6aq5 to el84 converter

[davent]

Thanks fellas. I'm looking for one of these, but not at this price:
http://www.ebay.com/itm/370638994599?_t ... EBIDX%3AIT

.

Shipping to Canada for one... a crack under $14US.

[billyoung]

from what i see 365 volts fixed bias for the jet city jca22h

bill

[billyoung]

heres jca20h service manual.

http://starin.info/Product%20Info/Jet%2 ... ematic.pdf

[Phil_S]

Thanks fellas. I'm looking for one of these, but not at this price: <link snipped for brevity>

Shipping to Canada for one... a crack under $14US.

That seller rarely has bargains. The advantage for me is that he's less than 25 miles from where I live, so I get it next day.
You might as well buy direct from China if you are willing to wait, which I am:
http://www.ebay.com/itm/2pc-bakelite-oc ... 2ecf7a7717
http://www.ebay.com/itm/10pc-bakelite-o ... 2ecf7a73ee
$2 each if you buy 10, $4 each for a pair. Shipping to Canada is likely same as to US. I'm thinking I might buy the lot of 10 and sell some of the excess in the $3 range including shipping. Maybe one lot of 4 or 6 to keep the hassle factor down.

[Phil_S]

Someone mentioned Yellow Jackets earlier in the thread. That is a device that does more than socket conversion. It allows you to plug an EL84 into a 6L6 or EL34 socket and supposedly takes care of the other compatibility problems. So, I'd expect to find more than a simple rewiring inside a Yellow Jacket.

You don't have compatibility problems between 6AQ5 and EL84. Basically plate load, bias requirements, and plate voltage limits are so similar that it shouldn't be an issue. It is much more a matter of simply building a thing to manage pin reassignment. You should change the bias resistor in a cathode biased amp. BTW, 6AQ5 is the same as 6V6 except I would not suggest the 6AQ5 can take the abuse of >300V we often see in 6V6 amps.

[billyoung]

the jca22h has plate voltage measuring 365, seems way too hot for our little 6aq5 ? Maybe a plate resistor in adapter ? biltagas current on el84 appears to be around 30 ma, not sure of bias voltage ?

bill

[billyoung]

this is guy i got parts from ......nice fellow

http://www.ebay.com/itm/390343499665

http://www.ebay.com/itm/7-PIN-TUBE-SOCK ... 5b07265ad7

http://www.ebay.com/itm/9-PIN-SOCKET-SA ... 5b0e88491f

this bit high priced

http://www.ebay.com/itm/8-PIN-OCTAL-SOC ... 5aef7397c4

[The Ballzz]

Someone mentioned Yellow Jackets earlier in the thread. That is a device that does more than socket conversion. It allows you to plug an EL84 into a 6L6 or EL34 socket and supposedly takes care of the other compatibility problems. So, I'd expect to find more than a simple rewiring inside a Yellow Jacket.

You don't have compatibility problems between 6AQ5 and EL84. Basically plate load, bias requirements, and plate voltage limits are so similar that it shouldn't be an issue. It is much more a matter of simply building a thing to manage pin reassignment. You should change the bias resistor in a cathode biased amp. BTW, 6AQ5 is the same as 6V6 except I would not suggest the 6AQ5 can take the abuse of >300V we often see in 6V6 amps.

Agreed, and while the Yellow Jackets are not actually available for EL84 to 6AQ5 conversion, they do offer an Octal to 6AQ5 unit:

https://www.tubesandmore.com/products/P-YJNOS

my point in mentioning them was that most of their products are more than simply a pin conversion device. The devices on the bay from Hong Kong do not give enough details to determine if they are just pin to pin converters or if they have something more going on inside.

I guess my big question is how well the 6AQ5 will fare with the voltages present in the fixed bias JCA22H. On my 6AQ5 build, I used an 8k ptimary OT. Maybe the specs of the OT are on it's label?

HTH,
Gene

[matt h]

(deleted)

[billyoung]

could i add a resistance in the adapter ?

what do you guys think ? I am not wanting huge output power .

[The Ballzz]

from what i see 365 volts fixed bias for the jet city jca22h

bill

Is that 365v the ACTUAL voltage measured at the plates or an extrapolation of voltage found elsewhere? Tubes installed or not?

matt h, you said:

"At those voltages, I would not expect 6aq5s OR 6bq5s to behave well or sound good."

The amp is already using 6BQ5/EL84 tubes in stock configuration. The reason I was asking is that 365v seems a bit high for an EL84?

billyoung,
On a slightly different point, while changing to 6AQ5's may change the sound a bit, don't expect a very noticeable difference in overall volume. And as far as the sound that you stated you don't like, are you certain that is caused by the EL84 power tubes? Is it possible that what you don't like is being created by the sum of the rest of the amp's design? I never played a JCA22, but have played quite a few JCA20's and found them to be pretty darned OKAY!

Just Sayin'
Gene

[billyoung]

I typed a huge post and lost it . Dammm.


I got 365 from net from a guy biasin one. I am trying to build

a real nice regulator circuit using a 450v three terminal device.

that might be best approach when i get it done (If too).

working on a variable three output regualor board for my current mini plexi

build, I like the tone of it on my test bed ( hammnd m100 chassis with all kinds of sockets). The hammond voltage is too high too like 420 for 6v6s
it had. I am guessing the adapters depend on what yu try to run them on.

anyone tried a 6ak5 in a ef86 type boost circuit. I got a bunch of em,
some are military versions( lil feckers lol)

bill

[Phil_S]

I have no basis for the following statement except for maybe a bit of common sense if I'm worthy of that. I'm thinking you are run a 6AQ5 at 365V if you drop the screen voltage below 250.

Changing the subject a bit, there is a Russian EL90 (really 6p1p-V) out there and it is a 9 pin tube for a noval socket. These are inexpensive and supposedly 6AQ5/6V6 equivalent. You still have to deal with pin compatibility conversion, but you might skate by on the higher voltage. The data sheet says 250V max, but the RCA data sheet says that for its 6V6, too. I'm just speculating here, as I have no experience with the 6p1p.

[billyoung]

check out this guys store he has some 8 pin sockets no ears or anything


http://www.ebay.com/sch/m.html?item=331 ... re&_sop=15

some nice caps

wish i knew russian tubes

[Phil_S]

Yeah, those sockets need a retainer clip, and it doesn't look as if they are provided. Uh, huh, no.