help me getting the most out of my dad's hi-fi
May 24, 2009 at 9:06 PM Thread Starter Post #1 of 31


100+ Head-Fier
May 1, 2008
back home, my long late father left me with his hi-fi setup. ever since i was little i have taken it for granted, but recently i realized how blessed i am.

*note that right now i dont have access as i am studying overseas but will return in a month

the setup is audio research D-110 and D-111 as power amp, and then audio research SP-6 as the preamp, and what i think are custom, huge floorstanding speakers.

somewhere between those are an equalizers and a crossover with cables going from here to there that i have yet to fully understood which goes to where.

the thing is, speaker setup relies on placement, right? that's the problem- this setup is confined in a way that each speakers are about 2.5 meters apart, BUT the furthest i can sit down to enjoy them are 1.5 meters from the point between the two. i dont think i would be able to move them for the time being. what ive done so far is angling the speakers- will that help? i have no access to them at the moment, but they are almost 2m tall and 1m wide with no identifiable logo or branding. how does one calculate the ideal distance and such?

how is the stuff there supposed to be arranged in sequence? i really have no idea other than preamp coming first and power amps last. why must there be two power amps incorporated? one for each speaker? if so, given the different model of amp being used, wouldnt that result in different coloration?

the speaker cabinet's inside foam had hardened. i dont know the exact terms- its when the foams had gone from being bouncy to not returning to the original state if poked. so you can poke finger holes at those. how does this affect the sound? is it crucial to replace the foam?

the preamp's gain is very high- going from my dad's nakamichi cd player, 8 o clock is too little a volume, while 9 o clock is already too high. i used my sony NW-HD5 lineout going to the preamp and its much more tolerable, 11 o clock is still okay. so is there a way to solve this? else ill stick with my digital source which i know wont be doing the system justice.

thanks, sorry for the jumpy writing, i am a total noob to speaker setups. hope you can all provide me with nice info for what i have in hand.
May 24, 2009 at 9:36 PM Post #2 of 31
That is a very impressive setup.
It is bi-amped. One power amp is for the low end, the other power amp for the midrange and upper register.
If I am correct there are two pairs of connectors on each speaker.
The crossover is to regulate the balance (low-end vs midrange/high end) between the two.
Positioning is difficult with these big speakers. They need some distance from sides and rear wall too (approx 3 feet usually).
Your distance from the speakers would be approximately 1.5 times as far from the (center between the) speakers as they are apart.
So if they are 2m apart you should be approximately 3m from the line between them.
May 24, 2009 at 10:17 PM Post #3 of 31
Thqt sounds like a great setup! Can you give us some more information about the speakers? Pull the drivers out (it's OK to unscrew them) and find the make and model of them. Someone may recognize them as a DIY model or might have more information. Placement is room dependent - the best you could probably do is play with placement and the angle until they sound good.
May 25, 2009 at 6:50 AM Post #6 of 31
thanks for the enthusiasm guys

unfortunately i will be able to be in touch with the system within 3 weeks or so from now. I just asked my uncle about the system and he said that the speakers are infinity bookshelf speakers, but i dont seem to be able to get any info nor pics of that particular model. is infinity any good? there are so many brands in the speaker world.

i enjoyed this system a lot, it is flat-sounding (compared to my headphones of course) but considering how debatable neutrality is i dont dare to say that it has perfectly flat frequency response or such. yes, the only thing is just that the placement sucks. as i stated above, will angling the speakers help? and is room dampening an important factor?
May 25, 2009 at 5:02 PM Post #7 of 31
Yes, dampening will help the room but if you are bowled over with primary wave energy, it probably won't be so noticeable. Toeing in the speakers will help imaging. My memory of Infinity was that they were a very detailed speaker. This was back in the 70-80s. Now a 6 ft. x 3 ft. speaker is not a bookshelf in my thinking. It could be made into a bookshelf but can't set on one. I'd say its a floorstander.

If the foam has dry rotted you do want to replace it. The pliability of the foam is what dampens the resonant frequencies of the cabinet. How is the woofer foam/rubber? You can rebuild them or get a speaker better sized for your room and store them until you do have the room. You have to get the info. from the speaker for Infinity (or supplier) to help you with driver replacement. What kind of tweeters do these have and the number and size of drivers?
May 26, 2009 at 6:09 AM Post #8 of 31
If you can post pics of the Infinity speakers someone (possibly me) can tell you which model they are. Include a pic of the crossover unit also, if you can. That will help with the ID.

Woofer surrounds should be replaced before you use the speakers any further. Rotted surrounds that now have holes in them can cause the cone to sag, which leads to the voice coil rubbing in the gap which can destroy the drivers.
Jun 14, 2009 at 5:30 PM Post #10 of 31
Ok guys, finally, here I am back home. I dug out all my dad's audio stuff and here's what I've got:

Here is the right speaker:

then its insides:

...well so you can tell that so far I havent found any indication about the model. I asked my uncle again and he said that during that time this is the second highest of Infinity speakers, just below their flagship.

Then here are the setup:




I have no idea what the black thingy does, I only know that it is some sort of a crossover. Sorry for not doing my homework.

I also found this thing but I've never seen it being used in the setup:

It says its a preamp, but what's with the EQ thingy. Analog EQ?

Then this is the original source component of the setup:

but as I have stated here and in another thread, the gain from the CDP is very strong that only three notches of the gain knob gave too loud a volume already (one of the reasons that I resorted to my DAP)


See how crowded the room is. That bookshelf is blocking the bass. A lot of work required to move it out of the way, for now
The speakers are about 2m apart, and I think my listening position in relation with the two speakers forms a triangle, 2m on all sides. Nothing I can do regarding these due to the crowded and hectic placement.
If I wanted to get serious on this, I really need a dedicated room with dampening and positioning, correct?

On to the second part. This is another rig that my dad owned, connected to BOSE 901s which I am not using anymore.


For now I used the preamp for a temporary headphone amp. It sound real good of course and an overkill.

And this is the power amp which is not being used at the moment:

Now, the fun thing is that this thing is hooked to the first rig originally but I moved it to feed the second rig (the headphone rig).



The phono cartridge is not installed, though. I moved it to the simpler rig because I am curious to start doing vinyl- and with simpler setup I will be able to play around first as compared to the speaker rig which needs warming up and such.

I am really anxious on starting vinyl, at least for this holiday at home. Anybody willing to educate me on how to start? My dad left some Yes and George Benson vinyls. Do I need to do anything regarding their age or just pop them into the turntable?

I am searching my house for the cartridges now, but I havent seen an actual one so I need to look real hard. Those cartridges are small aren't they. Are there any differences between different brands in terms of the cartridge installment?

Thanks guys for your time.
Jun 14, 2009 at 6:05 PM Post #11 of 31
The speakers are Infinity RS 4.5, based on the second picture. They were manufactured between 1979 - 1984 and were $4,200 a pair at retail. The black box, as you say, is the crossover that splits the signal and feeds it to the amp running the bass, and the other running the mid range and treble. IIRC, those crossovers required a top end/bottom end bi-amp configuration, which can allow for completely different amps being used, then the output corrected using the crossover controls.

The SAE is an equalizer, popular in those days, but with the crossover you shouldn't need it in the chain.

Preamp is an Audio Research SP-6, a tube unit, though I am not sure which version it is (A, B, C, or C-1).

The amps appear to be Audio Research D-79 (tube, 1979-1980, $3,700) and D-100B (solid state, 1979-1980, $3250). I'd hope the tube amp is driving the midrange/tweeter panels. BTW, I wouldn't run that tube amp (or the other power amp) with anything on top of them - they put out a lot of heat, which needs ventilation. Plus that heat will be transferred to the component above, and that can shorten component life.

The Adcoms are a tuner/preamp (I think, can't read the model), and a beefy GFA-555 (II?) power amp, a true audio beast. It looks like there were might have been two systems at one time, since you have an extra set of preamp/amp, more than the older system requires.

The table is a Technics SP-10mkII, which was made in the late 1970s - mid 1980s, and retailed for about $1200. If you are interested in vinyl, it is a very fine table. Get it checked out, belts changed (or is it DD?), and cartridge replaced and have fun.

If the foam on the Infinity bass drivers is hardened, as you say in your top post, I strongly urge you to stop running the speakers any further until you get the surrounds replaced. You can, and eventually will, destroy the drivers. Check around for a local audio repair shop, and see if they do that sort of work. If not, there are reputable shops around the country you can send them to. Just the drivers - you can remove those yourselves, pack them safely, and ship them.

Here is the manual for the RS 4.5, which may help you in terms of getting them set up properly. It does not seem to have much about the external crossover, so if you can find a model on it, I can find you the manual. It has been some years since I did any Infinity rebuilds, but I seem to recall the outboard crossovers came with their own printed manual.

This entire system would cost a lot of money to replicate today. It is worth putting some maintenance money into the speakers and turntable, after which you should get many years of good use from them.

EDIT: I emailed Infinity tech support to ask them which crossover came with those speakers, so we can get you a manual to down load.

EDIT2: Just looked and saw you are in Singapore. Apologies for assuming you were in the US. Still, if you have audio repair shops there you should be able to get the drivers repaired.
Jun 15, 2009 at 5:34 AM Post #12 of 31
Thanks for the very helpful reply. I studied in Singapore but am going back home to Indonesia for holiday. But there should be quite a number of audio repair shops around.

Regarding the foam, I dont know which one you mean whether it's the top cabinet or the bottom one. Here are the pics:

Top cabinet- you can seethe hardening foam I mentioned earlier. But those drivers dont look like dynamics.

Then here are the woofers- are they the ones that you are referring to? Which part of them are the foams?

Thanks for the suggestions, will start digging for the cartridge for the time being.
Jun 15, 2009 at 5:50 AM Post #13 of 31
The foam I was referring to is the gray surround roll around the edge of the blue/green/gray (not sure of the color from the pics) cones, that holds the edge of the cone to the frame. This eventually rots and comes apart, which does two things: 1) breaks the air seal the woofer and cabinet form together (which alters bass response and efficiency); 2) eventually allows the woofer to travel off center, which will damage the internal components of the woofer, i.e., the voice coil.

The foam surrounds (unless they are rubber? - doesn't look that way, but some of the big RS model woofers used rubber surrounds) should be very flexible and springy to the touch. You can check the integrity of them by pressing anywhere on the roll with your finger. They may appear intact to the eye, and if they are they will spring right back under your touch. If they are shot, the foam will crumble when pressed, even lightly.

Getting the surrounds replaced rejuvenates the woofers for another 10 - 20 years, and is far less expensive than a full woofer replacement, assuming the entire driver is even still available.

On the top cabinet it appears there may have been some sort of acoustic dampening foam beneath the grill cover? That might be replaceable by something more generic. have you tested all the drivers to make sure they are all outputting sound? I believe there is also a single EMIT tweeter on the rear of each upper cabinet.

I honestly cannot give you much advice about cartridges - I've been out of vinyl for quite a long time. Last carts I did use were Grados, which I liked a lot. Even the entry level ones perform well and were, at the time, not terribly pricey.

I've been in touch with Infinity about getting the right manual for the electronic crossover/eq unit. So far, not much luck, but we'll see.
Jul 2, 2009 at 5:09 PM Post #14 of 31
i've got a problem. the right unit's bass drivers arent working all of a sudden, while i was in the middle of a song. what can possibly be the cause?
Jul 2, 2009 at 5:13 PM Post #15 of 31

Originally Posted by aragornmustdie /img/forum/go_quote.gif
i've got a problem. the right unit's bass drivers arent working all of a sudden, while i was in the middle of a song. what can possibly be the cause?

Did you check the cable connections?

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