Discussion in 'Hardware Lounge' started by Mike, Jun 5, 2017.
Thanks David. I am going to strip out the cabinet today.
What if I did this?
Look what I found. Super tweeters?
re: your wiring diagram. NO. connecting both channels to the woofer will blow the amp. one POS to the woofer POS, the other POS to the woofer NEG is the only way to get a pseudo mono signal without using another device.
I assume you are talking about buying a stereo set of crossovers, and trying to use the existing speakers? Risky. Are you planning to buy new speakers too? If so then that makes things more possible.
The little square things could be anything. I noticed them on the schematic but had no idea what they are.
Oh man! This is super cool. I recall one of my relatives had one of these.
Dep3nding how much you want to spend - you may find vintage Grundig receiver and turntable to replace both on Ebay. Or perhaps something more easily found, both receiver (e.g. Marantz) and turntable (Dual or Garrad) from the 1970s.
While, I have never heard one personally, many people think this sounds very good for the money. If one has a passive sub with a crossover, it could be an interest option:
Tube Amp with Bluetooth 25-watt Stereo Hybrid - Monoprice.com
This is now what I have for power.
Nice - I think that will work well. Gives you FM and phono too.
So... do you intend to try and power the existing speakers with it?
From a "Vintage Radio" forum:
"They are electrostatic tweeters. And the probability is high that they are nonfunctional. Test by disconnecting the permag speakers so that just the tweeters are hooked up, then tune to a strong local FM station. If you hear anything at all, they are working. Even when brand new, the contribution of these speakers to the overall sound output of the unit was miniscule."
Also, they say the Grundig 7080WF is circa 1957.
I am looking for the impedance of the other speakers to see how they can be used with your receiver.
David, my hope is to use the existing speakers. It would just make life much more simple.
Picked up the receiver for 120 bucks. Lights up purple.
It had two things I was looking for, a phono-pre, and A/B speaker capability. I understand they were manufactured by Marantz.
OK, so I cannot find any information on the electrical rating of the speakers. So I will make a few assumptions and design a simple crossover for you. Stand by.
btw - hifiengine has some data related to the Marantz receiver - Superscope R-350 - Manual - AM/FM Stereo Receiver - HiFi Engine
They have the service manual in pdf format which gives schematics, list of parts, etc.
Here's what might work, assuming my estimates are OK.
IND 1 =low-pass inductor. "Dayton Audio 2.5mH 18 AWG Perfect Layer Inductor Crossover Coil" from www.parts-express.com!
CAP 1 and 2 = high=pass capacitors. 2 of these: "Dayton Audio DMPC-20 20uF 250V Polypropylene Capacitor" from www.parts-express.com!
Operate the receiver with speaker selector in "both" position and connect like this:
Might sound like ass if my impedance guesses are wrong. Might sound like ass if the speakers are crap. But nothing should blow up.
Amp has a mono switch on it. Any way that can play into this at all?
Now if you want to go really authentic!
*Grundig Very Rare Stereo Meister 300U Tube Radio W/ 2 Pin Din Conn & Pre Amp* | eBay
This may be a bit iffy but price is right -
VINTAGE 1970 GRUNDIG RTV 700 RECEIVER AMPLIFIER MADE IN GERMANY AUDIOPHILE RARE | eBay
I can order up those parts. Thanks David...I owe you something.
The speakers work fine, the amp that was in it was producing sound, there was just a really bad hum (not the speakers) and none of the selector buttons worked except the turntable one. And the turntable made a mechanical grinding noise. It was all pretty unusable, but the speakers all worked fine.
Very cool, but too big. This receiver has to be no more than 5" high. That was a determining factor in the choice of this one as well. I was looking at a nicer Kenwood model, but it was too big.
I have ordered he parts. We shall see.
I have gutted the cabinet and begun refinishing it.
Will install the electronics over the next few day in prep for the parts arriving so it should be a quick install.
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