking for some backup power tubes for my Scott 222C Amp. It had four 7189 Telefunken tubes when I received it.

Is an E84L tube a direct drop-in replacement for the 7189?

Note: Not EL34 or EL84, but E84L


Thanks,

Wb


Last edited by Wolfbane on Oct Wed 27, 2010 12:02 am, edited 1 time in total.

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 Post subject:
PostPosted: Oct Tue 26, 2010 11:58 pm 
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Definitely not, but you might consider an EL84, or the low budget E84L.
Also 6BQ5, and a few others I can't think of off hand.
Mark D.


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 Post subject:
PostPosted: Oct Wed 27, 2010 12:06 am 
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Mark,

I'm told E84L is okay, but not EL84 as a replacement for the original 7189 tubes.

With Scott long gone I've been doing Google searches and coming up with all kinds of conflicting info on this.

Wb


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PostPosted: Oct Wed 27, 2010 12:45 am 
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Wolfbane, you'll get all kinds of conflicting information on a Google search concerning almost any tube question. I'll try to help.

The E84L is the foreign equivalent of an industrial type, the 7320. This is a power pentode with the same pin-out as a 7189 and a 6BQ5. You may find data sheets on all three tubes here:

http://frank.pocnet.net/

The three tubes are roughly comparable, but not closely so. The 7189 may substitute safely for a 6BQ5, but not vice versa. Neither is recommended as a direct substitute for a 7320 (and vice versa).

In service as class A or AB1 amplifiers, the 7189 carries generally the highest ratings of the three (especially in terms of plate voltage).

In most equipment designed for 7189's, both 6BQ5 and E84L would very likely be operating at or beyond redline. Thus, significant alterations to the equipment would very likely be needed before either 6BQ5 or 7320 could be safely used.

Some chaps that I know and trust recommend a Soviet tube, the 6P14P-ER, as a direct substitute for the 7189. They claim excellent results, but the tube is apparently getting about as hard to find as 7189 tubes are.

I personally would be very leery of using anything other than a 7189 in a 7189 socket.

Hope this helps :),

Larry

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 Post subject:
PostPosted: Oct Wed 27, 2010 1:31 am 
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Not wanting to start anything here, but there is another side.
The SA-16 in my thread below has 7189's in it. However, it states right on the chassis that one can use 7189/EL34/6BQ5.
So I suspect that it all depends on how hard the tubes are being driven. If running in Ultra Linear, that narrows the field a lot right there. And high current would too.
I know nothing about his Scott amp, so am not prepared to say. But maybe a look at a schematic would tell whether yes or no?
Mark D.


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 Post subject:
PostPosted: Oct Wed 27, 2010 1:58 am 
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Mark, I looked at your thread once again.

You noted yourself that the SA-16 is an EL84 amp.

If it was designed for 6BQ5/EL84's, then of course it can be used with either 6BQ5/EL84's or 7189's. 7189's are legitimate and safe substitutes for 6BQ5/EL84's, as I noted above.

But not vice versa.

That is why a unit expressly designed for 7189's is another matter altogether. The Scott 222-C is such a unit.

Larry

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 Post subject:
PostPosted: Oct Wed 27, 2010 2:20 am 
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The 222C uses 420V on the output tubes, so 7189s must be used. The Russian 6P14EB is a good substitute - I've used them in a Lafayette receiver at 420V. These are also sold as EL84M - Jim McShane has them at 4 for $49.50 - http://pages.prodigy.net/jimmcshane/tubes.htm


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 Post subject:
PostPosted: Oct Wed 27, 2010 2:35 am 
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Larry,

Thanks for the tube link. I've book marked it.

I also found the following online comparison of the E84L, 7189 and EL84 elsewhere:

PaMax plate dissipation E84L 13,5 (watt)
PaMax plate dissipation 7189 12,0
PaMax plate dissipation Mul. EL84 12,0

VaMax plate voltage E84L 450 (volt)
VaMax plate voltage 7189 400
VaMax plate voltage Mul. EL84 300

The above is what had me thinking I could substitute the 7189 for the EL84 and the E84L for both of the 7189 or EL84 tubes and that the E84L is not able to be substituted by either of the other two tubes.

Tubes mostly disappeared from every day life before my time. I'm now trying to catch up on what I missed.

Wb


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 Post subject:
PostPosted: Oct Wed 27, 2010 12:29 pm 
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WB, you'd better go back and check again. Those ratings only tell part of the story. The rest of the story is the recommended values for continuous service in a given application (in this case, class A or class AB1 amplifier service).

:wink:

Larry

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 Post subject:
PostPosted: Oct Wed 27, 2010 4:57 pm 
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And I might add that the 7189A has some internal connections that the 7189 does not. That may be manufacturer specific, I am not sure.

For example in the 7189A, Pin 1 & 2 are internally connected and 6 & 9 are internally connected. You may have to look at the tube socket to be sure that those pins that are spare if the amp used a EL84, 7189 or 6BQ5. Could be that the connection is used to help dissipate heat from inside of the tube. Not sure.

http://www.nj7p.org/Tube4.php?tube=6bq5

http://www.nj7p.org/Tube4.php?tube=7189

http://www.nj7p.org/Tube4.php?tube=7189a

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 Post subject:
PostPosted: Oct Wed 27, 2010 6:07 pm 
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You also must consider the rating system used. 7189 is rated for 12W, "design center". That is, if you design for 12W maximum, you have some margin left (typically 10%) for line voltage variation, component tolerances, etc. 7189A is rated 13.2W "design maximum" - 10% higher - but its rating is "design maximum" - so you need to account for all possible conditions without exceeding 13.2W. In reality, it's rated no higher than 7189! The Philips 7320 data says 13.5W, "absolute maximum" - so it's likewise rated no higher than 7189. The same factors apply to the maximum plate and screen voltage - when comparing, be sure the same rating system is used, or adjust accordingly. Here's a discussion: http://www.tubecad.com/december2000/page17.html


Last edited by Tom Bavis on Oct Wed 27, 2010 6:12 pm, edited 1 time in total.

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 Post subject:
PostPosted: Oct Wed 27, 2010 6:10 pm 
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Well, that Fisher amp I called an EL84 amp actually does have the 7189's in it. But from way back, I've always considered the EL84, 7189, 6BQ5, et;al as pretty much interchangeable. So I call it an EL84 amp. But that amp actually has 7189's in it. However, they're being run pretty light. I recognize that. And that would be why any of the above tubes can be used in it.

I always saw the above tubes in the same vein as the EL34, 6CA7, and (as some people equate to) 6L6. I've never tried to run a 6L6 in place of an EL34, as I see no point. Probably couldn't handle the current or B+, depending on the amp.
I have actually swapped btween the EL84, 7189 family in the past with zero ill results. I considered the EL84 to be the mini-EL34, with a lot less power handling capability. So I guess I must have just been lucky over the years.
Mark D.


Last edited by Mark D on Oct Wed 27, 2010 6:56 pm, edited 1 time in total.

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 Post subject:
PostPosted: Oct Wed 27, 2010 6:35 pm 
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Thanks all!

There is a quad of matched Sylvania 7189 black plate tubes available locally so I may have a look and listen to these. I don't know how they'll sound compared to the Telefunkens but the tube specs will match.

Wb


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 Post subject:
PostPosted: Oct Wed 27, 2010 10:21 pm 
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Wolfbane wrote:
Thanks all!

There is a quad of matched Sylvania 7189 black plate tubes available locally so I may have a look and listen to these. I don't know how they'll sound compared to the Telefunkens but the tube specs will match.

Wb


Can't go wrong with 7189 tubes. I don't use a 6BQ5 unless that is all I have. I am a fan of the Soviet Military tubes. I use them in my HH Scott 299. I am very pleased with them...

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 Post subject:
PostPosted: Oct Wed 27, 2010 11:17 pm 
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Wolfbane wrote:
Thanks all!

There is a quad of matched Sylvania 7189 black plate tubes available locally so I may have a look and listen to these. I don't know how they'll sound compared to the Telefunkens but the tube specs will match.

Wb


WB, I'm glad you found that 7189 quad. Go for them. They're not plentiful enough to be lightly spurned, if they're good.

In the meantime, please don't fall for disinformation and outright mythology. If 7189's, regardless of the manufacturer, are up to 7189 specs (and are hence not defective), they will all "sound" alike, and this can readily be confirmed by a blindfold test at any time.

Good luck with your Scott and best regards :wink:,

Larry

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 Post subject:
PostPosted: Oct Wed 27, 2010 11:30 pm 
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Mark D wrote:
Well, that Fisher amp I called an EL84 amp actually does have the 7189's in it. But from way back, I've always considered the EL84, 7189, 6BQ5, et;al as pretty much interchangeable. So I call it an EL84 amp. But that amp actually has 7189's in it. However, they're being run pretty light. I recognize that. And that would be why any of the above tubes can be used in it.

I always saw the above tubes in the same vein as the EL34, 6CA7, and (as some people equate to) 6L6. I've never tried to run a 6L6 in place of an EL34, as I see no point. Probably couldn't handle the current or B+, depending on the amp.
I have actually swapped btween the EL84, 7189 family in the past with zero ill results. I considered the EL84 to be the mini-EL34, with a lot less power handling capability. So I guess I must have just been lucky over the years.
Mark D.


The relationship between 7189 and 6BQ5/EL84 is more properly analogous to the relationship between the 6L6GC and earlier 6L6 versions.

All earlier versions (6L6, G, GA, GB), were very closely matched in their ratings, and were interchangeable, physical space permitting. There was nothing to choose between them in terms of performance.

The 6L6GC, on the other hand, was endowed with a much higher plate dissipation rating than earlier versions, and was thus able to be safely operated at much higher plate, screen, and output ratings.

In circuits designed for the older types, operating at voltages appropriate for the older types, a 6L6GC will perform like those older types. It will show little or no improvement in performance over the older types. That is why it retained its "6L6" prefix.

On the other hand, none of the older types may be safely used in any circuit expressly designed for the 6L6GC, for it will be volted well past redline for the older types. Thus (very shortly!), happy 4th of July!

The 7189 and 6BQ5/EL84 exist in much the same relationship. In expressly-designed 6BQ5 circuits, the 7189 will perform much like the 6BQ5, and will show little improvement in performance, if any.

On the other hand, a 6BQ5 in a 7189 circuit is simply asking for trouble fast.

Hope this makes things a little clearer.

:wink:

Larry

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 Post subject:
PostPosted: Oct Thu 28, 2010 5:45 pm 
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Hi Larry. I understand what you are saying. I picked up on that right away, in your first post on the topic. My thoughs were that I know I've plugged EL84 tubes into a number of amps that had 7189's originally without a thought. That is what I meant by I was just lucky, I guess. Either that, or the EL84's were just hanging on regardless.

I'm amazed at how familiar you seem to be with so many amplifier models. Like, you seem to know all about this Scott amp that is the topic of this thread as though it's common as dirt. Like a 350 Chevy.
That is impressive.
Mark D.


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 Post subject:
PostPosted: Oct Thu 28, 2010 6:34 pm 
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Don Cavey wrote:
Wolfbane wrote:
Thanks all!

There is a quad of matched Sylvania 7189 black plate tubes available locally so I may have a look and listen to these. I don't know how they'll sound compared to the Telefunkens but the tube specs will match.

Wb


Can't go wrong with 7189 tubes. I don't use a 6BQ5 unless that is all I have. I am a fan of the Soviet Military tubes. I use them in my HH Scott 299. I am very pleased with them...


After reading this, let me qualify what I said. I will only use a 6BQ5 if the circuit originally called for it. Sorry if it sounded confusing...

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 Post subject:
PostPosted: Oct Thu 28, 2010 8:14 pm 
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Mark D wrote:
Hi Larry. I understand what you are saying. I picked up on that right away, in your first post on the topic. My thoughs were that I know I've plugged EL84 tubes into a number of amps that had 7189's originally without a thought. That is what I meant by I was just lucky, I guess. Either that, or the EL84's were just hanging on regardless.

I'm amazed at how familiar you seem to be with so many amplifier models. Like, you seem to know all about this Scott amp that is the topic of this thread as though it's common as dirt. Like a 350 Chevy.
That is impressive.
Mark D.


Many thanks, Mark :wink:. The truth is that I physically have had my hands on comparitively few amps. Instead, I've accumulated some of the literature, some info here at ARF, some elsewhere.

Aside from that, it's amazing what an Allied Radio catalog can tell you about a piece of gear. I have most Allied catalogs between 1946 and 1970, and I'm filling in the remaining gaps as fast as I can :wink:.

Our good friend Don Cavey is the real Scott aficionado here. I'm primarily a Fisher fan.

Best regards :),

Larry

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 Post subject:
PostPosted: Oct Sat 30, 2010 6:18 pm 
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Mark D wrote:
The SA-16 in my thread below has 7189's in it. However, it states right on the chassis that one can use 7189/EL34/6BQ5.


On my Mc 40s, on the chassis by the output tube sockets, "6L6GC/7027A" appears. The 7027A has pins 1 & 4 tied together and 5 & 6 also. The way MY Mac was wired, unless you snip off one of the pins (I can't remember which), the sound is greatly attenuated. The 6L6GC's "empty" pins were used as a "terminal post" for other circuitry.

Charlie


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