Aesthetix Io Users Group

[audioquest4life]

Hi OGH,

Good luck with your experiments. Ironically, I posted that my system was quiet with the stock JJ tubes, but today, I also have the Io sitting on the floor getting ready to to a tube swap in V1/2. Perhaps, KCIN jinxed us when he said that the JJs are prone to noise after some use.

For what its worth, I did some extensive tube rolling in 2008 which concluded that a quad of matched low noise Sovtek 12AX7 LPS in V1/V2 have been key to low noise enjoyment. No matter what other tubes were used in the other V locations, which seemed to change the characteristics and nature of sound, the V1/V2 responded very well with these Sovteks In terms of lower noise. I again endorse that statement as of 6 months ago when i placed a quad of 12AX7s in the same positions and the Io was quiet. I only have Tesla E83CCS, Mullard (new versions)12AX7, and some Gold Lion ECC83 to experiment with as I investigate the JJ tubes. I had my system on for about 12 hours yesterday so don’t know if heat was causing the issue or not, but going to do the test anyway.

I am contacting a dealer to procure some vintage tubes which were recommended.

Here is my 2008 Aesthetix Io tube rolling report: https://forum.audiogon.com/discussions/aesthetix-io-tube-rolling-experiment-at-area-51

Good Luck,

Ciao,
Audioquest4life

 

[audioquest4life]

Installed the Toslavek E83ccs in V1/V2 and all is quiet for now. The Tesla’s in this position sound pretty good to me. The system is cold, so will see how things pan out later. Have the Mullards and TADS which I could also try if things go south.


Thankfully, I hoarded a bunch of these over the years. Within the week I should have four sets of 12AX7s to try, new Genalex E83, new Sovtek 12AX7 LPS, and a few quads of NoS once the dealer gives me the recommendations.

 

[OGH]

Dear all

Here is my test procedure, so far. The goal is to change tubes in order to minimize tube noise. You need your ears, and a db meter, maybe the mic in your phone will do. Preferably, with C weight slow type measurement (I use a Velleman db meter). Your meter / mic needs to be good down to 50db at least, it must pick up low level background noise in your room.

First shut off all other noise sources in the room, and play music at high volume (for example, I used Taylor Swift: Cardigan), and adjust so it plays at ca 93 db, measured from the listener position.

Next, stop the music source, lift the cartridge, with the volume constant, and measure the sound level from ca 30 cm in front of your speakers, left and right, and then, from the listener position. This way you get info on channel balance / problems as well as the overall noise level.

Note these figures in your log book – the front left is xx db, front right xx db, listener position xx db – and also note your subjective impression, listening by ear, in each position. Is it noisy or not.

Next, change the tube set in v1-v2 in the Io, and compare.

So far, I have found that this method does tell me of actual noise level differences and the actual signal-to-noise ratio. Yet my ears are more critical. So, for example, I have found that the tubes in v1-v2 differ only 2-3 db in noise level when the reference level (with music) is set at 93 db, while becoming much more evident when I turn up to very high volume 100 db. Now I measure a 5-6 db difference, or more.

Yet my ears tell me that the difference is important lower down in volume too. Maybe like meteorology. Temperature is only minus two but it “feels like” minus four! Anyway the tendency is, the volume meter predicts what I hear quite well, but it tends to underestimate the difference, unless I turn the volume very high, higher than I usually listen to.

My best tests so far, at 93 db music level, are down to 50-52 db noise level, from the most quiet tubes in v1-2 (JJs from Aesthetix). My NOS tubes have 2-3 db more noise at that level, and 5-6 more at 100 db music level. I will test more of my 12ax7 tubes - I have a few more NOS (telefunken, rca) and some more Sovtek LPS and LP. This method, using a db meter, gives a fairly objective measure of the noise level, as well as subjective impressions.

 

[audioquest4life]

@OGH,

Wow, that’s some very detailed analysis. I just swapped tubes and am listening with the Toslavek E83CcS for now. Rather than me measure the output in db, I just used the volume and watts used as measured on my amps along with the loudness levels rising to evaluate the tube noise. You set the bar high now...I have to break out my db meter and perform this test as well.

When you powered down the Io did you lower the volume level and raise it back? Did you mark your volume location for either experiment if you did? I am sure you did. You have volume on your preamp and phono stage? I always turn the volume down, mute, and then power down when messing with the Io. I put a dab of Porsche Guards Red on the little dot on my volume so that i can see it when the room is darker and also as a reference point. I can barely see the little dot on the volume control otherwise so I always have to figure out the perfect volume when I am in the listening position. Just wondering how you powered down to maintain the same volume for the tests.

 

[OGH]

Some follow up
Oldvinyl - you are writing about 70-80db gain - but what exactly goes on, in the three gain stages of the Io? How much are they demanded to do? Why is the first gain stage so much more critical than the others? I dont fully know, but as far as I know, the two tubes in v1-2 are driven in parallell, with up to a 40db demand on each. On paper it maybe isnt that much, but in practice (to my ears), quite another story. I am no engineer so I dont know.
Kcin - regarding JJ tubes, maybe you are right, but so far, except for the failures I noted, I have not heard increasing noise.
Aq4L - pushing 30 watts - could you give a db measurement, from your listening position? JJs from Aesthetix tested for low noise - yes, I have that confirmed from them. Re: Hotel California - you can check in any time, but you can never leave - but maybe we want to stay there - ?
The tubes in my Eclipse including the two power supplies were updated when it was repaired in 2017, and since then, it has been used quite sparingly, say, 1000 hours,

 

[Kcin]

Hi OGH,

Good luck with your experiments. Ironically, I posted that my system was quiet with the stock JJ tubes, but today, I also have the Io sitting on the floor getting ready to to a tube swap in V1/2. Perhaps, KCIN jinxed us when he said that the JJs are prone to noise after some use.

For what its worth, I did some extensive tube rolling in 2008 which concluded that a quad of matched low noise Sovtek 12AX7 LPS in V1/V2 have been key to low noise enjoyment. No matter what other tubes were used in the other V locations, which seemed to change the characteristics and nature of sound, the V1/V2 responded very well with these Sovteks In terms of lower noise. I again endorse that statement as of 6 months ago when i placed a quad of 12AX7s in the same positions and the Io was quiet. I only have Tesla E83CCS, Mullard (new versions)12AX7, and some Gold Lion ECC83 to experiment with as I investigate the JJ tubes. I had my system on for about 12 hours yesterday so don’t know if heat was causing the issue or not, but going to do the test anyway.

I am contacting a dealer to procure some vintage tubes which were recommended.

Here is my 2008 Aesthetix Io tube rolling report: https://forum.audiogon.com/discussions/aesthetix-io-tube-rolling-experiment-at-area-51

Good Luck,

Ciao,
Audioquest4life

Dear Audioquest... please don't bestow upon me that kind of power to affect your tubes through thousands of miles!

I traditionally test my own tubes and have added a Maxi Pre II. I use a bluetooth speaker with 3.5mm out from the RCAs to listen for noise. This along with the VTV analyzer zeroes in for noise , gain and transconductance. All very relatable to the Amplitrex I have on loan. I sort through 50- 60 tubes at at time to get where I want to go.

For off the shelf ... I still maintain the Sovtek LPS is going to be your quietest for the longest time. JJ are nice but I personally, have not had good luck. Perhaps that has changed or I had a bad batch. Heat should not have any effect on your Io if it s situated well ventilated and your tube sockets are clean and tight. I will say that I have never had noise issues with my Io after going through this procedure in the many years I have had the unit. It does take time and you have to have the constitution for it.

Good luck on sorting things out.

 

[audioquest4life]

Dear Audioquest... please don't bestow upon me that kind of power to affect your tubes through thousands of miles!

@Kcin...LOL. Yeah, that would be an incredible feat for sure. Agree with you regarding the Sovtek 12AX7 LPS being the quietest over a longer period of time. I guess that’s why I seem to gravitate back to them. The Maxi Pre had been out of stock for a long while. Just checked, looks like they are back in stock. That is definitely a great tool to evaluate the health of your tubes. Time to order one.

You definitely have invested the time to realize the maximum performance that the Io has to offer. I am slowly getting there.

 

[Kcin]

@Kcin...LOL. Yeah, that would be an incredible feat for sure. Agree with you regarding the Sovtek 12AX7 LPS being the quietest over a longer period of time. I guess that’s why I seem to gravitate back to them. The Maxi Pre had been out of stock for a long while. Just checked, looks like they are back in stock. That is definitely a great tool to evaluate the health of your tubes. Time to order one.

You definitely have invested the time to realize the maximum performance that the Io has to offer. I am slowly getting there.

I have committed to the Io and I am a tinkerer - so I invested. The VTV is excellent... but is unavailable. The Maxi Pre II does everything the VTV does and has 4 tube inputs so the selection process is very quick. Amplitrex does some other things and of course does power tubes/rectifiers- but is slow and plodding. The Maxi Pre has Amplitrex relatable results in a far more modern format IMO. Amplitrex needs a software re write to bring it out of the 90's - I feel the Maxi is fair investment for a committed Io user!
YMMV and all that.

 

[oldvinyl]

Some follow up
Oldvinyl - you are writing about 70-80db gain - but what exactly goes on, in the three gain stages of the Io? How much are they demanded to do? Why is the first gain stage so much more critical than the others? I dont fully know, but as far as I know, the two tubes in v1-2 are driven in parallell, with up to a 40db demand on each. On paper it maybe isnt that much, but in practice (to my ears), quite another story. I am no engineer so I dont know.
Kcin - regarding JJ tubes, maybe you are right, but so far, except for the failures I noted, I have not heard increasing noise.
Aq4L - pushing 30 watts - could you give a db measurement, from your listening position? JJs from Aesthetix tested for low noise - yes, I have that confirmed from them. Re: Hotel California - you can check in any time, but you can never leave - but maybe we want to stay there - ?
The tubes in my Eclipse including the two power supplies were updated when it was repaired in 2017, and since then, it has been used quite sparingly, say, 1000 hours,

OGH - think of the gain stages as a series of buckets. The signal goes from bucket to bucket and the amplitude of the signal increases along the way. The output of a moving coil cartridge may be 0.5 millivolts, while the preamp output is several volts. Overall, 80 dB means that the signal is magnified by 10,000. Note that 0.5 millivolts times 10,000 is 5 volts. The signal from the cartridge is first amplified in V1, then V2 amplifies the output of V1. If I remember correctly, V3 amplifies the output of V2, V5 amplifies the output of V3. Any signal, or any noise in V1 is amplified through each successive stage. If the noise if injected in V2, then it get less overall amplification. The noise can come from several sources: groove noise, tape noise in the LP (if mastered from original analog tape), shot noise in the resistors/capacitors, noise from the power supply (rectification and line noise) and of course tube rush from the electron flow in the tube.

From the Aesthetix manual: The phono stage contains three main amplification sections and an output buffer section. The first section is a high gain, low noise, zero feedback single ended amplifier composed of two low-noise 12AX7 vacuum tubes. This then feeds a high gain, low noise differential amplifier (two 12AX7 vacuum tubes) which amplifies the signal and produces a complementary minus phase signal. Thus, the unit is balanced from the second amplification section through the output. The signal is then applied to the third amplification section which is nearly identical to the second. It also contains two 12AX7 vacuum tubes. The filter is next in the signal path, a purely passive design with the highest grade capacitors and non-inductive wirewound resistors throughout. Lastly, the signal is buffered and sent to the output jacks in balanced form. Each separate amplification section has its own power supply filtering network and regulated heater supply to isolate the individual sections and prevent them from interacting. The "filter" would be the RIAA correction of the high frequency pre-emphasis and low frequency de-emphasis made in the recording stage, it has to be undone or reversed in the phono stage to restore correct frequency balance.

So, V1 and V2 are in series (not parallel). Each gain stage has about 20 dB of gain or an amplification of about 10 (20 dB in V1, 20 dB in V2, 20 dB in V3 and 20 dB in V4). That is pretty typical for a 12AX7, it lets it operate in a nice linear range.

Also note that the "character" or timbre of the output of V1 is carried through V2, V3, V5 and V7. That is another reason why it is important to get a low noise, wide bandwidth tube that does not impart its character or "flavor" to the signal. That's why Telefunkens in V1 and V2 are so desirable - they are fairly transparent to the signal and do not "flavor it much".

Hope this helps.

 

[OGH]

Oldvinyl - thanks for walking me through the manual, plus extra info.

There is something here, that I don't understand (quite a lot actually, I am no engineer).
If the gain is equal across the gain stages, 20db each, why is the first gain stage so much more critical regarding tube noise, than the next stages?

My impression is that the four tubes in this stage are "stressed" much more than the others, so if these aren't extremely low noise, you'll get a noise problem - like you say - along the rest of the chain. It also makes me wonder, why is the amplification single-ended at this stage, since the cartridge, as a famous OTL manufacturer has stated, is "an inherently balanced device", and everything else on the Io is balanced? It is because this stage is extremely critical - is my guess - summing up the channels (single ended) is maybe needed to get a strong enough signal?

I would like the tube seller to tell me the relevant noise level. Not having to discover for myself. But for this, I need more exact info on what exactly to test for, since on paper, the first gain stage demands aren't so special.

 

[OGH]

Todays testing reminds me of Blind faith: Had to cry today. Just joking! Heads up in these times...

Cry, because I have to give up on my trusted NOS. But some smiles at the end of this story also.

I first tested the four best-measuring (on the beck rm1 tube tester) of the seven Sovtek 12ax7LPS that I have as extra. These clearly had lower noise level than the four Telefunken I had sitting in the first gain stage (v1-2) in the Io. I listened, measured with my Velleman db meter, and compared - no doubt whatsoever. At the margin of how loud I sometimes play music, in my room (93 db average), I heard (listening without music playing) ca 54-56 db tube noise with the Telefunken set in the first gain stage, as compared to ca 50-52 with the Sovtek (and with the JJ). This is still louder than my digital music input, but doesn't bother me much, in practice.

The best of "new production" clearly beats "the average NOS", in my case at least. I tried two more sets of NOS tubes, of extras I have, all measuring very well on the tube tester. However, the noise level was back to where I started, with my "best" Telefunken set (selected in 2017, and in the Io since then), or even worse.

I mainly listened for noise, and just a bit to how each set sounded with music playing. When disregarding the noise, I felt, Wow, these are good-sounding tubes! - both in the case of the Telefunken and the RCA sets I tested. So it is sad to say goodbye to them.

The testing confirmed that the ultra low noise demand is mainly (90 percent?) in the first gain stage. If these four tubes do the job well enough, I don't have any problems in the later gain stages.

It is possible that I can use my best NOS in the second or third gain stage, to help curb the worst problems of the Sovteks. Maybe I don't have to say goodbye. Not tested yet.

The testing confirms the importance of the background noise level for the information retrieval in the first gain stage. With the best low noise (Sovtek / JJ) tube sets in the first gain stage, I can hear more low level detail, rising above the background haze.

The Sovtek LPS now need some burn-in before I can say more.

Oystein

 

[audioquest4life]

It is possible that I can use my best NOS in the second or third gain stage, to help curb the worst problems of the Sovteks. Maybe I don't have to say goodbye. Not tested yet.

The testing confirms the importance of the background noise level for the information retrieval in the first gain stage. With the best low noise (Sovtek / JJ) tube sets in the first gain stage, I can hear more low level detail, rising above the background haze.

The Sovtek LPS now need some burn-in before I can say more.

Oystein

Oystein,

Your results back up what I have discovery learned over the many years owning the Io.

1. The Sovtek LPS used in the first stages results in low noise, significantly below the music threshold.

2. The Aesthetix supplied JJs while initially sounding good, have a noise life expectancy that is sometimes cut short.

3. Any tubes used behind in other stages, also need to be tested for low noise, but these stages are more forgiving than the first stages.

4. If using NoS tubes such as Telefunken or others in the first stages, these must be tested for low noise. Generally speaking, others who have gone the NOS route have had many successes going this route.

Ordered the Maxipre this morning.

Ciao,

Audioquest4life

 

[Kcin]

Oystein,

Your results back up what I have discovery learned over the many years owning the Io.

1. The Sovtek LPS used in the first stages results in low noise, significantly below the music threshold.

2. The Aesthetix supplied JJs while initially sounding good, have a noise life expectancy that is sometimes cut short.

3. Any tubes used behind in other stages, also need to be tested for low noise, but these stages are more forgiving than the first stages.

4. If using NoS tubes such as Telefunken or others in the first stages, these must be tested for low noise. Generally speaking, others who have gone the NOS route have had many successes going this route.

Ordered the Maxipre this morning.

Ciao,

Audioquest4life

Audioquest,

Congratulations on the Maxipre.

I am liking mine a lot and I have 5 other testers in the house. Remember it is a relative reading you are looking for against a known good type. Different Mfrs will have different readings ... My experiences are that ordinarily real TFK tubes measure lower than say a mullard or amperex or any good new production. I made a chart of what I have come to expect and compared them to the Amplitrex and others. The Maxi is consistent with good comparable results.

For the noise test on the Maxi.. it would have been nice if they added a cheap chip amp and speaker in the unit to listen for noise... but they did not. I use a cheap Bluetooth speaker with a dual RCA to mini plug and it is compact and works fine. See link below.

Now you will have even more fun documenting your tubes!

https://www.amazon.com/Anker-SoundCore-Super-Portable-Noise-Cancelling-Microphone/dp/B01HTH3C8S/ref=sr_1_14?dchild=1&keywords=anker+sound&qid=1614014620&sr=8-14

 

[oldvinyl]

Oldvinyl - thanks for walking me through the manual, plus extra info.

There is something here, that I don't understand (quite a lot actually, I am no engineer).
If the gain is equal across the gain stages, 20db each, why is the first gain stage so much more critical regarding tube noise, than the next stages?

My impression is that the four tubes in this stage are "stressed" much more than the others, so if these aren't extremely low noise, you'll get a noise problem - like you say - along the rest of the chain. It also makes me wonder, why is the amplification single-ended at this stage, since the cartridge, as a famous OTL manufacturer has stated, is "an inherently balanced device", and everything else on the Io is balanced? It is because this stage is extremely critical - is my guess - summing up the channels (single ended) is maybe needed to get a strong enough signal?

I would like the tube seller to tell me the relevant noise level. Not having to discover for myself. But for this, I need more exact info on what exactly to test for, since on paper, the first gain stage demands aren't so special.

OGH - not sure where the "stressed" idea came from. Each gain stage is 10 times the input or 20 dB. That is an easy walk in the park for a 12AX7 tube.

What is going on gain wise looks like this:


A cartridge with a maximum .5 millivolt output would result in a 5 volt output is the Io is configured for 80 dB of gain. This would correspond with the volume control set to maximum if the Io has the volume controls. Please note that dB add algebraically, while the gain multiplies. 20 dB + 20 dB is 40 dB which corresponds to 10 times 10 or 100.

Noise wise, any noise from the first gain stage is amplified by all subsequent gain stages (same as the signal). Or, any tube frequency emphasis or timbre is amplified by all subsequent gain stages. I think of it this way:


I don't know how else to explain it, but then again I have a degree in electrical engineering.

In order for the Io to be fully balanced from input to output, there would need to be 4 more tubes added to the Io. The first gain stage (V1) of each channel would need an additional tube to handle the opposite side of a balanced signal. Same for second gain stage (V2). This would increase the number of components and the power supply size. It is a design trade-off (decision made by the circuit designer). Balanced devices require a differential input amplifier to get rid of common mode noise. This noise would be more apparent in long runs of cables. Most phono stages and cable from turntable to phono stage are rather short - for lots of reasons (low signal level, need for good shielding, need for low capacitance). The cartridge is not inducing common mode noise, it would have to be picked up by (unshielded or poorly shielded) phono cables. It is more common that longer run cables are needed between preamp and amplifiers. If the amplifier has a true differential input, then a balanced output will help remove noise.

 

[audioquest4life]

Thank you. I like how you stored your tubes in flat boxes with the measured readings on labels. Are the labels the regular Avery or generic Label?

When I ordered the MaxiPre a pop up appeared stating the Pre is delayed by 10 days

 

[audioquest4life]

Audioquest,

Congratulations on the Maxipre.

I am liking mine a lot and I have 5 other testers in the house. Remember it is a relative reading you are looking for against a known good type. Different Mfrs will have different readings ... My experiences are that ordinarily real TFK tubes measure lower than say a mullard or amperex or any good new production. I made a chart of what I have come to expect and compared them to the Amplitrex and others. The Maxi is consistent with good comparable results.

For the noise test on the Maxi.. it would have been nice if they added a cheap chip amp and speaker in the unit to listen for noise... but they did not. I use a cheap Bluetooth speaker with a dual RCA to mini plug and it is compact and works fine. See link below.

Now you will have even more fun documenting your tubes!

https://www.amazon.com/Anker-SoundCore-Super-Portable-Noise-Cancelling-Microphone/dp/B01HTH3C8S/ref=sr_1_14?dchild=1&keywords=anker+sound&qid=1614014620&sr=8-14

The speaker has been ordered. Thank you for the link.

 

[Kcin]

OGH - not sure where the "stressed" idea came from. Each gain stage is 10 times the input or 20 dB. That is an easy walk in the park for a 12AX7 tube.

What is going on gain wise looks like this:
View attachment 75272

A cartridge with a maximum .5 millivolt output would result in a 5 volt output is the Io is configured for 80 dB of gain. This would correspond with the volume control set to maximum if the Io has the volume controls. Please note that dB add algebraically, while the gain multiplies. 20 dB + 20 dB is 40 dB which corresponds to 10 times 10 or 100.

Noise wise, any noise from the first gain stage is amplified by all subsequent gain stages (same as the signal). Or, any tube frequency emphasis or timbre is amplified by all subsequent gain stages. I think of it this way:
View attachment 75273

I don't know how else to explain it, but then again I have a degree in electrical engineering.

In order for the Io to be fully balanced from input to output, there would need to be 4 more tubes added to the Io. The first gain stage (V1) of each channel would need an additional tube to handle the opposite side of a balanced signal. Same for second gain stage (V2). This would increase the number of components and the power supply size. It is a design trade-off (decision made by the circuit designer). Balanced devices require a differential input amplifier to get rid of common mode noise. This noise would be more apparent in long runs of cables. Most phono stages and cable from turntable to phono stage are rather short - for lots of reasons (low signal level, need for good shielding, need for low capacitance). The cartridge is not inducing common mode noise, it would have to be picked up by (unshielded or poorly shielded) phono cables. It is more common that longer run cables are needed between preamp and amplifiers. If the amplifier has a true differential input, then a balanced output will help remove noise.

Nice explanation Oldvinyl- you and I have similar professions but you have good patience to explain this configuration.

 

[audioquest4life]

OGH - not sure where the "stressed" idea came from. Each gain stage is 10 times the input or 20 dB. That is an easy walk in the park for a 12AX7 tube.

What is going on gain wise looks like this:
View attachment 75272

A cartridge with a maximum .5 millivolt output would result in a 5 volt output is the Io is configured for 80 dB of gain. This would correspond with the volume control set to maximum if the Io has the volume controls. Please note that dB add algebraically, while the gain multiplies. 20 dB + 20 dB is 40 dB which corresponds to 10 times 10 or 100.

Noise wise, any noise from the first gain stage is amplified by all subsequent gain stages (same as the signal). Or, any tube frequency emphasis or timbre is amplified by all subsequent gain stages. I think of it this way:
View attachment 75273

I don't know how else to explain it, but then again I have a degree in electrical engineering.

In order for the Io to be fully balanced from input to output, there would need to be 4 more tubes added to the Io. The first gain stage (V1) of each channel would need an additional tube to handle the opposite side of a balanced signal. Same for second gain stage (V2). This would increase the number of components and the power supply size. It is a design trade-off (decision made by the circuit designer). Balanced devices require a differential input amplifier to get rid of common mode noise. This noise would be more apparent in long runs of cables. Most phono stages and cable from turntable to phono stage are rather short - for lots of reasons (low signal level, need for good shielding, need for low capacitance). The cartridge is not inducing common mode noise, it would have to be picked up by (unshielded or poorly shielded) phono cables. It is more common that longer run cables are needed between preamp and amplifiers. If the amplifier has a true differential input, then a balanced output will help remove noise.

@oldvinyl,

That is a great diagram and explanation of what is going on with the various stages and the corresponding gain associated with each. Much appreciated.

 

[Kcin]

Thank you. I like how you stored your tubes in flat boxes with the measured readings on labels. Are the labels the regular Avery or generic Label?

When I ordered the MaxiPre a pop up appeared stating the Pre is delayed by 10 days

I am quite sure with their last run they only filled backorders... my MP was part of that last shipment. I must of waited about 6 weeks even though the website and phone call I got suggested much less. They only bring in enough parts for a run.. maybe 10-20 at a time ? I'm guessing --and then they re order major parts. Communication was good along the way. You just may have to wait 6wks or so if they don't have the major parts... transformers.. cases etc.

The labels are a small avery type. I usually enter them in a spread sheet and figured out how to print them - but sometimes you get lazy

 

[OGH]

Oldvinyl - thanks for the diagrams. So, to replicate the situation in the Io, the first gain stage tube noise level will be multiplied by the two next stages, with a total of 1000 x signal / including noise amplification. So it is not that the tubes in the first stage are especially 'stressed', but only that whatever goes on there, is very strongly amplified later. Correct? And the net result of this, is that the tube noise level in the first stage is very critical, while not so much in the later stages - and least in the third stage I presume. These are more "forgiving".
Audioquest4life - I hope the MaxiPre does the job especially in terms of noise. My Beck RM1 is flexible and convenient (also, good support), but doesn't tell me much about the actual noise when I try the tube in the Io.