Erik Mandaville Posted November 20, 2006 Share Posted November 20, 2006 Speakerfritz: Sure, we have discussed transformer-based passives in the past, but I'm sorry I don't have a link for you. I seem to be sort of 'challenged' when it comes to things like that. In general: Resistive based attenuation can bring about poor impedance-matching characteristics between the input of the control and out to the amplifier being used. Whether one is using a log or linear taper resistive element control, or fixed resistors on a switch, the problem has to do with the need for an appropriately high input impedance, along with a low output impedance. Low output impedances are better able to handle capacitive loads, such as what might be imposed by along length of interconnect between the passive device and amp. Conventional volume pots don't fit those requirements as well as a transformer coupled unit. Frequency response problems and roll-off may (often IC length related and dependent) also be associated with resistor-based controls Proper impedance matching can be better achieved with a transformer between the input and output. The transformer will have a primary with a high input impedance (a good thing) and a multi-tapped secondary with an extremely/comparatively low output impedance connected to the amplifier (also a good thing). One drawback (a subjective one) of passive preamps that use transformers is that in some cases the steps of attenuation may be found to be 'course' or too abrupt, thereby preventing finer adjustment of the volume. This is really dependent on the transformer in question. In either case, the transformers used for this application are NOT cheap, and it's possible to very easily spend more money on this type of control than one might on an active linestage kit. On the other hand, I have also had some very decent performance from in-line passive controls using pots available at Radio Shack. In all of these cases, my interconnects were not longer than 3 feet. Erik Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 20, 2006 Share Posted November 20, 2006 S&B transformers http://www.stevens-billington.co.uk/page102.htm Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 20, 2006 Share Posted November 20, 2006 And from Thorsten: edit: I remember some of the language, while nothing really terrible, might not be considered altogether 'family friendly.' I've edited this post, but it and others on the subject can be found in a search. Hope this helps; sorry I don't have links for this forum. Back to the preamp suggestions: I don't know if the Transcendent Grounded Grid was mentioned, but it's also a really great linestage, and dead silent even with the most efficient speakers. The Welborne, Ultrapath BP, as mentioned above, is also really enjoyed by some, and some thought the batter PSU was kind of a pain. I think it's a pretty cool idea, and brings back some of the very early history associated with the battery powered tube radios from companies like Atwater Kent, Crosley, and others. Erik Quote Link to comment Share on other sites More sharing options...
dhtman Posted November 20, 2006 Share Posted November 20, 2006 Intact Audio http://www.intactaudio.com/atten.html Quote Link to comment Share on other sites More sharing options...
tillmbil Posted November 20, 2006 Share Posted November 20, 2006 Funny thing, I just received an Adcom 555II also as a loaner, it is is really suprising. I had my MC402 playing through the Merlin to some bookshelf speakers by Phillip Clements called Sc-6's. The speakers are un-released to the public yet. Anyway, the sound is very impressive to say the least. A great match for SS gear. Quote Link to comment Share on other sites More sharing options...
playntheblues Posted November 20, 2006 Share Posted November 20, 2006 The Transcendent Sound Grounded Grid is a VERY good pre and it's cheap. A lot of bang for your buck here is the link http://www.transcendentsound.com/preamp%20kit.htm Quote Link to comment Share on other sites More sharing options...
George Roland Posted November 22, 2006 Author Share Posted November 22, 2006 I'm from the Meadville north of Pittsburgh, long way from Baltimore! Great idea though! Thanks for the suggestion! George Quote Link to comment Share on other sites More sharing options...
redwood forest Posted November 23, 2006 Share Posted November 23, 2006 NOSVALVES: The Placette Preamplifier got the GOLDEN GLOBE AWARD in 2000 for it's transparency in sound quality as opposed to your GOLDEN MOUTH AWARD for sticking your foot in it! Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted November 23, 2006 Share Posted November 23, 2006 R. F. don't forget to bring up SET also... it always adds fuel to the fire 'round here..... Bwaaaaaahahahahaaaaaa...!!!!!! Quote Link to comment Share on other sites More sharing options...
redwood forest Posted November 23, 2006 Share Posted November 23, 2006 NOSVALVES: The Placette Preamplifier got the GOLDEN GLOBE AWARD in 2000 for it's transparency in sound quality as opposed to your GOLDEN MOUTH AWARD for sticking your foot in it! Of course I meant GOLDEN EAR AWARD! (Insert foot in mouth) Quote Link to comment Share on other sites More sharing options...
ben. Posted November 24, 2006 Share Posted November 24, 2006 NOSVALVES: The Placette Preamplifier got the GOLDEN GLOBE AWARD in 2000 for it's transparency in sound quality as opposed to your GOLDEN MOUTH AWARD for sticking your foot in it! Of course I meant GOLDEN EAR AWARD! (Insert foot in mouth) Quote Link to comment Share on other sites More sharing options...
edwinr Posted November 24, 2006 Share Posted November 24, 2006 Hey, George. I currently own an Audio Research LS 25 mkII preamp. It has switchable gain and is, I think, much more neutral than previous ARC's. In saying that, I tend to agree with Duke, the ARC range wouldn't be my first choice to go with Klipschorns. My preamp is still on the drier side of neutral. Of course I have carefully matched my ARC with a suitable power amplifer, being the Classe Model Twenty Five. So the overall combination is fairly neutral. In any event, I would second any recommendation to look very carefully at Juicy Music's product range. Any amplifier designer who has considered the actual speakers his preamp may be matched with, has to be several steps ahead of other designers who have to accomodate every known combination. I'm not suggesting that Juicy Music is a one trick pony that only works with horn speakers. To the contrary. The Peach would be my choice, with it's built in flexibility and superior technical specs. Also I would be guided by the positive comments made by numerous happy customers. Quote Link to comment Share on other sites More sharing options...
Old-Tube-Sound Posted January 3, 2007 Share Posted January 3, 2007 If you have a SP-8 MKII Rev. 5, 6 or 7 take the cover off the bottom of the preamp in there you will find two resistors that are soldered to stand off's on the circuit board you can't miss them they are the only resistors that are connected to stand off's unsolder one leg on each resistor and that will reduce the gain of the preamp 6db add 12 db attenuators (you can buy them at parts express) to the inputs at the amplifier and that will calm the preamp down to a level that will make your horns sound like you have never heard them before. The SP-8 is one of the best preamps ever made, I use mine with two Acrosound ULII's mono blocks on my K-Horns and the sound is simply to die for. Do those couple of steps to your SP-8 and you will be giving it a big bear hug when you listen to it again. If it still sounds like crap then something else is wrong. Quote Link to comment Share on other sites More sharing options...
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