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.
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.