ferninando
Lunatic Member
1%mf Rs and silver mica 1-5% caps
Creating parallel resistance and capacitance kit
- Thread starter steelglam
- Start date
Thanks, ferninando.
I need to place an order from MAT Electronics for other stuff next week, and I was thinking about including some of the stuff for these kits in the order as well. MAT doesn't carry 1/4W metal film resistors, but they do have 1/4W carbon ones in various values ranging from 1kOhm-1000kOhm (which is what I would need). I notice that DaveyW says he uses carbon resistors in his loading plugs. I assume these would be OK, then? Is there a reason why one would use carbon vs. metal film resistors for this application?
I need to place an order from MAT Electronics for other stuff next week, and I was thinking about including some of the stuff for these kits in the order as well. MAT doesn't carry 1/4W metal film resistors, but they do have 1/4W carbon ones in various values ranging from 1kOhm-1000kOhm (which is what I would need). I notice that DaveyW says he uses carbon resistors in his loading plugs. I assume these would be OK, then? Is there a reason why one would use carbon vs. metal film resistors for this application?
ETI_5000
Super Member
10kΩ in series with a 47kΩ preamp means 17.5% voltage lost across the 10kΩ resistor....
That's quite a bit - I'd call it a considerable penalty. I agree with Felix that a series resistor isn't a good idea, although they are occasionally used in smaller sizes (e.g. 500Ω - 1kΩ) on phono preamp inputs for RFI suppression, often in conjunction with an inductor.
rnorton
Super Member
I'd go in and replace the original 47k's with 100k or 150k.
rnorton
Super Member
I used a Y splitter that was more cheaply made than it appeared to be. The case actually popped open and the piece of brass spring stock that was the ground flew away, causing 120 dB of 60 Hz hum to kill both main drivers on my left channel B&W 330. Be warned.
Actually, I just found this thread which seems to indicate that numerous folks prefer the metal film resistors over carbon ones for this parallel cartridge loading application because of lower noise.
http://www.audiokarma.org/forums/showthread.php?t=355531
DaveyW, have you had any problems with noise using the carbon ones, or have you tried metal film ones?
rnorton
Super Member
They used to make microphones from carbon.
DaveyW
Well-Known Member
I've not tried metal film resistors, but that's because I don't hear any added noise with the carbon resistor plugs in place v's removed from the splitter.
Maybe different TT's and/or phono stages are a little more sensitive?
I actually just use my potentiometer based variable resistor box now.
I like the flexibility to tweak the loading for the odd recording on the fly.
I did have to tinker with earthing of this though to tackle a few hum demons.
Cheers
Dave
totem
Addicted Member
I thought the y splitter was a pretty good idea, but the rotary box method
makes on the fly adjustments the Bees knees or something like that.
Anyway seeing as cyto and Dave have taken a stab, I wonder if we might be
able to put together a build of some sort, a combining of the minds thing.
Looks to be a project many would be interested in and very worth while!
Not being that technical, I will need to take some inspiration from those that know exactly how to proceed.
makes on the fly adjustments the Bees knees or something like that.
Anyway seeing as cyto and Dave have taken a stab, I wonder if we might be
able to put together a build of some sort, a combining of the minds thing.
Looks to be a project many would be interested in and very worth while!
Not being that technical, I will need to take some inspiration from those that know exactly how to proceed.
Thanks, folks. Those boxes look sweet!
catman: My Apt and Onkyo preamps have switches for 47k and 100k, so I don't really need to modify those further. My Adcom pre only has a 47k input, though...and I do like the sound of the phono stage on it (better than the Onkyo, in fact). So maybe at some point down the road I'll modify that. Unless it's an easy fix...I guess I could do it sooner if that's the case. Would it be a simple mod to change it from 47k to 100k?
DaveyW: Got it on the carbon resistors. I'll make a decision about whether to go with those or metal film, probably driven in large part by which vendor I decide to go with. Before I order online, I've got a local electronics surplus store to check out and see what they have in stock.
catman: My Apt and Onkyo preamps have switches for 47k and 100k, so I don't really need to modify those further. My Adcom pre only has a 47k input, though...and I do like the sound of the phono stage on it (better than the Onkyo, in fact). So maybe at some point down the road I'll modify that. Unless it's an easy fix...I guess I could do it sooner if that's the case. Would it be a simple mod to change it from 47k to 100k?
DaveyW: Got it on the carbon resistors. I'll make a decision about whether to go with those or metal film, probably driven in large part by which vendor I decide to go with. Before I order online, I've got a local electronics surplus store to check out and see what they have in stock.
cyto
Super Member
Actually that is the input impedance.
cyto
Super Member
It is much better, and I thank you for the suggestion to go to a higher input impedance :thmbsp:
I have been using the M97 at 62K and my AT440mla at 32K. But since I have the ability to change the impedance with the flip of a switch I use the M97 most of the time and use 62k.
IMHO the M97 at 62K sounds better than the AT440mla at 47k and about the same as the AT440mla at 32k but the M97 picks up far less surface noise.
This is the thread where I posted pix of it: http://www.audiokarma.org/forums/showthread.php?t=418599
Thanks again catman!
Last edited:
DaveyW
Well-Known Member
:thmbsp: - If you detect any additional noise with the plugs in situ on the splitter then maybe a move to metal film is where to look next.
DaveyW
Well-Known Member
Hi Totem,
OK - Good Call - Here's my thoughts on this topic.
Rightly or wrongly, I didn't want to go down the switching route for on the fly tuning.
I was and remain very nervous of signal spikes when switching from one resistance to another.
I know the risk is very low and that others do it, but I do not want to introduce any risk to my long loved amp and speakers.
Also, I wanted an infinately variable set up - on certain carts I can easily hear the difference between 8k and 10k ohms.
For me a rotary poteniometer was the way to go.
My first attempt was to drop a calibrated 100k pot onto each channel loading resistor on the phono stage - I just couldn't slay the hum demons.
So application as a parallel load became the focus.
This is what my experimental meanderings ultimately led to;
And here's the very basic circuit (please excuse me if this is not the expected methodology to draft an electrical circuit - I am no electrical engineer
)
I kept the two 100k pots as this allowed sufficient accuracy to accurately (enough) align the left and right channel resistances using the dial pointer lengths that kept the whole package to a sensible size.
Dropping down from 47k only gave a range of 100 ohms (note the 100 ohm base setting resistor) to 32k.
So I switch in a series 100k ohm resistor to offer a 100k-200k parallel range delivering a 32k to 38k load.
I do have some RCA plugs for a few settings between 38-45k but rarely use them.
Initially my plan was just to use this to identify the preferred resitance and then make up plugs, but I found that the Loading Box was good enough and added the incremental versitility of tweaking loadings on the fly for the odd bright or dull recording.
Also I run two sets of speakers in adjoining rooms using the same deck and amp. One set is brighter than the other, I have two loadings for carts depending upon which room I end up listening.
The Loading Box is a permanent addition to my set up when running HOMC, MM & MI carts.
I have to earth this box back to the phono stage earth point, specifically the pot bodies otherwise I did get quite noticable hum. Otherwise all is well.
There you go - A little bit more background on my approach.
Always good to hear others experiences and approaches to this topic.
Optimised Cartridge Loading (to the nearest 1k Ohm
) is a must have for me.
cyto
Super Member
Hi Totem,
OK - Good Call - Here's my thoughts on this topic.
Rightly or wrongly, I didn't want to go down the switching route for on the fly tuning.
I was and remain very nervous of signal spikes when switching from one resistance to another.
I know the risk is very low and that others do it, but I do not want to introduce any risk to my long loved amp and speakers.
Also, I wanted an infinately variable set up - on certain carts I can easily hear the difference between 8k and 10k ohms.
For me a rotary poteniometer was the way to go.
My first attempt was to drop a calibrated 100k pot onto each channel loading resistor on the phono stage - I just couldn't slay the hum demons.
So application as a parallel load became the focus.
This is what my experimental meanderings ultimately led to;
And here's the very basic circuit (please excuse me if this is not the expected methodology to draft an electrical circuit - I am no electrical engineer
I kept the two 100k pots as this allowed sufficient accuracy to accurately (enough) align the left and right channel resistances using the dial pointer lengths that kept the whole package to a sensible size.
Dropping down from 47k only gave a range of 100 ohms (note the 100 ohm base setting resistor) to 32k.
So I switch in a series 100k ohm resistor to offer a 100k-200k parallel range delivering a 32k to 38k load.
I do have some RCA plugs for a few settings between 38-45k but rarely use them.
Initially my plan was just to use this to identify the preferred resitance and then make up plugs, but I found that the Loading Box was good enough and added the incremental versitility of tweaking loadings on the fly for the odd bright or dull recording.
Also I run two sets of speakers in adjoining rooms using the same deck and amp. One set is brighter than the other, I have two loadings for carts depending upon which room I end up listening.
The Loading Box is a permanent addition to my set up when running HOMC, MM & MI carts.
I have to earth this box back to the phono stage earth point, specifically the pot bodies otherwise I did get quite noticable hum. Otherwise all is well.
There you go - A little bit more background on my approach.
Always good to hear others experiences and approaches to this topic.
Optimised Cartridge Loading (to the nearest 1k Ohm
I thought of using pots but wanted the values to be exact every time and pots are notorious for having a slightly different value in the same position after moving. I did use a non-shorting switch, I thought this would be less likely to introduce a spike if changing "on the fly".
When I experiment with different positions I turn the volume down to be safe. I did try flipping the switch with the volume up and music playing and it did not create a spike or click.
DaveyW
Well-Known Member
Fully understand and appreciate your angle Cyto :thmbsp:
I did re-cal the pots (new cover hand marked up) after the first couple of months of usage - I do periodically check and both appear to have settled down OK.
Also my switching fears have been somewhat erroded with time.
I do occasionally hit the bypass and 2nd range switches on the loading box while the volume is low.
OK - So it's really down to the convienience of infinitely variable v's precise loading.
Yep difficult call :scratch2:
Very much down to personal preference isn't it.
Good stuff!
Dave