Wm goes Thermionic

Hi,

I might, where are you?

Ciao T

 

North London.

At the moment I have a diy volco unit. High quality switch and attenuator with welwyn resistors buffered by a active stage. I am running triamped so the volco must drive 3 pairs of power amp inputs in parallel accross 3m of cable so pure passive isnt an option. I looked at mfaudio to make a custom unit but it ran into problems in prototype and they soon lost interest. They would have put together a 1:3 o/p transformer but it would be possible to use 1:1 and just have three pairs of output sockets connected, taking into account matching issues. Be interesting to see how one compares with my pre, especially as I thinking of going the route of extremely expensive power supplies and discrete dip-8 opamp replacements. If your pre with the tx102 sounded much better then I could just scrape out the buffer and attentuator and purchase a tx102 to take its place...

Then I have only to locate the mystical runestaff and travel to the Eternal City from whence I will rule the audio multiverse bwahaha

 

Why does that not surprise me , maybe you were poltely offering advice on a hourly basis

 

No it rang like a bell due to the loading - I think the issue was getting the 1 input transformer to 3 output transformers working properly (balanced). I didnt have any advice to offer at all not knowing anything about the topic.

Did you get my emails WM? I am still waiting for the connector details ... will send them along when i get them.

 

Hi,

Me too....

I agree. I/We designed the Euridice for exactly that job, plus to have enough gain to compensate for the use of passive level matching, equalisation and LC crossovers.

So, a 102 only will likely not do.

I remember that one, it was you then....

Wanna come over and have a listen to it in my system? I also have a Consonance Reference transformer passive here.... You would have to buffer the several outputs somehow though.

Indeed, but you need to get there at the right time.....

BTW, I'll have the black sword instead if I may....

Ciao T

 

Ah you are thorsten right?

I have known of you for sometime via audio asylum - didnt know this was you as well.

I could replace the stepped attenuator and keep the buffer. It only has to drive 4 bryston amps (6 channels). Is it not just a case of getting a custom transformer from s&B with the right characterisitcs? Maybe if I only go for a 1 way balanced transformer they might be able to manage it? I found mfaudio a little bit slow. It dragged out for months and in the end and then it just went quiet.

What is the euridice? Sounds like greek to me

Ah my friend ... I am a thousand times more evil than thou! The conjunction of the spheres approaches!

Nick.

 

Hi,

Yes, I thought the sig would tell...

The bryston Amplifiers have not really got true balanced inputs actually, if you use them via RCA inputs you have 3 X 50K load, which the MF Audio preamp will be just dandy with, 3m cables are okay too, if they are low capacitance.

The balanced inputs of the bryston Amps are lower in impedance (a little unpredictable as well due to the particular input circuit used) and might be a little too much not just for the preamp itself (Martin Colloms measured it with 600Ohm load and it did fine) but for whatever has to drive both transformers AND the three paralleled inputs.

See if you can organise a MF Audio Preamp loaner somewhere....

It is greek, I did cover it a little earlier in this thread.

Ciao T

 

Not really possible as I need three balanced outputs. Unless I go back to monoblocks just to compare. Do you have an mfaudio unit? Or perhaps I could compare my volco with your tx based unit in your system if the offer for a listen is still open?

HAve you tried the S&B step xformer plus active stage plus riaa module approach?

Yup I know my classics

 

Hi,

You could build a single balanced interconnect (try my CT-100 based recipy - use the centerconductor for pin 1 and add a pair of goldplated silver wires from wires.co.uk for signal hot and cold fed down the air cells in the CT-100) and make a 3-Way breakout at the end (use the cheap all plastic Cliff XLR connectors, they sound best anyway) and you can use a single XLR Output preamp and you get less cable salad on the floor....

Yes, I now have a current MF-Audio unit, I do the occasional bit of consulting for them.

You can, the offer is allways open, even to my most bitter on-line "enemies".... ;-)

I'm afraid I must admit to being the person who got S&B to start making TX-102 Transformer Volume Controls, the TX-103 MC stepups and both the 600 Ohm and 10K RIAA Modules. In fact, i did a good deal of the design work for the RIAA Modules.

So of course my Phonostage uses TX-103's and EQ-600's.

I use two active stages, first stage is a Siemens E810F high transconductance pentode (gives a gain of around 28db into the 600 Ohm load presented by the RIAA with exceptional linearity and overload margin) and after the RIAA I use a Siemens D3a triode wired for around 2K Output impedance and 32db gain (so overall gain of the RIAA is 40db on the MM input and 66db on the MC Input). The powersupply is a bitr overbuild with a powertransformer from a Mullard 12 Watt Poweramp, 8pcs 10H chokes and 6pcs 120uF Ansar MKP capacitors for +B filtering (plus local RC filtering) and choke filtered heater supply with a 68,000uF final filter capacitor.

Ciao T

 

Am I a bitter enemy? :O Surely you are not one of those pink fishes!

Ok yes then I am very interested. I can disconnect the tri-amping and just use the monos for evaluation in ym ow system as well. In the long term I will go active anyway (maybe quite soon if I get my bonus!) so then I will just need single xlr out for the crossover. I am also interested in listening to the phono.

What are the limitations of the transformers that I need to be aware of in terms of loading and voltage limits?

 

Hi,

No on both counts, I merely keep an open door to all, even to those who disagree with me in the most disagreeable fashion.

Then you definitly need to come over, I might have lugged the MFA Pre over, but the Phonostage and Powersupply are well too heavy for that.

Source needs to be able to drive the load by itself and should have ideally < 5KOhm output impedance for 0db operation and < 1KOhm for +6db passive gain. Loading limit suggested is 10k//1nF for 0db and 40K//250pF for +6db.

Ciao T

 

3m balanced cables are 70 pf/m so should be ok. Ok sounds like I should bring the phono, volco and a psu and do a comparison! Will let you know as soon as they are "sorted". I have found the best combination of opamps for each but neither is completely stable so they need a little bit of tweaking.

 

Hi,

I think comparing your phono to mine to determine if you should try the LCR RIAA Module is not meaningful, as they also use a drastically different sets of technologies.

Preamp's we can compare easily, I need a few balanced inputs though (Phono, CDP)....

Ciao T

 

True but its always good to listen to other tech Be interesting to get your opinion on the phono riaa and step up - I could always construct one around something like a discrete buffer...