Frequency response 88 Cassette

[padgett]

Anyone know what the frequency response capability is of the head in an 88 Cassette. Been trying to figure out how to connect my cell phone and looks like the easy way is one of those casette adapters with a coupling head.

Anyone know ?

[KDirk]

I suspect it doesn't go beyond a theoretical limit of about 13-14kHz. Most casette decks were anemic in the high end anyway (mostly due to poor azimuth) and the Delco units while well built were certainly not close to hi-fi in the sense of the fabled decks Nakamichi once made. Even with the azimuth precisely dialed in on a gnat's ass, clean de-magnetized heads and a recording made on a reference deck it was difficult to reliably hit solid 20kHz at the upper end, which is typically the minium ceiling spec'd for high fidelity. And yet, most people can't really hear up there anyway. Using a frequency generator and a piezo tweeter I can't really hear, as much as "sense", a sine wave over 17-18kHz and that has been true for many years (even in my 20's). Aging robs the high end first anyway.

I looked at the Delco cassette service manual and it doesn't show any official specs. Just teardown and alignment/adjustment data plus schematics and parts lists. Keep in mind the deck contains a preamp that boosts the tape head signal level going to the CDM module. The electrolytic caps in the signal path are going to be iffy now after so many years and that will further hamper the audio quality when using a tape adpater.

The adapters aren't great to begin with so while you can get listenable output, it will be noticeably well off CD quality and maybe even FM broadcast sound (though most radio stations now have a mediocre audio chain at the studio due to lack of good engineers on staff) by comparison.

I am very critical of audio quality (one of my other hobbies) and the stock setup in the 88/89 is simply not good enough to my ear even when fully working. In it's typical age-degraded state it is terrible. YMMV.

KDirk

[padgett]

Don't forget I am 70 DB down on the high end and have worn hearing aids since 1974. Remember getting new hearing aids one time and was the first I'd heard the shells tinkling as Trinity fired the gunship gatling.

 

At the same time I can tell a big difference between my cell phone on Bluetooth and Sirus/XM - the satellite stuff sounds "flat" even with boost.

 

So suspect anything over 10K may be "in the noise" to me. We'll see.

[KDirk]

Sirius/XM suffers from the same issue all digital broadcast does to one degree or another; namely compression. HD terrestrial radio is even worse for this and if you are listening to an FM with two or more subchannels it becomes even more obnoxious. If you think MP3 at a 128kbps/44.1kHz rate sounds marginal (and it is), HD is noticeably worse than that, especially on the .2 and .3 subchannels where the total bandwidth is maybe a touch over 3kHz. A common phone line (straight landline without extensive multiplexing to create additional circuits on limited cable pairs) is 3.5kHz and of course is good enough for human voice but awful for music unless you really like the sound of a Victrola.

I don't care how good the codecs get, most of this stuff is barely useful as background noise (music on hold, restaurant/retail Muzak type applications) and not nearly good enough for serious listening (though precious few people really do that these days).

I do serious listening. Put on an album (vinyl or CD) dim the lights, tweak the EQ and balance if needed and just sit and enjoy the music. I do not treat the car as a serious listening environment though I am intolerant of poor sound there because I have come to expect a certain minimum level of fidelity just from long term exposure to the kit at home. I don't know how so many can go through life with an IPhone holding a bunch of digital music and pop it in a docking station with a couple of 3" cone drivers and consider that good sound. Of course, the emphasis is on sight, thus the (needless) rush towards 4K TV and screen sizes in the 70"+ range being the rage now. Maybe if there was good programming on offer I'd feel differently. Most often if I am within range of a TV I can hear my brain cells screaming as they self destruct.

Worse still, what passes for music now (contemporary pop) doesn't stand to benefit from really good gear at playback so the under 25 set isn't really bothered by the garbage in-garbage out effect. On the hardware side, see the popularity of Beats by Dr. Dre line of headphones and accessories for this. All image and little substance except big thumping bass. A set of Sennheiser or AKG circumnaural headphones will beat the pants off that stuff any day, but lacks the all important sex appeal of the well known stylish brand name. Same as it ever was.

I really shouldn't complain. Like the Reatta, the more people get interested in good hi-fi gear, the more expensive it gets for those of us who were doing it before the cool kids took notice. Besides, I rather enjoy my status as an perpetual outlier. If everybody is thinking alike, nobody is thinking.

KDirk

[Machiner 55]

I can hear my brain cells screaming as they self destruct.

 

I'd always wondered what that noise was I'd hear from time to time.

Thanks for clearing that up for me.

 

John F.

[drtidmore]

A nice, more up to date solution for smartphone connectivity is the iSimple ISFM2351 Bluetooth setup.   

 

http://www.amazon.com/iSimple-Hands-Free-Calling-Streaming-Smartphones/dp/B00FRU5UNA/ref=sr_1_1?s=car&ie=UTF8&qid=1443276955&sr=8-1&keywords=ISFM2351

 

I installed these on both my 2000 vette and the '89 Reatta.  It provides a complete hands free operation of the bluetooth phones as well as enabling streaming audio from internet radio apps and navigation apps.  It connects into the car audio system via the antenna lead, broadcasting on a user selectable FM channel.  Interference from existing over the air signals is nonexistent as the system actually disconnects the external antenna from the radio when in operation.  The result is a crystal clear sound with NO wires.  I found that when used with iPhones, the result is actually superior to most other systems as it provides the equivalent of "holding the home button" which alert Siri and then you can do a whole world of things on the phone via voice.

 

Installation was NOT difficult.  I did have to buy adapters for the radio antenna leads as GM used a smaller connection than the standard "motorola" connector.  I found the adapters at BestBuy, but they are also available online.  I installed the unit inside the center console to the left of the shifter, wiring it into the same power and ground connections as the radio so as to have retained accessory on the unit.  The microphone lead I ran behind the dash, over the steering column routing such that I could then run it behind the trim to the left winding up with the mic itself at the top of the trim between the door and the windshield.  I put the small push button just to the upper left of tranny selector panel (i.e. on the console trim itself running the small flat wire between the console trim and the shifter panel).  All in all, a simple afternoon install that is very professional in appearance and works perfectly

 

david t

[padgett]

Does the iSimple require an antenna adapter ? Also it appears to include a microphone but not the triple 3.5 mm connector (right, left, mike) for a cell phone - how does that work ? Finally how is it powered  (hopefully not by batteries) ?

 

Seems like most great ideas are doomed by something simple missing.

[padgett]

BTW I just got one of these. Seems to work very well at least I can't tell much difference from the factory BT in the Jeep (and much better than Sirus/XM). Have not tred the mike yet (kinda hot out there) but can see the three way mike plug in the advt.

 

Just need to hide the red wire to my Cell Phone on a CD mount using the ashtray lid slot.

[drtidmore]

Does the iSimple require an antenna adapter ? Also it appears to include a microphone but not the triple 3.5 mm connector (right, left, mike) for a cell phone - how does that work ? Finally how is it powered  (hopefully not by batteries) ?

 

Seems like most great ideas are doomed by something simple missing.

The ISFM2351 includes permanently wired pigtails for the standard "motorola" car radio antenna connector (i.e. both male and female).  The issue is that GM developed and uses a "mini" version of the antenna connector.  There are numerous sources of adapters to/from the GM standard to the more typical motorola connector.  So the short  answer regarding the antenna adapters, is YES, they are required for GM vehicles but NOT included.  You simply unplug the Reatta antenna connection from the radio, plug it into the adapter and then plug the adapter into the ISMF2315 antenna input pigtail.  You do the same for the ISFM2351 antenna output and plug the adapter into the Reatta radio.  FYI, the adapters did cost me about $35 for the pair, but I could have gotten them cheaper online had I been willing to wait for shipping.  I was already into the installation when i realized the need and BestBuy had them.

 

The setup includes a noise cancelling microphone that plugs directly into the ISFM2351, NOT into the cell phone. The unit when operating totally replaces the cell phone's mic and speakers using the included mic and the car's speakers.  You can leave your cell phone in your pocket or as I do, put it in a mount such that I can see who is calling or for visuals when using my choice of navigation apps.  It is really nice with using navigation as the audio announcements of upcoming turns/etc come thru the car speakers (i.e. the app automatically mutes any other audio source currently streaming thru the iPhone, makes the announcement, then resumes whatever streaming audio it might have interrupted). 

 

The 3.5mm connector (left,right) jack that you mention is for those cars that have aux audio inputs.  This allows a direct connection into the car's audio system vs the FM modulation route.  As our Regattas don't have an AUX capability, at least without bastardizing the tape input, I chose to go with the FM station mode of connection into the audio system which is rock solid.  As stated, it actually disconnects the car's antenna from the radio when the bluetooth connection is made.  When the unit is NOT connected to a bluetooth phone, the ISFM2351's FM modulator is disconnected from the radio's antenna input reconnecting the car's antenna making a direct connection (via an internal relay) between the car radio and the Reatta external antenna allowing normal over-the-air radio reception.  The ISFM2351 mic is STILL used even with the AUX connection.

 

The ISFM2351 does NOT connect physically to the cell phone in ANY manner, just via bluetooth.  For trips lasting several hours, I do plug my iPhone into a charger unit, but for the overwhelming majority of the time, that is NOT necessary.

 

It is a sweet setup that works as well or better than any of the factory bluetooth setups.  It is powered by the car's 12v system.  I wired mine into the retained accessory buss (actually the radio power wire since it was only inches away).  With the exception of having to buy a pair of antenna adapters (1 GM male to motorola female, 1 GM female to motorola male), EVERYTHING else was included in the kit that you need to install it into a Reatta.  

 

When I start the car, there is a brief instant where the radio goes live with over the air (I chose a freq WITH an existing, semi-desirable local station) then the ISFM2351 connects to the cell phone via bluetooth which silences the radio.  Then a simple press of the ISFM2351 button activates the internet radio app I use on my iPhone tuning me to an all 80s radio channel.  When an incoming call arrives, the cell phone handles muting the music and sending the ring and finally the call thru the setup.  When I want to call someone, I simply press and hold the ISFM3251 button for about 2 seconds and Siri comes on and I simply state either the phone # or the person I want to call and Siri and the iPhone handle the rest.  It works way better than I anticipated and again as well as ANY factory system I have experienced. 

 

I really like the fact that once installed, it is there, no messing with wires, cassette adapters and no more fumbling with the phone while driving.  I just get into the car, press one button and my iPhone is integrated into the vehicle.  

 

iSimple does make a non bluetooth kit, but cell phones have had bluetooth capability for so long, I can't imagine anyone with a cell phone make in the past 5 years or so that does not have bluetooth. 

 

David T

Edited September 27, 2015 by drtidmore (see edit history)

[drtidmore]

A correction from my previous response.

 

There is a hardwired pigtail from the ISFM2351 that provides left/right audio for input to AUX connections on the vehicle audio system (if the vehicle audio system has AUX input this can be used rather than going down the FM modulated antenna input).  This pigtail terminates in male 3.5mm connector.  The 3.5mm female jack on the ISFM2351 is for the supplied microphone.   

 

I just had a reason to be in the console of my Reatta and looked at the ISFM2351 and realized that I needed to clarify what I had stated earlier.

[padgett]

Makes sense that you have a choice of the RF tuner and direct to an aux. Have you trie both and is there a difference in sound ?

 

Now understand that the mike is for the iSimple and there is a BT connection to the phone/etc so it does not need a mike.

[Guest HuevosRanchero]

BTW I just got one of these. Seems to work very well at least I can't tell much difference from the factory BT in the Jeep (and much better than Sirus/XM). Have not tred the mike yet (kinda hot out there) but can see the three way mike plug in the advt.

 

Just need to hide the red wire to my Cell Phone on a CD mount using the ashtray lid slot.

hmmm my 'rita came with an adapter and I was very disappointed with the sound quality playing my ipod through it. Am thinking though that its more a failure of the cassette read head.

[drtidmore]

Makes sense that you have a choice of the RF tuner and direct to an aux. Have you trie both and is there a difference in sound ?

 

 

I have not tried the AUX outputs from the ISFM2351 as I found the FM modulated audio was excellent.  Compared to over-the-air FM, music from my iPhone via the ISFM2351 is noticeable superior overall.   I have never detected ANY distortion or rolloff of frequencies (outside of those expected by the Reatta audio system).  In the vette, the sound is superior to the Reatta but that audio system (bose) is simply a decade later design.  Any car is a compromised listening environment so audio performance is relative.   In my home setup, I am far more discriminating.

[padgett]

Had a few people listen to some of the songs on my phone using the cassette adapter and concensus was that it is as good as FM stereo and a lot better than Sirus/XM. For $9 from Amazon for the Cassette adapeter with mike (Handsfree mike is built into the plug that goes in the top of the phone & works well) and $18 for the CD mount (fits nicely in the slot made by a partly open ash tray. Only issue is you have to hit "play" every time the car is turned on.

 

Now I just have to figure out where to relocate the cupholder that went on the ash tray lid.