My really dumb tube mistake(s)

I am not an EE minded person, but share time with Audio Enthusiasts  that are adept at EE and build/modify Audio Devices.
In many cases I am able to audition equipment in a HiFi System I am familiar with, which helps when being asked to attend a home, with a purpose to take part in a Device Audition, and offer a assessment.

I have supplied ears for assessments and listened to SS Stereo and Monoblock Power Amps that have been built, as well as,
modified Versions of builds and Branded Amps, where changes are being made, with the intent to improve on such builds.
From my limited experiences, any perceived sound changes with SS,
are to me, being perceived as quite limited, even though a change to the SQ and Performance can be noticed.
I have heard SS Power Amps that I have been impressed by, any one of these could very easily be accepted to be trialled to be used in my system. 

I am a Valve Power Amp Owner for many years, starting with Stereo and today Monoblocks are in use.

I have again had the opportunities to assess Valve amp Builds and Branded Valve Amp's as well as a few other Devices modified to work with Valves.
The range of Valve Amp's I am familiar with are:
 Phonostage > Pre Amp > Power Amp's, Valve Modified CDP's and DAC's.
Apart from being familiar with adept EE minded Audio Enthusiasts,
another Plus Point is that a Friend can be described as having a specialist knowledge of Valves through their life experience, and is in possession of a Two Generation Collection of Valves, which has a vast catalogue.
This friend has always expressed generosity and been willing to aid others with allowing for Tube Rolling to be undertaken with a variety of very closely matched Valves.

Again my experiences are limited but have been revelatory.
One thing I feel very sure of,  is that a Valve Device can undergo perceived changes in the SQ and Performance that can be seen as a exceptional improvement over a previous guise, as a result of
exchanging Valves, if a opportunity to Tube Roll was undertaken,
this can make the observation even more apparent, as to how a selection of Valve will interface with a Device, the marriage will be for better or worse. 

I have also auditioned Valve Amp's, where Components have been exchanged in the circuit.
In one case a particular component (Copper Foil Cap's) was Rolled,
using different Brands,  and at one stage a selected component was perceived as a noticeable improvement over other respected Brands.
When this selected Cap' was in the circuit and Z Foils were introduced to the circuit, the perceived changes were phenomenal.
My limited knowledge would not be able to comprehend why their were such perceptions of improvement.

After such a impression, this device was taken to my friends to undergo 
Tube Rolling.
The Builder of the Device was present and was quite sure, prior to Tube Rolling,  his selected Valves were not to be improved upon.
Well he got a shock on two accounts when the Input/ Output Valves were
rolled, the Device found a new level with a Permutation that was used.
Then followed a few swaps of Rectifier Tubes and another level of performance materialised.

As for Valves vs SS, 
If one discovers a exceptional performing SS Device, that is what it will be.
I feel fortunate to have been able to hear SS Devices that have made such a positive impression.
In my limited experience, If the chosen SS Device is modified,  the perceptions of improvement on offer are with limitations, and opinions will vary on how noticeable they are.
These modifications will also be best carried out by a very adept EE minded person.
There is no doubt in my mind that others who have more experience than mine can dispute the above.  

 If one discovers a Valve Device that is offering a very satisfying performance, in my limited experience that will be a Device that can potentially offer much more.
The chances are that if a investigation is undertaken,
that is limited to Tube Rolling only, a opportunity will be arising, that can potentially offer a perception of improved performance, beyond a persons expectation.
When a Valve is perceived as offering a improvement, there is usually a unanimous agreement, what would be more of a discussion is how much the cost will be as a result of the valves availability.
 
To achieve such a perception, is only a case of exchanging a single Valve or a Selection of Valves, depending on a Device, and generally does not require a EE minded person to achieve this is Valve Sockets are used as the connections. 
To the person considering Tube Rolling, if a single Valve Exchange is
a option, in most cases this would be the most cost effective, and would be a good place to start, i.e, a rectifier.
Note: Tube Rolling can be costly, so learning in advance of how a particular Valve might interface and offer a improvement would be time well spent.
                     
  

    

pindac 

good to meet you.. that was quit a bit of information..

Did you say "if you roll tubes, you can get good result, but you can have bad result too". I agree.. :-)

Regards

Not only should power tubes be replaced for reasons of performance, letting them go too long will cause damage to many amplifiers.  Typically amps with a manual bias.  We output tubes can go into a runaway state where they draw ever more plate currently.  Hopefully just the cathode resistor goes, but in some cases, the output transformer is the victim.  

Being fairly new to tubes and dealing with 2 reputable guys in the NOS tube business, I’ve had very good luck thus far until the other day. I got some 1958 Mullard 12AU7 long plates several months back that I put in my Primaluna Dialogue Premium preamp.
The other day I was showing off my turntable to a friend and I was knocking on the maple isolation shelf while it was playing showing how the table doesnt skip a beat.
It seemed like I could hear a door bell off in the distance. After some investigating found it was tube in my preamp one shelf below. As I tapped or even rubbed a finger on the glass it sounded like a ringing door bell. The tube is now crackling weeks later.
That’s my first experience with a tube going bad.
What I paid for a matched Octet of Mullard EL34 XF2’s has my fingers crossed on those.
Although I have seen several posts here and elsewhere about owners of Primaluna amps using current production Gold Lion KT88’s with favorable results. Maybe a second set of power tubes to switch out now and then would be a good idea to keep the hours down on the Mullards.

Sorry for the long post, but I felt the explanation would help.
This is a subject that is for me difficult to cover without explanation.

I personally look at tubes as an electronic Interface, that has a ease of use, as a method for carrying out exchanges. 

My personal experience from taking part in carrying out exchanges,
has on most occasions been done as part of group, with myself supplying the device to undergo Tube Rolling.  
Doing this has allowed me to experience quite a lot of Tubes, of which some are very well regarded.
I have heard well regarded Valves, that when placed into a Circuit, 
which have almost needed to be removed with immediate effect, 
as the SQ was not one that was wanted.
This was not a personal choice, but a request by a group in attendance.

If I recollect a Orange Print Amperex Bugle Boy was one such Valve used in a DAC,I knew of it, I was interested in it, when used, 
it was a very short lived audition.
On a later occasion, the exact same pair when used on a Phonostage,  were very well received, if a little thin in the presentation.

My experiences allows me to say that Valves with a Good Reputation and are to be found as recommendations, can fail to deliver a good result,
when used in a certain electronic interface.
So jumping into Tube Rolling without acquiring knowledge, seems to be a increased risk, to successfully finding a Personal Sweet Spot with the Valve selection.    

Tube rolling can prove costly, the cost can be impacted by Valve Selection, or accumulating Valves that have not met expectations, and then there are other pitfalls of being supplied Valves that are not measuring up to a usable standard.

I ordered during 2020 Two Matched Pairs of Same Brand 1960's ECC 83 from the same Vendor.
With the intention of producing Two Close Matched Sets.

It was agreed that I would have them Tested on a AVO Test Rig and a return would be accepted pending the test .
One Pair measured very high and slightly over the New Measurement,
(very pleased).
One Pair was between 50% to 70%, depending on the Valve
It took two further supplies of ECC83's that were still measuring quite low, before I got a refund on one pair.
Not all Vendors will be so tolerant.  
Prior to this, a Vendor sent me abusive mails for requesting a Valve return following a Test carried out at my end. 
  
If a modern $20 - 40 Rectifier Valve is claimed to have a similar 
 SQ / Performance of a $200 NOS Valve, and a person is entering into the world of Tube Rolling, the cheaper Valve would be the most cost effective place to start, if a Valve is to be exchanged. 
There should be a change in a performance that will allow an assessment as to the value of the addition.  

I have devices that use ECC88, ECC81, ECC83, 6SN7 and 845's
I have been supported by being loaned Valves that are Closely Matched NOS,  that have been Tube Rolled, those being all the above apart from the 845's. 
As a result some of my Valve Choices have been, more a case of having the Valve to be used already identified, and a purchase tested, to make sure the Valve is sold as described.