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Post by guadixman on Oct 20, 2008 11:12:07 GMT
Hi all,
first post here. I have a problem that I´m sure I have the answer but it never hurts to have the opinion of others.
I bought a Lehman Black Cube phono stage in 97 but only used it for 3 years until I built the original WAD Pre 2 series of valve phono stage/PSU and valve pre.
I never managed to get rid of hum which I believe came from the PSU.
When I bought the Bada PH12 h/amp it was impossible to use the WAD phono stage at all, so I resurrected the Lehman.
I still was not happy with the sound but at least I could use my vinyl. I decided to try soem ERSE 2.2uFs inplace of the WIMA caps and the difference wasa not subtle - I now think that Norbert Lehman designed a superb circuit but used crap components.
I have now changed all the caps and decided that the resistors he used were no great shakes either.
Now here´s the problem/situation - I measured all the resistors and checked my m/meter readings against the banding info and was surprised to find 2 pairs of resistors that measured nothing like the declared banding read.
First up was a pair that should be 47K but actually measured 100r & 101R. The second pair should have been 220R but actually measured around 19/20R.
I don´t believe that a 47K could drift so much down to 100R - rationally I want to order 100R and 22R - what does the panel think.
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Deleted
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Post by Deleted on Oct 20, 2008 11:40:29 GMT
guadixman Perhaps you are misreading the the markings ? Some colours are difficult to identify, unless in good lighting too. SandyK Attached is a resistor colour code chart ,for members who may not be familiar with resistor colour codes.  |
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Deleted
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Post by Deleted on Oct 20, 2008 23:49:15 GMT
Miguel
I can email it if you like, but many members may not realise that you can "right click" on
posted images, and choose the option "save picture as."
Let me know if that works for you.
Alex
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leo
Been here a while! 
Team wtf is it?
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Post by leo on Oct 21, 2008 3:34:13 GMT
Did you measure the resistors whilst they was still soldered to the pcb? if so that can give false readings, to be sure its best to remove them from the circuit and measure them
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Deleted
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Post by Deleted on Oct 21, 2008 4:13:48 GMT
Leo is absolutely correct.
If an incircuit resistor does not read close to it's marked value,even after turning the meter probes around the other way, unsolder one end of the resistor clear of the PCB, and read across the resistor again.Capacitors in the circuit may also alter meter readings , as they attempt to charge or discharge.
A capacitor that has retained a charge, may occasionally cause a resistor to read a much higher value,as well.
SandyK
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Post by guadixman on Oct 21, 2008 6:37:23 GMT
I have no problem with reading the colour bandings, I always work with a daylight lamp and use a stamp collectors magnifying glass. I also use a brilliant resistor code facility which automatically tells you what the value is as you punch the colour bands in - www.samengstrom.com and crosscheck these readings with the Maplin r/chart online. Leo, I would agree with you but this situation has never occurred before with reading/measuring resistor values in situ. Also there are around 22 resistors in the Lehman phono stage and only with these 2 pairs is there this anomoly that don't come near their banding values. The PCB has been removed from it's housing for a few days now so no residual effect should be there and remember both pairs measure as same or very close to each other. Remember this is a phono stage, so no high current throughput here. I shall remove one of each pair to measure and I would like to be pleasantly surprised. If I was going to use cheap replacements I would buy and try both the stated values and the ones my m/meter tells me they are but as I have been so knocked out with the sound I get from the cap modded Lehman I want to lash out for naked Vishays and they don't come cheap. I will get back when I have done this. |
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Post by guadixman on Oct 21, 2008 22:06:40 GMT
Leo/sandyk,
you were spot on about the resistors, I removed them and they measured as per their banding info, so now I know for the future.
It still seems strange that only those 2 pairs were out of kilter but now I can order the Vishays with confidence, thanks a lot.
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Deleted
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Post by Deleted on Oct 21, 2008 22:14:23 GMT
guadixman
Care to post a few photos of your unit's internals after you complete the mods, as well as detailing the audible improvements ?
SandyK
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Post by guadixman on Oct 22, 2008 10:19:50 GMT
Hi sandyk,
no can do with pics at the moment - I need to buy a digital camera and a new computer, this one is malfunctioning, too old and too much heat here behind the Sierras.
What I can say is that removing WIMAS has to be a very good thing wherever they are found, they just seem to sit on the sound.
I removed 3 WIMA 0.1uf that were used as snubbers on the valve bases in my Bada PH12. I did'nt realise just important these caps were. I have spent some serious money on Dutch silver foil caps and paid little for the brilliant ERSE caps - removing those WIMAS has raised the quality of playback in a way I would not have believed - I have definately reached the end game where the h/amp is concerned and I think that when I have finished the Lehman, that's another end game reached as well.
I started with the Lehman by replacing the WIMA 2.2uFs with ERSE and was impressed with the difference these made. I removed all the Jamicons from the phono and the plug/PSU and replaced with Philips LL and some BGs I had in the PSU. The output caps were changed for BG non-polars (because I had them spare). There are 5 x 0.1uf WIMAS per channell before the OP275, which will be changed for 1 x 0.33uF and 2 x 0.1uF ERSE.
All signal path resistors will be naked Vishays/TX2352 from Texas Instruments and all the other Rs' will be replaced by Welwyn RC55Y.
There's a lot of rubbish talked about tubes v SS, right now this part modded Lehman is very good, getting rid of the last WIMAS and using very good resistors will lift it much further. I will be replacing the SSM2017 op-amps with THAT 1510/1512 and the OP275 with AD/LM op-amps (suck and see).There are no hum issues even using low o/put cartridges - top to bottom there is an open sound stage and real timbre on piano/guitar/cello. Voices and instruments are defined and you get to hear what the recording engineer did, for better or worse - I don't see any way back to a tube phono stage, though I would never give up using a 6SN7 pre a la the Bada PH12.
The bad news is that s/hand Lehmans hold their price very well, which is strange because if you don't mod the Lehman it is nothing special. However the circuit is a cracking design and the layout has been very carefully worked out - choose the right components (to suit your own taste) and you've got a phono stage that I think would be hard to beat.
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Post by PinkFloyd on Oct 22, 2008 11:16:28 GMT
Miguel I can email it if you like, but many members may not realise that you can "right click" on posted images, and choose the option "save picture as." Let me know if that works for you. Alex  |
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rickcr42
Fully Modded
Rest in peace my good friend.
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Post by rickcr42 on Oct 23, 2008 2:23:06 GMT
Resistance problem ? I thought Everyone knew RESISTANCE IS FUTILE ! |
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Deleted
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Post by Deleted on Oct 23, 2008 2:36:28 GMT
Resistance problem ? I thought Everyone knew RESISTANCE IS FUTILE !Rick Have you posted this in the right thread ?  Alex |
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Post by guadixman on Oct 24, 2008 11:56:04 GMT
Having a lot of trouble finding quality 0.1%/1% resistors at values of 22R. These are for attenuating the o/put of the op-amps. Welwyn do the ones I need but no one seems to stock them at this value. There are 2 pairs of 1W resistors right in the signal path, Wewyn make 1W/1% that would do nicely but again I can't find a retailer.
I suppose I can try Welwyn direct but most Brit companies are very snot nosed about things like this.
The Texas Instrument resistors - TX2352 (made under licence for Vishay (Israeli) are going to cost me a lot more as the £ and Euro are in freefall against the $ and Yen - a good time for Americans and Japanese with money to spare to buy foreign at the moment - the £ is down around 60% against the Yen, yes 60% since August last year - buddy can you spare a dime!
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Post by guadixman on Oct 24, 2008 11:58:13 GMT
Having a lot of trouble finding quality 0.1%/1% resistors at values of 22R. These are for attenuating the o/put of the op-amps. Welwyn do the ones I need but no one seems to stock them at this value. There are 2 pairs of 1W resistors right in the signal path, Wewyn make 1W/1% that would do nicely but again I can't find a retailer.
I suppose I can try Welwyn direct but most Brit companies are very snot nosed about things like this.
The Texas Instrument resistors - TX2352 (made under licence for Vishay (Israeli) are going to cost me a lot more as the £ and Euro are in freefall against the $ and Yen - a good time for Americans and Japanese with money to spare to buy foreign at the moment - the £ is down around 60% against the Yen, yes 60% since August last year - buddy can you spare a dime!
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rickcr42
Fully Modded
Rest in peace my good friend.
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Post by rickcr42 on Oct 24, 2008 12:54:25 GMT
I beleive so bubba unless the title "Resistor Problem" is a secret code for "grammies carrot cake recipe"  |
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Oct 24, 2008 12:59:13 GMT
oh an BTW-many get confused on the resistor "banding" when the parts have the extra band denoting 1% because they read from the wrong end |
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Post by guadixman on Oct 27, 2008 11:45:21 GMT
rickcr42,
do you have any input re. Reidon resistors ( a California company) they have some very close tolerance foil resistors and they do some 1W types that I need?
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rickcr42
Fully Modded
Rest in peace my good friend.
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Post by rickcr42 on Oct 27, 2008 22:55:38 GMT
If you are referring to the "non inductive wirewound" type I have no actual listening time with the particular device (some thing I hope to change in an upcoming "Flea" amp build still in the planning/designing stages ) but I do have time with the Mills non-innductive types which are my preferred choice the "type" but reports from Ron Welborne of Welborne Labs are that this part sounds better than the Mills counterpart though why and where and in what way it sounds better is not explained so take it with a grain of salt that A-Welborne Labs is phasing out the Mills and replcaing them With Riedons B-They state the move is to a better sounding part yet offer little evidence to support the statement which may or may not means squat. C-Welborne Labs products mostly have a good reputation on SQ but it also is not uncommon in any trade to move to a parts supplier that offers a better profit margin then in an effort to avoid any whining pre-empt the would be complainers by stating the "new" part is better and was the determining factor in making the change. Not saying this is the case here (or that it is not ;D) just that when you have a statement that something is better you like a minimum of "meat" on the bones of the statement,something you can chew on and digest,which apparently is not the case here so my thought is that maybe the only way to ge the "flavor" of the part is to do a bit of home cooking and a sit down dinner to make the call  |
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rickcr42
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Post by rickcr42 on Oct 27, 2008 23:58:58 GMT
It seems I mispoke in the previous post.I seen "1W" and assumed the resistor was for the power supply section hence my mini-novellla on the Mill/Reidon comparisons. Seeing that the actual question was for a 1% precision resistor that is to be used in the signal path ?Disregard the above On this I have totally different requirments and if precision at all an issue I go right to the Vishay Bulk foils.Name the wattage,name the value,name the package and you will find one that suits with the only downsides being cost.They are expensive buggers but to be honest a case of you get what you pay for and if you go beyong just the precision issue tou also get a part that is STABLE. no small thing when you consider the reasons why you chose a precision part to begin with.Noise,sonics,stability-all good.Price ? Not so very but hell can't have everything.As for the Reidons ? No clue.A total unknown and when it is resistors in the signal path being considered specs just won't get it because resistors DO have sounds of their own and thus require listening in that particular position in that particular amp before you can actually know if it is suited or not. If i know one thing about audio DIY it is that you can NOT take someones word for it when they spout "this is the best resistor" or "this is the best capacitor" because that tells you they have zero clue and are more plug and play types that think because they read somewhere of have heard or even because the part sounded good in ANOTHER device that everything that follows must also sound good with the exacty same parts-WRONG ! There are "knowns" such as what parts are a good starting point,what to look for in a part for a particual topology or circuit point but hardly if ever is there a part you want to be the same everywhere My "starting point" is usually one of the Vishays for everything precision work (filters,compensation networks,IV resistors,EQ networks,etc),low or zero inductance resistors in the Anode Resistor (for VT circuits,the "source in a jfet or the +v/-V postion in an opamp cicuit) spot and as often as possible Carbon compositions,Rikens or Tantalums if directly in the signal path with the choice determined solely on how it sounds in THAT circuit though there are some "knowns" that help in making an educated guess right at the outset with those loosely- 1-Carbon comps in tube gear signal paths 2-Tantalums in bipolar/monolithic signal paths 3-Rikens in all of the above 4-Mixing all of the above usually best with the Rikens or tants in the front end,any of the three depending on the circuit in the middle if there is one and the Carbon Comps in the output where precision is less important than good pulse response and smooth sonics.Being that this is almost always a low impedance section of the circuit the resistor value will be small hence noise not an issue and if you match the resistors into left/right pairs (WAY more important in generic audio circuit positions than hitting an exact VALUE) and the part will not be exposed to a very high temperature level has no downsides either quantitive or qualitive at least in my opinion |
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rickcr42
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Post by rickcr42 on Oct 28, 2008 0:37:14 GMT
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insomniac
Been here a while!
Team Zopiclone
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Post by insomniac on Oct 28, 2008 1:19:39 GMT
Having a lot of trouble finding quality 0.1%/1% resistors at values of 22R. These are for attenuating the o/put of the op-amps. Welwyn do the ones I need but no one seems to stock them at this value. There are 2 pairs of 1W resistors right in the signal path, Wewyn make 1W/1% that would do nicely but again I can't find a retailer. I suppose I can try Welwyn direct but most Brit companies are very snot nosed about things like this. The Texas Instrument resistors - TX2352 (made under licence for Vishay (Israeli) are going to cost me a lot more as the £ and Euro are in freefall against the $ and Yen - a good time for Americans and Japanese with money to spare to buy foreign at the moment - the £ is down around 60% against the Yen, yes 60% since August last year - buddy can you spare a dime! Guadixman How about these Japanese Shinkoh Tantalum resistors: 22R 1W/+/-1%...£4.60 each +vat +p&p from: www.hificollective.co.uk/components/shinkoh_resistors.htmlThey seem expensive for resistors but... |
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Post by guadixman on Oct 28, 2008 13:05:34 GMT
Hi Rick,
some of that info you supplied I had already seen which is why I decided to try the 'naked' bulk foil type Vishays made by TX under licence. With these I could'nt see any that were rated at 1W.
If I can, I use a larger wattage than required. I've used Tants in a phono stage and in a valve power amp. I noticed in the phono stage that some of the Tants drifted over time. I've used Tants/Rikens/bog standard metal films as shunt resistors and up till now I found the Welwyn 0.1% to be best used with an Alps Blue. However I shall definately order a pair of 47K Vishay to try in this position
Like you say specs don't tell you how a component will 'sound'.
Until quite recently I sort of accepted that neutral meant 'boring/bland' now I dispute that entirely - the more neutral a component is the more of the original sound 'get's through'.
I also could'nt agree more about having to try components yourself but with a caveat - I have a Dutch friend who has the same h/amp as me (Bada PH12) and we have tried various caps and so on and so when one of us tries a particular component and expresses an opinion, we both know we can rely on the other's interpretation.
He was instrumental in showing me that I had over-looked a fundamental point in designing interconnects, once I saw the light on that, the next pair of I/Cs was so much better.
Eg. there is an op-amp thread on this forum and the opinion of the writer re. the AD 823 is at total variance with another opinion on another site - so like you say it's nec. to 'suck and see'.
I shall get in touch with Reidon to see if they will offer samples or if a no-go on samples, 2 pairs of their USR 2-1510 type. Ideally it would be nice to try both the Vishays and the Reidons to see just how much and what kind of difference there is.
A bit off topic but could part of the problem with CDP be a mis-match of components as much as the digital sound. I would'nt be prepared to spend so much on an SS phono stage if I had'nt already 'lost' that hard edge with which SS is condemned out of hand by the valve/tube brigade.
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Post by Deleted on Oct 28, 2008 21:15:46 GMT
guadixman
Interesting reply. Not much to disagree with there.
I did however wonder why you were being so fanatical with your choice of output resistors, when as you concede , the choice of an opamp can make such a difference in different systems.
I strongly believe that the major reason for the same opamp sounding so different in other equipment, comes down mainly to the PSU area, where it can be readily demonstrated that the choice of values,number of , and even brand of electrolytic, can make such noticeable audible changes.
Having read your closing paragraph, I better understand where you are coming from. Once you get to a certain degree of excellence in performance, it's often hard to leave it at that ! ;D
SandyK
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rickcr42
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Post by rickcr42 on Oct 29, 2008 0:47:16 GMT
probably because unlike EVERY other resistor in a phono stage excluding any output volume pots or unless it uses a splt active/passive or all passive RIAA EQ network is directly in series with the signal thus everything that goes in goes through it before it comes out which in short means is a dominant player in the passive parts selection process (much as is any power supply SERIES resistors if any).
Yes,shunt position parts have an audbility factor as do any feedback loop passive parts but neither is a direct signal placement which is and can only be in a coupling position between any two sections or stages..........
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Post by guadixman on Oct 29, 2008 8:46:47 GMT
What I find so amazing is that you reach a certain level of quality sound reproduction and think - 'it can't get any better' - but it does!
In the ph/stage changing out just the pair of WIMA 2.2uF for ERSE caps made such a qualatitive difference that I had to go on. So yes Rick is right there are always dominant components in any circuit and identifying them and getting them 'right' (to your own taste) is half the battle.
I don't think I am being fanatical about the resistors but a few modders I know and respect keep banging on about Vishays and it seems that those who have tried them and not liked them complain about sheen or brightness in the sound but with any component that is really neutral, it will expose shortcomings upstream.
One of those who has a mantra - may all your resistors be Vishays, is Beau in New Zealand who put together the hybrid - Moskido on the DIY forum, he also turned me on to the Russian specials 1578/1579 valves - I hear these wonderful valves exactly as he does, so it's very likely I will hear the Vishays the same way too.
Op-amps are a new thing for me being as I am now a heretic who really enjoys the 'hybrid sound'. I have always supported the view that the PSU is so important to any piece of equipment and just changing the caps in the original Lehman plug/PSU was evident immediately.
BGs have a 'very strong following' but I have a load of the Philips LL 4,700uF x 25V which I bought when they were still in production, thanks to Richard the moderator on WAD who rec. them for all the WAD PSUs. I managed to find some of the higher voltage type for use in the Bada - both the Bada and the ph/stage benefitted noticeably with more air and yes just a hint of warmth.
If anyone wants to try the 4,700uF x 25V type let me know, I can spare a few.
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