Phono input usable for other components?

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camusmuse

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Joined 2003
#1
Title basically says it all......

I picked up a great old tube "portable" radio and turntable. It has what I believe to be the standard RCA inputs for the Phono section.

My question is this......

What do I need to use this input for standard "line-level" sources, such as a CD player?

Most of what I have searched here has given solutions for the opposite of my dilema(phono to line level step up conv.), but I've yet to find the reverse.

Any help or guidance would be greatly appreciated........

Thanks....... Nate
 
#6
Well I just placed my order with digikey(radio shack is such a joke these days)...cant wait to get the parts.....

Though I do like the idea of passive EQ and attenuation would it be possible or even preferred to use an active eq to do the same job? I was thinking of using an old parasound eq that I have....thoughts?

I figured that there would be some sort or commercially made "magic" box....but I do enjoy the DIY......
 
#10
Franz -

I'm pretty sure that it has the RIAA network. I hooked up my dvd player and though it passes signal, its WAY too loud(especially compared to the fm section) and sounds a bit distorted and "tinny", much like when I tried the same thing in my youth(before I discovered the beauty of vinyl and was playing around with HT on an old SS Kenwood int. amp that had an unused RIAA phono section, all the other inputs were filled)

After thinkin some...yeah I know, careful Nate....careful.....hehe, I decided to provide the model #. Its a General Electric T1000-C. Has the speakers in the front "doors" that swing open to show the controls(the speaker "wires" attach to the hinges. It normally sits atop a matching turntable that flips down(hardly portable but looks really cool), but I'm not using that now as I have a much better vinyl setup in my main system. Though I was thinking of making a simple switching network to run both the turntable and a cd player.

Why, you might ask, am I putting all this time and energy into this..... guess I'm just an old radio geek that prefers the wood and tubes to the chips and plastic that now plagues the store shelves.....plus i only paid $10 for the radio and the turntable...gotta love garage sales huh?

Thanks again for all the great info.....
 
#12
My Scottish amigo's got a point; I think your "tinny" sound is probably down to very likely impedance inconsistencies. If it was a modern(!) phono stage, you might expect the volume to be very high & the bass very boomy with muted treble. Franz G was dead on re. the old crystal/ceramic cartriges; my late dad actually employed a similar principle when he built a system around a diy JLH amp ~ 30 years ago; he couldn't be bothered to build a phono stage so used a high output ceramic. The frequency responce is so dire (I cannot concieve that it was contrived!) that it pretty much performs the equalisation process itself!

I've got a horrible feeling you'll be making matters worse by attaching the RIAA inverter. It sounds like you need a passive RIAA circuit!
 
#13
Yeah I believe that you are both right. The more I listen to it the better it sounds. I think that I may have had an intermittent tube problem. I'm fairly sure that they are the originals.

When I have the time and more importantly the cash, I'm going to tear into the amp and see exactly what I have going on back there. I have a few "upgrades" in mind. A fresh set of "good" tubes should help. Any recommendations? Honestly I don't even know what tubes are used, but I'm guessing that the output is pp el84.

I have recently added "subs" to the setup(It has external speaker jacks on the back that I wired to a pair of 8" vifa's). The main fold out speakers are just paper 6x9's(or some odd oval shaped speakers), so I will replace them with a pair of peerless dome mids and an infinity emit tweet per side. I also plan on using some "recycled" infinity quantum 5 passive crossovers that I think should work well.

Back to my phono input....... the cd(line level) now sounds much better and I think the only problem that I may have is the impedance mismatch. However I am not sure if that is a problem as sometimes its sounds GREAT!!!

I guess I really need to get my workbench set back up so I can put it through its paces. A few tone sweeps and decibel readings(poormans RTA) will let me know for sure whats going on with it. I've heard good things about some PC based RTA's though so maybe this is a good time to step up and see whats available....and more appropriately what I can afford.

Fezz, you mention that I might need a passive RIAA instead of an inverter. Pardon my ignorance, but what exactly is the difference. I was under the impression that the "contraption" mentioned earlier was a passive eq. A full explanation is not expected, but if you could point me to some relevant text it would be greatly apprecitated.

Thanks again for all the input....I'll keep this thread up to date on my progress if there is any interest. I would really like to find someone else who has the same or similar unit. For what it is I think it's superb...especially compared to today's mass produced "plastic" crap.
 
#14
Not to anger the mod gods but I do find it rather entertaining that the word c r a p was censored in my last post. The word is actually an "homage" to the toilet's inventor.....John Crapper. At least I think thats how the story goes. If that word offends any readers here I am truly sorry, but I just had to pass on what I know about it.

If it wasnt obvious I'm a George Carlin fan, his "seven dirty words" routine is one of my favorites... Its not the word, its the context.....

No hard feelings.....just had to vent some......

Thanks again.......

Nate
 
#15
Hi,
don't put down paper cones as JUST. Some of these old paper coned drivers are very efficient. If you change to a modern 2way you may discover that the valves just cannot perform.

A word to the moderators. I too have just come across the automatic editing out of dubious words. I resent that intervention when the context is appropriate and I/we are not putting down any person/company/service.
 
#16
As "JUST"??? Is that a typo or do I just not know the terminology?

I whole heartedly agree that there are some GREAT paper cone speakers out there, old altec lansing comes to mind. But these are not them. For one they are oval(ever see an oval speaker under a strobe around its resonant frequency.....scary), I really prefer round or planar speakers(or a combination thereof).

I havent even hooked up a meter to see what the nom. impedence of the ovals is, but the "subs" that I hooked up are actually an 8ohm two way design that I had come up with a while back that I simply disconnected the tweeters for this application. Before that they sounded great running full range and the amp seemed to drive them just fine. In fact it sounded much like my old Dynaco st-70, just not quite as loud, that's why I assume its el84 based instead of the dynaco's el34. Loud volumes arent really required anyway as this is in an apartment.

I can see now that I may be pulling the back cover off this afternoon, at least to see what I'm working with.

muchas gracias por las informacciones

(yeah i cant spell in spanish either....lol)
 
#17
The word is actually an "homage" to the toilet's inventor.....John Crapper.
Click to expand...

Oh dear; this is where I get all pedantic, steeple my fingers & study you over the top of my ficticious half-rim spectacles...

The "Water Closet" was in fact invented by Sir John Harrington, godson to Queen Elizabeth I, set about making a "necessary" for his godmother and himself in 1596.

Source: http://www.plumbingsupply.com/pmtoilet.html

The much celebrated Thomas Crapper, had little to do with the progression of the "bog" other than being a promenant manufacturer during the Victorian popularisation of the aforementioned utility...

Source: http://www.plumbingsupply.com/pmthomas.html

Ahem.

As "JUST"??? Is that a typo or do I just not know the terminology?
Click to expand...
I think the esteemed Mr. T was refering to your earlier point:
The main fold out speakers are "just" paper 6x9's
Click to expand...
.. as you were...

Cheers, Jezz😉
 
#18
Oh yeah...

Fezz, you mention that I might need a passive RIAA instead of an inverter. Pardon my ignorance, but what exactly is the difference. I was under the impression that the "contraption" mentioned earlier was a passive eq. A full explanation is not expected, but if you could point me to some relevant text it would be greatly apprecitated.
Click to expand...

What I meant was if you're going to use it for phono (which by now I take it your not) you'll need to use a passive RIAA filter as opposed to the opposite of an RIAA which you would need to correct the existing RIAA circuit (if there is one) to use as a standard line in. To be fair, if there is an RIAA in situe, it'll probably be easier - and you'll see far better results - by simply removing the circuitry!

Cheers, Jezz
 
#19
Potty talk...coincidence, I dont think so🙂

LOL...I just knew that would get a rise out somebody. I do remember there being some controversy over who exactly invented the WC, but alas my memory just aint what it used to be.

Dear Fezz...Being the expert on crap that you present yourself to be, can you tell me where did the term "John" (my erronious assumption of Mr. Crapper's first name) come from? I know there's some sort of story there. Please, shower me with enlightenment....:angel:

Just to not make this totally off topic......

I believe these are the tubes in my unit

12ax7 x2
12at7
6aq5 x2
6ez8
6ew6
6au6 x2
6ba6

Those may have been misread off the sheet on the back, it's pretty worn and hard to read. I am assuming the dual 12ax7's are the pre stage, then one of the other "pairs" of tubes is the output stage. I suppose actually pulling the cover to see what tube is where could tell me, but I want to wait to tear into it until I have everything I need. Anyone wanna play the "whats that tube do" guessing game?😀
 
#20
tell me where did the term "John" (my erronious assumption of Mr. Crapper's first name) come from?
Click to expand...

Dunno is the honest answer; everybody seems to make the same mistake with Joseph Merrick AKA The Elephant Man. Interesting to note how many of you "colonial" types(😉) refer to the item in question as "The John" though... Wonder if it's a bastardisation of two names (did that get through?😀 ) as for your component list, you're bordering on cranial melt-down for me. If you can put a schematic diagram together I can probably help - you'd get far more sense from the Gurus on the "tubes" page though! :xeye:

The Fezz
 
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