# What makes a good tweeter amp?



## Vancomycin (Mar 21, 2011)

What charactersitics/properties/specs?

And which would you recommend for about 60-100 W RMS?

Thanks.


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## sqshoestring (Jun 19, 2007)

IMO a high quality amp with better specs, though what you see on paper is not always what you hear. That said I don't think you need a really expensive amp and smaller amps are cheaper anyway. For many systems 50rms/ch is plenty, more if you want to play it really loud or have really inefficient drivers. Always run a cap on tweeters is what I recommend. In the old days we ran SS D60 on tweeters (often 1" domes) all the time even in large systems with LP 5002 on 15s. It was iirc 2x30rms @12v but the old SS was one of the best comparable to a Nakamichi back then. IMO the smaller LP was not as good like a 1002 or 952, but some appear to have good luck with them today. I think its much easier to find an amp with enough quality today of course, they nearly have to try to use junky enough parts to make an amp sound bad. One problem is a lot of pots are not balanced well so the two channels are different gains, so separate gains would be nice but not often found. You can simply measure AC voltage on a sine to see how far it is off. You want an amp that plays clean, with high tolerance to electrical noise, and one that clips with lower harmonics. I find out little researching that because nobody tests amps into clipping, but the old TO3 amps did that and is what many like about them. They clip in the bass first while a cheap amp will turn to static in clipping, though some could be because old non mosfet amps have weaker power supplies. A lot of those type of amps would go much louder playing treble than bass, while many new amps don't have near the difference there. As always that leaves you with testing them in person, but amp quality is far higher today most well known brands would work well and with more power you stay away from clipping. I still like to clip just not in the higher ranges, it keeps me away from high dBs lol. If your tweeters start to sound harsh only at high volume and you start to EQ it up there because of that, its clipping. Some amps clip that gradual and I don't like it, while others I do like tend to nearly start to cut out at high volume more of a stutter. I don't know how else to describe it, while I work on amps I am not an electronics guru enough to know exactly what the differences are. An amp is the sum of its parts more than anything, and while many designs are off the shelf and common, without being a designer/R&D on amps it appears to be very difficult to identify what makes the differences in that area. One of the cheaper amps I like on highs are the old alpine 35xx and most mrv that came after them. Why, not sure, and some people say their SQ is good but not great. There are a lot of amps I've not run out there that I am sure work well too. This dragster I have is not that old, it works better than I expected. The old Nak, HK, SS are good amps for that but getting up there in age you have to test them to make sure the caps are still good. Other people on here can suggest newer amps that are good such as Tru/etc. though they are significant coin I don't know your budget. I'd not recommend a kicker assuming they are all similar topology, though a good amp for normal use. Kenwood are cheap and actually quite clean, but reliability can be similar to price if you abuse them. I'm sure if you do some reading in the SQ section you can find a lot of info, I stopped running active tweeters mostly because I can get them to work passive one way or another, so I concentrate on bass issues where I seem to have more problems getting the response I want.


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## Vancomycin (Mar 21, 2011)

Thanks sqshoestring for taking the time to post a meaningful answer.

I am powering 8 ohm Morel MDT-22 with channel B of my Audison SR4 (channel A is powering two Infinity Kappas in the door). I re-wired the Morels and they sound fine now (I had a previous unanswered question about whether it was okay to run a pair of 8 ohms and 4 ohms off the same amp.)

So....an old school Alpine 35XX ehh? .....hmmm....look what I scored 2 months ago (part of a $40 package deal, including a nice Sony XM-100HX I bought for a friend's wife's car)....Alpine 3513 (which I previously, not knowing, thought was der shietzen)....











http://imageshack.us/photo/my-images/840/img9667n.jpg/


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## sqshoestring (Jun 19, 2007)

Lol! Look I'm on the internet!! Lol.

I'm not saying they are fantastic, sometimes I used something else depending on the setup but I've used those a lot of times. I have a 3518 I've run many years on highs its only 2x40 but only alpine din it has no gain and you need a RCA adapter and can't even bridge it. I bought a second one for $5 once with some other amps, they run hot too I use a fan on them. Most of those alpines are similar topology inside. If you have it, I would try it that costs nothing. The biggest problem with the old alpines is most of them don't have any power, most are small amps (2x50 or less) so they only fit uses with lower power (on the other hand they don't blow stuff up lol). I have a couple 3555 4x50 to try but hard to find the larger ones. IIRC they were very expensive back then alpine was good stuff in the 80s and into the 90s. As they got newer they added more features, in the mid 90s everything from everybody went cheaper for the most part.

Sure 8+8 ohms is 4, that 4+ (your other) 4 = 2 total, all in parallel. Unless the one is tweeter and other mid, then they run at different frequency if they don't really overlap they don't add the ohms up. Pair of 8 ohm tweets at 4 and a 4 ohm mid would be mostly 4 ohm load on an amp at any frequency unless you overlap the xover a lot.

A lot of people used to run 3522S its 2x35 or 1x90, sometimes they go for cheap one of the newest old 35xx series they have some xovers and stuff on them. People used to get 4 of them and run one bridged on each channel it sounded that good, there are tons of them out there. Lots of people dog alpine now but back then they were impressive. But I have always used whatever amp worked best, only saying many times it was an older alpine but not always. I don't really care what the name on top is and think I have run matching amps 1% of the time. Actually I have a 3522 here someplace, a 3527 (a 4ch version pretty much), and others. Have a newer mrv-t757 and 407. The 7 series were mosfet amps, mosfet outputs like a mtx or old autotek. The new cheap line of alpines the last few years are actually similar to the old ones, went back to normal transistors. Have a mrv 1002 and it has only mosfet powers supply. The mosfets can sound a little harder IMO, but it really depends on how the designer wants it to work. I do think the alpines tended to have a slight EQ built in, but nothing like old RF amps did.


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## Vancomycin (Mar 21, 2011)

Thanks SQ!
I ran better 16 gauge wire to the Morels (passively crossed at 1800Hz, their Fs is 650Hz) and they sound very much better with no clipping etc. I haven't had much time to listen to them yet, but I was very impressed with the half hour of Focal test CD listening last night at 9/10 volume (even my son joined me in the garage).

Unless you strongly recommend, I will leave the set-up as is, without trying the tweeter amp for now. I have three amps in the trunk of my S2000 (one to sub, one to rear JBLs behind seats). And Audison SR4 to dash tweeters and door mids.

Sound is incredible (to my ears).

Can get an Audison SR1D (900W RMS) for $200 locally. I own three Audisons and like them, but not sure if it's a good choice for sub (IDQ10v.3, 350W RMS)powering (some say its soft). But I'm tempted to buy it anyway....

Regards to Jennifer Granholm.


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## sqshoestring (Jun 19, 2007)

I recommend you use what sounds good, you might put that in and not like it hard to say its pretty subjective. If you are happy go drive someplace (if you can afford it lol) and listen. I am going to swap to 350rms on my subs I think 500 is plenty and would rather a smaller amp in the rack *if* it will work. Pair of 15s IB.

Oh not Jenny, she didn't leave us in too good of shape. I heard she was going back to Berkeley in Cali to_ teach_.....good place for her IMO this place is an economic dumpster, of course CA is broke too. Best of luck to her hope she finds success in some other place. Not that I have faith in some other politician, just that this place is a mess after 8 years of her, none of them did much IMO. This is/was a manufacturing state and nobody liked manufacturing, you can't do that...you can't crap on your #1 thing you have going and look for something to replace it. NAFTA was the worst, maybe good idea but certainly an incorrect implementation. It is amazing how near nobody in this country cares about jobs and wealth right now, I guess everyone wants to be more poor-er. (or is that just the politicians?) You don't get all the good stuff if you are poor, and poor people don't pay big revenue to the government so it can afford it.


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## Vancomycin (Mar 21, 2011)

Thanks again.
Here's the specs on my DIN sized dynamo....

Alpine 3513 50 watt power amp 
2 channels; bridgeable. 25 watts x 2 cont. avg into 4 ohms with .08% 
THD, 35 watts x 2 avg into 2 ohms or 70 x 1 cont. avg into 4 ohms with 
0.8% THD Features Duo-Beta Feedback circuitry; no currect limiting; 
discrete output circuitry; 12db/octave input line filtering. RCA 
connectors; *continuously variable input sens. (100mv to 2v) S/N *105dBA; 
slew rate 5. 
7 7/8 X 1 5/8 X 5 1/8 inches. 
List price... $160 and it is in the '92 lineup. 


My HU is triple 6V pre-outs, so if I wanted to play with it, is the low input sensitivity range problematic?


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## sqshoestring (Jun 19, 2007)

If you max the HU out it could overdrive it. You can put a resistor inline iirc I'd have to look it up, to slow it down if it was a problem.


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## wheelieking71 (Dec 20, 2006)

MDT22's are a really nice often overlooked tweet for auto-sound. i have a pair that has to be going on 18yrs old. every time i dig them out, i cant figure out why i dont just permanently install them LOL.


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