Mike Dubay

I'm not much for putting anything in line of the music that is not necessary. I would say that if the system sounds clean, and no noticable distortion is coming from either the speakers or the amplifier then I would believe you are ok. Generally you end up damaging speakers by driving an amplifer into distortion before you end up sending to much RMS music to the speakers. The RF7 are rated for 250Watts, so the yamaha should be a good match.

Dynakit makes a 35 watt el34 sterei amplifier with in your price range. I have been using a pair of MKIII's for a few years and I am quite happy with the quality of the kits and love the sound of them on my KG5.5's.

PartTime, I have always enjoyed the sound of passive preamplifiers. I have compared both tubed and a few high dollar solid state preamplifiers against passive preamplifiers and I find more sparkle and detail using passive preamplifiers. I'm sure there are active preamplifiers out there that can excell again passive preamplifiers, I just have not had the chance to listen to one and have a direct test against a passive. I find they provide a lot of bang for you dollar, spending about $200 can get you an excellent sounding passive that would take many times that cost to get a similar sounding active preamplifier. I will have to see if your CD player provide enough gain to fully drive your amplifier, most modern CD players can drive most modern amplifiers. You will also have to get a separate phono section. My passive preamplifiers consist of selector switches, potientiometers, wire, and phono plugs. Good selector switches have silver contacts, coil silver or silver plate. Grayhill is one of my favorites. For phono plugs, I use gold plated Dayton phono plugs. Wire consists of 18 or 20 gauge copper, either from Carrol, or Radio Shack. I use silver based solder for assembly. I find that stepped poentiometers win out slightly over high quality carbon potentiometers such as an ALPS blue velvet. There are several kits out there that provide the switches and resistors to build yourself a stepped potentiometer.

Attached is a file that was posted a while back with a KG5.5 cross over. Also look at the link to Bob Crites web page, I believe Bob will sell you all of the components as a kit and you can assemble the cross over, or you can just purchase the caps instead. I plan on doing my KG5.5 cross overs this summer. kg55cross.pdf

Kevin, The gloss black paint turned out excellent! Have you had a chance to listen to them yet? - Mike

Here is a closer look at number #1 which is the ugly duckling. Active corrosion on the chassis was sanded off, and had to evacuate a mouse nest from this one. Luckily the wiring was not chewed on what's so ever. Boy, do these "twins" play loud and clear. I listen to these while working out every evening through my KG4's. They can take all of the output from my Sony CD player and my PC with no audible distortion. The output transformers are rated from only 60 Hz to 20kHz. With a little bit of equilization at the Microsoft media player I get nice solid bass. I would have to say that the 60 Watts these are rated for is very conservative.

Here is a couple of quick pictures of my most recent projects. I picked up two Bogen M60A PA amplifiers on the cheap. First one was at an antique fest, got the seller down from $35 to $12. Surprisingly, another one came up on ebay soon after wards, had a good experience, $70 delivered from Texas. So $82 for the pair was not bad. One of the two had a pair of 8417's that have some life in them, tested at 135% and 134%. Both 7247 tested good for ma and transconductance. Spent the fall and early winter modifying them for Hifi use. I removed all of the microphone inputs, tone controls, and volume controls. Stripped it down to just the 7247 tube for gain and splitter and the two 8417's. I rebiased the 7247, intially is was biased too close to 0v for 1 volt inputs. Completely recapped it, scrapped the can capictor and got 330 uf of electrolytics under the chassis. Replaced the coupling caps with polyproplyene, nothing special run of the mill from Cornell Dubilier. I added an adjustable Bias network, span and balance, and a ma meter for the 8417's. Replaced the power bulb with an LED lamp to illumiate the cat's eye lens. Added a stand-by network to keep the 8417's reigned in during warm up. Replaced the one unit that did not have a grounded power cord with a 3 wire plug and grounded the chassis. Yikes! 605 volts to the output transformers and an ungrounded chassis? Each unit was converted to a star ground system. They have not been cleaned up for looks just yet. I'm running them with out the covers to promote cooling.

Very cool Russ. After spending the morning in my wood shop, I found I had the house to myself for the after noon. Decided to listen to "Boston's Greatest Hits" at rafter shaking levels. After listening to some Miles, will put on LZ I and II myself! I was in the same boat as you, no name import 4 way speakers, 25 watt Technics reciever, and a BIC turntable all the early 70's. But at 2.10 an hour, lots of burger flipping done to afford even that. I still have the Yamaha. Listening to the Cornscalas this after noon,

Aj, Some well thought out questions, since I am working toward the same goal I will put my 2c in. 1) No problem using a passive cross over for the mid/tweeter and active between them and the bass, it's a common thing to do. I currently have an SE tube amp powering my tweeter and squawker and a solid state amp running the woofer. I'm currently doing my crossover passively, using an attenuation switch to balance the woofer and the squawker/tweeter along with a passive preamplifier. Saving for an Ashley myself. 2) Yes, I doubt if this would be a problem, but out of my area of expertise. 3) Most of the bass bins using ported boxes come in around 100 db/watt, 103/105/watt for some of the folded horns. Horn loaded squawkers provide around 105 to 108 db/watt. So the 3 to 8 db attenuation would fall with in the abilities of the Ashly xr1001. 4) For the best efficiency gain you can run the two woofers in parallel, you gain about 3 to 4 db/watt that way. Your amplifier has to built to handle the low impedance generated by doing this. If you start with 4 ohm woofers, and your amp is not rated for 2 ohm loads then wire them in series. 5) No software recommendations here. I use test tones recorded on the CD player and a Radio Shack SPL meter.

The "fine" switch steps are in 1 db increments. So I could tell by the position of the switch at which -db point the preamplifier was set. The 1 db difference makes my point, it is an inaduible amount of volume difference so it was not just a 'louder sounds better' effect. But I could tell something was amiss. Yes, moving to the next position added a resistor in the ladder, so there was a resistor that had not 'broken in' yet. So this would indicate that there CAN BE some type of a 'break in' period for even some thing as mundane as a resistor. Hard for me to believe, but this antedotical evidence supports it. Gets me thinking of a blind A/B test that could be done. Put two resistors in line to the preamp, run them in for several months. Then take one out and replace it with a 'fresh' resistor. Have my wife then selects 1 of 2 channels on the preamp based on a random number generator. Have the preamp covered so I can not tell and have me blinded while doing this. Both same source material, and I have to tell which one has the old and which one has the new resistor. Then repeat this several times. This can be the fun stuff of this hobby...

I had my cross overs run in over a few weeks, then settled in to a sound. Here is a good story. I'm not much into the thought of passive components such as wires and resistors breaking in. But I have a passive preamplifer, and I have been listening to it for an extended period of a few weeks at the same volume setting. One weekend the family went away, so I exercised the amplifiers, then returned the volume control to nearly the same position, but 1 db setting higher. Turned on the amp the next day and the sound seemed veiled and off. Upon a quick investigation, I reduced the stepped attenuator by the 1 db, and every thing sounded as it should. Still can't seem to figure that out or even reproduce that effect. Short after this it sounded fine at all volume settings near the point I was listening to. Maybe just needed to move the switch a bit to clean the silver contacts? Read some articles on things like resistors and cables having a break in period, but I have no first hand knowledge of that.. Any thoughts from forum members?

"Pass over the entry level Chinese stuff - they won't sound very good for hifi. Something like Ashly's XR series (I think - their step-up series) sounds much better. If you are in a decent sized town, you could probably rent one from a PA house for very little money to see what you think." So would the XR-1001, which is a simple stereo 2 channel be recommended? Here is a link to the Ashley web page. http://www.ashly.com/product/xr-series.htm I will investigate if I could rent a unit for a short term test.

Rudy, Currently I'm working toward active biamping of my cornscalas. For an intial experiment I'm going passive biamping, using a solid state Adcom for the woofer duties, and a SE KT-88 tube amp for the squawker/tweeter. Using the basic AA crossover between the tweeter and squawker. I have listened to Khorns with the SE tube amp and duly impressed with the mid range clarity, along with the nice tight bass. My cornscalas just don't have enough sensitivity to go SE for the woofer. To me solid state for the woofer and tube SE for the mid and tweeter is at least worth the experiment. It should give me the best of both worlds, tight bass, and the smoothness in the midrange. If this does not work out, then back to passive crossovers and a full range tube amp. Any other recommendations on active crossovers? I'm looking at the DBX234 XL, 2 in 4 out.

Had a great listening session with Kevin last Sunday. The large mid horns do open up the sound. A very impressive sounding system! And Kevin still wants to tinker? The bug has bitten him badly.

Nice, Similar to what I want to do, but drawers for CD on bottom. Also the additional vinyl I will continue to work on.. I didn't recognize the avitar, but the user name I do. Are you back to the forum? I'm honored.

Yes, mine are backed up on that also, a very efficient use of space! I see you went with steel and black plastic, and interesting expression of style.

I LOVE my media storage solution... Yes very nice MA&R system. More of a veritical solution, but can sections add on as collection grows. This is giving me some good ideas, thanks for the pic. Making a system modular and reconfigurable is a good idea...

Yes, very nice. This is pretty much what I was thinking of, with probably 3 or 4 drawers of CD's on bottom and 3 rows of albums. I'm guessing the length is between 4 and 5 foot?

And my crude bins made of CDX ply wood, a rustic "keep then off the floor for now" solution.

I will soon be making a custom CD/Album storage unit for myself. I would like to have some pictures of what the forum users have to store albums and CDs and comments on the likes and dislikes of the system they have. I can start with my basic CD cabinet that I will be growing out of shortly that I purchased from Naked Furnature many years ago. I plan on having open bins on top for albums, and pull out drawers for the CDs. My thought is that since the unit will be deep enough for Albums, putting CD in drawers would utilize the space better.

Would you be willing to shart your cross over design?

A few weeks ago, I got to do an A/B test of D250Xs and a K-55-V in my 230Hz tractrix horns. The K55V was in one speaker, with an ALK "universal" cross, the D250X on the other speaker with my type A cross overs. Both crossed at 500 Hz. Used Kevin from Flint's new ST-120 KT-88 amp. Both Kevin and I gave a slight edge to the K-55V's in the lower mid range, mostly exhibited in vocals. It was a pretty slight advantage, and other than that, I'm very impressed with the D250Xs. Right now I'm using a solid state amp, but will be making my way to valves in the future.

Great job on the oak veener horns! Are you in need of any 1 inch wide iron on oak veener? I have a bunch left over from my last project. What is going to be your driver for the tractrix tweeter?

For really on the cheap, look at the older Sony's with Burr Brown A to D's. A 241 single disk player just sold at my local record shop for $25. To be sure ask if you can remove the cover, the BB a to d's can be identified by their markings on the chips.

Great job on the rejuenavated Cornscalas! Like to see some one mix things up and try different drivers. I used the selenium D250X in my cornscalas which saved amount $250 on the build. Enjoy!