Coincident Statement Line stage, which I also own (if it can be called it anymore), has quite poor quality stock transformers and mostly everything else regarding the components. Transformers use SiFe core (lamination thickness which I would pass for a power tranny) and have poor response near 20khz and high H3 at low freqs (core saturation), fake Rubycon caps, regular magnetic resistors - in short cheap Chinese craponents. I have changed everything inside them, signal transformers (Noguchi and J&K), power supply caps (Jensen polyprop in Oil), power supply chokes (Noguchi and Lundahl), power transformer (Monolith Magnetics). Output transformer Noguchi FM-10k-600CT, TVC's made by J&K from double-C core Permalloy 80. The Statement Line Stage was the piece of equipment that introduced "the ultimate" 101D schematic to me, which I have copied everywhere, but the components need "tuning" if the ultimate is sought after. It sounds good as stock and I was also fascinated by it, but holy bananas how good this type of simple transformer coupled 101D circuit sounds with state of the art quality components and heater supplies.
I recommend 2W Audio Note non-magnetic tants for line level tubes' cathode res and AN Kaisei electrolytics for bypass them. If cost is no object I suggest to use choke separated heater supplies (= analog/passive version of high output impedance heater supply like Tentlabs). They make DHT's ultimate silent and less prone to microphonics and hum from external fields, and clean up the sound. Very crucial detail in DHT amps. Meaning regulator --> choke --> tube in simplest form, prefereably regulator --> choke --> filter cap --> choke --> tube. The choke needs to be the last component before the tube. I recommend Lundahl Chokes for this particular job, connected in "CMR-mode", one coil in + and - legs. Noguchi also makes double coil chokes with Finemet core, but they are very expensive.
Adjustable heater supply very much needed is the choke separated supplies are used. It is a must.
My adjustable heater supplies, at least Google Chrome shows these. I can measure the output voltage and adjust if directly from the front panel.
I recommend 2W Audio Note non-magnetic tants for line level tubes' cathode res and AN Kaisei electrolytics for bypass them. If cost is no object I suggest to use choke separated heater supplies (= analog/passive version of high output impedance heater supply like Tentlabs). They make DHT's ultimate silent and less prone to microphonics and hum from external fields, and clean up the sound. Very crucial detail in DHT amps. Meaning regulator --> choke --> tube in simplest form, prefereably regulator --> choke --> filter cap --> choke --> tube. The choke needs to be the last component before the tube. I recommend Lundahl Chokes for this particular job, connected in "CMR-mode", one coil in + and - legs. Noguchi also makes double coil chokes with Finemet core, but they are very expensive.
Adjustable heater supply very much needed is the choke separated supplies are used. It is a must.
My adjustable heater supplies, at least Google Chrome shows these. I can measure the output voltage and adjust if directly from the front panel.
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Thanks Legis for the extra information. I currently use a Tram II DHT OTL 45 with Rod Coleman's regulators on the heaters. They have worked very well. I am currently experimenting with Bartola valves Gyrator on the B+. The pre is filled with 2W shinkoh resistors, Jensen's in the PS and Cast Duelunds in the signal path. I am however over that pre for now and my thoughts are now with the 101d.
I, probably like you, just love the simplicity of the 101d circuit and after reading your reply am so excited for this thing to arrive this Tuesday. Is it worth experimenting with the UX201a? You are the first person that I have seen that has completely modded the Coincident pre and I must say that I am in awe.
At the moment I am thinking that my first option is to implement the Rod Coleman regs as I have those on hand and then hopefully with your guidance of the highest value to $:
Interestingly I am using:
DAC Heavily modded TDA1541a Killer Dac --> 6c45pi output and vintage chokes/Caps & Jensen Caps in PS, 2W shinkoh and Alan Bradley's. Duelund VSF output caps.
Amp (mod. Line Magentic LM503PA's):Lundahl Grid choke --> 310A tube --> 0,47µF Jupiter copper foil/wax/paper capacitor --> 300b --> Stock output transformers for now
. Audio Note Silver 2W Tants in signal path.
Fun times ahead
Thank you for your time and help, I look forward to your advice.
Have a threat weekend
Greg
I, probably like you, just love the simplicity of the 101d circuit and after reading your reply am so excited for this thing to arrive this Tuesday. Is it worth experimenting with the UX201a? You are the first person that I have seen that has completely modded the Coincident pre and I must say that I am in awe.
At the moment I am thinking that my first option is to implement the Rod Coleman regs as I have those on hand and then hopefully with your guidance of the highest value to $:
- Resistors and caps --> Amtrans/Takman carbon film resistors, Audio Note Kaisei lytics and 2W AN non-magnetic tantalum resistors. Russian KBG-MN's in PS
- Output transformer Noguchi FM-10k-600CT wound on double C-core Potted?
- TVC's made by J&K from double-C core Permalloy 80 (may I ask you for the specifications?)
- Chokes as direct replacements? 2pcs of Finemet chokes (FMC-3070H) Potted?
Interestingly I am using:
DAC Heavily modded TDA1541a Killer Dac --> 6c45pi output and vintage chokes/Caps & Jensen Caps in PS, 2W shinkoh and Alan Bradley's. Duelund VSF output caps.
Amp (mod. Line Magentic LM503PA's):Lundahl Grid choke --> 310A tube --> 0,47µF Jupiter copper foil/wax/paper capacitor --> 300b --> Stock output transformers for now
. Audio Note Silver 2W Tants in signal path.Fun times ahead
Thank you for your time and help, I look forward to your advice.
Have a threat weekend
Greg
Circuit?
Are you able to post the schematic for the 101D driver stage? I'm very interested.
The "final solution" to the amp, I revamped the 300B/GU-50's driver stage to 101D/UX201A (etc.) + Noguchi FM728D interstage at 1:2 step-up ratio. The visible switch changes the circuit into capacitor coupled form (Duelund Cast Cu DC) where the primary of the transformer acts as a anode choke.
Everything falls in place always with this simplistic "101D et al." circuit, component choices and the choke separated DC heater supply. That's why I have replicated it everywhere, DAC, preamp and now also the power amp
Are you able to post the schematic for the 101D driver stage? I'm very interested.
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I'm using Chrome, and I can't see it.
Can't see it using Safari or Firefox either. Can you please post it again?
Richard
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Thanks Legis for the extra information. I currently use a Tram II DHT OTL 45 with Rod Coleman's regulators on the heaters. They have worked very well. I am currently experimenting with Bartola valves Gyrator on the B+. The pre is filled with 2W shinkoh resistors, Jensen's in the PS and Cast Duelunds in the signal path. I am however over that pre for now and my thoughts are now with the 101d.
I, probably like you, just love the simplicity of the 101d circuit and after reading your reply am so excited for this thing to arrive this Tuesday. Is it worth experimenting with the UX201a? You are the first person that I have seen that has completely modded the Coincident pre and I must say that I am in awe.
At the moment I am thinking that my first option is to implement the Rod Coleman regs as I have those on hand and then hopefully with your guidance of the highest value to $:
- Resistors and caps --> Amtrans/Takman carbon film resistors, Audio Note Kaisei lytics and 2W AN non-magnetic tantalum resistors. Russian KBG-MN's in PS
- Output transformer Noguchi FM-10k-600CT wound on double C-core Potted?
- TVC's made by J&K from double-C core Permalloy 80 (may I ask you for the specifications?)
- Chokes as direct replacements? 2pcs of Finemet chokes (FMC-3070H) Potted?
Interestingly I am using:
DAC Heavily modded TDA1541a Killer Dac --> 6c45pi output and vintage chokes/Caps & Jensen Caps in PS, 2W shinkoh and Alan Bradley's. Duelund VSF output caps.
Amp (mod. Line Magentic LM503PA's):Lundahl Grid choke --> 310A tube --> 0,47µF Jupiter copper foil/wax/paper capacitor --> 300b --> Stock output transformers for now
Fun times ahead
Thank you for your time and help, I look forward to your advice.
Have a threat weekend
Greg
I currently have only one pair of UX201A, but 3 more are on their way. I'd say the UX201A pair (CeCo) I have is not better than 101D in my Coincident (quite on par). It all depends on taste, transformers/loading, system synergy and needs et cetera. I bought 3 NOS-measuring pairs (RCA, Cunningham, Sylvania) for ~120USD, UX201A can be had at a competitive price sometimes, which cannot be said about 101D.
Maybe you can focus on 101D at the start and then make some modifications - is still interested - that enables you to roll out different type of tubes?
3A/107A is also a nice DHT pre tube. I'm still waiting for the UV4-->UX4 adapters to be able to use them properly but I have tested them without the adapters, very good sound. I have to listen to them more in the future after the adapters arrive and they have had some more break in time. They were true NOS, unopened wave cartong wraps and all.
Yes I have removed the steel around the Noguchi transformers and chokes and potted them with epoxy myself (those which were not potted at the factory). These transformer covers are exact same as Coincident originals, except the bottom plate (those I have salvaged from original transformers): ER10 90x80xH100mm Coincident enclosure is stainless steel, very PITA to drill holes in it so I try to use original holes as long as possible.
Other TVC's would also pass when done properly, or Noguchi Finemet AVC if galvanic isolation is not needed (pricey though even when purchased directly from Japan). I specified the J&K TVCs to have quite big C-core, small air gap (handles couple mA DC offset if it's ever present), maximum input swing of around ~5Vrms @ 20Hz without saturation and to have wide bandwidth also when driven from ~10kohm source impedance. I'm sure they can wind the same TVC's for you if you ask them referring to my project. Permalloy is a good match in otherwise Finemet transformer system, it is so smooth sounding yet does not distract the ultimate neutrality and finesse of Finemet too much, very good match in my system. The difference to original SiFe TVC was staggering as TVC is not a "biased" transformer (like SE transformers that pass DC through the primary), low hysteresis Permalloy core totally destroys SiFe in unbiased applications.
I have tried Amtrans res, hard to think other boutique resistor that I dislike more than Amtrans. Very bright and edgy sounding top end for me, which I did not expect from a resistor that is advertised to be carbon film. For I/V resistors they were just unbearable. Not my cup of tea. Takmans are ok, but not on the same level Audio Note non-magnetics in places i have tried them. I haven't tried the silver legged and capped non-magnetic Audio Note tant yet. I have always liked copper things more, but maybe I should still try the Silver tants sometimes. Anything that comes from AN tends to be very good sounding
.I liked the sound of Line Magnetic LM210IA original transformers. Nothing wrong with them, nor the amplifier in stock form, quite thought out matured sound even though components are basic.
I have KBG-MN caps in every PSU as the "first cap". Also in Coincident, but KBG-MN's are in parallel with 33µF Jensen PP in oils in the first two cap stages. By the way I have removed the regulator and the other transistor the Coincident original power supply has (which you'll see), made it to be regular passive/linear PSU with three 30H Noguchi chokes. The regulator and other transistor are unnecessary IMO. Just adjust the voltage with some resistors. I use 100-130V on anode on every 101D stage, I tend to like lower anode voltages more, more relaxed sound usually. It is beneficial to use parallel res/shunt res to prevent the anode voltage to go much higher when other small-current tubes are used, if one wants to be able to use different tubes than 101D.
I also suggest to try out different components, it's very system and speaker tonal balance dependant IMO which gives the best synergy. For example I dislike Amtrans res, some might like them.
Have you logged in to Chrome? It's over my head why some cannot see them. If somebody CAN see them then could share which browser, OS etc. was used.
Here in Mediafire: File sharing and storage made simple
And hotlinked from Google Pictures:
An externally hosted image should be here but it was not working when we last tested it.
I currently have only one pair of UX201A, but 3 more are on their way. I'd say the UX201A pair (CeCo) I have is not better than 101D in my Coincident (quite on par). It all depends on taste, transformers/loading, system synergy and needs et cetera. I bought 3 NOS-measuring pairs (RCA, Cunningham, Sylvania) for ~120USD, UX201A can be had at a competitive price sometimes, which cannot be said about 101D.
Maybe you can focus on 101D at the start and then make some modifications - is still interested - that enables you to roll out different type of tubes?
3A/107A is also a nice DHT pre tube. I'm still waiting for the UV4-->UX4 adapters to be able to use them properly but I have tested them without the adapters, very good sound. I have to listen to them more in the future after the adapters arrive and they have had some more break in time. They were true NOS, unopened wave cartong wraps and all.
Yes I have removed the steel around the Noguchi transformers and chokes and potted them with epoxy myself (those which were not potted at the factory). These transformer covers are exact same as Coincident originals, except the bottom plate (those I have salvaged from original transformers): ER10 90x80xH100mm Coincident enclosure is stainless steel, very PITA to drill holes in it so I try to use original holes as long as possible.
Other TVC's would also pass when done properly, or Noguchi Finemet AVC if galvanic isolation is not needed (pricey though even when purchased directly from Japan). I specified the J&K TVCs to have quite big C-core, small air gap (handles couple mA DC offset if it's ever present), maximum input swing of around ~5Vrms @ 20Hz without saturation and to have wide bandwidth also when driven from ~10kohm source impedance. I'm sure they can wind the same TVC's for you if you ask them referring to my project. Permalloy is a good match in otherwise Finemet transformer system, it is so smooth sounding yet does not distract the ultimate neutrality and finesse of Finemet too much, very good match in my system. The difference to original SiFe TVC was staggering as TVC is not a "biased" transformer (like SE transformers that pass DC through the primary), low hysteresis Permalloy core totally destroys SiFe in unbiased applications.
I have tried Amtrans res, hard to think other boutique resistor that I dislike more than Amtrans. Very bright and edgy sounding top end for me, which I did not expect from a resistor that is advertised to be carbon film. For I/V resistors they were just unbearable. Not my cup of tea. Takmans are ok, but not on the same level Audio Note non-magnetics in places i have tried them. I haven't tried the silver legged and capped non-magnetic Audio Note tant yet. I have always liked copper things more, but maybe I should still try the Silver tants sometimes. Anything that comes from AN tends to be very good sounding
I liked the sound of Line Magnetic LM210IA original transformers. Nothing wrong with them, nor the amplifier in stock form, quite thought out matured sound even though components are basic.
I have KBG-MN caps in every PSU as the "first cap". Also in Coincident, but KBG-MN's are in parallel with 33µF Jensen PP in oils in the first two cap stages. By the way I have removed the regulator and the other transistor the Coincident original power supply has (which you'll see), made it to be regular passive/linear PSU with three 30H Noguchi chokes. The regulator and other transistor are unnecessary IMO. Just adjust the voltage with some resistors. I use 100-130V on anode on every 101D stage, I tend to like lower anode voltages more, more relaxed sound usually. It is beneficial to use parallel res/shunt res to prevent the anode voltage to go much higher when other small-current tubes are used, if one wants to be able to use different tubes than 101D.
I also suggest to try out different components, it's very system and speaker tonal balance dependant IMO which gives the best synergy. For example I dislike Amtrans res, some might like them.
Big thank you for the information. I had contacted J&K earlier today and they had your requirements on file
Initially I will do as you suggest and use the 101d and explore other options at a later date. The Audio Note 2W silver Tants are very good but take a long unlistenable time to burn-in. Generally my go-to resistors are 2W Tants or Alan Bradleys for less than 1K.
What value of Audio Note Kaisei lytics are you using in the pre, I noticed in some of your other posts that you recommend 1000uf 16v?
I think that the reason your journey interests me the most is that I to am using a horn speaker setup and the balance can be tipped in the wrong direction very easily. I just can't wait for the delivery.
Thanks again
Greg
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Yes I use 220µF - 1000µF, 1000µF in DAC and pre, 470µF in the driver stage and 220µF for the 300B. They are rated for 16V or 25V in the pre and driver stages, 100V for the power stage. I have tried many caps as bypass, but the Kaiseis have multiplied and then stayed. They are PIO-like smooth, smoother than Silmic II. They are not the very last word in resolution, but the sound is very agreeable and easy to like. I have polarized versions, maybe the bi-polars are even better. I use big caps to get the least amount of hum with DHTs. Coincident originals were 470µF IIRC and 10,000µF to bypass the small 47ohm balancing resistors which create a center point for the cathode resistor. These 47ohm resistors can be taken out when using my heater supplies, maybe they can be omitted also with normal regulated heater supplies like stock Coincident.
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Thanks Legis, Hopefully tomorrow is the day that it arrives.
Im looking forward to opening it up.
Which of your mods made the biggest difference to the pre?
Kindly
Greg
The biggest one is hard to say, transformers, heater supplies, PSU all make a big difference, as does the cathode res and bypass cap. I'd be prone to say the transformers, but in the end all of these are very important.
So if I have this right, to get me started I need the following for the Coincident pre:
Main Pre Output chassis:
2 x Noguchi FM-10k-600CT
2 x J&K Permalloy Double C core - 23 steps - HLI TVC
Resistors
6x 1000µF 25v Audio Note Kaisei
PS chassis:
2 x Noguchi FMC-3070H
6 x Jensen polyprop Oil 50uf 150v caps
2 x KBG-MN PS Caps
Ouch!
Main Pre Output chassis:
2 x Noguchi FM-10k-600CT
2 x J&K Permalloy Double C core - 23 steps - HLI TVC
Resistors
6x 1000µF 25v Audio Note Kaisei
PS chassis:
2 x Noguchi FMC-3070H
6 x Jensen polyprop Oil 50uf 150v caps
2 x KBG-MN PS Caps
Ouch!
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So if I have this right, to get me started I need the following for the Coincident pre:
Main Pre Output chassis:
2 x Noguchi FM-10k-600CT
2 x J&K Permalloy Double C core - 23 steps - HLI TVC
Resistors
6x 1000µF 25v Audio Note Kaisei
PS chassis:
2 x Noguchi FMC-3070H
6 x Jensen polyprop Oil 50uf 150v caps
2 x KBG-MN PS Caps
Ouch!
Also get accustomed with the pre for some time before doing anything. Did you receive it already?
Order the Noguchi chokes/trafos directly from Japan. I have used a proxy shopping service company called J-Goods many many times.
Two Noguchi chokes and one Lunbdahl. Lundahl is the first one, connected in CMR-mode like in it's pdf. For every PSU, the first choke always CMR-Lundahl is my current style. I have LL2743/100mA for the pre: http://www.lundahl.se/wp-content/uploads/datasheets/2742.pdf
Here's my little "secret" if one want's to make a diode rectifier that sounds almost as good as tube rectifiers. Use current limiting resistors that limit/damp the swithing currents and transformer secondary. One can also use series res between the diode bridge and the load/first cap. Diodes are germanium for their low forward voltage = low "crossover distortion" (lower noise) if the rectifier is thought analogically to be a class-B amplifier.
Please note that the rectifier bridge itself is connected wrong in the picture
(do not connect it that way!). That's an old picture and I'm lazy to correct it. That is just to illustrate the style how to damp a diode bridge. The amount of series res varies from circuit to circuit depending on the circuit's current.
Some smaller details in my pre:
- New circular male/female connectors and the umbilical cord (0314 03 LUMBERG - Liitin: M16 | TME - Elektroniikka komponentit, cord is Tunami Terzo, I use Oyaide cabling everywhere)
- Audio Note RCA connectors
- Audio Note UX4 tube sockets
- Furutech IEC connector
- Seiden switches for TVC
- Duelund DCA20GA for wiring the TVCs, elsewhere DCA16GA
- 15µF Mundorf Supreme Evo Oil for "local filtering" (also oily polyprop like Jensen caps). Mundorfs were a finding from my shelves, I think they are reasonably good cap for PSU. Do not sound harsh in my system like many other non-oily/regular PP sound in comparison to oil PP, PIO etc caps.
Happy modding. These things that have such non-compromizing attitude towards every detail and component, especially when in combination of using fully transformer coupling and DHT tubes, do not grow on market's shelves, only way to get something like this is by doing it yourself.
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Also get accustomed with the pre for some time before doing anything. Did you receive it already?
Order the Noguchi chokes/trafos directly from Japan. I have used a proxy shopping service company called J-Goods many many times.
Two Noguchi chokes and one Lunbdahl. Lundahl is the first one, connected in CMR-mode like in it's pdf. For every PSU, the first choke always CMR-Lundahl is my current style. I have LL2743/100mA for the pre: http://www.lundahl.se/wp-content/uploads/datasheets/2742.pdf
Here's my little "secret" if one want's to make a diode rectifier that sounds almost as good as tube rectifiers. Use current limiting resistors that limit/damp the swithing currents and transformer secondary. One can also use series res between the diode bridge and the load/first cap. Diodes are germanium for their low forward voltage = low "crossover distortion" (lower noise) if the rectifier is thought analogically to be a class-B amplifier.
Please note that the rectifier bridge itself is connected wrong in the picture
Some smaller details in my pre:
- New circular male/female connectors and the umbilical cord (0314 03 LUMBERG - Liitin: M16 | TME - Elektroniikka komponentit, cord is Tunami Terzo, I use Oyaide cabling everywhere)
- Audio Note RCA connectors
- Audio Note UX4 tube sockets
- Furutech IEC connector
- Seiden switches for TVC
- Duelund DCA20GA for wiring the TVCs, elsewhere DCA16GA
- 15µF Mundorf Supreme Evo Oil for "local filtering" (also oily polyprop like Jensen caps). Mundorfs were a finding from my shelves, I think they are reasonably good cap for PSU. Do not sound harsh in my system like many other non-oily/regular PP sound in comparison to oil PP, PIO etc caps.
Happy modding. These things that have such non-compromizing attitude towards every detail and component, especially when in combination of using fully transformer coupling and DHT tubes, do not grow on market's shelves, only way to get something like this is by doing it yourself.
Thank you Legis, truly you don't have to take the time to reply yet you do so with a wealth of information and experience with the Pre.
The Pre arrived today however it is so noisy, it is only slightly better with the ground lifted.
My speakers are very sensitive like yours B&C DCM50 in JBL EVEREST 55000 horn. Yamaha 15" ja3803 below in steel lined cab. Fostex T500II. 8x 15" eminence Beta open baffle for 40hz and below.
I have opened up the pre and there is 1000uf Mundorf M lytic x6 as bypass Caps and the 470uf Silmic's.
Not much done to the PS apart from some M-Lytics across the diode bridge.
I can't get the volume above 9 o'clock as there is way too much gain. No hum and buzz when the mute switch is activated. The 101d's are very prone to microphonics and bringing my hand anywhere near them causes more hum.
Man I am so disappointed.
Oh well onwards and upwards.
Stock Coincident should not have high hum, but it's not totally silent either as it is with choke coupled heater supplies. I have used it with solid state amp and stock Line Magnetic, which both have quite high gain. I never experienced too much hum. Also my bass horns are 100dB+ sensitive.
Move the pre away from any equipment you have, also leave at least 1 feet distance to the external power supply. The stock Coincident picks up hum easily from other equipment. I don't experience it anymore with my modded version, propably the new transformers are less prone to pick up external fields.
The hum caused by your hand goes away only with current source/high output impedance choke coupled heater supplies which I previously talked about. It vanishes totally.
DHT's are very application dependant. Thomas Mayer said wisely that if the application is not perfect, he would rather use IdH tubes because DHT's do not allow skipping in application.
You will eventually get there. Once you try choke coupled heater supplies, finemet transformers et cetera, there is no going back.
Thanks Legis,
I have been sitting here googling all of your posts to gather as much information as possible (I now feel like a stalker)
I had tried all of the basics that you mentioned with no luck (perhaps a little better)
I have some Coleman regs on order for the heater supplies which should be here soon. I currently use them on my DHT 45 Pre which is almost dead silent. If they don't work then I will give your ones a go. I will check to see what the pre B+ is and perhaps lower it as you suggested to 100-110v.
Do you get past 9 o'clock volume with the J&K tvc transformers?
I have been sitting here googling all of your posts to gather as much information as possible (I now feel like a stalker
)I had tried all of the basics that you mentioned with no luck (perhaps a little better)
I have some Coleman regs on order for the heater supplies which should be here soon. I currently use them on my DHT 45 Pre which is almost dead silent. If they don't work then I will give your ones a go. I will check to see what the pre B+ is and perhaps lower it as you suggested to 100-110v.
Do you get past 9 o'clock volume with the J&K tvc transformers?
Thanks Legis,
I have been sitting here googling all of your posts to gather as much information as possible (I now feel like a stalker
I had tried all of the basics that you mentioned with no luck (perhaps a little better)
I have some Coleman regs on order for the heater supplies which should be here soon. I currently use them on my DHT 45 Pre which is almost dead silent. If they don't work then I will give your ones a go. I will check to see what the pre B+ is and perhaps lower it as you suggested to 100-110v.
Do you get past 9 o'clock volume with the J&K tvc transformers?
Ok, those Coleman regs also seem to be high output impedance supplies which is good.
My gain structure is completely different and can be varied greatly depending if I use transformer coupling or capacitor coupling in the three 101D stages and which tube types I use in every stage. With all transformer coupling and 101D tube in every stage (lowest gain setting) I have to turn the volume almost completely up for max boom levels, propably cannot even get everything out from 300B. For typical listening a setting of 12-2 o'clock is ok and for "wine tasting"/night listening levels the couple first steps are ok in this scenario.
If I use UX201A tube (higher µ than 101D, maybe 2-3dB higher gain) or 6SN7 (much higher µ, propably 7-10dB higher gain) in some of the 101D stages, and/or use capacitor coupling in the DAC or pre, the gain becomes much higher. Capacitor coupling in DAC or pre adds +12dB per capacitor coupled stage (Noguchi FM-10k-600C has 4:1 transformation ratio so "bypassing" it yields +12dB). The 6SN7s in DAC and pre and fully capacitor coupled signal path would result in massive gain, max boom (even clipping) in the very first step of the pre. Possible, but not feasible setting. The main thing is I can tailor the gain structure to be good for every situation, very low level recordings and different tube combinations. Normally all transformer coupled ("lowest gain") 101D setting is enough but if the recording is very low level, or I want to blast Hugh Masekela "Stimela" or similar with almost everything the 300B has, then one stage has to be capacitor coupled or one 101D tube has to be changed to 6SN7 or all 101D have to be changed to full house of UX201A's... or...
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