[Tjj226 Angel]

Dont forget the uranium paint.

 

[2359glenn]

Between the asbestosis and the lead poisoning I'll be dead in 10 years, but I'll die with a smile on my face listening to pure class A

Naa it will take longer then that.
I been doing this for 52 or more years now when all solder had led and capacitors had PCB I am still here.

 

[L0rdGwyn]

Another pair of NOS 6A5G arrived today, a decade older than the Philcos, 1947 Sylvanias. Tubes are in great shape and test very well. I wasn't happy with the price quotes I was getting from the few USA tube sellers who have some of these tubes, so naturally I had to go to the other bedrock market for USA-made tubes, Japan. Seller reassured me the tubes were 100%, I am not dissappointed, they are pretty much immaculate. Got them for a relatively good price, may go back for more.



I know these updates aren't sexy, some unexpected scheduling changes put the project on ice for a few weeks. Should have some more substantial progress to post soon.

 

[mordy]

Are you able to give some links where to look for tubes in Japan? Are there things to keep in mind when buying from Japan?
Thanks

 

[L0rdGwyn]

All of the parts for this build have been ordered and they are starting to arrive. Unfortunately, Lundahl's US dealer does not have my LL1620 output transformers on hand, so they are being ordered and will arrive in late Feb. The rest of the build can continue and they will be dropped in at the end. I've had several delays with the chassis which was ordered in late November, hopefully will arrive next week. Otherwise, I am going to post the parts as they come in here to show what is going into this build and why.

Yamamoto sockets - I posted these before, but going to consolidate here. These are excellent sockets, B4 for the MH4 driver tubes, octal for the 6A5G output tubes, and an interesting UX4-B4 combo socket that will allow the use of European 4-volt rectifiers (U18/20, AZ50, RGN2504, FW4/500, etc.) and 5-volt rectifiers (5Z3). Figuring out the optimum wiring for the rectifier socket has been...interesting, we'll see if I can hear the magic when I roll rectifier tubes.



Goldpoint V47 stereo stepped attenuator - I added one of these to my Glenn OTL and really like it, so this amp is getting one as well.



Kiwame carbon film resistors - these are widely used in the DIY community, relatively inexpensive, they are actually rebranded KOA Speer resistors under the Japanese Kiwame brand. Regardless, I replaced the driver plate resistors in my Glenn OTL with these and A/B'd them against some Audio Note tantalum resistors. To my surprise, there was a significant change in sound and I much preferred the Kiwames, so I've committed to using them in this build where applicable.



Clarity Cap TC series filter capacitors - using a 10uF 800V cap as the resevoir capacitor in the power supply (the first cap after the rectifier) and 130uF 600V caps in the last position of the power supply. The 130uF caps will be in the signal path of the output stage, so these high-quality film caps were used. The 130uF are also four-pole AKA Kelvin lead capacitors, which offer extended high-frequency noise suppression (see Morgan Jones Valve Amplifiers). The middle PS cap is a 100uF 600V Nichicon which is on the way.



Miflex KPCU-02 copper foil poly/paper in oil capacitors - these are the coupling caps I am using between the input and output stages. These Polish capacitors are not very well known, but testimonials I have come across say they are a step above the Jupiter copper foil coupling capacitors sonically. Who knows if that's true, but it helps they are also 1/3 of the price and radial-leaded, so much easier to mount in the chassis with a capacitor clamp. Physically, they certainly exude quality.



Audio Note Kaisei non-polar electrolytics - these are what Audio Note has come up with on their quest to re-engineer the famous Black Gate capacitors with the help of Rubycon. These are the cathode resistor bypass capacitors for the output tubes. The driver tubes will not have bypass caps. They are non-polar for reduced distortion.



WBT RCA sockets and speaker binding posts - not much to say on these, they are high-quality German-made sockets and binding posts. A nice feature of the bindings posts is they come with a "puzzle plate system" that locks them in place so they do not twist when being tightened. Noice.



Apex Jr. mil-spec silver-plated copper PTFE wire - Steve at Apex Jr. has been supplying this copper wire to DIYers for a long time. It is good quality, inexpensive, and I didn't want to pay the audiophile markup for boutique wire. Have some shielded single-conductor wire on the way to for the inputs. This will do nicely.



AMR gold fuse - that's right, I bought an audiophile fuse LOL but I didn't feel like going to the hardware store, and it wasn't expensive. I am certain this fuse will be transformative and take me to the audiophile promised land.



The Lundahl mains transformer, chokes, and CCS kits should be here later this week, then the chassis next week, then the fun begins

 

[Monsterzero]

Kiwame carbon film resistors - these are widely used in the DIY community, relatively inexpensive, they are actually rebranded KOA Speer resistors under the Japanese Kiwame brand. Regardless, I replaced the driver plate resistors in my Glenn OTL with these and A/B'd them against some Audio Note tantalum resistors. To my surprise, there was a significant change in sound and I much preferred the Kiwame's, so I've committed to using them in this build where applicable.

Im curious. What changes did these make? Glenn mentioned them as a possible upgrade to do on my GOTL when it goes in for surgery.

 

[L0rdGwyn]

Im curious. What changes did these make? Glenn mentioned them as a possible upgrade to do on my GOTL when it goes in for surgery.

Hey D - I only compared them to the other resistor I had on hand that I was planning to put in, the Audio Note tantalums. I talk about it in this post:

https://www.head-fi.org/threads/2359glenn-studio.600110/post-15291953

My impressions aligned very closely with what I found here, quite an old post but the point is the same: https://www.head-fi.org/threads/carbon-film-vs-metal-film-revisited.121104/

 

[Tjj226 Angel]

Hey D - I only compared them to the other resistor I had on hand that I was planning to put in, the Audio Note tantalums. I talk about it in this post:

https://www.head-fi.org/threads/2359glenn-studio.600110/post-15291953

My impressions aligned very closely with what I found here, quite an old post but the point is the same: https://www.head-fi.org/threads/carbon-film-vs-metal-film-revisited.121104/

BTW, try NOS allen bradley resistors. You have to buy a handful of the values you need and match the right resistances, but for what ever reason they have always sounded the best to me and I have a small bin of both kimwame and audio note resistors at my disposal.

I have a feeling its because carbon comp resistors have really low (pretty much 0) series inductance, but that's a complete shot in the dark.

 

[L0rdGwyn]

BTW, try NOS allen bradley resistors. You have to buy a handful of the values you need and match the right resistances, but for what ever reason they have always sounded the best to me and I have a small bin of both kimwame and audio note resistors at my disposal.

I have a feeling its because carbon comp resistors have really low (pretty much 0) series inductance, but that's a complete shot in the dark.

I've heard very good things about the Allen Bradleys and the discontinued Japanese Riken carbon comps too. Thanks for the recommendation, I'll probably give the ABs a shot at some point down the road. I'm using Riken carbon comps for my grid stoppers.

 

[whirlwind]

All of the parts for this build have been ordered and they are starting to arrive. Unfortunately, Lundahl's US dealer does not have my LL1620 output transformers on hand, so they are being ordered and will arrive in late Feb. The rest of the build can continue and they will be dropped in at the end. I've had several delays with the chassis which was ordered in late November, hopefully will arrive next week. Otherwise, I am going to post the parts as they come in here to show what is going into this build and why.

Yamamoto sockets - I posted these before, but going to consolidate here. These are excellent sockets, B4 for the MH4 driver tubes, octal for the 6A5G output tubes, and an interesting UX4-B4 combo socket that will allow the use of European 4-volt rectifiers (U18/20, AZ50, RGN2504, FW4/500, etc.) and 5-volt rectifiers (5Z3). Figuring out the optimum wiring for the rectifier socket has been...interesting, we'll see if I can hear the magic when I roll rectifier tubes.



Goldpoint V47 stereo stepped attenuator - I added one of these to my Glenn OTL and really like it, so this amp is getting one as well.



Kiwame carbon film resistors - these are widely used in the DIY community, relatively inexpensive, they are actually rebranded KOA Speer resistors under the Japanese Kiwame brand. Regardless, I replaced the driver plate resistors in my Glenn OTL with these and A/B'd them against some Audio Note tantalum resistors. To my surprise, there was a significant change in sound and I much preferred the Kiwames, so I've committed to using them in this build where applicable.



Clarity Cap TC series filter capacitors - using a 10uF 800V cap as the resevoir capacitor in the power supply (the first cap after the rectifier) and 130uF 600V caps in the last position of the power supply. The 130uF caps will be in the signal path of the output stage, so these high-quality film caps were used. The 130uF are also four-pole AKA Kelvin lead capacitors, which offer extended high-frequency noise suppression (see Morgan Jones Valve Amplifiers). The middle PS cap is a 100uF 600V Nichicon which is on the way.



Miflex KPCU-02 copper foil poly/paper in oil capacitors - these are the coupling caps I am using between the input and output stages. These Polish capacitors are not very well known, but testimonials I have come across say they are a step above the Jupiter copper foil coupling capacitors sonically. Who knows if that's true, but it helps they are also 1/3 of the price and radial-leaded, so much easier to mount in the chassis with a capacitor clamp. Physically, they certainly exude quality.



Audio Note Kaisei non-polar electrolytics - these are what Audio Note has come up with on their quest to re-engineer the famous Black Gate capacitors with the help of Rubycon. These are the cathode resistor bypass capacitors for the output tubes. The driver tubes will not have bypass caps. They are non-polar for reduced distortion.



WBT RCA sockets and speaker binding posts - not much to say on these, they are high-quality German-made sockets and binding posts. A nice feature of the bindings posts is they come with a "puzzle plate system" that locks them in place so they do not twist when being tightened. Noice.



Apex Jr. mil-spec silver-plated copper PTFE wire - Steve at Apex Jr. has been supplying this copper wire to DIYers for a long time. It is good quality, inexpensive, and I didn't want to pay the audiophile markup for boutique wire. Have some shielded single-conductor wire on the way to for the inputs. This will do nicely.



AMR gold fuse - that's right, I bought an audiophile fuse LOL but I didn't feel like going to the hardware store, and it wasn't expensive. I am certain this fuse will be transformative and take me to the audiophile promised land.



The Lundahl mains transformer, chokes, and CCS kits should be here later this week, then the chassis next week, then the fun begins

Very nice....those sockets will last forever.

 

[L0rdGwyn]

Very nice....those sockets will last forever.

At $50 each, they better!

Some more 6A5G tubes arrived today, of different construction. From all of the digging I have done, I have only seen these tubes in three different versions.

The early Sylvania black plate foil getter versions I have posted earlier in the thread (analogous to the "spring top" Sylvania 2A3)
The French-made black plate version manufactured by Visseaux, which I do not have yet
And the ribbed plate D getter version that I received today, made in 1953 (analogous to the "dual mono plate" Sylvania 2A3)

From the short time I have been hunting these tubes, this "dual mono plate" version seem to be much less common. It will be interesting to see how they compare, I'd imagine the differences in sound would be nearly identical to the differences between their 2A3 cousins.

 

[mordy]

At $50 each, they better!

Some more 6A5G tubes arrived today, of different construction. From all of the digging I have done, I have only seen these tubes in three different versions.

The early Sylvania black plate foil getter versions I have posted earlier in the thread (analogous to the "spring top" Sylvania 2A3)
The French-made black plate version manufactured by Visseaux, which I do not have yet
And the ribbed plate D getter version that I received today, made in 1953 (analogous to the "dual mono plate" Sylvania 2A3)

From the short time I have been hunting these tubes, this "dual mono plate" version seem to be much less common. It will be interesting to see how they compare, I'd imagine the differences in sound would be nearly identical to the differences between their 2A3 cousins.

Is this National Union 6A5G a Sylvania rebrand?

http://vinylsavor.blogspot.com/2019/12/tube-of-month-6a5.html

 

[L0rdGwyn]

Is this National Union 6A5G a Sylvania rebrand?

http://vinylsavor.blogspot.com/2019/12/tube-of-month-6a5.html

Yessir, those National Union tubes are rebranded Sylvanias. I haven't come across any evidence that these tubes were manufactured by anyone but Sylvania and Visseaux in France, likely under Sylvania licensing.

Obviously some of this is conjecture, but here is a Sylvania 6A5G datasheet, in what language? French

http://www.nj7p.org/Tubes/PDFs/Frank/121-Sylvania/6A5G.pdf

Interestingly, I have come across WWII Visseaux-manufactured 6A5G with German Wehrmacht branding, indicating the tubes were manufactured in France under Sylvania license during WWII German occupation! That pair sold on eBay shortly before I was in the market, unfortunately, although it has some undesirable symbols on the tubes, if you catch my drift.

 

[whirlwind]

At $50 each, they better!

Some more 6A5G tubes arrived today, of different construction. From all of the digging I have done, I have only seen these tubes in three different versions.

The early Sylvania black plate foil getter versions I have posted earlier in the thread (analogous to the "spring top" Sylvania 2A3)
The French-made black plate version manufactured by Visseaux, which I do not have yet
And the ribbed plate D getter version that I received today, made in 1953 (analogous to the "dual mono plate" Sylvania 2A3)

From the short time I have been hunting these tubes, this "dual mono plate" version seem to be much less common. It will be interesting to see how they compare, I'd imagine the differences in sound would be nearly identical to the differences between their 2A3 cousins.

Nice tubes.

I think I may have Glenn add that Yamamoto socket that allows the use of 4 and 5 volt rectifiers to my build.

 

[L0rdGwyn]

Made some progress on a few things today, so thought I would post an update.

First off, I finished stuffing the attenuator board for my Linear Audio Autoranger. I haven't talked much about this device on this thread, I have on others, but it essentially attenuates any input signal down to 1.0V (or 0.4V) such that audio measurements can be made with an audio interface (AKA sound card) without damaging it. Using this, I will be able to crank this amp to clipping and take accurate audio measurements on my MOTU M4.

Here is a link to the device page, engineered by Jan Didden: https://linearaudio.nl/la-autoranger



By the way, this is where the amp building will be done. It ain't sexy, but it gets the job done space heaters required (please excuse the creepy manequin head in the corner, one of the previous owners of this home was a hair stylist and it has continued to live in the garage for...actually I don't know why it's still there).



Still have to finish the controller board on the Autoranger and finish up some wiring, but the bulk of the work is done with the attenuator board finished.

However, that has been put on the back-burner, since some items of much greater intrigue arrived today...some iron



Got the first shipment of Lundahl parts from K&K audio. Includes the LL1648 mains transformer, LL2742 choke, a pair of LL1685 chokes, transformer covers, and two cascode constant current source kits. I made a very last minute decision to switch from the LL1650 to LL1648 mains transformer. They are nearly identical, except the LL1650 has four 6.6V secondary windings for tube filaments, whereas the LL1648 has a pair of 6.6V and a pair of 5.9V filaments. This will work better for my project as I am using dropping resistors to reduce the voltages of two of the filaments anyway, so the pair of 5.9V is better since I will not have to dissipate as much power.

One thing I wanted to get done today with the mains transformer was wiring up the primary and checking the filament voltages with my dropping resistors. The ratings given by Lundahl are for 115V out of the wall, so they will be a little high for 120VAC in the USA. On top of that, my wall AC runs a little high around 122V, and my isolation transformer bumps it up to 124V, so that is where I am testing (I have a second DMM attached to my variac). Here is a pic of a Fivre 5Z3 the dropping resistors in place to get the 5.9V winding down to 5V, looking good. Based on this, safe to say the 4V rectifier dropping resistors are good as well.



I also checked the 6.6V windings with 124VAC into the mains transformer. Given that primary voltage, I am getting almost 7.1V on the filaments of the 6A5G off the 6.6V windings. May even have to add some droppings resistors for them as well. 7.1V won't burn out the filaments right away, but could reduce the life of the tubes. Have to give that some thought before I start drilling holes.

Checking the 4V driver tube dropping resistors is more tricky since the filaments are wired in parallel, will probably tackle this tomorrow with a tangled mess of alligator clips.

To be continued...