If a tube is shorted, the fuse should blow. But as @JTbbb said, only ever put tested tubes in the amp. Usually if tubes are going to die, it happens suddenly.

That type of emission on the top of heaters is not uncommon, are you sure it wasn't like that before? Only way to test the tube is to test it...either in a circuit or a tube tester. 600V Jupiter Copper Foil should be fine if you want to keep using them, or go for the V-Cap ODAM. I have a...

I don't think the burning in of tubes is a well enough understood phenomenon to say whether or not playing music is necessary. But probably the most scientific explanation is the getters are collecting stray gas, or the emissive layer of the cathode is burning off impurities in NOS tubes. In...

No, you don't need to do that.

Transformers and chokes were custom wound by Cayin for the project. Don't forget there is a dedicated Aegis thread @meomap if you want to talk Aegis and tubes there. https://www.head-fi.org/threads/zmf-aegis-official-thread.972476/

Wow nice Matt! I've been practicing for about 10 years myself! And my partner is certified, about to pick up her first teaching gig 🧘‍♂️ Cat yoga is highly recommended.

Wow, definitely something I could get into. I've only tried cat yoga because that's all I have on hand around here.

Awesome, glad you like it. Sorry you hurt your back though! I've resorted to yoga + daily stretch routine to keep my own back problems at bay.

I'm definitely open to it! Haven't set aside any PTO, but if I think it could work I'll definitely consider it! @erics75 did you get your Aegis yet?

Just booked flights to CanJam SoCal. Maybe I'll see some of ya there to talk Aegis and tubes :gs1000smile:

I'll add it to the compatibility sheet with the caveat that one has to be mindful of not using very high current output tubes.

Yeah 5Z4 will work. It has a relatively low Vdrop of around 20ohms, but can only handle 125mA of DC output current. I would probably avoid pairing it with high current tubes, like KT88, 6550, etc. The high Vdrop of low current rectifiers like 5Y3 (max DC output current 120mA) sort of protects...

5V4G and GZ32 are near equivalents, so it's very likely they are actually identical and Mullard just labeled as a 5V4G.

Fair points! Thanks for the input gents :beerchug:

I'm interested in picking up either a JAR600 or JAR650, but I can't decide which one...I still have my trusty HD650, so maybe JAR600 is the move :thinking:

Like @sam6550a said, never have both hands near a live circuit. Make sure there are no loose wires with live voltage on them that are going to drift. Unused mains transformer leads I secure with a helping hands tool, for instance. And frequently check and recheck connections to make sure...

The main reasons is copper losses in the transformer. A higher turns ratio is used to achieve a lower output impedance, but the DC resistance of the copper wire of the transformer begins to make up a significant portion of the load at higher turns ratios and output voltage is lost across it...

I wouldn't worry about degrading the signal, should be fine with a switch in series. I mean, the original design has a switch in series, which is just a metal-to-metal contact. Same goes for the relay switch that is being worked on. Don't overthink it. As far as the voltage divider goes...

I went psycho DIY today in a way I haven't in a while. I decided I HAD to get a listen to my HY69 circuit in fixed bias, or at least a close approximation of it, to make sure we are on the right track. So wired up the bias supply (and by wired, I mean alligator clipped) using the new mains...

They are branded Mullard, but only GEC ever made true KT77.

No there's no problem with that. The two outputs aren't run in parallel, when you switch to one using the output selector switch, the other is disconnected.

Oh, sorry, that wasn't my intention whatsoever...:smirk:

All NOS KT77 were made by GEC / Marconi / Genelec, so the two pairs you have are from different eras, but same manufacturer.

274B? No, accommodating that rectifier means making a change that hurts performance for every other rectifier, namely lowering the value of the reservoir capacitor from 22uF to 4uF. Always a battle of compromises.

Someone in the ZMF Aegis thread, who has on loan some VERY bespoke tubes, claims that the Gold Lion KT77 (real ones) have an even larger stage than the EL37! Pretty interesting. But real KT77s are some of the rarest power pentodes ever made, moreso even than GEC KT88. So something tells me...