preamp/equalizer for old powerfull speakers?

[SpeedDMN]

I am getting bleary eyed from trying to find a good preamp for my girlfriend's father. Though he doesn't probably want to play stereo wars with me at 71, he needs a little more power for his existing speakers for the new receiver he just bought. Sorry I don't recall the name, but nothing to write home about. The speakers however are a little special. Sorry I can't remember the name right now of them either. I will get it later. Suffice it to say they have at least 12" sub woofers and pretty big mid range and tweeters too. All I want is a reasonable preamp/equalizer (used/ebay/whatever) that will do the speakers justice even at low volume (again no stereo wars here. Besides I would win ) Any suggestions would be great. I have been digital for so long I don't even know what exactly I'm looking for anymore. TIA guys

[ctal]

I'm confused by several things in your question. "Big, old speakers" are normally very efficient and don't need a lot of power. And power comes from a power amplifier, or the power amplifier section of a receiver. So why are you asking about a preamp to provide "a little more power"? Also, a "receiver" includes a preamp, although these days it may lack a phono stage if that is what you are looking for.

I don't understand the statement about doing justice at low volumes, either -- are you referring to a "loudness control" type of function, that boosts the bass and treble at low volumes, to compensate for the ear's high and low frequency roll-off that occurs at low volumes? The receiver may have that function, and if not all you need is an equalizer, not a preamp/equalizer.

I'll say also that I for one am not a believer in equalizers. Good speakers properly placed in the room don't need them, and they will usually do more sonic harm than good.

Finally, besides the make and model of the receiver and the speakers, it would be helpful to know what kinds of music he usually listens to, and what kinds of program sources (cd's, records, cassettes, dvd/home theater, etc.).

Regards,
-- Al

Edit: I'm wondering if by "power" you really mean "bass punch," and not watts. If so, again all you need is an equalizer, not a preamp/equalizer, assuming the receiver's tone controls and/or "loudness control" is/are not adequate. And, again, I'm a non-believer when it comes to equalizers.

[SpeedDMN]

The speakers were made by "Soundfield" which I don't think even exists any more. The Wattage is rated at 250W per speaker continual Ahemm Cough... Needs a preamp. period. Anyone else have a suggestion? Sound quality is not in direct correlation with volume though a preamp should boost that as well if desired. It's not just "loudness", but an entire equalizer I am looking for. I need some old audiophiles on this one since I have fallen into the digital pit myself. My stereo runs off an X-fi soundblaster at 400W. Never had it to the top.

edit: I don't remember the name of the POS amp they are hooked to now but there are no preamp jacks on it so in the bin it goes. These speakers are awesome and I will build the stereo around them, not the other way around

[Briton]

250w continuous at what ohm? A receiver that handles 150w @ 8ohms/channel generally would work fine for a 250 at 6 or 4 ohms.

[ctal]

I think I see what was confusing me. You had mentioned that he had bought a new "Receiver." To an audiophile, a stereo receiver means something that combines a tuner, a preamp, and a power amp on the same chassis. But I suspect you were using "receiver" to indicate just a "tuner," with no preamp or power amp function. And you are getting rid of the existing power amp. So you want a preamp, a power amp, and an equalizer, with the preamp and equalizer possibly combined in one unit. Correct?

As for the speakers, perhaps you are referring to the dbx company's Soundfield speakers, from the 1980's. Here is a link to a review. It looks like they came with some sort of electronic equalizer, although that was probably just intended to shape the response of the speakers themselves, and not to provide the flexibility of a conventional separate equalizer (which could be used in addition to the one for the speakers).

dbx Soundfield 1A speakers: 8 woofers, electronic EQ and the best way of clearing out the house

Regards,
-- Al

[ctal]

I have no recommendations concerning the preamp/equalizer, but for the power amp I would suggest going to eBay and buying a 1980's Carver "magnetic field amplifier." They shouldn't cost more than a few hundred dollars, at most, and are extremely powerful. Some of the model numbers are the M400t, M-1.0t, M-1.5t, etc. Only get one that has the "t" suffix, which indicates that the design was "transfer function modified" to supposedly match the sound of a super-multi-kilobuck Mark Levinson ML2. Bob Carver actually demonstrated that by feeding the same music into both amplifiers simultaneously, electronically subtracting the output signals from one amplifier from the output signals of the other, and getting something like a 40 or 50 db null, which is pretty incredible.

I've used an M400t (200 watts/channel; some of the other models are 350W or thereabouts) for many years in an otherwise expensive high-end system and I've been very pleased with its sound. And on a watts per dollar basis, that series was the best there was (and possibly still is) among amps that provided quality sound.

Regards,
-- Al

[ctal]

Re the preamp and equalizer, I'd suggest getting them as separate components. A combo preamp/equalizer is likely to be junk.

Among modestly priced preamps that are widely available on eBay, NAD and Adcom are two names that come to mind that are known for providing good quality and value. You should be able to do well with those names for perhaps $100 to $500. What price range were you considering?

Below is a link to eBay's equalizer category. A good quality parametric equalizer provides more flexibility than a good quality graphic equalizer, but as I indicated above my feeling is that any equalizer that costs a sensible amount is likely to do more harm than good.

eBay Equalizers

Hope that helps,
-- Al

[ctal]

Here is the only high quality preamp/equalizer that I know of, the Cello Palette. Recently offered on eBay, used, for only $14,750.

Cello Audio Palette Preamplifier MIV and Master Supply - eBay (item 150262519532 end time Jul-01-08 20:48:48 PDT)

-- Al

[ctal]

Originally Posted by SpeedDMN

Ahemm Cough... Needs a preamp. period.

A further thought. I want to make sure it is clear to you that a preamp will have no effect whatsoever on the maximum amount of power that the system can deliver to the speakers (which corresponds to the maximum volume the speakers will be able to generate).

Different preamps (or the preamp sections of receivers) may provide somewhat differing amounts of gain (signal amplification), but the only significance of that is that you will wind up setting the volume control to a different point to get the same loudness. It will have no effect whatsoever, though, on the volume level at which the sound starts breaking up and distorting due to the system not having enough power (referred to as "clipping"), which is solely a function of how much power the power amplifier (or the power amp section of a receiver) can deliver into the particular speaker's impedance (the "ohms" rating, as Briton correctly pointed out).

In other words, with one preamp or receiver the loudness may max out at the 2 o'clock position of the volume control; with another it may max out at the 4 o'clock position (for the same source material). But in both cases the maximum loudness that you hear will be exactly the same. Connecting a preamp to the "preamp in" jacks that some receivers have will not change that.

Regards,
-- Al

[SpeedDMN]

Originally Posted by ctal

A further thought. I want to make sure it is clear to you that a preamp will have no effect whatsoever on the maximum amount of power that the system can deliver to the speakers (which corresponds to the maximum volume the speakers will be able to generate).

Different preamps (or the preamp sections of receivers) may provide somewhat differing amounts of gain (signal amplification), but the only significance of that is that you will wind up setting the volume control to a different point to get the same loudness. It will have no effect whatsoever, though, on the volume level at which the sound starts breaking up and distorting due to the system not having enough power (referred to as "clipping"), which is solely a function of how much power the power amplifier (or the power amp section of a receiver) can deliver into the particular speaker's impedance (the "ohms" rating, as Briton correctly pointed out).

In other words, with one preamp or receiver the loudness may max out at the 2 o'clock position of the volume control; with another it may max out at the 4 o'clock position (for the same source material). But in both cases the maximum loudness that you hear will be exactly the same. Connecting a preamp to the "preamp in" jacks that some receivers have will not change that.

Regards,
-- Al

I used to have an old Kenwood receiver with 120W studio monitors (I know nothing about ohm ratings) I had a cheap Realistic preamp/equalizer and it made ALL the difference. It sounded 20x better with it then without it. I guess I am trying to make a repeat of that setup without really knowing what I'm doing. I still think the speakers are under powered, ranged, something. I don't know ratings other then wattage I listed earlier, but I think it is safe to say they are all extremely high. These speakers look like Marshal stacks! I appreciate all the advice so far, but still pretty lost I can't go bother him right now though later I will get the exact make and model of the speakers/monitors and maybe someone will be familiar enough with the particular type. I realize it's kinda a difficult question as to what to get. TIA.

[ctal]

Not sure how to explain your experience with the Kenwood and the preamp/eq. Maybe the preamp section of the Kenwood was poor quality, or defective.

In any event, you had said you wanted to get rid of the existing amp anyway. So what I would suggest is getting a separate power amp (not a receiver), a separate preamp, and a separate equalizer. Separates will cost a bit more than combo units, but will almost invariably provide much better quality and performance. There is no technical reason why that has to be so, it's just that the designs of separates and combo units target different kinds of buyers and different selling prices.

I think you'll be very satisfied with the Carver, Adcom, or NAD equipment that I suggested, which you can get very reasonably on eBay. Just be careful, of course, with who you are buying from and with respect to the condition of the equipment. And if you want suggestions in a higher price range, just let me know.

Don't worry about the ohms factor. Although a lower impedance means the amp will be able to deliver more power, power is not all that critical once you get beyond a certain point. The ear hears loudness logarithmically, not linearly. One-tenth the power (in watts) will produce a sound that subjectively seems one-half as loud (and I mean that literally and exactly). Conversely, ten times the power will produce a sound that subjectively seems only twice as loud. Assuming the room and the distance he will be listening from are of average size, I would think any amp from 100 watts to 400 watts would be fine, given that the speakers can handle 250 watts continuously, and are probably very efficient (meaning lots of sound per watt).

Good luck with it! Starting with excellent speakers, and building around them, is THE way to go with stereo equipment.

Regards,
-- Al

[TQ]

Originally Posted by ctal

I think you'll be very satisfied with the Carver, Adcom, or NAD equipment that I suggested...

Very good names in the audio industry. Especially Adcom and NAD, who have for years offered wonderful sounding equipment at a reasonable price point.

[ctal]

There's an Adcom GFP-565 preamp that ends tonight on eBay, that looks to be in good shape and from a seller with excellent feedback. "Stereophile" had a very lengthy review of this model in Feb. 1990 that concluded with: "The GFP-565 now sets the standard for preamps under $1000, and should remain a worthy contender for years to come." It cost $798 in 1990. Search "gfp-565" on eBay and you'll find it easily.

Regards,
-- Al

Edit: Well, it ended, at only $207.60. Someone really got an exceptional value.