His Master's Noise: A Thoroughly Modern Tube Phono Preamp

Hi guys,
i´m lucky, my system is running, the riaa curve is matched. I couldn´t get the last 0,5 dB to 20 khz. But i think, i don´t hear that.
Sounding is great.
I´m now using a CSS of 13 mA in the first Stage und 6/8mA in the second Stage.

Congratulations on your successful build. It sounds like only a few make it to the finish line, so pat yourself on the back for a job well done.

Any pictures to share?

Jac
 
Oh no!
I think that serves as a reminder to us though, even when these things are put together by experts occasionally a duff solder joint, over stressed component, faulty component etc can get hot enough to smoke without drawing enough to start blowing fuses.
I never intentionally leave my amps on when I go out, even just to the local shop.
I'm probably being paranoid as I suspect most components are designed to not catch fire in the event of a fault but I'd still rather not have to rely on that!
I've tended to use bigger boxes than necessary to give everything a bit more space incase something does go wrong and starts getting hot.
I have to say though I'm most worried about the hmn. Probably because it my case it has the most hand wired circuits out of the three projects.
 
Hello Everyone,

Late last year I bought a Goldring Elite MC cartridge (.5mV output) and since then I've been looking to build a tube preamp that could extract a better sound from my new cart. My cheap solid state doesn't cut it anymore.

I've been studying SY's design with great interest and I'm about ready to start ordering parts.

I've read many of the posts from the past 7 years over the last few weeks and I seem to remember that at some point someone (maybe more than one person) designed a PCB.

Did anyone ever had a batch of these made and had them available for sale? Any group buys? I'd be most interested in buying a set, at least for the audio circuit. If not, I guess a strip board for the power supply circuits and CCSs and most probably a point to point around the tube bases for the audio circuit will have to do.

Any tips for a new HMN builder?

Cheers,
Luis
 
I got some pcbs for the audio circuit here. Everything else I hardwired on the fibreglass board with just the holes in it. I came to the conclusion that strip board may not have been suitable for the high voltages due to the risk of arcing. The bare board was actually pretty straight forward and I think in future I'm going to use that more than strip board.

I'm in the process of moving house so everything's packed up but I'll have a look to see if I have some photos of the build to give you a start laying out the regs and the heater circuit.

I got the new sowters that replace the ones mentioned in the article and used them at 1:10 for a 0.4 or 0.5mv cart. This gives nearly as strong an output as my dac. Just check that the impedance of your cart is supported, I think these particular ones don't like more than 14ohm. (sorry, can't remember the model but 1452 rings a bell).

With these new sowters apparently only a resistor is needed for loading but I did end up using a zobel in combination to try and dampen ringing. I tried loads of combinations but really I should try just the resistor at some point. Anyway, the trebles and mids sound a bit better than my dac and the bass isn't as taught but supposedly adding the better psu on a gyro se should sort that. The point being is that I think the phono stage is performing as it should.

Regarding the power transformers, I got one wound for the high tension and found another for the heaters. This hummed chronically and I ended using a torroidal I had kicking about. This turned out to be much better. I know sy's article said to avoid torroids but I'm finding that high grade torroids are much easier to find in the UK than normal laminated types which seem to be a constant gamble. For any further projects I will be going straight for the supreme grade torroidy transformers with the electrostatic shields. They've proven to be no more expensive than the other large tx and I at least know they'll be decent.
 
Hello Dave,

Thank you for your prompt and detailed reply!

I'm interested in a set of boards for the audio circuit. How did you do it?
Two boards, one for each channel? Tube sockets on bottom so they can pop out of the box?
Pictures of the assembled boards would be great!

My cart has the following specs:
Sensitivity: 0.5 mV +/- 1 dB @ 1 kHz
Load Resistance: 100 Ω
Load Capacitance: 100 - 500 pF
Internal Inductance: 2 uH
Internal Resistance: 8 Ω

Will the Sowter 1480 be a good match?

Cheers,
Luis
 
Sowter has a chart on their site with recommendations for transformers based on your cartridge.

Hi Tubesman,

I found that chart, but unfortunately my cartridge is not listed there.

However, in the datasheet for the transformer that replaces the one in SY's design it says: "Suitable for cartridges in the range 2 to 15 Ohms".

I guess it will work well with my cart.

Cheers,
Luis
 
I am surprised, it seems to be a very comprehensive chart. I guess you could look at carts similar to yours.

You mean this chart: MC PHONO CARTRIDGE SUT TRANSFORMERS

Well, actually my cart is there, I didn't find it at first because I was expecting to find a good number of Goldring carts which is also a UK company.

After using the search in page feature of my browser I found it. It's the only Goldring cart in that list. And yes, the 1480 is one of the SUTs that work with it.

Cheers,
Luis
 
Just placed an order on Mouser for all the semiconductors and heat sinks.
Next is capacitors and resistors from a different supplier and I'll start putting the PS circuits together.

I already have the transformer and some caps (will have to check which) and a pair of EH6922 gold pins. Still need to find the D3a. Does eBay sound like a a good place to shop for tubes like the D3a?