Upgraded resisters

[Thoburn]

Forgive me if this topic has been hashed over before. But, I was wondering what, except maybe reliability, does upgrading the resistors in the Stereomour do for the sound? In particular the resistors directly connected to the tube(s).

 

[Grainger49]

I am assuming the circuit hasn't changed substantially since the Paramour II circuit.  There are two resistors on that schematic that are connected to the grid of the driver and the output tube.  Neither is considered in the audio path.  If you do change them it could cause noise.  They are chosen for low noise operation of a "grid stopper" resistor.

The Stereomour has a volume control.  The quality of the volume control will affect the sound.

In order of magnitude of difference I would rate new iron first being the largest difference, then upgrading capacitors second (coupling and Parafeed) and tube rolling third.  Let's throw in upgraded quality of the power supply caps too.  The circuit doesn't really have any resistors in the audio path; except in the case of the Stereomour input volume control if it is not at maximum or bypassed with a fixed input resistor.  The volume control is in the audio path and can be upgraded.

 

[JC]

I'm guessing that you will get more responses as more Stereomours  are built and tweaked.  Might be a little soon for that.

Having said that, I believe Bottlehead pays particularly good attention to selecting the type of resistor for a given service.  So I would recommend that you take this into consideration when selecting any upgraded ones.

 

[Thoburn]

Thanks for the advise on resistors. The thought of upgradings the iron is a bit too daunting for me. All that unsoldering and then trying to get the mass of new wires in the right places without messing something else up. I think I would rather buy another kit and start from scratch with a set of magnaquest iron. Actually, it might be nice if you could order a Stereomour with upgraded iron instead of the stock stuff.

 

[Grainger49]

The upgrade iron doesn't appear on the Stereomour page.  Bottlehead doesn't sell upgrade iron for their kits, MagneQuest does.  So you couldn't order with the iron since they don't sell it.

This is the MagneQuest product page.  There is no Stereomour upgrade listed.  The Paramour will probably work. 

http://www.magnequest.com/products.htm

 

[ssssly]

I have not built the Stereomour but have several versions of the Pamamour. I have found several resistors that have directly affected the sound. In the PI and II the input resistors were the biggest difference. So for the paramour I would imagine that as stated the volume control would be the best bet to attack first. A nice stepped attenuator or fixed resistor, appropriate to your system of course, would be your best bang for resistor buck.

I also noticed marked improvement in upgrading the C4S resistors. I would list this as #2 resistor upgrade for a Pmour.

Next I would look at improving the power supply resistors or replacing them with inductors.

Upgrading the caps is generally more bang for the buck. But once you get the caps the way you want them, the resistors are fun to play with as well.

Enjoy,

 

[Grainger49]

ssssly,

I understand what an audio path resistor needs.  But what characteristics would a good "#2" (and thanks for labeling it) resistor have? 

The resistor types I am familiar with are MF, CF (these being film are somewhat inductive), CC, wire wound (both inductive and non inductive) and tantalum.  I don't know if tantalum is inductive or not but are reputed to sound good.  Any advice there?  Also the nude Vishays, Nekkid in the South, are said to sound good.

Good advice on the upgrade of the PS resistor to an inductor.  Those of us who upgraded Paramour and Paramour II are aware of it but the OP probably isn't. 

 

[Thoburn]

Actually, it might be nice if you could order a Stereomour with upgraded iron instead of the stock stuff.

I wrote the above this morning while rushing for work. I realize that my choice of words was poor. I have over 120 hours on my completely stock Stereomour and I love it. It sounds terrific. Even my wife, who is a casual music listener, has commented that the Stereomour is a marked improvement over my previous tube amp and pre-amp setup. The whole process of building and listening has been great fun and, like any addict, I just want more and more. I'll say it again, thanks to the Bottlehead crew for the great product.

 

[ssssly]

ssssly,

I understand what an audio path resistor needs.  But what characteristics would a good "#2" (and thanks for labeling it) resistor have? 

The resistor types I am familiar with are MF, CF (these being film are somewhat inductive), CC, wire wound (both inductive and non inductive) and tantalum.  I don't know if tantalum is inductive or not but are reputed to sound good.  Any advice there?  Also the nude Vishays, Nekkid in the South, are said to sound good.

Good advice on the upgrade of the PS resistor to an inductor.  Those of us who upgraded Paramour and Paramour II are aware of it but the OP probably isn't. 

I generally use Shinkoh Tantalum for high voltage and Vishay/TI bulk foil for low voltage. Both the Shinkoh and the Nakeds are rather large though. Where I physically can't fit either I am currently using Takmans. They make a very nice sounding stepped attenuator. Have them in the sweet whispers in my, kind of still a FPII.

For C4S, after significant assistance from PJ, I have started buying bunches of Takman metal films in the available Shinkoh values 4 up and down from the calculated value for testing. Once I have the B+ where I want it with the Takmans I buy the Shinkohs (they can get kind of spendy for experimenting with). The tolerances on the Takmans is usually very good, they do not maintain as tight a tolerance as the Shinkohs at higher temps in my experience though.

Some Tantalum caps are inductive some are not. Tantalum in and of itself is not inductive but the end caps and leads used by some manufacturers are. Shinkohs are completely non inductive. Most other tants out there are slightly inductive, would have to check manufacturer by manufacturer. (Takmans are also non inductive).

 

[Paul Joppa]

...
This is the MagneQuest product page.  There is no Stereomour upgrade listed.  The Paramour will probably work. 

http://www.magnequest.com/products.htm

Once again, I lost my post - someone posted while I was writing, and I failed to check. Sigh.

OK, the Paramount iron is too big to fit the mounting holes. The old Paramour II upgrade plate choke does fit, but the output transformer is the same as Paramount and won't fit. And all of the above units have exposed solder terminals and are not suitable for top mounting - it's a safety issue.

Mike at Magnequest knows what the specs have to be, and I expect he'll come up with a suitable upgrade set once there are enough potential customers to make it worthwhile to wind a run of transformers. Remember he'll have to design a new OPT, probably something in between the EXO-35/36 and EXO-45/46. (The plate choke is just a format change, the winding is the same as the Paramour II upgrade.)

The old Paramour I upgrade output transformer will work, of course - but frankly, and not to toot my own horn too loudly, I think the stock transformer is better.  :^)

 

[Grainger49]

PJ,

Thanks for the clarification.  If I had read it before I had forgotten.  I did know that the stock Stereomour iron is a considerable upgrade from the old stock Paramour iron.