[hpamdr]

A solution would be to resolder these tubes and also to solder directly the tube on the adapter.

The old tubes used pure lead for soldering wire to the tube base. It could be difficult to remove old stuff without heating too much. Instead of re-soldering the best is probably to first de-soldier competetelly using flux and pump and then cleanup wire and change base to octal.

 

[OctavianH]

You are most probably right but I am not very pleased to rebase these, not that I would have the skills to do this properly and I would not start with these ones anyway. I see them as a piece of history and I would like to use them as they were built. We wil see, I am in no shortage of them so there is time to deliberate. In the meantime I put the Valvo pair to work and these have no problem in the adapters where RT stopped working. So, hell knows.

 

[hpamdr]

For the curious one, For those who like to look under skirts...

This is inside my new amp, no printed pcb just testing ones to soldier the CAPs . All is on the AIR and the transformer have been built on demand in pure old tradition..

 

[Isaacc7]

I have switched back to the triode mode with the 6bg6ga Sylvania and wow! Dunno if the 13d1 has burned in more or if the ultralinear mode was too lean or what but switching to triode feels like coming home. The bass, mid bass in particular has improved. I’ve lost some clarity but gotten some extra goodness in the midrange. Voices are just lovely. The system has gone from interesting to arresting.

I have heard some tube heads claim that extra bass with lower output power is actually caused by distortion. I don’t care lol.

 

[Designsfx]

I have switched back to the triode mode with the 6bg6ga Sylvania and wow! Dunno if the 13d1 has burned in more or if the ultralinear mode was too lean or what but switching to triode feels like coming home. The bass, mid bass in particular has improved. I’ve lost some clarity but gotten some extra goodness in the midrange. Voices are just lovely. The system has gone from interesting to arresting.

I have heard some tube heads claim that extra bass with lower output power is actually caused by distortion. I don’t care lol.

When using the 6BG6GA which pin do you tie to the plate in your adapter? I’ve used a 6BQ6GT Sylvania in my Lampizator with great results. It seems the 6BG is similar in function but with a higher amplification factor. It might be worth a try but I’m thinking it would require a different adapter.

 

[Isaacc7]

When using the 6BG6GA which pin do you tie to the plate in your adapter? I’ve used a 6BQ6GT Sylvania in my Lampizator with great results. It seems the 6BG is similar in function but with a higher amplification factor. It might be worth a try but I’m thinking it would require a different adapter.

I don’t know. I just order the adapter and switch the amp into triode mode lol. Pretty sure plate is tied to g2 but not 100% on that.

 

[OctavianH]

When using the 6BG6GA which pin do you tie to the plate in your adapter? I’ve used a 6BQ6GT Sylvania in my Lampizator with great results. It seems the 6BG is similar in function but with a higher amplification factor. It might be worth a try but I’m thinking it would require a different adapter.

Yes, 6BG6 needs a different adapter than 6BQ6.

In general adapters are built 1:1, but in case when triode strapping is needed, G2 is linked to Anode via a resistor (tipically 100 Ohm) and G3 to Cathode.

 

[Isaacc7]

Yes, 6BG6 needs a different adapter than 6BQ6. Usually to triode strap a pentode you tie G2 to Anode via a resistor (usually 100 Ohm). A good guide and analyse you have here.



Most standard adapters are linking G3 to Cathode (if not already internal connected like on many tube types) and G2 via a resistor to Anode. The rest goes 1:1.

In my case I am using an adapter that changes the pin out of the 6bg6 to a 6l6. My amplifier can switch between triode and ultralinear. That is different than the adapters I use for pairs of pentodes to 6sn7. Those convert the pentode to triode in the adapter itself.

 

[OctavianH]

In my case I am using an adapter that changes the pin out of the 6bg6 to a 6l6.

6L6 and 6V6 have the same pinout.

 

[Isaacc7]

6L6 and 6V6 have the same pinout.

Yes but typically you’ll see the adapters sold as 6l6 ones because of how close those tubes are. My main point was that adapters you buy for 6bg6 usually don’t include conversion to triode in them.

 

[OctavianH]

Yes but typically you’ll see the adapters sold as 6l6 ones because of how close those tubes are. My main point was that adapters you buy for 6bg6 usually don’t include conversion to triode in them.

Yes, you are right, because 6V6 is a beam tetrode and has G1/G2 then adapter is made 1:1 and Anode is linked to top cap. I gave a general answer regarding how adapters are made and how they are strapped if needed (for 6SN7/6J5). I edited the post to avoid confusion. Anyway 6BQ6 and 6BG65 need different adapters.

 

[Isaacc7]

I continue to be impressed with the 13d1/6bg6ga combo. I need to do some testing to see if the sound is because of that particular combo or the operating points. I had been running all of the 807oids at 320v 40 ma based on the data sheets I found online. These particular 6bg6ga can actually handle a lot more voltage than a stock 6bg6 so I opened it up. I am now running them at 350v 60ma and sounding good. After reading a bit it looks like all of the 807 should be able to handle those settings.

Incidentally, I found a really good blog of a guy making amps and doing really interesting measurements. He has great pages on the 6v6/6aq5, 6l6gc, and 6080 along with amp designs. https://www.cascadetubes.com/

 

[hpamdr]

In my case I am using an adapter that changes the pin out of the 6bg6 to a 6l6. My amplifier can switch between triode and ultralinear. That is different than the adapters I use for pairs of pentodes to 6sn7. Those convert the pentode to triode in the adapter itself.

In a plain old standard design (cathode follower Push Pull) you can have ultra-linear/Triode switch done inside the amp. You MUST use switch as it is not only strapping pin of the tube it is also changing connection to output transformer.
In our amplifier we just have triode mode using strapping method. As said by @OctavianH connect together K and G3 and G2 to A using a resistor. In Infinity it is done internally from EL34 / 6L6 / 6M6 .... pinout with a pair of resistor having very close value of R. So in our Case we can also use a Triode adapter as G2 pin will not be part of the output just skipping strapping.

I also finally found the builder of my amp... He is not yet retired and continue to build mostly in DIY mode (for fun (he only implements what he likes ) and seling to buy new part for the next one). The one i have is not a toy for tube roller as plate voltage goes up to 450V so I'm limited in tube choice as regular limit is 350V for many tubes...I also have limitation in divers as it was optimized for a low current coupling with followers...
About the builder, he is a very nice 60 years old electronic designer working 10 minutes from my home and not in headphone amp but curious. I plan to show him my infinity and see what he think and if he can repair it in case of failure. His motto for design is simplicity, efficiency and compromise. he also wire himself all the transformer, hand-wound transformers, close-coupled windings, layer-by-layer coating, insulation between layers and reinforced between windings...
You can give a look to a big boy using 807 in output and balanced input.

 

[OctavianH]

A post regarding variance in construction of Philips 4654. Besides the 5 construction types I have already found and tried, even the ones looking indentical are in fact not identical. I investigate construction and try to associate it to factories but it is not very easy because of no standard date codes. I have here 4 pieces which look identical.

This is the first type I ever listened when discovering these. If you look closer the color of the grey coating is not identical, and when you look from the top you see more differences. Another thing is the top cap, just look at them, not identical.

There is a very big variance in these, and I have no idea if these are different factories or just different batches of production where they used different materials. One thing is for sure, if you want to pair these also based on construction you need a box of them, and I am lucky to have one already. LOL

 

[OctavianH]

But the reason I started again to measure and pair 4654/EL50 is that I finally reached the point where I can compare different tubes of the same types from the Philips red series. I always said these sound close and do not put you in front a specific house sound, but I never tried them extensively. The reason is the socket, that these are rare and precious to me and also that these do not really like to be turned on/off often. I observed some interesting behaviors if you do this often (change of bias point for example). In short, these are old, valuable and need special care. But now I already have 3 sets of adapters for them and I can start to double check my assumptions: are different construction types sounding different?

In my view not, and these are good news. So all 4654/EL50 I have listened here sound more or less the same. Thing which cannot be said about EL3N or EBL1. My RT EBL1 have nothing in common with the RT sound (currently on input here in the photo) and sound differently than the WIRAG EL3N I listened a lot in the past. And here we are again at the elephant in the room, the true old sound of Philips and the tubes made with Philips materials.

PS. We will speak more about EL3N because it is a remarkable tube.