Re: My beomaster 4500 actually has an internal riaa preamp!

joeyboygolf — Sun, 17 Feb 2008 11:07:57 GMT

In fairness, I didn't know such a thing existed. We live and learn!

Re: My beomaster 4500 actually has an internal riaa preamp!

camshaft — Sun, 17 Feb 2008 11:02:41 GMT

casdave:
Sounds like a classic case of knowing too much and not being open to ideas that conflict with 'what I know for sure'
I somehow don't think you are alone in this, maybe we could call it something like 'Acute Expertitis'

I think so, but at the same time I wouldn't give myself that much credit I should have been smart enough to think from the intense noise that there was so much gain that I probably had 2 preamps going through each other.

joeyboygolf:
Part number 8002956 RIAA pre amp was an accessory. Of course, I knew that all the time...........nobody asked!

Hi Joeyboy, as I said I saw in the service manual that that part was available for the 4500. But as I had never seen it mentioned before, and because the ebay seller was just one of those ebay resellers where you drop off your old stuff to sell, I had never actually thought the previous owner would have bothered to have this installed.

Austin

Re: My beomaster 4500 actually has an internal riaa preamp!

joeyboygolf — Sun, 17 Feb 2008 09:46:42 GMT

Part number 8002956 RIAA pre amp was an accessory. Of course, I knew that all the time...........nobody asked!

Re: My beomaster 4500 actually has an internal riaa preamp!

casdave — Sun, 17 Feb 2008 09:20:58 GMT

Sounds like a classic case of knowing too much and not being open to ideas that conflict with 'what I know for sure'

I somehow don't think you are alone in this, maybe we could call it something like 'Acute Expertitis'

My beomaster 4500 actually has an internal riaa preamp!

camshaft — Sun, 17 Feb 2008 00:40:04 GMT

Not sure whether the beosystem 4500 counts as vintage or not, so I just posted here.

About a year ago I acquired a mint beosystem 4500 (minus turntable) with cx100's (in need of refoaming) for $525 US on ebay. I believe it was one of the best b&o bargains I will ever come across. I think part of the low price was because there was absolutely no description. It was only through multiple questions to the seller that I determined the condition.

Anyway, my dad bought a beogram 1202 back in 1976 when he lived in the UK. The turntable had been sitting unused in our basement for quite a few years. I had wanted to connect it to the 4500, but knew I would need an riaa preamp as the preamp was built into the turntable of the 4500 series rather than the receiver. I'm the diy type, and I also wanted the clean look of an external preamp with DIN connectors on it so I wouldn't need RCA adapters. Therefore I built my own riaa preamp with a circuit board kit, made a basic +/- 12V dc supply and put the assembly in a nice aluminum housing with DIN connectors on the back. After spending quite a few hours on it, I excitedly plugged the turntable and preamp into the phono input of the 4500. As soon as the needle dropped, even on the lowest volume, I was greeted by the most awfully loud noise ever. It was just garbled noise that sounded as if my speakers were going to blow out. I spent many more hours fiddling with wires, reheating solder joints, and doing anything I could think of trying to fix it. I had thought maybe the ridiculously loud noise was because my signal had shorted to one of the power rails. My dad asked what would happen if I just tried plugging the turntable directly into the beomaster without the preamp. I shrugged off his suggestion, telling him I knew for certain the 4500's didn't come with riaa preamps in them.

So then I soldered a headphone connection onto the preamp so I could try it with my computer, and only have to worry about damaging the cheap computer sound card and speakers rather than the beosystem. Worked perfectly. I figured it worked now because of something I changed or accidentally fixed when I was trying to tweak stuff after the first time it didn't work. So thinking it was fixed, I just kept listening to records through the computer instead for a couple weeks. In the meantime I noticed in the beomaster 4500 service manual that there was mention of a part number for an internal preamp option. Having never heard anything of it, I figured it was just some really rare or obscure option, and there was no chance that this beomaster off of ebay actually had that installed. So after a couple of weeks successfully running the preamp through the computer, I took the turntable and preamp back downstairs to plug into the 4500 system hoping it would work....nope. Same exact problem as before. I was so mad and frustrated. I posted my issue on a technical diy turntable forum, and one member said my situation sounds just like what would happen if you tried to run one preamp through another preamp before going into the receiver. He said just for the sake of checking to try plugging turntable directly into the receiver. Figuring at this point I had nothing to lose, I tried.

I couldn't believe my ears as I turned up the volume. Everything sounded perfect. The 4500 had the internal preamp. As happy as I was that it worked, I felt like such an idiot for never trying that in the first place.

So maybe this can help some other people. Before just assuming you're 1990's beomaster, such as the 4500, 6500, or 7000, doesn't have an internal riaa preamp try it first!

Austin

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Re: My beomaster 4500 actually has an internal riaa preamp!

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My beomaster 4500 actually has an internal riaa preamp!