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Marantz 7 and 8B / Homade variac

uenjoymyself said:
About how much should I be prepared to pay for a "real" pair? I just read a valuation for Phillips E90F and it said an authentic Holland made tube is worth upwards of $200.00 !!!!
http://www.worthpoint.com/worthopedia/e90f-6bh6-philips-mesh-plate-tubes-98805858

Is that possible????????????
Click to expand...

That was a couple of years back. However, the fella you mentioned seems to have located a big lot of them. So the price went down significantly.

Law of supply and demand I guess...

However, a 1950's version with square getters should still fetch quite a bit of dough, as they are sonically superior to the 1970's versions being sold now.
 
crooner said:
That was a couple of years back. However, the fella you mentioned seems to have located a big lot of them. So the price went down significantly.

Law of supply and demand I guess...

However, a 1950's version with square getters should still fetch quite a bit of dough, as they are sonically superior to the 1970's versions being sold now.
Click to expand...

Do they need to be matched?
 
Matching is non critical on these.

However, the phase splitter 6CG7's would preferably be matched for best AC balance.

Did your amp come with the clear top RCA 6CG7's?

I use early 60's version with shield between plates. Later versions omit the shield. They sound the best to me.
 
crooner said:
Matching is non critical on these.

However, the phase splitter 6CG7's would preferably be matched for best AC balance.

Did your amp come with the clear top RCA 6CG7's?

I use early 60's version with shield between plates. Later versions omit the shield. They sound the best to me.
Click to expand...

Yes they are RCA and the tops are clear, unlike the power tubes and the 6bh6's, but I'm Not sure about the shield. Can I determine this visually?

I'm almost positive the tubes are all original to the amp so.....

Does matched mean that they both test the same on a tube tester?
 
uenjoymyself said:
Yes they are RCA and the tops are clear, unlike the power tubes and the 6bh6's, but I'm Not sure about the shield. Can I determine this visually?

I'm almost positive the tubes are all original to the amp so.....

Does matched mean that they both test the same on a tube tester?
Click to expand...

Ok, I was just going through a bag of extra boxed tubes that came with the model 7 and I found another set of clear top 6cg7's mixed in with the extra 12ax7a's.

These DO have the shield and test at 112%, both tubes, which is better than 90% for the ones in the amp. Ill have to do a comparison to see which I like best.

Cant wait for the E90F's and Svetlanas to arrive!!!!!!!!!!!! :music:
 
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uenjoymyself said:
Yes they are RCA and the tops are clear, unlike the power tubes and the 6bh6's, but I'm Not sure about the shield. Can I determine this visually?

I'm almost positive the tubes are all original to the amp so.....

Does matched mean that they both test the same on a tube tester?
Click to expand...

Look in between the two little plates on the tube. Should be a third element. Thinner. A metal shield. I will try to show a pic later today.

Matched for mutual conductance or gm is what I mean. If the tube tester does mutual conductance and can test each section of the tube individually, then they can be tested so that each section measures similarly.
 
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