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610 st

O

oldamp

New Member
I have a 610 ST Amp.Taken out of an old console. I have another Post int he Tube section(sorry wrong post area) labeled 610 -ST, and was given some answers about it. J Cricket told me that it was a MONO Amp only. I am sure he is right as I can see by his Posting that he has been here a while. A couple of things still have me puzzled though. The original console cover clearly says there is an option to make the sound Stereo,but there is only one place to connect speakers,unless I don't see them. RCA connectors or some other option.I know the Amp works. Just wondering what I might have to do to make this Amp Drive another pair of Speakers.I don't know much about this. Many thanks again.
 
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I have the 610ST as well. In order to achieve stereo you need a second amp and speaker - sold by Fisher as a "Companion Speaker" and housing a seperate 30-A amp.

Even with this setup only the turntable is in stereo - the 610ST does have connections for an MPX adapter to turn your mono FM into stereo (assuming you have the companion speaker).
 
Visman is correct. You will need another mono power amp (like the Fisher 30-A) for the "B" channel. Note the purple coded RCA output on the back of the 610-ST labeled "TO AMP B": That is the line-level output from the 610-ST's stereo pre-amp that you would connect to the input of your "B" power amp.

610-STChassisRear.jpg
 
Many thanks. I may just put the Amp up for sale somewhere. I do not think I will be able to find the "Companion" amp and speaker to make this work. Too bad as it probably would have great sound. Does anyone have a picture of the Console this came from? Was just wondering what Make and Model this came from as I run into these units an the occasion. Again Thank You.
 
Right side, stacked on each other.

Looks like a couple of Motorola's to the right of what look like 901's.

The booby prize is the dust off the tops, right?

Larry
 
I recently won this consolette set on ebay (i.e. the 610 and 560 companion speaker). They are in decent condition, but I unfortunately do not have the Fisher 30-A amp for the companion speaker. I have a couple of questions -

1) Any idea where I can get a Fisher 30-A amp other than just waiting for one to show up locally on craigslist or on ebay?

2) Can I use any mono amp for the meantime to play the companion speaker? If so, should I plug that amp into the aux AC on the back of the 610 (to make sure they turn on and off at the same time)? If I use a standard mono amp, should I hook up the speakers in the companion part to 4 ohms? I know the speaker configuration should be for 2.5 ohms, but I thought this might be close enough.

I hope these questions make sense....thanks in advance for any ideas you can give me. I am planning today to try to hook up an eico HF-20 to the companion speaker using this method - http://tronola.com/html/hf-20_monoblock.html The HF-20 is not EL 84, but I figured it might provide a similar sound until I can find a Fisher 30-A.

By the way, thank you for all the information you have already provided on these forums for the 610-560 combo. There is nothing else on the internet.
 
I can't see any reason you couldn't use another mono amp in the companion speaker - (the 30-A is a stand alone mono amp).

Not sure if matching impedance is an issue - my 30-A is connected to the speakers at 16 ohms.

Also - be careful buying a 30-A as some have only a 2.5 ohm connection.
 

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Actually, I am fine with the idea of the 30-A only having 2.5 ohm connection (maybe that will make it cheaper). By the way, is your 30-A plugged into the 610 to turn them on and off together?
 
Yes - the power chord and mono connector plug into the 610-ST and both turn on and off together.

I may be wrong - but if the companion speaker is configured for 16 ohms you can't just connect to a 2.5 ohm output.

Of course I am no expert on this so maybe someone else can jump in.
 
I actually think the companion speaker is configured for 2.5 ohms....3 8 ohm speakers together or something like that. It is the same setup as in the main consolette, which has only the 2.5 ohm connector.
 
You're more likely to find a used 2.5 ohm 30A available than the one with the 4, 8, and 16 ohm taps . . . if that's any consolation.
 
Well - I'm not sure I understand it either - but in my case - my 610ST is connected to the speakers at 2.5 ohms (the only output option) and my 30-A is connected to the companion speaker at 16 ohms - this is how I got it from the original owner. In fact my 30-A does not even have a 2.5 ohm option - it's 4,8 or 16 ohms.

Curious isn't it?

I'll put an ohm meter on each set of speakers and see what I get.
 
Visiman; That's right. The 30-A was used in more than a few setups for a couple years. All the main unit is doing is sending a signal to the 30A via a line level. With the main unit, being a 2.5 oHm, I wouldn't think it puts out more than 1-2 watts.

Larry
 
Well, if anybody sees a 30-A around for sale (reasonably), send me a message. I would like to get this system running in stereo. I have to say, though, the 610 consolette sounds pretty spiffy in mono too!
 
Seanrr - just remember that you will only get stereo through the turntable - the FM tuner requires an external MPX adapter.

Still the system on AM and FM in mono sounds very good with both speakers - IMHO.

E-Pay seems to have 30-A's from time to time - so that may be your best bet.
 
seanrr said:
Well, if anybody sees a 30-A around for sale (reasonably), send me a message. I would like to get this system running in stereo. I have to say, though, the 610 consolette sounds pretty spiffy in mono too!
Click to expand...

I'm afraid you'll find the competition pretty stiff for a loose 30-A, especially the multi output ones. I'd love to get my hands on one too, but I'm not holding my breath.

One thing you could do is find an extra 610 ST 2.5 ohm OPT and custom build a 30-A clone from the schematic....:scratch2:
 
Alan, did you ever get a chance to look for your 610 service manual? Since yours appeared to be an actual Fisher SM, I had hoped it might have a page showing the console speaker arrangement and parts list which could help explain the mystery of the 2.5 ohm OPT. The Fisher SM for my Premiere has such a page showing all 16 ohm drivers configured to be driven by the 16 ohm taps of my TA-600. I noticed Visman's 560 companion was connected to his 30-A's 16 ohm taps and wondered if it was possible that one set of drivers could be configured to run off a 2.5 ohm tap while the other was configured to run off a 16 ohm tap. It just doesn't make sense to me. The 610-ST and the 30-A have almost identical amp circuits with the only difference being the OPT. Why would Fisher do this?
 
It also begs the question - why did Fisher make one 30-A with only a 2.5 ohm tap and another with 4,8 & 16 ohm taps?

Is it possible some companion speakers (maybe by age) are set up for 2.5 ohms and others (again by age) for 4, 8 or 16 ohms?

I agree that the logic would be my companion speakers 30-A should only have a 2.5 ohm tap to match the 610-ST - but it does not - and as TheRed1 points out is connected at 16 ohms (and sounds great by the way).
 
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