nimo Posted April 2, 2020 Posted April 2, 2020 Hi Gurus, Need some help to attenuate gain. Current volume knob at 7 o'clock is plenty. Hoping to get it to 12 o'clock for normal listening volume. Figured I add a couple of resistors in series after the volume POT. What resistors should I use so i don't mess up the sound? ceramic, metal foil? 0.25w? 10k+1k or 20k+2k?
wizardofoz Posted April 2, 2020 Posted April 2, 2020 I would google L Pad calculator and apply to the source input maybe -10db or even -20db or can buy inline attenuators your image link is Adult content?
nimo Posted April 3, 2020 Author Posted April 3, 2020 No adult content...but I see what you mean. Updated the settings. Just schematics of tube pre in case that matters.
jaffrie Posted April 3, 2020 Posted April 3, 2020 Hi Nimo, Look at that feedback 24K resistor at the output, reduce the value & gain will be reduced.
nimo Posted April 3, 2020 Author Posted April 3, 2020 Hi Nimo, Look at that feedback 24K resistor at the output, reduce the value & gain will be reduced. Thanks jaffrie. Would you suggest adding one in parallel or outright replacing it? What values might you suggest I try? I want to avoid messing up the sound of course. Volume knob is 100k. Sent from my iPad using Tapatalk
jaffrie Posted April 4, 2020 Posted April 4, 2020 Hi Nimo Go buy some cheap carbon resistors to test it out can try around 12,16,18k resistors to test. Once you get what your after go look for Allen Bradley 1 watt carbon resistor of the same value. Cheers
nimo Posted April 4, 2020 Author Posted April 4, 2020 Hi Nimo Go buy some cheap carbon resistors to test it out can try around 12,16,18k resistors to test. Once you get what your after go look for Allen Bradley 1 watt carbon resistor of the same value. Cheers Cool! Will try that. Thanks jaffrie!
nimo Posted April 5, 2020 Author Posted April 5, 2020 So I managed to put in a temporary fix while I order a bunch of cheap resistors online for a few bucks...I have a SCHIIT SYS passive preamp so here’s what I did. Tube Preamp (inherent 8-10dB gain) > SCHIIT SYS > ICEpower 200ASC/AC I set the SCHIIT to 12 o’clock, then started turning the volume knob on the Tube Preamp....bang on 12 o’clock, it’s at good normal/comfortable listening levels. Should I just leave the setup as-is; don’t bother swapping out the 24k feedback resistor on the Tube Preamp? I’m assuming the SCHIIT SYS being a passive pre should not be messing up the sound or am I missing something? Sent from my iPad using Tapatalk
Audio Posted April 5, 2020 Posted April 5, 2020 I would take the easy approach and just add a reduction resistor in series with the 100K potentiometer. No need to cut anything, you don't need to modify your amp. I would start by adding a 56K resistor and increasing the value until you get what you want, 68K, 82K, 100K..... (Audio) 1
nimo Posted April 5, 2020 Author Posted April 5, 2020 Thanks Audio. This sucker has an input selector switch next to the volume pot. Will try see if I have enough space under the hood to work with. Current a Alps type 16 100k pot in there. Will swapping out to a Alps blue 250k pot be another alternative or bad idea?
Audio Posted April 5, 2020 Posted April 5, 2020 Frankly, you can do this without even touching your amp. You install the resistor to the RCA plug , a 56K resistor can be soldered to center pin inside the plug. (Audio) 1
Audio Posted April 5, 2020 Posted April 5, 2020 If not, you DIY an RCA female to male adapter and connect it between your interconnect cable and your amp input. (Audio)
Boxerfan88 Posted April 5, 2020 Posted April 5, 2020 If not, you DIY an RCA female to male adapter and connect it between your interconnect cable and your amp input. (Audio) Functionally similar to his Schiit SYS passive pre workaround isn’t it? Sent from my iPhone using Tapatalk
Eric Teh Posted April 5, 2020 Posted April 5, 2020 A resistor L-pad would be sonically superior to the Schitt passive. Not to mention putting the passive pre between a tube pre and power amp is a pretty bad idea as you end up with quite high output impedance. ICE power in stock form have very low input impedance, so I am surprised there is no bass roll-off. The other million dollar question is what source is being used ? Unusually high output ? I had a similar problem many years ago, with the integrated amp being unusually sensitive. I soldered a resistor L-pad directly into an interconnect cable which I constructed - problem solved. 1
nimo Posted April 5, 2020 Author Posted April 5, 2020 A resistor L-pad would be sonically superior to the Schitt passive. Not to mention putting the passive pre between a tube pre and power amp is a pretty bad idea as you end up with quite high output impedance. ICE power in stock form have very low input impedance, so I am surprised there is no bass roll-off. The other million dollar question is what source is being used ? Unusually high output ? I had a similar problem many years ago, with the integrated amp being unusually sensitive. I soldered a resistor L-pad directly into an interconnect cable which I constructed - problem solved. Thanks for pointing that out. With the passive pre in between, I think it was sounding a bit messed up; congested and nasal. Maybe that too would make it hard to pickup on the bass roll-off? I did listened to it for awhile in different tracks just to be sure. Didn’t sound right. Source at the moment is a normal NAD CDP. Haven’t tried my TT yet.
jaffrie Posted April 5, 2020 Posted April 5, 2020 Bad idea Nimo besides having a tube pre will add some nice color which should be good with your class D amp.
jaffrie Posted April 5, 2020 Posted April 5, 2020 Btw if you want to go passive, the pot should not be more then 10K connected directly to say your CDPs output.
nimo Posted April 6, 2020 Author Posted April 6, 2020 Bad idea Nimo besides having a tube pre will add some nice color which should be good with your class D amp. Yah, the coloured sound is interesting. I was fine with my passive preamp (very neutral and accurate I think) but needed more inputs and was curious what a tube preamp would do...holographic space like in the outer rims...lol Well, I order some bits and odds. Waiting for them to arrive. Circuit breaker now, no hurry to go anywhere. Damn tubes I ordered now cost as much as the preamp with stock Chinese tubes. Maybe I should have just gotten a Tisbury Mini II or maybe built one; definitely cheaper. Then maybe no gain issues...and then miss out on a bit of the fun here. I will take all pointers from sifus here. Try the suggestions when my bits arrive. Sent from my iPad using Tapatalk
jaffrie Posted April 6, 2020 Posted April 6, 2020 Hence my suggestion of using Allen Bradley resistor after you find the right value for your set up Nimo cause this resistor has got a pretty nice sound to it. Btw was looking into the Ice Power modules, seems like input impedance varies alot with frequency & the effect might cause a lack of deep bass. Not sure if you're experiencing this. Cheers
nimo Posted April 6, 2020 Author Posted April 6, 2020 Hmmm...I haven’t noticed that really. That said, I came from a full SS pre+pwr setup. NAD C162 Pre + ARCAM 290P. The C162 is a great unit. 290P had power and that’s about it. After putting in ICEpower in place of the 290P, I found bass kicks more articulate. Low extensions were more defined. The 290P was more muddled in comparison. I A/B using the Dali CD Vol.3 (red album, tracks #1 thru 4). Actually don’t find the ICEpower lacking. Didn’t pickup any noticeable bass roll off. My wife on a few occasions thought I was playing through my *3way floorstander (was actually using my *2way monitors). The 290P has tendency to mess up the bottom end. ^all DIY 4ohms speaker, no subwoofer.
jaffrie Posted April 7, 2020 Posted April 7, 2020 Good that your not experiencing it. When I restarted this hobby 4 yrs back I saw all that rave about Class D so jumped into it with Hypex of all sorts including OEM modules but one day when I connected my good old SS amp then I heard what was missing & when I decided to go into tubes again I too heard what was missing from SS amps. Morale of story, if you enjoy what your hearing just go with it don't compare coz it's a heep of never ending search. CHEERS 1
nimo Posted April 7, 2020 Author Posted April 7, 2020 True that. But I’m also one of those itchy backside. Lol! Been on Class A/B forever. Tried a EL84 integrated briefly...was missing something. Then decided to do Tube Preamp and Class D power. Theoretically should give best of tubes in upper mids and speed of Class D + slam. Was considering Hypex Ncore at some point but ICEpower friendlier on the wallet. Been great so far so all good.
jaffrie Posted April 7, 2020 Posted April 7, 2020 Maybe some day you might drop by to hear my set up, ever evolving as I experiment a lot that is if you visit Batam. lol
nimo Posted April 25, 2020 Author Posted April 25, 2020 Hi Nimo Go buy some cheap carbon resistors to test it out can try around 12,16,18k resistors to test. Once you get what your after go look for Allen Bradley 1 watt carbon resistor of the same value. Cheers My cheap metal film and carbon film resistors arrived. Read up a bit but any real advantage between metal or carbon film? I see a bunch of metal film in my target install location. The 24k feedback resistor is metal film from looks of it.
jaffrie Posted April 25, 2020 Posted April 25, 2020 Just test out the 24K resistor replacemnt & think about other stuff later. Carbon or metal all have certain sound signatures.
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