Wm goes Thermionic

WM, can you outline what's different (it's kinda like looking at one of those "there are 10 differences between these pictures - see if you can spot them all" things)?

John

PS. No plans to modify my MM until the warranty runs out in 2008

 

i think i'll be ready to consider it at the end of next year.....

 

Ok guys here's a stock one.............

 

basically lots of big fat hovland caps?

 

Yep thats a Kev mod, plus those 2 larger 5.6uf units marked 'Living Voice'. made by 'Iew'
So Far replced the 0.1ufs bypass with some serious quality units, changed the resistors on the input side for 102 Visheys, rewired a couple of runs, new sockets to go in FRiday, along with the rest of the cap changes, new main rail wiring, a couple of Quantum filters.
And the new Valves will be here, I procuded that Genelex Goldeb lion for the Rectification stage , plus the Correct 4003 mullard's cryo'd.
I would like to point out these are pretty basic mods, nothing thats not been done before, but its a low cost project so it would keep it all in perspective (except the golden lion valve )
Should help bring it all together a little more. Wm

 

Hi,

The maker is ICW, you used to get them at Maplin, when Maplin still sold quality components.

Interesting to note that you removed the Teflon V-Cap's and replaced them by Hovelands. I tend to avoid Hovelands myself....

For the Minimax the sound is dominated by that dreadful Alps "High End" Pot and and the basic circuit + Valves.

I would suggest completely replacing or completely dropping the cathode bypass capacitors on the input valves, Rubycon SWR or a range of other low voltage mylar capacitors are a great choice and drop that Alps thing, replacement even by the cheapest 470k linear track carbon pot plus a 10k lawfaking resistor is needed, better choices, such as the PEC carbon pots exist. Then a really high quality output coupling capacitor should be used (I know what my first choice would be).

I personally would also replace the input valve anode resistor and the cathode follower valve cathode resistor with constant current sources, but some may feel that this makes the preamp too little "tube" sounding.

Finally, if the mains transformer can supply enough heater current, changing the valves to 5687 will make another major step forward.

Or one might just scratch-build such a preamp using a Scroff 19" case from RS Components, a handfull components and som e ellbowgrease. But then again, in a scratch build better sounding circuits may be used.... ;-)

Ciao T

 

NO T, the other way round, I think Hovalnd are dire sir
To be fair, yes I could do the from scratch thing T.
However, Its a play thing for a while, Valves I'm still learning plus I hate vol knobs .
THough I do cheat, set the MM to the correct setting and use the Vol control on the Wadia, cheat fair I always say
Hooking up the power amp direct this morning, has shown in no small terms how far off the MM is from main sound, oddly enough in vocal dept.funny old world isn't. T.

 

Hi,

Ahh, mea culpa, I took the "few bobs...." comment to be below the picture it referred to. I have not quite been myself in recent times.

That makes two of us.... ;-)

Indeed.

I'm all valve myself, but I like to keep stages to a minimum....

I have 4 active stages (open loop), 3 coupling capacitors (5 if you include cathode bypass and output stage WE capacitor whioch should be the case) and 3 transformers between MC Pickup and Speaker, no electrolytic capacitors anywhere at the signal!

For digital I have two transformers, 2 stages and 1 coupling capacitor (3 if you count the ones mentioned above) after the Player, one of my players adds another active valve stage after the DAC and a coupling cap, the other uses a LC Audio Zap Filter....

Getting rid of all the unneccesary stages does clean up the sound no end.

Ciao T

 

T, I've played around with transformers in the output stages, even have custom wound units with trick wire and 2:1 etal, just didn't groove & flow at all, lovely big open spactial natural sound, but no balls and drive to music or for that matter overly great vocals.
But I see the appeal, I like things a little different.
Can't agree more on the less stages thing, my output stage has 2 coupling caps, the right ones & custom i/c driven configable feedback loop opamps (dual diff if required too), which are rather damn good, ultra quiet and seriously fast and smooth too (Oh, 2 more caps on that board SMT oscons).
The difference is not subtle. Its a matter of personal taste & how we arrive at it, sometimes we start at opposite ends & end somewhere in the middle, and learn a lot on the way too.
T.

 

Hi,

Hmmm, transfomers are a black art, not many can do it right. Also, really high quality transformers need rather large cores. Try borrowing a Music First Audio passive preamp, you will understand what I mean.

Ciao T

 

The mullards arrived this morning, and they do bring a few extra's to the party.
Vocals are more prominate (Though a bit forward for me at present), a smoother sound, tighter and deeper bass, and touch more flow too, A fuller and richer texture to the sound too.
(I can see why these are popular valve upgrades)
Nice upgrade for £44 Wm

 

That about sums up my experience with the CV4003, tho mine aren't cryo'd.

Still interested in the GG Tone?

 

One thing, its a bit pipe and slippers for me now. Just a rocker at heart I spose
Proplem is I've been spoilt by the mono's
Its still a nice sounding combo for sure, I further upped the power amp, some neat main cap by-passing and a spot of rewiring with some 'wanky wire'. New sockets too.
Filter network next. then rewire on the MM, plus some more proper caps and maybe a decent Vol pot

 

Try the pseudo shunt with existing pot

 

stepped attenuator?

 

I have a spare one.

 

Andy,

Can you give me a ring & we'll sort out the weekend. Ta

 

Will do Tone, in about 20

 

Hi,

To quote my sensei....

"We tried resistor ladder attenuator, it gives hilarious dummy sound!"

I agree. The attenuators with as many daisychained resistors as are steps sound quite bad, each and every resistor in the chain compounds the sonic signature.

If you want a switch based device use one that has only 2 resistors per position. These can be made constant impedance (more parts needed, more expense) or variable impedance.

By the time you build this with good quality resistors (Vishay S102 anyone?) and all you start seeing the attraction of transformer based controls as easier and more economical solution, which, as Martin Colloms found also provides material gains over a Vishay resistor based attenuator in sonic terms....

;-)

Ciao T

 

I agree, hence the stepped attenuator is a spare part