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Author Topic: Adjustments for tube rolling?  (Read 6208 times)

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Offline jlschweiger

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Adjustments for tube rolling?
« on: February 28, 2012, 04:58:57 PM »
Forgive this basic question, but if I were to substitute a different set of tubes for the originals (say 7119 PQ) would adjustment of the active loaded hybrid tube/solid state shunt pot be needed any time the tubes were changed?  Thanks for any replies!
John Schweiger
Chromcast Audio -> Paramounts -> Triad bookshelf
ADCOM-575 -> Smack -> HD800

Offline Grainger49

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Re: Adjustments for tube rolling?
« Reply #1 on: February 28, 2012, 10:33:31 PM »

A good safe question. 

Tubes have equivalents and almost equivalents.  The "almost" needs circuit adjustments.  In the case of the tubes mentioned on the product page, 5687/7119/7044, these are all drop in replacements.  That is, no circuit adjustments needed.  There are probably others that might need a cathode or plate resistor change, maybe both and some that need different heater wiring schemes.

I hope this helps.

Offline Doc B.

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Re: Adjustments for tube rolling?
« Reply #2 on: February 29, 2012, 06:20:36 AM »
Yeah 7119s plug right in without any changes and the PQs sound great. That's what I use in mine.
Dan "Doc B." Schmalle
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Bottlehead Corp.


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Re: Adjustments for tube rolling?
« Reply #3 on: July 31, 2012, 08:22:19 AM »
Hello tube rollers

Can I also use a E182CC as replacement without modification of the circuit?

Is there eventually a list of tubes that can be used for the Smack without modification?

I searched the manual for this info but did not found anything.

Thanks in advance and Kind Regards

« Last Edit: July 31, 2012, 11:33:29 AM by Dwight »

Offline Paul Joppa

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Re: Adjustments for tube rolling?
« Reply #4 on: August 27, 2012, 06:13:03 PM »
The E182CC is obviously not an exact replacement, since it has a mu of 25 vs. 17 for the 5687. It may or may not be close enough to work - we have not tested other tubes. The heater current is a bit lower, so if you try it check the heater voltage to be sure it's OK - you may need to increase the resistor in the power supply. Then check the tube pin voltages and report any that are off by more than the usual 15%, and I'll assess the consequences and possible cures.

When checking this, I noticed that the power supply circuit shows 12AU7 tube heaters - those should be 5687 types! Sorry for the typo.

Sorry this reply is late; sometimes I just don't see posts until a few weeks later.
Paul Joppa