DizRotus

I would also be interested scanned sets of the plans. If you don't post them to the BB, I would be grateful for a set emailed to the address in my profile.

They only appear deeper, due to now being narrower. See the dimensions included in auction listing "Standard Dimensions are 38"H x 25"W x 15.5"D. 108 lbs. New Dimensions are 30"H x 18"W x 15.5"D." If the listed dimensions are accurate, the modified enclosures are ~43% smaller than original. The bass had to suffer.

Thank you all for the replies. Lowther-type back loaded horn speakers are interesting. I'll watch for an opportunity to audition them. Perhaps a trip to a meeting of the Chicago Horn Speaker Club is in order.

Has anyone on this BB auditioned a single Lowther driver horn loaded speaker, or something similar? Two examples can be seen at the following sites: http://www.carfrae.com/ http://www.beauhorn.com/ The concept of eliminating the X-over is interesting. IMHO the cost of the Carfrae and Beahorn versions is exhorbitant no matter how good they might sound.

Did they look like either of the single Lowther driver horn loaded speakers shown at the following sites? http://www.carfrae.com/ http://www.beauhorn.com/ Has anyone on this BB auditioned a single Lowther driver horn loaded speaker? The concept of eliminating the X-over is interesting. IMHO the cost of the Carfrae and Beahorn versions is exhorbitant no matter how good they might sound.

In the 70s there was a small company (probably a guy from his garage) that sold a unit that purported to combine the bass horn of a Khorn (a copy) with the nine drivers of a Bose 901. I don't recall if there was a dedicated tweeter. If memory serves, ads were run in Audio. Does anyone remember these odd creations?

I assume that lynnm's email has indicated a desire to buy it. If not, please reply to the email that I sent.

Wes, Your collection of Klipsch and tubes is awsome. Now that the weather has cooled and the windows are open, if you play it loud in Southfield, I could hear it here in Birmingham. But then I'd no longer be content listening to Ed Love on Heresys powered by a Dyna SCA 35. The diminishing return factor hit me already. Enjoy! Neil

The posts regarding tube gear seem to justify a dedicated forum.

FWI, please recall that the old phenolic (?) PCBs have been replaced by fiberglass PCBs. There is no additional space, but they are not brittle from age. It would be no problem to snail mail schematic in print or on a disc.

I enjoyed your description of gingerly moving the K-horns. It reminded me of the many times I moved 4 SK-horns. 26 years ago I dragged 4 Speakerlab K-horn clones (I know, no match for the real thing in quality, but they weighed the same) around in a mobile disco business. With 300 watts/channel of Dynaco SS power (into the 4 ohm load of the two 8 ohm speakers/channel), I deafend adolescents all over the Detroit area. It would have been sacreligious--and prohibitively expensive--to subject real K-horns to that abuse. I knocked down the plywood shipping crates to permanently attach false corners. As I would roll the first one off the trailer using a dolly, people would gasp at the size of the flat black wooden refrigerator-sized speaker. When I told them that three more were coming, they'd freak. The sound from those knock-offs was loud and clear, although I fried the T-35 voice coils regularly. EV gave me an open account. A call on Monday would have the new voice coil and a bill for less than $20 at my door in time for the next weekend. One time a woman called to again book my services. She asked if the price quoted included the drummer. I had a diffcult time convincing her that there had not been a real drummer the last time. She was not used to hearing horn-loaded bass speakers played at high volume. I wish I still had those speakers. Actually, I wish I had the money and space for real Klipschorns. For now I must remain content listening to Heresys. This message has been edited by DizRotus on 08-16-2002 at 10:27 PM

Craig, I agree regarding HT. I use a Sony STR D515 AV Receiver to power LS3/5A clones (KEF drivers) and passive but equalized subs that each contain a KEF B-139 driver in a large transmission-line enclosure. The surrounds and center channel are Audio Source (they were free). I have never felt the need to improve upon that for listening to TV and movies. Afterall, it's not like it's real music. Neil

I'm not looking for more power, Just improved sound and the pleasure of working on the thing. You asked about what replaced the 4-section filter cap. The following parts (excluding the Ruby 50/50uf 500 volt Cap that sits next to the cap board) were installed on the fiberglass PCB sold by Sullivan. 3 22uf mini Electrolytic 2 47uf mini Electrolytic 1 100uf mini Electrolytic 1 50 Ohm 5watt resistor 1 100 Ohm 5watt resistor 1 2200 Ohm 1 watt resistor 1 Ruby 50/50uf 500 volt Cap It seems to work fine. It's my perception that it sounds better, but the difference is subtle. My DMM could only test the 20uf section of the old cap, which measured 15uf, but after forty years they were due to be replaced. What is you opinion of the above as a replacement for the 4-section cap? Do you have an alternative? The attempt to email the PDF file of the schematic failed. If you did not get at least one email w/o the PDF, let me know. As I type this I'm listening to the Ed Love Jazz program on WDET, the Public Radio station in Detroit. It sounds pretty good coming through that SCA 35 and out of the Heresys. Neil

Norton AntiVirus is slooooowly scanning a PDF file that is being emailed. If it does not arrrive satisfactorily, let me know and I could mail you a CD with the schematic. The email also advises that I use the SCA 35 to listen to CDs and FM on 1982 Heresys. Neil

mdeneen, I'm interested. I would greatly appreciate a schematic showing the suggested mods, when you get the time. While I could not design modified circuits, I can follow a schematic and solder--and arc weld and braze--so performing the necessary surgery on the SCA 35 would be no problem. I'm especially interested in finding alternatives to the 7199's. Have you seen this web site: http://home.netcarrier.com/~rstevens/sca-35.html ? If so, what do you think of the elimination of the tone controls? Does the suggested procedure make sense, or is there another way to bypass or eliminate the tone controls? Thanks for your suggestions, Neil

mdeneen, Thanks for confirming my assumption regarding the mechanics of testing pin voltages. I'll do it for the experience, even though it probably won't solve the squeal. Your memory is good. It's an SCA 35. I replaced the 4-section filter cap with the board sold by John Sullivan on eBay and used the parts that he suggested. There are more details in the "Squealing Sovtek 7199's" thread that Craig just resurrected. The problem existed before and after the "upgrades" that are described in the "Sqealing ..." thread, so I agree with Craig that the Sovteks are probably the culprits. Do you know if it is possible to adjust the bias on the SCA 35? If so, how? If you get a chance to check out the "Sqealing ..." thread, I'd appreciate any comments or suggestions about what I've done or what you'd recommend to be done to this humble amp. Regards, Neil

In response to my earlier "Squealing 7199s" thread mdeneen and NOS440 mentioned testing the pin voltages to diagnose the problem. That thread seems to have gone to its grave before mdeneen and NOS440 revisited it to see my follow-up question regarding testing pin voltages. Being new to tube gear, I can only guess at how to test pin voltages. My assumption is described in the earlier thread. Could someone please describe how to test tube pin voltages using a digital multimeter?

I agree with Gil. Start with high quality efficient speakers using the existing electronics. Out of curiosity, I used my son's Dell laptop (DVD-CD-RW combo drive)to power my 1982 Heresys (usually less than $400 on eBay). Dave Brubeck's "Take Five" sounded very good at moderate levels. Later you could get some better electronics as the budget might permit.

Mobile Homless and others have recommended that CD players be left on at all times. Could there be advantages to leaving tube equipment powered up at all times? Which causes more wear on the tubes, idling with no input signal or the thermal cycles going from cold to hot to cold, etc.? An obvious drawback to constant power is the cost of the electricity. Is that expense outweighed by sonic benefits or extended tube life? Perhaps the variables among the many different pieces of equipment are too great to generalize. Has anyone left tube gear powered up indefintely? If so, what were the consequences? If NOS440 or mdeneen view this post, please re-visit my earlier post about Squealing 7199s. I have questions about testing pin voltages. Neil

Space Cowboy, I found "How to Service Your Own Tube Amp" by Tom Mitchell a useful primer on tubes. It's available from Amazon.com. I've enjoyed getting my feet wet with a Dynaco SCA-35. It's spartan by comparison to other tube gear, but it's a leap over the SS receiver it replaced. BTW, if you think NOS stands for New Old Stock, you're wrong in this case. NOS440 refers to Craig's 440 cubic inch Camaro that runs nitrous oxide. Craig is a man of varied interests and talents. Craig, please check out my post on Squealing 7719's. I'd like your advice regarding testing pin voltages. Regards, Neil

lynnm, NOS440 & mdeneen, Thanks for the input. To answer mdeneen's questions, yes I replaced parts, but no I did not change circuits (unless replacing the multi-stage electrolytic can capacitors is changing circuits. In any case, the oscillation problem manifested itself before I changed anything other than the Sovtek 7199 tubes. I was hoping that the new parts might solve the problem, but no such luck. In the interest of full discloure, I bought the fibergalss cap and output boards sold on eBay by John Sullivan. I used his suggested parts list to replace the can capacitors. The output boards received all new coupling caps and resistors of the same value. Only the two ceramic disc capacitors on each output board were re-used. They tested OK, and I could not find modern equivalents. I also installed ceramic tube sockets. I'd like to take the advice about measuring pin voltage, but, as a tube tyro, I'm not certain as to how to do it. I assume that the negative lead of the DMM is attached to the chassis and that the positve lead is sequentially touched to the pin terminals, with the DMM at the proper settings. If my assumption is incorrect, please let me know before I destroy the amp, the DMM or myself. Has anyone had experience with the cap replacement sold by John Sullivan on eBay? If so, what are your opinions. Is there a better alterantive to forty-year-old can capacitors? NOS440, someday I'd like to drive to Burton to check out your new La Scalas and that Camaro. Now that my kids are too old to get excited about a ride on the Huckleberry Railroad, I don't get up that way often, but I would make a special trip to meet you and get some expert tube advice. Regards, Diz

As my first venture into tube gear I have restored a Dyna SCA 35 to drive Heresys. Everything went well until I replaced two different brand 7199 tubes with Sovteks. Upon powering the unit, with the volume at zero, there is a squeal from the speakers that varies in pitch and volume and sounds like a doppler demo. It lasts approximately three seconds and then everythingg is fine. If the unit is turned off then turned back on within a few minutes it does not happen again. After the unit has been off awhile the noise returns when first turned on. I experimented by replacing a single Sovtek with one of the old 7199's. The squealing returned in both channels as long as at least one Sovtek was in either channel. What gives?

Thanks to one and all. The information is right on target.

Guy Landau, Thanks! Those are just the kind of sources I'm looking for. Similar suggestions from others are still welcome.

I'm finally getting around to restoring some old Dynaco tube gear. In addition to Parts Express, Antique Electronic Supply, Triode Electronics and Radio Shack, what are some mail order and/or online sources for the resistors, capacitors, etc. that would be needed to restore vintage tube gear? No one place seems to have a full range of parts and a few of the oddball parts are not at any of the places mentioned. Thanks for any suggestions.