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Old 16th Sep 2020, 9:58 am   #1
Valvepower
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Join Date: Aug 2008
Location: Rayleigh near Southend-On-Sea, Essex, UK.
Posts: 1,852
Default EL95 bit’s this and bit’s ‘a that amp (from Wanted section) …

Hi,

From the post for large B7G bases in the wanted section as I felt a separate thread was in order here.

It’s uses a pair of EL95’s in push pull with a Radiospares Hygrade output transformer. The EL95 specifies 10K a-to-a, however the Hygrade is 8K a-to-a, but given this amp is being made with parts from the spares/toy box there is going to have to be some artistic licence! I’m hoping the Hygrade has a reasonable primary inductance to give a decent LF response. I could slightly re-bias the EL95’s to accommodate the 8K a-to-a though.

For the driver I’m thinking of using the Jeffery (Wireless World Aug 1947) high gain phase splitter using EF184 valves, again using valves found in the spares/toy box.

The chassis is an early Sterns 5-10 chassis which had been liberated of its transformers and other “useful” parts – this explains wanting the bigger B7G valve bases.

The mains transformer could be a 2x 50V medium sized toroid with series windings configured as a full wave voltage doubler to get the necessary HT. An alternative to this is a Radiospares Standard transformer with a 275V-0-275V at 100mA which is more than enough.

I'm not aiming to set the world alight with audio performance, but make something using parts from the spares/toy box

Regards
Terry
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