BVNr. 519 Inductor (v76s)

[rjuly]

I wonder if anyone can point me to a source for these inductors for a V76s build I will be attempting. Failing that, any information that would help me specify it for fabrication would be gratefully accepted.

I realize that this component and/or parts of it's associated circuitry has sometimes been recommended to be omitted from this type of build, in order to 'open up the high end', however I would like to be able to see exactly what the effect of having it in versus out, is, if I possibly can.

- Richard

 

[gyraf]

That inductor is one of the hardest part about the V76 - and probably why there are no (real) clones out there

I think our user MrDude/Audiosohn (Felix) is probably the only one that has succeeded in making this in a convincing form

/Jakob E.

 

[Ilya]

Sowter makes them as well. I have a couple made for a client. Haven’t finished the units yet though.

 

[rjuly]

That inductor is one of the hardest part about the V76 - and probably why there are no (real) clones out there

I think our user MrDude/Audiosohn (Felix) is probably the only one that has succeeded in making this in a convincing form

/Jakob E.

It certainly is a challenge. It will be interesting to see how close I can get.
- Richard

 

[rjuly]

Sowter makes them as well. I have a couple made for a client. Haven’t finished the units yet though.

Sowter makes them? I have ordered their versions of the BVNr. 514 and 515 inductors but I didn’t see anything listed for the 519. Would you tell me the model number they use for that inductor please?
- Richard

 

[MaxDM]

Not sure that Sowter makes exact copies.

 

[Ilya]

Sowter makes them? I have ordered their versions of the BVNr. 514 and 515 inductors but I didn’t see anything listed for the 519. Would you tell me the model number they use for that inductor please?
- Richard

My apologies. I've missed the "s" completely. No, Sowter doesn't make the 519 choke. Maybe they can do a custom one-off, but this will probably cost a lot.

 

[rjuly]

Also, I would like to identify what looks to my untutored eye like another inductor, which is unlabled on the schematic - number 84:



from this schematic:



If anyone can identify this I would be most obliged.

- Richard

 

[dmp]

There are two chokes on the plates and they are needed for v76 build. You can find these.
The other two (84 and 519) are used in the filters, which are often omitted when building a v76 There's a hpf and lpf. If you wanted to add these filters, carnhill has a multitap inductor that could be used, but would need to check the right cap sizes

 

[rjuly]

My apologies. I've missed the "s" completely. No, Sowter doesn't make the 519 choke. Maybe they can do a custom one-off, but this will probably cost a lot.

No worries - thanks for the reponse. A pity - I thought I saw some daylight for a second

 

[rjuly]

There are two chokes on the plates and they are needed for v76 build. You can find these.
The other two (84 and 519) are used in the filters, which are often omitted when building a v76 There's a hpf and lpf. If you wanted to add these filters, carnhill has a multitap inductor that could be used, but would need to check the right cap sizes

Indeed yes, thank you. I will look into that.

- Richard

 

[moamps]

I think the values of these two inductors can be determined relatively easily using a simulator program. The first network is HPF C-L-C with Rg=Rl= 80kOhm, C1=C2=25nF, we need to find L values for frequencies 60 and 120Hz.
The second network is LPF L-C with Rg=Rl=80kOhm and we need to find L for 200pF and flp=12kHz, for C=300pF and flp=10kHz and for C=400pF and flp=8kHz.

 

[Ilya]

No worries - thanks for the reponse. A pity - I thought I saw some daylight for a second

Well, they did wind the Bv. 516 for me (100H inductor), so they can probably do a multitap 519 as well. You'll need to figure out the inductance though.

 

[lukas]

...maybe this schematic tell something more.

 

[CJ]

That 100 H inductor does very little, the 517 series choke is done on a pot core, it is supposed to be 850 milli Henries but the glue that holds the pot core together always goes bad which makes the inductance drop way down, Oliver at Funkenwerk reissued the V76s and did not use the Bv Nr 517 .

 

[CJ]

The switches on the hi and lo cut that control the caps are subtle but useful.

 

[Ilya]

That 100 H inductor does very little

That's the 80Hz HPF. That's not "very little" in my opinion.

 

[CJ]

Get the thing to run flat and connect it to the Pultec.

 

[rjuly]

...maybe this schematic tell something more.

Hi Lucas,

Yes, I know this schematic - it for the v76 rather than the ‘s’ version if I’m not mistaken.

- Richard

 

[CJ]

Sounds like you are building a 76. Watch your heater voltage. The EF804/806s run with 680 degrees C, the coldest cathode for any type of pentodes ever made. Do not increase the voltage above 6.6V otherwise the carbonates burn off. BTW, Jensen 1:10 input sounds better than original 1:30 input.