Audio Asylum Thread Printer
Get a view of an entire thread on one page
|For Sale Ads|
I have this little Heathkit (AA-32) vacuum tube integrated that sounds so good nothing else I have can knock it off the top of the hill. Until I get around to putting in some gold jacks I'm using the originals cleaned up the best I can.
As in most vintage gear the jacks are too close together to fit in a modern cable next to each other.
Instead of right next to each other I'm using the ceramic phono input jack for a high level input instead of the tuner jack.The ceramic's input sensitivity is the same as the tuners, 250 millivolts. The input impedance for the ceramic is 2.2 megaohms while the tuner and aux. are 47 ohms.
I know the ceramic input was made for kiddie phonographs in the day.
So here is my question; Using you guys as my ears, are there any sonic pitfalls in doing this? I am feeding my TV into a wireless Kodi 4K steaming device. It goes from there to a Fiio Taishan 25 dollar DAC which excepts an optic cable but outputs with 2 gold RCA jacks to the ceramic jacks on the Heathkit.
My Samsung tv had no audio RCA output jacks. On the other high inputs the sound is first class but I was wondering if ceramic had any thing in the path to shorten the 20 to 20,000 range?.....thanks alot.....3rd day of
snow in Maine, thats why you get questions like this....Mark K.
Roger Russell has a great page on ceramic photo cartridges given he was an engineer for them early on...they are not just a kiddie toy.
When dealing with the closely spaced RCA females found on older equipment, Neutrik/Rean NYS352(B)G plugs make your day. ;> ) Make up interconnects with the narrow plugs on the Heath end and Canare F-10 RCA on the "upstream" end. MarkerTek is a good source for the plugs and they also carry Mogami 2549 bulk cable, which is highly satisfactory.
Hi Eli, thanks for the tip. I checked the site you gave me but could not find the plugs. I'll do some more searching. In the past I would use Phoenix Gold cables. They were gold plated and had the plug end molded right on to the wire so they never would come apart or loosen at that junction. With a sharp knife I could shave the plug part down so they would fit beside each other with no strain.They were gold and cheap but well made. Thanks Eli, the search continues...Mark K.
Some "deep" links at MarkerTek follow. Your browser has to temporarily allow all the java scripts MarkerTek employs.
Thanks again for your help. When I looked at the schematic it takes a simple change of a cap. and resistor to mirror image the tuner and aux. section more or less just like you said. If I change the ceramic jack to the values of the other tuner and aux. I think I'll be ok. .....Mark K.
Instead of installing new gold jacks on some tight spaced vintage jacks I want to build a new set of cables with the stuff you recommended. My old jacks will be shine inside and out and be taut with some needle nose work.
I hate to sound like a dope but the Mogami wire has 3 inside wires not 2. Do 2 go to the ground spade or 1 to the ground spade and 1 to the copper braid with the strain crimper? I have not seen the wire yet and am thinking in co-axial terms. Thanks Eli or anyone else....Mark Korda
That third wire, the copper one is the shield, which should be connected at one end only. You connect the shield at the source end except for phono, where you connect it at the destination.
Hi Crazy Dave, thanks for the info. I saved you one of those crazy AR dust covers.Not quite done because of constant shoveling up here in Maine but right behind me in my projects to do pile...thanks bud...Mark K
Hey Eli, I found them. Parts Express, slim and sleek and shiny.I'm ordering some tonight...thanks Eli. David D., I'll check that ceramic cartridge site out tonight. 2 problems about to be solved because of all of your help guys.....thanks again...Mark K.
Sometimes, there is a small capacitor installed between the input jack and tube grid. Also, there maybe a large inline resistor to increase the input impedance, which can end up decreasing the level of the input signal. The small input coupling caps were fine with the high impedance crystal and ceramic carts of the day, yet not needed with an input which is of low impedance.
So, do you have a schematic of this fine little sounder ? If not, simply trace out the signal path from the ceramic input jacks. You will see a large (Ohmic value) resistor to ground at the jack or on the selector switch. You might also see, or only see another high value (in Ohms) resistor from the ceramic input jack to the mag phono input jack or wiring. There may be a small ceramic capacitor across that R or simply a small cap from one jack to the next, as was an inexpensive wiring method back then. Simply "bypass" the "inline" gain robbing (resistor) and frequency dependent(small capacitance value cap) parts with wire, for your newfound application.
While you are carefully looking "inside" the amp, are there any other high gain inputs, like a Mic or Tape Head input ? With some serious studying and realizing the selector switch wiring pinouts, we can "convert" those typically unused high gain inputs into extra phono inputs. Of course, we would need to know the R-C values to apply and install the phono EQ, but everyone should have two turntables nearby and ready to play, right ?
Thanks alot! A great answer. You made it simple enough for me to do as a project tonight. I have the Heath manual. This integrated has only 4 selections ceramic or crystal phono,magnetic phono, tuner, and aux.
All report on my findings Interstage, thanks again..Mark K.
Post a Followup:
Post a Message!
This post is made possible by the generous support of people like you and our sponsors: