Eros Phono kit is in transit - any capacitor upgrades?

H

Henry2011

New member
Some of us have Eros Phono kits in transit.  I would like to do any recommended capacitor upgrades during the initial build (as I did with my SEX amp).  What capacitor (or other component) upgrades have proven worthwhile in the Eros Phono?  Are there any other mods to the Eros Phono that have shown a performance improvement?

My phono cartridges are relatively high output Grado moving iron (in the 4mv to 5mv) range so I am not considering SUT installation.  The Eros output will go to my SEX amp input.
 
The high voltage supply is regulated and isolated with a C4S.  The heater supply is regulated as well.  The most important capacitor in the circuit is the output capacitor.  The output stage is designed around the Seduction final stage.  PJ has said that a 0.47uF was the design value.  0.47 in this position will cover all audible low frequencies.  The 1.0uF that is supplied with the kit is an upgrade; not because of the increased value but because it is a PP film cap, better sounding. 

I was musing online with Paully about the use of two 0.22uF 600V KK Teflons (in parallel to achieve 0.44uF) there.  This is the largest value I could find in a 600V KK Teflon cap.  These caps are very nice sounding and unusually inexpensive.  PJ urged Paully to try just one 0.22uF at first.  The indication was that a second might not bring any additional bass information to the table at all.  Bass is what is sacrificed with a lower value at this point of the circuit, nothing else.

Edit: I tried one 0.22uF and two 0.22uF caps in parallel.  I preferred the single 0.22uF cap.  There was no audible loss of low end.

So my obvious suggestion is for you to buy some of these, break them in as I have posted and report back.
 
Hello,
I was wondering if anybody tried these capacitors with the Eros
http://www.v-cap.com/teflon-capacitors.php
http://www.v-cap.com/copper-teflon-capacitors.php
I was looking at 0.47uF 600V caps there - but they are pretty expensive.
Right now I am using soviet military Teflon caps 0.22 uF 600V (thanks to Grainger for recommending me those). Soviet caps sound beautiful, especially considering the price. Prices on V-cap are quite high and I was wondering if the sound improvement will be great enough to justify the price? Or is it just a waste of money?
I would appreciate any feedback/opinion on this.
Thank you

Anton
 
The coupling caps in the stock kit are 1.0uF Solens (though we may have shipped you 1.5uF's in their place).  This would be the most significant upgrade, and you could easily go much lower than 1.0uF, .47uF is a decent choice.

There's also a 0.1uf cap in the shunt regulator circuit that's potentially worth upgrading.  A 400V cap is OK here.

The 75K 1/2W and and 47K 2W resistors are also very much in the signal path, those could be upgraded, but be sure to use 1% parts or buy enough to match.

The 10.5k resistor, 0.030uF, and 0.010uF caps make up the RIAA network, you can find decent upgrades for those at Parts Connexion, but again, keep the resistors as 1% parts, caps at no more than 3% unless you can find a pair that measures closely.  For the 0.030uf cap, paralleling two 0.015uf caps tends to be easier to implement than finding a 0.030uf.

-PB
 
Paul,
Thanks for your response. Yes you are right - I had 1.0 uF 630V caps with my Eros.
I replaced those with 0.22 uF 600V teflon capacitors. I noticed an improvement.
I guess what I really was asking - if anybody tried those V-cap Teflon capacitors I mentioned above
and if it worth to upgrade considering their price.
Thank you for other recommendations too.

Anton

 
I have V-caps in my personal Tube Phono, they take a long, long time to break in, but are well worth it, especially in a circuit as well designed as the Eros.

-PB
 
Check out these pages: http://www.v-cap.com/hank-murrow.php  &  http://www.v-cap.com/bottlehead.php

For a Custom Bottlehead system using V-caps throughout.

Cheers, Hank
 
Caucasian Blackplate said:
I have V-caps in my personal Tube Phono, they take a long, long time to break in, but are well worth it, especially in a circuit as well designed as the Eros.

-PB
Click to expand...

As the output caps or in the RIAA?  If output caps, what size are they?  My tube phone has v-caps in the RIAA but Auricaps in the output.
 
Coupling only, the typical tolerance on the V-caps isn't quite tight enough for RIAA use, though you can always e-mail Chris and ask about getting a pair matched close to your intended values. 
 
PB, I have Dan's old Tube Phono (which you built correct?).  It looks to have V-Caps in the RIAA but Auricaps as coupling caps. It sounds great but I would be willing to upgrade the coupling caps if it might make an improvement. What value would you recommend?
 
A quick note - I chose 0.01uF and 0.03uF for the Eros (Seduction has 0.033 and a paralleled combination of 0.01 and 0.0012 for net 0.0112) partly because exotic capacitors are often not available in all values, but 0.01 is always available, and you can parallel three of them to get 0.03. And this way you can buy ten of them to get a price break, with only two left over. If you have a capacitance meter, you can sort them for the best matches.

I've never done this, but the possibility is built into the design on purpose  :^)  However, you are on your own finding a way to fit them in!
 
Paul Joppa said:
A quick note - I chose 0.01uF and 0.03uF for the Eros (Seduction has 0.033 and a paralleled combination of 0.01 and 0.0012 for net 0.0112) partly because exotic capacitors are often not available in all values, but 0.01 is always available, and you can parallel three of them to get 0.03. And this way you can buy ten of them to get a price break, with only two left over. If you have a capacitance meter, you can sort them for the best matches.
Click to expand...

The ever thoughtful PJ again offers a smooth path to upgrades!  Cheers, Hank
 
Would a precisely matched pair if 0.033uf caps work in the RIAA circuit in lieu of the .030?  Is there a way to adjust the R value to accommodate this?
Thanks,Mika
 
Yes it can in theory be done, but you'd have to calculate the value, and replace, several other components. The calculations are not exactly trivial.
 
If you want to use .033uF cap, you'll have to change:

75K resistor to 72.2K
0.01uF cap to 0.0104uF

The 10.5K resistor can stay.

After making these changes, you'll want to measure RIAA accuracy to be 100% sure that the component values are agreeing with the calculations. 

To be fair, there are $10,000+ phono preamps on the market that use the exact same caps in the RIAA eq. 
 
By my calculations, the following changes are necessary (nearest standard 1% resistor in parentheses):

75K becomes 68.7K (use 68.1K)
0.030uF becomes 0.033uF
10.5K becomes 9636 ohms (use 9530 or 9760)
0.010uF becomes 0.0113uF

301 ohms on the C4S feeding the plate  becomes 288.5 (use 287)
 
Paul Joppa said:
By my calculations, the following changes are necessary (nearest standard 1% resistor in parentheses):

75K becomes 68.7K (use 68.1K)
0.030uF becomes 0.033uF
10.5K becomes 9636 ohms (use 9530 or 9760)
0.010uF becomes 0.0113uF

301 ohms on the C4S feeding the plate  becomes 288.5 (use 287)
Click to expand...

I really appreciate the input. I think that is more work that I am interested in...
I have two v-caps that measure .009840 uF and .009843 uF.  Are these going to be sufficiently close to 0.010 to work in the "stock" RIAA network?
I seem to recall reading that the "ideal" value is actually just a bit above 0.010, which has me a bit concerned...
Thanks,
Mika
 
The theoretical ideal second cap is 0.010288uF, but the 6922 input Miller capacitance is around 50pF. the wiring probably adds another 10pF, so the target should be 0.010228. Subtracting the measured v-caps gives a residual of 388pF, the closest standard value is 390pF. That leaves you with a ~4% error - not big but possibly audible under some circumstances. Why not pick up a couple and bypass the V-caps?

Ceramic caps are crap for audio, with the exception of Type C0G or NPO which are said to be excellent; their main problem is that only very small values are available. 390pF is very small, and since it is dominated by the v-cap, you do not need precision in the bypass. For small values like this, mica and polystyrene are widely likes as well.
 
You must log in or register to reply here.

Similar threads

Omegabuzz
Another Eros II finished
Replies
2
Views
5K
Thermioniclife
Thermioniclife
T
Eros 2 questions [resolved]
2
Replies
31
Views
13K
Paul Birkeland
Paul Birkeland
O
Upgrade parts questions
Replies
11
Views
4K
Doc B
Doc B
M
How to reduce gain in the Eros TH (and phono) preamp
Replies
2
Views
14K
Doc B
Doc B
K
to SUT or not to SUT- that is the question
Replies
12
Views
4K
DesignTaylor
DesignTaylor
Back
Top