Pland Posted November 17, 2002 Share Posted November 17, 2002 Hi , Sorry for the brain fade.Wire wound resistors(not carbon comps) generally stay stable over time. Out of curiosity,I poked around looking for 165's.I found 160,162,169,but no 165.These are all 10% though,so a 162 or 169 would be in spec. unless you were + - on two resistors.Most of the mills or caddock resistors I've checked have been either accurate,or open(as in fried).Ohmite used to make neat looking and very good tubular resistors,but I think they've been gone forever. If Craig is getting correct measured voltages at the test points that are 5% +- deviation,that's about as good as it gets.I don't think changing the bias resistors out would even be measurable at that end of the parts chain. All vintage shematics I've seen assume 117v household current,and I've never seen a 10% difference in any of the houses in our Bottlehead group,which leads me to believe that spec'ed voltages and parts ratings are still the way to go in a vintage rebuild. BTW,I swapped out the American Capacitor Co. original caps in my 222c for Jensen copper pio yesterday(rrrreeeeaaaallll tight fit).I was going to leave the amp bone stock,but I didn't want a 40 year old coupling cap to take out those beautiful Telefunken 7189's.With no break-in the sound is just lovely,enough to break your heart.I played it side by side with a Fisher 400 and the Scott just stomped all over the Fisher.It's going to be a pleasure to break in the caps. Mobile will love this one.I pulled out my Thorens TD125 mkII with Stanton MkII (blue) and hooked it up to the Scott.Keep in mind that this turntable is from 73 or so,and other than replacing the belt is untouched from my college days.I did set the cartridge up with my mirror protractor,but everything was pretty close. I'm here to tell you guys,if we've gone anywhere with analog in the last 30 years,it's not too far.This table is very close to my LP12,and probably better mechanically.The arm is too heavy,but so what.The old SOB is musical and very involving and is built like an armored personel carrier.I don't know what these go for these days,but if you see one in good shape,don't pass it up. Best, Pat Anybody want a Rega Planar 2,glass platter,AT cartridge cheap? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Pland, There's alot to be said for any descent older Mid Fi Turn Table with a descent Cartridge. The difference in today's audiophile setups is small at least with my limited experience. The Scott Phono section really does shine doesn't it !! I really don't blame you for switching out the caps. So you like the PIO's did you replace all under chassis with these ?? This is like 12 right ? what did that set you back ?? Do you think its was worth the extra bucks for these or will the jury be out till they breakin. Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted November 17, 2002 Share Posted November 17, 2002 Well, I guess ole Chris is doing well then. Obviously, this ole thread has not gone my way...and now the TD-125 MKII is considered "mechancically superior" to the Linn LP-12; well, I wont go there suffice to say that the "platter - bearing assembly" alone is quite a bit higher on the ole mechanical scale then the entire TD-125, but hey... why be contrary? Pat, I will say you are very lucky to be the original owner (or near it) for a Thorens TD-125ii. I am trying to wonder why THIS was in a closet with money spent on a Rega P2? Heh... One thing of caution about buying the old Thorens used is that not all models are created equal; in addition, many will need some tweaking to reach full potential and the bearings on the old arms can sometimes be problematic. I have some neat articles from the past on bringing the TD-125-160 up to top notch performance. I personally think most of the Thorens are a step down from a properly setup Valhalla LP-12, at least the ones I have heard (note that Allan has the collectors item TD-124 which is now going in the 800-900 area for great condition - it's a BEAST!). But hell, the TD-125 MKII is a nice table and I would surely put that out of the closet long ago. It is surely WAY WAY above the average Duals and other 70s tables. What arm is on there? Have you considered adding the Incognito wire upgrade to your Rega RB-250 and putting it on the Thorens? I cant remember the hassle involved here for this. Well, you must have spent a bundle putting those nice Jensen Copper oils in that big ole Scott! DId you just do a few or all the coupling caps? For those that dont know, we are talking close to $20 or more a piece depending. Did you snag the Angela versions which I think are the cheapest? DIY-HIFI has ok prices on the Jensen branded version. But to outfit a vintage with these beauties is quite expensive. Nice to hear someone trying this out. I can only say, your pocket is deeper than mine on this one! I would love to see some pics of this unit. kh Additional note: Jeff (Jean-Francois) did a line test on his place in Quebec City and it was 125v! Just goes to show you the differences. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Chris, I wouldn't worry about the power difference at all just run the amp and enjoy. I believe its going to take some time for these caps to break in and I hope you made the right choice. I listened to your amp on and off for most of the day stopping my little projects a number of times to just sit and listen to songs I really like. I played Vinyl and CD's . The phono section is much quieter now but still has a mild hum out of the right channel at above 6 on the volume it was pretty bad at first and I messed around and found its the PEC's or RIAA circuit which is a all in one component the can't be replaced it sits mounted to the back of the tone control pots there are 2 of them. One was resting against one of the pots. I moved it and the hum Lessoned to a great degree. There isn't any easy fix for this. But its really a none issue I don;t think you will listen at the levels that above 6 produces anyway. With music playing you really don't hear it unless there is a real silient spot in the music. So then I soldered the Kiwame resistors in a HF-81's Phono section and it has the same type of hum at about the same level. I fired it up and played the same record SRV Tin Pan alley that i just played on your amp . I was amazing that mine had much more detail with the great tube warmth intact. I really love my Vintage Russian caps. I will add just to stop the bombardment this statement will most likely produce my HF-81 has very few hours on it but still more than Chris's so my caps have a slight breakin advantage and if these auricaps take a long time to breakin this could all be a moot point. Your channel imbalance ? what channel was stronger ? Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted November 17, 2002 Share Posted November 17, 2002 You can BYPASS the tone controls. And from what I can ascertain, those caps on the back of the tone controls have nothing to do with the phono stage. The line stage goes through the tone controls as well. IF they do, how is that possible? I havenet mess with the phono stage much since I usually run an external one. But if interested, here is a method for bypassing the tone controls which will also bypass 1/2 of the 12AU7. I will post it today on my site and run a link. Craig, I couldnt follow your last part... are you saying you put in oil caps or did you mean Kiwami resistors? I thought the HF-81 had Kiwami in the phono since you first started? But the Auricaps definitely need break-in. Of course, I DO love oil caps as you know. I am tempted to put some in that 299. I dont know...I kind of am a mind to give up on the comparing of these amps. I reminds me of comparing cars with my car friends and is about just as fruitful or unbiased! heh.. kh Quote Link to comment Share on other sites More sharing options...
Pland Posted November 17, 2002 Share Posted November 17, 2002 Hi Mobile, In terms of superior bearings,noise floor,and arm ,no question the LP12 is better(I've got one).What I'm talking about is general brick ****house build quality,the kind that stands up to flying beer cans,spilled drinks(probably Boones Farm at the time),and careless moving and set up.It has a Thorens arm (I think)or at least it's not the SME.And I've still got the original box ,papers,and manual for it.It's the polar opposite of my finicky Linn,which relies on astral alignment as a design parameter(see Lowther,early Jaguar cars,etc.for similar characteristics).BTW,Craig this wasn't a mid fi turntable,it was high zoot when new.The receipt shows that it cost a whopping 565.00 at Bill Case Sound when I bought it. I bought the Planar(s) in 1995,gave the Planar 3 to my son,kept the Planar 2.I bought into the line that the new simple tables were far better than what I had ,and since most of my vinyl fell victim to attrition over the years,I never gave it the old first hand comparo.I inherited the Linn from a down and out friend,and never looked back. I only changed the coupling caps on the Scott,so I haven't gone totally insane as far as throwing money at it.The pio's are a different sound than the Auricaps,but the jury's still out as far as preference.I think I like both ,for different reasons.The Auricaps are fast,very smooth ,very airy.The Pio's are lusher,with better high end extension than I recall them having.Both are terrific.I'll re-post later after some break-in. Craig,the Auricaps need about 30 hours to open up,and trust me,they will.These are the first passive components that made me a true believer in break-in time.Let us know what you think. Best, Pat Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Mobile, Let me clarify. I put my Mysterous Russian Paper, Oil , Film and foil. In my HF-81 weeks ago and didn't give it serious listening time since because I was waiting for the Kiwame resistors for the phono section which I installed last night. I think your not clear on what happens with the phono section in a amp like this. The 12AX7 provide low level amplification to the raw signal from the turn table after this is accomplished it is handed of to the RIAA circuit to bring the compensation up to snuff in this amp its done with Pecs . The 12AX7's do not apply the RIAA EQ ! I thought I explained this to you in email. Bypassing the tone control circuit could I'm not sure here but may render the phono section useless if it requires elimination of these Pecs. My point about the 2 amps was at this point in the game I would take my Russian caps over the Auricaps hands down !! This may change with time but I wonlt have the time with Chris's amp so I'll stick with the Russians in my rebuilds unless the onwer specs it different which is after all his/her right. Craig Quote Link to comment Share on other sites More sharing options...
dubai2000 Posted November 17, 2002 Share Posted November 17, 2002 Being in Germany means people use/suggest different caps(brands). Has anyone hear of/used Wima caps. . The person having a look at my Eico at the moment seems to use them a lot when restoring vintage amps. I have not heard anything from him yet, but I'd like to be prepared as much as I (technical fool) can LOL. Wolfram BTW: I kind of listened to a set of MC 30s at his place - well, that's a cute little amp - any feedback on this one??? Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted November 17, 2002 Share Posted November 17, 2002 Craig, sorry, missed more than a few posts here this morning. Kids galore and carpooling. To balance the L/R sound, I needed to have the balance knob at about "9:30-10:00". There seemed to be a real weakness on one side. I would have absolutely no problem with bypassing the balance control since my listening position is centered now, and will be in the future. I'd rather worry about matching tubes and not having to deal with the balance issue. If you're hearing balanced sound with the setting at "noon", then I think the problem was fixed by something you did and I wouldn't worry about it. Kelly, I wasn't taking a position against you on this thread for sure. I've just been gleening pieces of everyone's thoughts and discussing them with Craig. Most of the input I've gotten in the last three weeks were, in fact, from you (thanks) and Tim Babb. But it's pretty obvious I have neither the technical knowledge nor the experience base to make these calls all by myself, so I think what I get back from Craig will need some listening to and then some subjective judgments on my part about what I like and what I have a problem with. Craig, if there's any way to get the hum out easily, fine ... but if it isn't noticeable until I'm in a quiet passage between 105 db sections, I'll be okay with it. I hardly ever listen to anything past 85 db anyway. Years ago, yes ... now, no. I reserve high noise levels for Rt 128 at rush hour. I've heard of Wima caps too ... When I was selling Philips' film caps, I used to compete against them often. I know they're highly thought of in computer/industrial applications, but I don't have a clue how they sound in audio gear. Quote Link to comment Share on other sites More sharing options...
Pland Posted November 17, 2002 Share Posted November 17, 2002 Hi Craig, What driver tubes are in Chris' HF81?A set of Telefunken driver tubes is a real ringer in this amp,much like a Scott. Best, Pat Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 They are Tele's as a matter fact LOL ! I was suprised of that when it got here the 12AU7's are mullards. Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted November 17, 2002 Share Posted November 17, 2002 NOS, if what you say is true, then the LINE STAGE goes through the RIAA phono circuitry as well, iF the phono RIAA stage is ON THE BACK OF THE TONE CONTROLS. These parts you are referring to are the Printed Circuit Plates PC1 and PC2. It appears to be the PASSIVE COMPONENTS of the tone controls and has NOTHING To do with the phono. IF so, the CD and line inputs would be having a lovely time with the RIAA circuitry! As my friend Jeff said, "if this is true, the bass boost provided by a RIAA eq would make your CD sound like a hiphop song played full blast in a yellow souped-up Honda with purple tinted windows." The LINE STAGE of the EICO HF-81 enters AFTER the phono pre and equalization stage. But the TONE CONTROLS are after the line stage. Please explain. kh Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Get the schematic out and trace the signal from the phono section and you will indeed see what I mean. If you notice the signal has a entrance into this part before the tone controls I'm personally trying to figure it out myself its different then a Scott but the part is the exact same values on a Scott and on a scott its is right on a switch to change between RIAA or NARB tape. One thing I do know for sure the RIAA compensation is indeed completely seperate and done with the values in that PEC . You may be able to bypass the tone controls without stopping the use of this PEC but it wouldn't solve this problem. Besides this is really a none issue its really not that bad at all. Just at extreme volumes. Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted November 17, 2002 Share Posted November 17, 2002 Craig, in the manual is states that ALL phono amplification and equalization occurs BEFORE the line stage and hence before the tone controls. Where do you see an entrance to the PEC before the tone control that would be used by the phono and NOT the line stage? It looks as if the RIAA Eq is done by R15,R21, C9, C11. How can the line stage be going through the RIAA as well??? I just cant see it on the schematic. http://engr.uark.edu/~lar/hf81pg1.gif kh Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Mobile, look at the next page of the schematic between V3A and V3B you will see the pec and also notice the route around the PEC like I said I'm not sure how EICO handles this but I know your looking in the wrong area on the 12AX7 phono amplification stage. The 12AX7 does not apply RIAA it amplifies the low Mag input to something near the level of a tuner or CD input. Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted November 17, 2002 Share Posted November 17, 2002 What the Sam Hell are you talking about? First of all, please dont bring up something that I NEVER said that is incorrect, acting as if I stated it. I hate this tactic; for instance, I never said the actual 12AX7 does the RIAA! IT does additionally amplify the phono signal, but has NOTHING TO DO WITH RIAA. 1. Clearly stated, I said I believe parts R15, R21, C9, C11 handle the RIAA on the EICO (Please see the schematic pic supplied). This is NOT the PEC in the tone control! 2. I dont see ONE SINGLE link to the PEC from the phono only. And the parts mentioned above are after each phono input and I belive are handling RIAA (and WAY before the PEC which handles both the phono and the AUX). But I could be missing the whole boat and I had a late night. Please dont put words into my mouth that arent there nor twist the wording to make it look like I dont even know where I am looking. I looked at the other side of schematic as well. kh Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Well here now !! your getting awfull snippedy there my little friend aren't you. I have other things to do rather then have a pissing match with you. I'm busy right now and will research this further later. I can't believe that is indeed a RIAA circuit for this amp. Like I said before I haven't researched it real well but if that is indeed the RIAA circuit they are applying it before the 12AX7's which I find strange but possible I guess. I screwed up the numbers you gave me and thought you meant R11 rather than C11 which was part of the 12AX7 circuit. Let me finish all I have do to here and I'll be back and we can get to the bottom of this. It is indeed a strange setup. If the phono RIAA is indeed not involved with this PEC than why the change in hum when messing with it ? There a absolutley no hum with either AUX inputs or Tuner. This would lead me to believe this PEC has something to do with it. Craig Quote Link to comment Share on other sites More sharing options...
Deang Posted November 17, 2002 Share Posted November 17, 2002 What a great a thread. I have no idea what anyone is talking about. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Deang, I'm sitting here scratching my head wondering if Mobile and myself do either LOL !!!!! I'm comparing schematics now and he may very well be right not sure yet. I was real busy earlier doing some book work that I'm wwwaaaaaaaaayyy behind on and was just half paying attention ! If he is indeed right they sure did there RIAA circuit strange compare to scott. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 17, 2002 Author Share Posted November 17, 2002 Okay I'm starting to trace this and were going to do this step by step The phono signal enters the input selection switch on terminal 8 and looks to me like it enters the 12AX7 pin 7 from terminal 5 of the switch untouched which would make sence then it is amplfied. Then it leaves the 12AX7 thru pin 1 and from the best I can figure runs back into the input selector switch. I think mobile is indeed partially correct here but I think that there are more components then just the 4 he lists. No wonder the darn thing is noisy running thru all those different connectors on that vary large complicated switch. I bet a good portion of the hum is created by this switch not being sheilded from the all components (transformers, tubes and what not above chassis) this circuit is very well sheilded on a Scott amp. I still would love to know why the pec seems to omit some hum into this circuit but not into the Aux input. maybe it was just a fluke ! I guess we need to research this further and see what can be done to these parts on the selector switch to further quite phono on these beast. Craig Quote Link to comment Share on other sites More sharing options...
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