1st post what can i build with this?

[turnthetable]

Hi , this is my first foray into amplifier building, I have recapped a sherwood s8000iv but am still a little fuzzy with terminology etc.
I want to get better at understanding tube topology and function so I figure a build is the best way to figure some stuff out.
I have a shaub lorenz console for parts that used 12ax7's and ell80's etc. I have taken out the power transformer and the output trannies and have it available for other parts. it has no center tap and had a selenium rectifier but the hv put out 300v. there are three heater voltages measured 2 @ 8.75v and one at 3v. These seem a bit low so i could have read them wrong???
For tubes I have some nos and used mullards but the nos in pairs are... ecc82 ecl82 ecl80 pcl82 pcl83 el95(may be used) and a GIANT box of other stuff I haven't gone through yet.
I have a dynaco 410 and would consider building a small line stage preamp or I would be interested in a small clean se amp to plug my tt into and play over my jbl l-26 speakers (if they're efficient enough)

Is this doable and can you offer advice or plans?

 

[planet10]

The ELL80 is an interesting tube, i'd build an amp with that. Was the console SE (1 ELL80) or PP (2 ELL80). 'd also build it so as to easily swap in 2 EL95 for each ELL80 if a new one became necessary and hard to find.

dave

 

[turnthetable]

there were 2 ell80 and 2 12ax7.
One has gas though(ell80) that's why I would like to work with some of my pairs, but I could find another ell80...

I also have three 6kd6's that may check out ok,

I have to compile a spreadsheet of the tubes I got so I can see what is useable. I have a sencore mighty mite 2, just an emission tester but it will help.

I really want to know what you all recommend, so thanks.
TTT

 

[Eli Duttman]

RES has a $45 per tube listing for the 6HU8/ELL80. Whether or not they have stock is TBD.

IIRC, Fisher used the twin power pentode in a top of the line console model. Digging Avery's schematic up may be worth while.

 

[VictoriaGuy]

Though you can certainly build a phono preamp stage successfully, it's a lot easier to build an amp to work with CD-level signals. You can get away with a lot of 'bad' wiring techniques when you have 2v input signal; not so much with phono-levels (some mV?).
Lots of possibilities out there.
I don't focus too much on which tubes I have in my stash when picking a design- most common tubes aren't terribly expensive (I'm not talking 300B/2A3 here...); you have the iron and that's the most important thing to keep costs down.
If you can figure out the output transformer primary impedance, that can narrow your power tube choices for the project.
Keep us posted with what you decide!
John

 

[planet10]

there were 2 ell80 and 2 12ax7.
One has gas though(ell80) that's why I would like to work with some of my pairs, but I could find another ell80...

Too bad. I have some, but i'm not giving them up (yet anyway). An ELL80 is essentially 2 EL95 in 1 bottle. The reflected impedance that i have seen in amps using these is very high.

dave

 

[miklos]

EL95 / ELL80

I guess you have push pull output transformers.
Build a 2x7W amp with them.
Check this page for more:
Röhren-Verstärker mit EL 95

 

[turnthetable]

Is there a way to tell if they are pp opt or se opt's by looking at them? A pic of them for you perhaps?
TTT

 

[Eli Duttman]

It's a near certainty that you have PP O/P "iron". Each ELL80 can support a PP O/P stage. You have 2, unfortunately 1 is gassy.

 

[planet10]

With an ELL80 per channel they are almost guaranteed to be PP.

You can verify from the lead-outs on the OPTs.

dave

 

[turnthetable]

With an ELL80 per channel they are almost guaranteed to be PP.

You can verify from the lead-outs on the OPTs.

dave

Dave the lead-outs of the opt are center tapped so definately pp no?
Trouble is I don't have a center tap on my power tranny I have to look to see how power gets to the plates right?
Eric