I had always wanted to build something with globes. When (recently) these were released I decided it was time. I built three of these and two got sold off one on commission.
I called the first preamp “Grace” then the next two “Elite”. The difference between Grace and Elite is a premium stepper attenuator at twice the price of Grace’s. Better parts are; Jensen copper paper and oil output caps, premium stepper and twin PIO final storage caps. The tubes are very expensive compared to even good quality 6SN7s but sound excellent.
But I think the ShuGuang CV-181Zs may sound better. I built yet another of these preamps with the ShuGuang tubes and some slightly less expensive parts and think it sound better. See other of my posts here.
retro-thermionic: "Elite" - 6SN7-SE preamp with low noise tubes
retro-thermionic: "Grace" - 6SN7-SE preamp
I called the first preamp “Grace” then the next two “Elite”. The difference between Grace and Elite is a premium stepper attenuator at twice the price of Grace’s. Better parts are; Jensen copper paper and oil output caps, premium stepper and twin PIO final storage caps. The tubes are very expensive compared to even good quality 6SN7s but sound excellent.
But I think the ShuGuang CV-181Zs may sound better. I built yet another of these preamps with the ShuGuang tubes and some slightly less expensive parts and think it sound better. See other of my posts here.
retro-thermionic: "Elite" - 6SN7-SE preamp with low noise tubes
retro-thermionic: "Grace" - 6SN7-SE preamp
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I use an XLR Plug and socket to bring in the HT and DC heater voltage from the external choked supply. Male on the back of the preamp and female on the lead.
I use to use XLR like that.
Then I discovered that most are rated at 125V, and it seems the 250V rated plugs are becoming scarcer.
After that I wouldn't risk them with HTdc.
I've used Amphenol connectors but 500V rated, but prices are variable and more costly than an XLR. Clones exist which are cheaper though.
Then I discovered that most are rated at 125V, and it seems the 250V rated plugs are becoming scarcer.
After that I wouldn't risk them with HTdc.
I've used Amphenol connectors but 500V rated, but prices are variable and more costly than an XLR. Clones exist which are cheaper though.
I realise it is beyond thier rating but I have never had a problem and by the way they are constructed I would image they can take quite high voltages.
How are the microphonics on these globe tubes?
My first DIY preamp used 71A globe tubes and the microphonics were so bad that someone could shout on the tube and the sound would be amplified (in a low distorted way) through the speakers. Fun party trick!
My first DIY preamp used 71A globe tubes and the microphonics were so bad that someone could shout on the tube and the sound would be amplified (in a low distorted way) through the speakers. Fun party trick!
Only if I tapped on the top plate did any noise appear. I’d say not too bad. In one of my tube HP amps I had a few very microphonic tubes. Fortunately I had a few and found one which was dead quiet. The other were really bad.
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