[JazzVinyl]

Maybe their descriptions are not correct. I lack the proper understanding to benefit from detailed answers. I'm just able to listen and then some...

I'm not even an expert...

Hello @triod750 -

I doubt LD lies when describing their amp's topology. I am sure there a way to consider your MK IV SE 'Push-Pull' and do it OTL.
Sounds great is sounds great, no matter what the topology used.

Very happy with the MK9 and cannot imagine (from the way it sounds) that the input is being split in half, amplified and then re-connected.

 

[triod750]

I don't say that they lie but I've read somewhere that their description isn't accurate. Don't remember which amp was under discussion. Several people have been mumbling when I have asked for a thorough explanation of what SEPP really is. These people build amps . Maybe they just think that I wouldn't understand anyway so it wouldn't be worth their effort...

Last night I listened to a pair of Tung-Sol 6BX7 with a Telefunken smooth plate 12AU7/ECC82 for input. The sound was very clean, cleaner than with the Ken-Rad 6C5 i used before. Not yet sure which I prefer.

BTW; the Thomson tubes you use for output are the 6080 type, aren't they?

 

[JazzVinyl]

I don't say that they lie but I've read somewhere that their description isn't accurate. Don't remember which amp was under discussion. Several people have been mumbling when I have asked for a thorough explanation of what SEPP really is. These people build amps . Maybe they just think that I wouldn't understand anyway so it wouldn't be worth their effort...

Last night I listened to a pair of Tung-Sol 6BX7 with a Telefunken smooth plate 12AU7/ECC82 for input. The sound was very clean, cleaner than with the Ken-Rad 6C5 i used before. Not yet sure which I prefer.

BTW; the Thomson tubes you use for output are the 6080 type, aren't they?

Photos of the MK IV SE board (populated underside) would show that transformer just prior to the headphone out, if it were in use.

You were using one 6BX7 per side as output tubes? I had a lot of 6BX7 tubes at one time. As I recall most sounded pretty similar with some Sylvania triple mica ones that you could get some extra splash from. Always heard it said that 2x per side was preferable and even 3x per side (requires external heat @ 2x & 3x).

I always liked 12AU7 for input...your using one per side? I would love to hear your amp. You will have to bring it over for a side by side with the MK9

Yes, the CSF-Thomson are 6080 style. Not tried anything else. I would love to find/fall into a pair of GEC 6AS7G brown base...

 

[triod750]

Photos of the MK IV SE board (populated underside) would show that transformer just prior to the headphone out, if it were in use.

Can't remember if I have seen such photos. Will have to look for them.

You were using one 6BX7 per side as output tubes? I had a lot of 6BX7 tubes at one time. As I recall most sounded pretty similar with some Sylvania triple mica ones that you could get some extra splash from. Always heard it said that 2x per side was preferable and even 3x per side (requires external heat @ 2x & 3x).

I'm using one 6BX7 per side with external heater psu since they need 1,5A each. I have GE, RCA and T-S and they all sound slightly different with RCA being warmer and GE least impressive. I also have two pairs of Sylvania 6BL7, (
flat plates and T plates), but now have a slight preference for 6BX7. (With C3g the 6BL7 were taming the highs).
I had the opportunity to try a WA3 which arrived with a 7236 for output. I tried different output tubes and liked the tone from 6BX7 the most in it but prefered my Little Dot by far.

I always liked 12AU7 for input...your using one per side? I would love to hear your amp. You will have to bring it over for a side by side with the MK9

I'm using one for both sides, using adapter and external psu for heaters. I use this for other dual triode input tubes too. Next time we meet I will try to remember to bring my Dotty for comparison. I would also like to compare my Dotty to her big sister.

I would love to find/fall into a pair of GEC 6AS7G brown base.

I found a quad of these and bought them for a friend a couple of years ago. I didn't regard my amp worthy of them. I already had GEC A2293/CV4079 with adapters and decided to stay with them. But I mostly use 6BX7 and Melz 6N12S for output and several different tubes for input, such as 6C4/CV133, 6J5, 6C5, EL42, E80CC, 6N7 and then some.

 

[JazzVinyl]

@triod750 -



This is supposed to be the MK IV SE populated board bottom...I do not see a final transformer. I believe the output solder lugs are the three holes just under and to the left of the gain/tube selection switches. This is not the best photo, but have not seen any others, yet.

Also interesting is that LD claims this was their pinnacle of SEPP design, which would put it higher on the food chain than the MK9.



If this is a stock MK IV SE...I see a couple of caps (maybe the output caps) that are upgraded French Solen caps? Seen to the left and blurry foreground of the gain/tube selection switches.

 

[JazzVinyl]

Can't remember if I have seen such photos. Will have to look for them.


I'm using one 6BX7 per side with external heater psu since they need 1,5A each. I have GE, RCA and T-S and they all sound slightly different with RCA being warmer and GE least impressive. I also have two pairs of Sylvania 6BL7, (
flat plates and T plates), but now have a slight preference for 6BX7. (With C3g the 6BL7 were taming the highs).
I had the opportunity to try a WA3 which arrived with a 7236 for output. I tried different output tubes and liked the tone from 6BX7 the most in it but prefered my Little Dot by far.


I'm using one for both sides, using adapter and external psu for heaters. I use this for other dual triode input tubes too. Next time we meet I will try to remember to bring my Dotty for comparison. I would also like to compare my Dotty to her big sister.


I found a quad of these and bought them for a friend a couple of years ago. I didn't regard my amp worthy of them. I already had GEC A2293/CV4079 with adapters and decided to stay with them. But I mostly use 6BX7 and Melz 6N12S for output and several different tubes for input, such as 6C4/CV133, 6J5, 6C5, EL42, E80CC, 6N7 and then some.

All of your combinations sound really good to me! I do not believe I ever heard C3g sound better than they did, adapted to MK IV.

I would imagine the C3g/Melz 6N12S would be a compelling roll. Also loved the flat plate Sylvania 6BL7's when I was a 'rollin - but they are hard to find anymore.

6N7 was also a fave of mine, that metal envelope Tung Sol is dandy, and definitely the 6/12J5's sounded fantastic and were easy to find cheap and NOS or NIB.

If you could have just one set of tubes for MK IV SE....(I know that is a tough question) what would you choose?

.

 

[triod750]

If you could have just one set of tubes for MK IV SE....(I know that is a tough question) what would you choose?

Under normal circumstances it is a tough one. Now it is even more difficult since this Telefunken smooth plate ECC82, not used previously, will make it neccessary to re-evaluate my preferences. I dug it out last night and don't want to change anytime soon. I use it with a pair of RCA 6BX7 now, my 'warmest vintage'. My favourite output tubes has been Melz 6N12S for quite some time. I have yet to try them with this Tfk.

When I want to visit a smoky jazz club I use these RCA 6BX7 with Adzam branded Mullard manufactured EL42. Smaller soundstage and not as much detail but intimate, warm and cosy. Makes for very relaxed listening. (Inspired by @gibosi to use these. I have several different pairs from different manufacturers. Wouldn't want to be without them). They are pentodes for car radio but become triode wired in Dotty, one per channel via adapters from @Deyan . He made the adapter for using dual triodes for input to; one for both channels.

I haven't finished evaluating 6J5/6C5. But if I don't want to use external heater supply, Ken-Rad 6C5 with Melz 6N12S is a combination hard to beat.

Regarding C3g, I have found Siemens to be slightly too much in the treble with Melz. Genuine Lorenz made are a better match to my ears. The difference is clear. I was lucky to find a reasonably priced pair but haven't used it much. My journey took another direction.

I haven't said anything about 6C4/CV133 that needs adapters but no external psu. Since they are half a ECC82/12AU7, I have to go back and compare them with this Tfk ECC82.

So I can't answer your question...
Sorry

 

[JazzVinyl]

I haven't said anything about 6C4/CV133 that needs adapters but no external psu. Since they are half a ECC82/12AU7, I have to go back and compare them with this Tfk ECC82.

So I can't answer your question...
Sorry

I see! I like the "Ken-Rad 6C5 with Melz 6N12S is a combination hard to beat" - I take it you enjoy cavernous bass?

 

[triod750]

I see! I like the "Ken-Rad 6C5 with Melz 6N12S is a combination hard to beat" - I take it you enjoy cavernous bass?

No, bass isn't a priority, balance and tone is. I mostly listen to acoustical music and jazz oriented music.

 

[JazzVinyl]

No, bass isn't a priority, balance and tone is. I mostly listen to acoustical music and jazz oriented music.

Understand. I like tone and balance an cavernous bass too.

Jazz is my main language. But also listen to a lot of World and 'New Age" stuff.

I loved a really old/crusty pair of RCA 6C5 in the GOTL....they (RCA) do really well at presenting everything in an even handed way.

MK9 - Seems Tung Sol rules the roost.

 

[triod750]

MK9 - Seems Tung Sol rules the root.

And this is what this thread should be about, not MKIV. But I also like RCA 6C5...

 

[JazzVinyl]

MK9 6/12SL7 Driver report:

I obtained a rare-ish early National Union brown base military spec 6SL7GTW that @mordy refers to as the "Umbrella Spoke" model. It has short flat plates, a chrome dome and the curious "Umbrella Spokes" which appear to be levers that press outward against the insides of the glass in four corners, to avoid micro-phonics.

Tried it last night. It is better sounding to me than the NU black glass and the 12SL7 NU clear top that I have.

When comparing it to the Tung Sol 6SU7GTY - the NU is very nice but the Tung Sol wins for evenness of tonal response and separation of instruments.

When I compare the Tung Sol 12SL7 BGRP to the 6SU7GTY, the BGRP wants to lull you in, as it has special attributes with the sound stage. No other 6 or 12 SL7 is as special with the relationship of 'sound to space' as the BGRP.

However, the Tung Sol 6SU7GTY has superior clarity/tone and air between instruments.

Both the Tung Sol's are my absolute favorites. I have to give the crown to the 6SU7GTY followed by the 12SL7 BGRP.

Others of high mention are:
6SL7GTW Brown Base "Umbrella Spoke"
12SL7GT RCA clear top
Melz 6N9S
6SL7 Sovtek (same as the supplied Chinese tube?)
6SL7 Tung Sol brown base (modern made Russian replica of a USA made 6SLtGTW)

All of the 'High mention' tubes are very listenable for extended periods. The top flyers give you greater details and separation / air / space in sound stage that make them special. 6SU7GTY the most impressive for absolute honesty/transparency as well as air and separation.

The only 'Flops' have been:
GE Nickel (silver) Plate 6SL7GT (no bass and sibilant)
RCA Grey Glass 6SL7GT (very lacking in bass, treble heads may love it)

Have not tried Sylvania, Raytheon or Fivre 6SL7GT's.

Cans are the ZMF Aeolus, exclusively.

As always, my ears, my gear, you mileage may vary

.

 

[mordy]

MK9 6/12SL7 Driver report:

I obtained a rare-ish early National Union brown base military spec 6SL7GTW that @mordy refers to as the "Umbrella Spoke" model. It has short flat plates, a chrome dome and the curious "Umbrella Spokes" which appear to be levers that press outward against the insides of the glass in four corners, to avoid micro-phonics.

Tried it last night. It is better sounding to me than the NU black glass and the 12SL7 NU clear top that I have.

When comparing it to the Tung Sol 6SU7GTY - the NU is very nice but the Tung Sol wins for evenness of tonal response and separation of instruments.

When I compare the Tung Sol 12SL7 BGRP to the 6SU7GTY, the BGRP wants to lull you in, as it has special attributes with the sound stage. No other 6 or 12 SL7 is as special with the relationship of 'sound to space' as the BGRP.

However, the Tung Sol 6SU7GTY has superior clarity/tone and air between instruments.

Both the Tung Sol's are my absolute favorites. I have to give the crown to the 6SU7GTY followed by the 12SL7 BGRP.

Others of high mention are:
6SL7GTW Brown Base "Umbrella Spoke"
12SL7GT RCA clear top
Melz 6N9S
6SL7 Sovtek (same as the supplied Chinese tube?)
6SL7 Tung Sol brown base (modern made Russian replica of a USA made 6SLtGTW)

All of the 'High mention' tubes are very listenable for extended periods. The top flyers give you greater details and separation / air / space in sound stage that make them special. 6SU7GTY the most impressive for absolute honesty/transparency as well as air and separation.

The only 'Flops' have been:
GE Nickel (silver) Plate 6SL7GT (no bass and sibilant)
RCA Grey Glass 6SL7GT (very lacking in bass, treble heads may love it)

Have not tried Sylvania, Raytheon or Fivre 6SL7GT's.

All drivers evaluated via CSF-Thomson 6080's - 1970's vintage. Have not dabbled in any other power tubes this far.

As always, my ears, my gear, you mileage may vary

.

Very nice!
I just looked through my stash of 12V tubes and found two GE 12SL7 tubes (did not remember that I have them). Tried a June 1954 GE round silver plate that I liked when I used it in the Little Dot MKIII (but have not used in a very long time). My notes say excellent with very good bass, pace and timing.
Said and done:

I am happy that I tried it - it sounds very good with a meaty bass. Not the ultimate in definition and clarity, but very nice.
Different amp, different tubes - YMMV.
You inspired me to pull out my box of 6SL7 tubes - I'm gonna look.

 

[JazzVinyl]

Very nice!
I just looked through my stash of 12V tubes and found two GE 12SL7 tubes (did not remember that I have them). Tried a June 1954 GE round silver plate that I liked when I used it in the Little Dot MKIII (but have not used in a very long time). My notes say excellent with very good bass, pace and timing.
Said and done:

I am happy that I tried it - it sounds very good with a meaty bass. Not the ultimate in definition and clarity, but very nice.
Different amp, different tubes - YMMV.
You inspired me to pull out my box of 6SL7 tubes - I'm gonna look.

That is an excellent photo, Mordy!!
Yes very interesting that the tube that is a fail in the MK9, pleases in the GOTL.

Listened some more to the NU 'Umbrella Spoke' tube and it most certainly is a great tube!! Wonder how it will do in the GOTL.

 

[JazzVinyl]

There are only two things wrong with Little Dot's MK9:

1> Gets too hot (cured by use of a fan)

2> Ridiculously smooth / rich / deep / wonderful sounding and therefore: ADDICTIVE (no known cure)