Graphic Equaliser - UK Vintage Radio Repair and Restoration Discussion Forum

toshiba tony · 6th Mar 2017, 6:03 pm

I'm struggling here. Been in the trade over 40 years but we all get stuck. Ordinarily I would run a mile away from graphic equalisers but my hearing is suffering at the top end. I got a 10 band Realistic equaliser, it looks good and certainly does as it should. I also have a Sony vfet amp. TAF7B. Lovely amp, and rare. It has the jumpers to insert said equaliser but the problem I am having is this. The volume control is before the jumpers, so when it put the eq in circuit I cannot utilise the two tape inputs it has built in. As soon as I plug a cassette deck in it blasts out, irrespective of the Sony's volume level. My amp has provision for two tape decks but they are both in use, "a reel to reel and a cassette deck" but I was also given a Marantz deck. Was it normal practise to put the volume control before the junction in the amp where the graphic goes. Or was it a case of any equalisers made in that period didn't have tape in and out on them. Think I'm goosed UNLESS some guru can put me right.
Thankyou

6th Mar 2017, 6:32 pm

It is a simple job to fit extra sockets and wire in just before the volume control. This assumes one is prepared to drill holes in the amp. and it has a proper volume control.

teetoon · 6th Mar 2017, 7:01 pm

Hi Tony. The normal way to connect a graphic to a home hi fi amp is to use the tape loop. If you look at the sockets on the back of the graphic it will have line in which comes from the tape out,or record on the amp, and line out which goes to the tape in,or play on the amp. The amp needs to have the tape monitor selected so that all other inputs are routed out to the graphic and back in to the amp.You then can connect a tape deck to the graphic so as not to lose an input and select monitor or tape on the graphic to listen to the tape deck through the amp.
Hope this makes sense. David.

sp10mk11 · 6th Mar 2017, 7:15 pm

Nice to know some one is running fantastic V-fet amp, Teetoon is absolutely correct in his advice.
Gary

toshiba tony · 7th Mar 2017, 8:43 am

Thanks all, and thanks Gary, for the comment on the amp. I was going to do the mods to protect the output fets (zenering) but it seems that this model is immune. And yes David, will do what you say, and thinking about it, connecting a deck between the audio in and out? There will be a break between the pre-amp and the power amp, hence no audio, I have dementia, or as John Cleese said, am I missing the bleedin' obvious!
Or are you saying replace the jumpers that bridges the pre and power. I suppose as a last resort I could use the inputs on my tape recorder, its a Philips N4506 with 4 inputs on it. But if David's idea works fantastic.
Thanks again.

Grubhead · 7th Mar 2017, 1:15 pm

Got a diagram to explain how to connect a graphic here.

toshiba tony · 7th Mar 2017, 1:44 pm

Thanks for that, that's exactly how I had it, till I got greedy and wanted to fit a third deck, the TAF7b Sony has provision for two decks, so far everything is OK. But I got a third deck, a rather classy Marantz. It looks as if I may have to make one playback only, but even then all my inputs are taken up, except for the two phono inputs, I will have to do some heavy attenuating and matching, although my Philips is a mixing reel to reel recorder. I wouldn't mind switching decks depending on my choice at the time but it's all built in to the wall.
What sane person wants 3 decks anyway! I hate getting rid of things though.

dseymo1 · 7th Mar 2017, 8:14 pm

Can you perhaps connect one deck indirectly, using a secondary line input (if available) and monitor output? Depends on what facilities your decks have, and how you use them.
Personally, I'd build a switch box, and have done so in the past in similar situations.

teetoon · 7th Mar 2017, 8:26 pm

Tony, from your description, the graphic has 2 tape inputs. The amp will also have 2 tape inputs, so with the graphic connected to tape 1 on the amp, you still have tape 2 on the amp which can be routed to tape 1 via the dubbing selector on the amp. That will send the signal out to the graphic and back when source is selected on the graphic. This means you can still connect 2 tape decks to the graphic so that makes 3 in all.
Hope it's not getting too complicated but I can assure you that this works.

David.

toshiba tony · 7th Mar 2017, 8:47 pm

Excellent David thanks, Iv'e drawn it out and it seems to have every facility I can ever need. Thank you, but how does it connect to the water mains!!!!!
I will let you know tomorrow, had a busy day on LCD tv's at work today. Cheers, Goodnight.
Tony

6th Mar 2017, 6:03 pm	#1
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Graphic Equaliser I'm struggling here. Been in the trade over 40 years but we all get stuck. Ordinarily I would run a mile away from graphic equalisers but my hearing is suffering at the top end. I got a 10 band Realistic equaliser, it looks good and certainly does as it should. I also have a Sony vfet amp. TAF7B. Lovely amp, and rare. It has the jumpers to insert said equaliser but the problem I am having is this. The volume control is before the jumpers, so when it put the eq in circuit I cannot utilise the two tape inputs it has built in. As soon as I plug a cassette deck in it blasts out, irrespective of the Sony's volume level. My amp has provision for two tape decks but they are both in use, "a reel to reel and a cassette deck" but I was also given a Marantz deck. Was it normal practise to put the volume control before the junction in the amp where the graphic goes. Or was it a case of any equalisers made in that period didn't have tape in and out on them. Think I'm goosed UNLESS some guru can put me right. Thankyou

6th Mar 2017, 6:32 pm	#2
Guest Guest Posts: n/a	Re: Graphic Equaliser It is a simple job to fit extra sockets and wire in just before the volume control. This assumes one is prepared to drill holes in the amp. and it has a proper volume control.

6th Mar 2017, 7:01 pm	#3
teetoon Heptode Join Date: Dec 2010 Location: Barnstaple, N.Devon, UK. Posts: 557	Re: Graphic Equaliser Hi Tony. The normal way to connect a graphic to a home hi fi amp is to use the tape loop. If you look at the sockets on the back of the graphic it will have line in which comes from the tape out,or record on the amp, and line out which goes to the tape in,or play on the amp. The amp needs to have the tape monitor selected so that all other inputs are routed out to the graphic and back in to the amp.You then can connect a tape deck to the graphic so as not to lose an input and select monitor or tape on the graphic to listen to the tape deck through the amp. Hope this makes sense. David. Last edited by teetoon; 6th Mar 2017 at 7:18 pm.

6th Mar 2017, 7:15 pm	#4
sp10mk11 Octode Join Date: Feb 2009 Location: Cornwall, UK. Posts: 1,275	Re: Graphic Equaliser Nice to know some one is running fantastic V-fet amp, Teetoon is absolutely correct in his advice. Gary

7th Mar 2017, 8:43 am	#5
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Graphic Equaliser Thanks all, and thanks Gary, for the comment on the amp. I was going to do the mods to protect the output fets (zenering) but it seems that this model is immune. And yes David, will do what you say, and thinking about it, connecting a deck between the audio in and out? There will be a break between the pre-amp and the power amp, hence no audio, I have dementia, or as John Cleese said, am I missing the bleedin' obvious! Or are you saying replace the jumpers that bridges the pre and power. I suppose as a last resort I could use the inputs on my tape recorder, its a Philips N4506 with 4 inputs on it. But if David's idea works fantastic. Thanks again. Last edited by toshiba tony; 7th Mar 2017 at 8:59 am.

7th Mar 2017, 1:15 pm	#6
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: Graphic Equaliser Got a diagram to explain how to connect a graphic here. Attached Thumbnails

7th Mar 2017, 1:44 pm	#7
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Graphic Equaliser Thanks for that, that's exactly how I had it, till I got greedy and wanted to fit a third deck, the TAF7b Sony has provision for two decks, so far everything is OK. But I got a third deck, a rather classy Marantz. It looks as if I may have to make one playback only, but even then all my inputs are taken up, except for the two phono inputs, I will have to do some heavy attenuating and matching, although my Philips is a mixing reel to reel recorder. I wouldn't mind switching decks depending on my choice at the time but it's all built in to the wall. What sane person wants 3 decks anyway! I hate getting rid of things though.

7th Mar 2017, 8:14 pm	#8
dseymo1 Retired Dormant Member Join Date: Dec 2007 Location: Shropshire, UK. Posts: 3,051	Re: Graphic Equaliser Can you perhaps connect one deck indirectly, using a secondary line input (if available) and monitor output? Depends on what facilities your decks have, and how you use them. Personally, I'd build a switch box, and have done so in the past in similar situations.

7th Mar 2017, 8:26 pm	#9
teetoon Heptode Join Date: Dec 2010 Location: Barnstaple, N.Devon, UK. Posts: 557	Re: Graphic Equaliser Tony, from your description, the graphic has 2 tape inputs. The amp will also have 2 tape inputs, so with the graphic connected to tape 1 on the amp, you still have tape 2 on the amp which can be routed to tape 1 via the dubbing selector on the amp. That will send the signal out to the graphic and back when source is selected on the graphic. This means you can still connect 2 tape decks to the graphic so that makes 3 in all. Hope it's not getting too complicated but I can assure you that this works. David.

7th Mar 2017, 8:47 pm	#10
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Graphic Equaliser Excellent David thanks, Iv'e drawn it out and it seems to have every facility I can ever need. Thank you, but how does it connect to the water mains!!!!! I will let you know tomorrow, had a busy day on LCD tv's at work today. Cheers, Goodnight. Tony