Chicago_Pete Posted January 14, 2007 Share Posted January 14, 2007 Here you go Gilberto[] http://cgi.ebay.com/Pair-Of-Rare-Marantz-Model-9-Amplifiers-Exc-Condition_W0QQitemZ130068257859QQihZ003QQcategoryZ50593QQssPageNameZWDVWQQrdZ1QQcmdZViewItem A little pricy for all those smudges on the faceplates[] I just made him an offer, but a frightfully low one though. The condition of the offer was money in hand, with personal pick up only. Gilbert, that guy being local to me, I have tried to buy a couple of items from him in the past. Tried being the operative word. He does not welcome inspection. I could understand this policy on an item worth a couple of hundred dollars but if I am going to shell out several thousand, I would like to see what I'm buying. Quote Link to comment Share on other sites More sharing options...
scott0527 Posted January 14, 2007 Share Posted January 14, 2007 Here you go Gilberto[] http://cgi.ebay.com/Pair-Of-Rare-Marantz-Model-9-Amplifiers-Exc-Condition_W0QQitemZ130068257859QQihZ003QQcategoryZ50593QQssPageNameZWDVWQQrdZ1QQcmdZViewItem A little pricy for all those smudges on the faceplates[]<?xml:namespace prefix = o /> I just made him an offer, but a frightfully low one though. The condition of the offer was money in hand, with personal pick up only. Gilbert, that guy being local to me, I have tried to buy a couple of items from him in the past. Tried being the operative word. He does not welcome inspection. I could understand this policy on an item worth a couple of hundred dollars but if I am going to shell out several thousand, I would like to see what I'm buying. Pete, I agree, that seller (myostuff), doesn't give me a real strong feeling of total honesty. I've seen some of his other auctions. On another note, the seller of the 8B conveniently left out (unitl Friday) a picture of the back of the amp which shows some not so nice discolorations in the finish. That's a bit on the unsettling side too. Quote Link to comment Share on other sites More sharing options...
Gilbert Posted January 14, 2007 Author Share Posted January 14, 2007 I enjoy your opinions.Shoot! With 4000 posts,you must know something.How about Skynard instead of Zepplin? Larry I hear that, "Oak Tree Your In My Way"..... oooo that smell! Quote Link to comment Share on other sites More sharing options...
Gilbert Posted January 14, 2007 Author Share Posted January 14, 2007 Mike, what the helll is that avistar of yours. I've been trying to figure out if it's a turd or a brown termite with 4 legs. [] Gilbert, you're one to talk. Just look at your avatar! That's one UGLY dog you have there! [H] I'd be ashamed to post his picture if I owned him. [:$] [:$] EDIT: Here's a shot of my better profile.... Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 14, 2007 Share Posted January 14, 2007 LOL [] Yea, like they're ready to just LAUNCH right outta there! [] WOT Good looking amp.................very affordable, nice deal..................Best of luck with it, more of a purchase that I can understand, are you going to use it or save it? Thanks, ol'buckster, although I havnt exactly got my meat-hooks on it yet. (it's being shipped this week) But yes I DO have plans for it and it WILL be played. Once I check it all out and recap it. Managed to find a SAM's for it on eBay- WOT Here's another pics from the rear, looks clean! Quote Link to comment Share on other sites More sharing options...
ben. Posted January 15, 2007 Share Posted January 15, 2007 WOT, where does it run the outputs? I've used the same quad of 350B in my Mc30 for a few years now with no problems so far. National Unions. Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 15, 2007 Share Posted January 15, 2007 WOT, where does it run the outputs? I've used the same quad of 350B in my Mc30 for a few years now with no problems so far. National Unions.Well based on the schematics that I've managed to find so far, it runs just a bit "cooler" than the Citation 2 (a good thing IMO) with 400V on the plates and 385V on the screens when using the 6L6GCs. I want to set it up with easily adjustable voltage/bias so I can try various tube sets like the 350B, KT66, KT88, KT90 (like the Leben CS 600 which has a trick switch setup to alter the plate voltages, cathode current and bias voltages). How do you find the 350B Nationals on the Mac? Enough bottom-end extension?? PS > sorry to the op for the thread jack - lol But I'm pretty sure nobody was able to talk you out of WANTING those 8's! (Seems someone ended up getting them for $2400 or so) WOT Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 15, 2007 Share Posted January 15, 2007 350B will run fine at 400V on the plates. They are good for 27 watts of idle plate dissipation so they could theoretically run 67mA of plate current at Idle with your plate voltage. The 350B is a really upgraded version of the original 6L6 just short of the 6L6GC spec Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 15, 2007 Share Posted January 15, 2007 350B will run fine at 400V on the plates. They are good for 27 watts of idle plate dissipation so they could theoretically run 67mA of plate current at Idle with your plate voltage. The 350B is a really upgraded version of the original 6L6 just short of the 6L6GC spec Thanks Craig, I was hoping someone like you would chime in. [] After I check this ol'girl out throughly and make sure I want to keep it, I will commence looking at possible mods to facilitate some fun tube rolling. This schematic I have is a lousy copy but when I get a decent original would you mind having a look at it and maybe give me some advice?? Thanks WOT Quote Link to comment Share on other sites More sharing options...
ben. Posted January 15, 2007 Share Posted January 15, 2007 WOT, where does it run the outputs? I've used the same quad of 350B in my Mc30 for a few years now with no problems so far. National Unions.Well based on the schematics that I've managed to find so far, it runs just a bit "cooler" than the Citation 2 (a good thing IMO) with 400V on the plates and 385V on the screens when using the 6L6GCs. I want to set it up with easily adjustable voltage/bias so I can try various tube sets like the 350B, KT66, KT88, KT90 (like the Leben CS 600 which has a trick switch setup to alter the plate voltages and bias loads). How do you find the 350B Nationals on the Mac? Enough bottom-end extension?? PS > sorry to the op for the thread jack - lol But I'm pretty sure nobody was able to talk you out of WANTING those 8's! (Seems someone ended up getting them for $2400 or so) WOT I'm extremely happy with the NU 350B in the 30s with my Khorns. I can't imagine any output tube of reasonable quality hurting your LF extension to the point where it would be evident with Lascalas or even Khorns. I recently auditioned the Valve Art KT66 and they had more bass, but I can't say they went any lower. see here: http://forums.klipsch.com/forums/thread/843116.aspx The 350B really shine in the mids. Of course, all the other tube selections have been made with the same quad of 350B in place, including those in my preamp . Are they worth the going rate? I don't know. They're pretty expensive unless you get lucky. Obviously someone like Craig is more able to speak to their electrical suitability than I. Most folks here don't mind a good threadjacking. I think some of the most interesting discussions come from tangents. Quote Link to comment Share on other sites More sharing options...
kev313 Posted January 16, 2007 Share Posted January 16, 2007 Jacksonbart, the chicken is probably the only one that will listen.....................alright guys, let me put it this way, Oldbuckster CANNOT afford such equipment...............You all tell me about collecting, Is anyone on this forum going to buy that amp? If the answer is No, then why all the static my way, because I disagree with the purchase.I do understand about collecting, but it is speculation, it can backfire in your face.I happen to think there are better ways, and things to collect.Land is a smarter investment, houses are a smarter investment, stocks, bonds, certificate of deposits are smarter investments. Cars and Audio equipment are not smart investments. It must be a wonderful feeling to spend $6000. for something to just sit around, unused, because it is a collectable. You know Gentlemen, this could go on forever, I've tried to be nice about it, that doesn't seem to be working, so I guess I'll just come out and say it, I think that is stupid to spend that much on one piece of Audio Equipment. Don't come back and talk about collecting, we are all collectors. Anyone on this forum that has CD's, Records, DVD's, we are collecting. You guys with 4,5,20 sets of Klipsch speakers, your collecting, you guys with 2,3 and 4 stereo systems, your collecting. So I do understand about collecting,and I also understand that anyone that would buy that amp is in a Minority. It is out of touch for the majority of people, big time exotic collectors are a very small percentage of the overall number of Audiophiles. I am looking at the whole picture, not just a bunch of people on a audio forum. The world is alot bigger than the Klipsch Forum. Call me a Rock Hard Skull if you will, but you know the way I feel, like it or not..................Rock on Bro.'s yasss....why buy those when you can have new green ones?! Quote Link to comment Share on other sites More sharing options...
oldbuckster Posted January 17, 2007 Share Posted January 17, 2007 kev313.......that is some fine, impressive looking equipment.........no doubt.......... Quote Link to comment Share on other sites More sharing options...
kaiser SET say Posted January 17, 2007 Share Posted January 17, 2007 I second my old pals thoughts Kev313, I knew you had some sweet gear and what a sweet representation there[] Quote Link to comment Share on other sites More sharing options...
kev313 Posted January 17, 2007 Share Posted January 17, 2007 Thanks - I actually just took those bottom Shindos - the Marantz Model 2 clones (but with an f2a as an output tube vs. the Marantz EL34) - in trade for basically all of my unused gear. I guess that's one way to clean house. Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 21, 2007 Share Posted January 21, 2007 350B will run fine at 400V on the plates. They are good for 27 watts of idle plate dissipation so they could theoretically run 67mA of plate current at Idle with your plate voltage. The 350B is a really upgraded version of the original 6L6 just short of the 6L6GC spec Craig, I finally found a schematic for this old HK A260 (see attached pdf). Any advice to modify it for 350B? Besides a recap and applying some McShane type "touches" to the power supply I was thinking of providing seperate individual cathode bias resistors (at this point each pair of 6L6GG appears to share R42 and R53) Any suggestions for a rewire to make the bias adjustable? Appreciate any comments/assistance... WOT My new baby... A260_schematic.pdf Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 27, 2007 Share Posted January 27, 2007 Another observation and question for some of the experienced tube amp boys here. I noticed in the schematic (full version attached in the post above) for this amp that the 6L6GCs appear to "share" a 3.3 ohm Cathode resistor. What are the implications of this in a fixed bias push-pull configuration? Is there some sort of "counter" electromotive force that affects each individual cathode's net current to ground between each cycle of the output tube set? I'm thinking of rewiring these into seperate circuits with fully adjustable bias (not just balancing) Any suggestions on doing this?? Thanks WOT Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 28, 2007 Share Posted January 28, 2007 The amp can easily be modifeid to allow for full bias adjustment and measuring. You simple have to install a pot in front of each DC balance control for the channels. You feed the -40V into one leg of each pot and the center lug of the pot (wiper) is voltage out to the balance pot, The third leg you will tie a resistor to ground and adjust its value so you can get about -24 to -36V adjustment range. I would use a 10K pot and try about 6.8K resistor to start. I would also add a 50uF @ 50V axial lead electrolyte to the center lug of these bias adjust pot and remember this is negative voltage so you install the electrolyte reverse polarity (plus goes to ground and negative goes to the center lug of the pot). Also take the 3.3 Ohm resistors out of each channel and split the connection between the two power tube cathodes then install a 10 Ohm cathode resistor on each tube to ground. With a 10 Ohm resistor I would try biasing the tubes to about 35 mA to start which would equal .35 Volts measured at each tubes cathode. Run it that way and check for 400V on the plates with the amp being presented 117V from the wall if the voltage is at or above 400V on the plates try .40 and see if the plate voltage drops much then repeat at .45 and so on. With 6L6GC's you should be able to bias the tubes up to about .70 wolts or 70 mA if the power transformer can deal with the load (seriously doubt it). If the plate voltage starts dropping then its a pretty good sign your drawing to much B+ from the power transformer. Thg existing setup was fairly common back in the day on lower cost integrated amps they only gave you DC balance control to help null out any hum from mismatched tubes. Its not uncoomon for the channels to have a wide difference in the current draw of each pair of tubes as it is now. I'd always mod an amp like this to have full bias control or at least offer for customer consideration. That looks like a really nice 6L6 based amp. 350B should work dard well in that amp as is along with EL34 and KT66's. I bet 350B's or 6L6GC's would sound the best in it though. Note you may also end up having to adjust R73 or R74 to get the -40 up to about -43 or so since you will loose just a bit of voltage in the new pots. Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 28, 2007 Share Posted January 28, 2007 Thanks for the suggestions Craig. I appreciate your willingness to share your expertise I really like what your saying which I guess (in a sense) is converting the circuit to be more like the Citation II bias circuitry. Bone stock with 6L6GC there is supposedly .5 volts on the "common" cathode circuit.(I now have a SAMs for this amp) I calculated that to be 150mA which seemed pretty high, and why I was wondering if having both cathodes sharing that circuit was a very good idea. (I presume that would mean 75mA each?) I'll have to pencil in what you are saying and see if I can make sense of it.I've still yet to get this amp through my door, but I'm trying to get my plan together to put it to work with my LaScalas. Yea, your right though- I believe this to be a very much under-appreciated HK amplifier circa 1960. You dont hear much about it anyway... compared to the slightly older (but more readily available?) Citation series.But the A-260 has a lot of desireable features IMO. The output trannies are certainly not as heavy as the Citations, however they are supposedly a special "grain oriented" high permeability core design that extends the frequency response across 15-30,000Hz at 1 watt (+/- 0.5db) that was "all-new" for 1960. I'm not sure about all the supposed "versatility" of that multi-switched speaker output network though. Just a bit too busy with all the switches, flip-flops and straps. I may just pull all that in favor of conventional banks of WBTs. I really like the idea of being able to mess around with various tube sets though.And your suggestions will obviously make this amp even more versatile. Besides the classic drivers you suggested I've also got nicely matched quads of Tungsol 5881 and GE 7581A that I'm looking forward to trying out as well. I've been looking for a good deal on a set of WU 350Bs or GEC KT66 but alas it appears they are rare as hen's teeth and worth their weight in gold these days. I've recently watched a few matched pairs on eBay going for $500-600 (and the Western Electrics are just rediculous) http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130070374918&ssPageName=ADME:B:WNA:US:12 I may just try out the Shunguang versions of these just to see what they sound like (for a more reasonable investment) I also have a spare set of HEXFREDs from my 300B projects that I was thinking of trying as well, hopefully to gain a bit more headroom for the power supply. Anyways thanks again for the advice Craig, I'll let you know how I make out once I finally get going on it (don't want to jinx it by getting too far ahead of myself while the the amp is still "vulnerable" within the shipping channels) [] WOT Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted January 28, 2007 Share Posted January 28, 2007 DELETE DOUBLE POST Quote Link to comment Share on other sites More sharing options...
Gilbert Posted January 28, 2007 Author Share Posted January 28, 2007 Double posts, wow, you really are greatful [] Quote Link to comment Share on other sites More sharing options...
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