Phono stage

I think a proper mc step up transformer is the only way to load an mc. However Borbely makes active stages so he's bound to favour those.

If you've heard the bass you want from the TT and tranformer via any other phono stage then you know its there to be had. Without looking very carefully at the schematic for the phono stage you have I couldn't tell whether that was likely to be the cause. Have you ever heard this phono stage delivering the bass you want even from a different front end?

You do seem to be loading the cartridge quite heavily though. Was the loading the same when the bass sounded ok with the WAD pre? Which turns ratio are you using in the step up transformers?

I'm not sure I'd agree that every ported loudspeaker has inaccurate bass but I'd accept that many do. However some IB bass systems are compromised dynamically aswell.

 

I havent heard the BA with any other deck than my own.

The loading was 5k on the wad - even lower. The step up is set to 20 db.

True - but you know what I mean. If someone has a speaker with true tight bass and if they listen to a certain type of music then and only then will they hear the difference.

If its there to be had then I gotta have it

There are some schematics on the BA web page.

 

Hmm. maybe not too low. 20 dB means the cartridge is now seeing approximately 70 ohms. Is it written anywhere what the source impedance of the EMT actually is?

when you say that the load was 5K with the WAD, was that the value of just the resistor used or the combination of whatever resistor you were using in parallel with the 47K mm input?

Obviously you've arrived at 8.2K somehow. How do you describe the effect of raising or lowering the load resistor value from the 8.2K you have now, both on the bass and on the overall balance?

 

Hi Murray,

If I could clarify the details of the wad:

Three valve MM phono stage (3xECC83) to which I've added a pair or Sowter MC transformers which have 12.5:1 ratio. Loading is variable with steps giving 50,100,150,250,450 and 900 Ohms and these are the reflected loading on the Tx primary by loading the secondary.
Nick heard it before the variable loading was added and I think it was set at 40 or 50 Ohms, so very low.

 

The Note Product PhonNote is very good indeed. You will find the transformers used familiar but the bass is well behaved (although I haven't heard it into transmission lines)

 

Hi Rob,

With 8K2 across the o/p of the S&B's and (presumably) 47K on the mm input of the Borbely BBV is currently presenting maybe 69 ohms to the EMT. Reducing the load resistor value further to perhaps 5K would reduce the load to the equivalent of what it was with your WAD ie 45 ohms (ish). This may tighten the bass up quite considerably but may also begin to shut in the hf aswell. However there is room for a little adjustment of that with his load capacitance.

The only answer with this is to try various values of resistor to get it right. It took me quite a while to get the value I was happy with with my cartridge and transformers. I haven't listened to the S&B MC transformers in isolation so can't really comment on their absolute quality.

Is the WAD circuit very different to the EAR 834?

 

I think the emt is 20 off the top of my head.

Raising the loading above 8.2k loosened the sound - at 10k there was a pretty clear difference on rock. At 5k it got just a little bit tighter (not that much though) but the treble became shut in and a bit rough sounding. Robs WAD might give better account of itself at 8k or so than it did at 5.

All the resistor values are in paralell with 47k - for both mine and rob.

 

what kind of resistors are you using?

 

Nick, this may explain why you are not 100% happy with the top end of the cartridge. The plot shows a standard EMT MC into 100 Ohms (cap not specified). It shows +4db lift at 20Khz which will certainly be audible. Naturally, the Brinkman version will be different in some ways but if it is based on the same basic design it may have similar characteristics. How do Brinkman recommend you load it.

(PS: don't have heart failure at the square wave ringing as this is cutter ringing - not a fault with the cartridge)

 

caddock 132

The lift is worse into 47k! But yes thats correct - even at 100 ohms it will still have a lift and recess. They need cap loading - you cant get it right otherwise.

Previously I loaded with 330 pf - plus say 270 pF for the leads and tenoarm cable. Now however the only loading is the 20cm of output lead from the transformer plus 5cm of cable internally. If I understand the effect of the stepup on capacitance correctly then only that part really matters and it is sure to be very low. It probably needs 30-50 pF - which will be seen as ten times that by the cartridge.

Some people load emts into an MC input with up to 1 nf.

 

Have you tried either the 14dB or the 26dB windings and compared them with the 20 dB?

Transformers often do work better the less transforming they are doing.

It might be interesting to listen to the 14 dB winding loaded by about 1K3 or alternatively the 26dB winding loaded by 36K to see what the effect is. The cartridge will still be seeing about 50 ohms.

Of course I might be missing some key point here but I'd try it!


Edit

The feasibility of this depends on the o/p level available from the EMT aswell.

 

No I didnt try - the BA has limited flexibility for gain.

I wil try fiddling with bthe cap loading first - and I have to tweak the crossovers anyway since the addition of the xbd after I decided to keep it.

 

I think they are different as many people on the WAD (now WD) forum have compared them and noted a very different sound.
I've never looked at the EAR circuit though I have the WAD schematic if you'd like it.

 

What would you say the improvements are with the latest set of mods? Will it work into the tvc now?

 

what a complicated mess of a thread, go and buy a Linto, plug it in, enjoy some records.

easy isn't it?

 

Dynamic Turtle hears the distant, but unmistakeable sound of a nail being hit firmly on the head.....

 

Indeed.

 

Have you tried 5751's in that? ECC83's aren't great in the circuit imo, particularly the third tube doesn't seem great at driving interconnects. 5751s are a slightly lower gain, drop in replacement for the 83, it'll sound slightly different at first but when you get used to it you should find improvements all round. There are some nice GE ones at Watford but they're £18 a tube or something daft. They do some others around £9 each (Phillips or something, can't remember off the top of my head) which are also very good.
I'd have thought they're worth trying in any amp using 83's really, which I think is better suited to guitar amps than hifi having a bit too much gain for my liking.

 

- Yes I'm currently using a 5751 as cathode follower on he output and like it a lot. I prefer ECC83 in the gain and EQ stages though. I'm running Mullards in those stages.

 

If the design has passive eq it relies on the o/p impedance of the 83's combined with the following filtering to get the right curves. Sustituting with a different valve may well make the eq inacurate.