Bose 802-E Equalizer Issues

October 14, 2016

I’d had already once before gone through my wiring setup and tried to find all the sources of hiss and buzz that I could with the intention of trying to minimize things as much as I possibly could and I did find a couple ground loops and a defective wire.  The ground loops were handled and the cable was replaced.  Issues resolved and I had a near perfectly hiss-free setup.

Today I found another source of hiss, and it’s a bit difficult to deal with.  It seems that the Bose 802-E equalizer has developed a good hiss (I am not an electrical engineer, but opening it up and looking inside I see resistors and capacitors, and both, as you may know, degrade over time.  In this case there are several other components inside that can also deteriorate overtime and cause issues).    It’s too bad that this happens, as this module is critical in making the Bose sound as good as they do.

First, I needed to find a way to test it out to be sure that it was the Bose EQ and so what I did first was of course listen to it as it is set up now.  Yup… it was hissing, this was pretty obvious to me.

Then I bypassed the Bose EQ and ran the wiring straight from the mixer to the amp.  The first thing that I noticed was how BAD the speakers sounded… totally flat and lifeless!  But there was no hiss, but was that because of the EQ raising things so much and showing the hiss or was it the box?  Well, first I needed to find out exactly what that Bose EQ did.

A quick search on the internet explained a few things nicely.  I discovered that the Bose EQ plays with the tonal curve **way** up the “wazoo”!  Here is the basic EQ curve:

20 Hz = -5 dB
30 Hz = -1 dB
40 Hz = +3 dB
60 Hz = +14 dB
100 Hz = +5 dB
200 Hz = +1 dB
600 Hz = 0 dB
800 Hz = 0 dB
1 kHz = + 1dB
2 kHz = + 4 dB
3 kHz = + 5 dB
4 kHz = + 8 dB
6 kHz = + 11 dB
10 kHz = + 15dB
15 kHz = + 17 dB

 

This was confirmed by a Bose 802 owner using advanced hardware and software:

802_controller

 

Another example of the Bose 802 tone curve  from another source. A company called Crown made a module that had to mimic the factory original curve, plus they made minor tweaks (confirmation that this kind of curve is actually what is used by Bose and what is needed to make the speaker sound as good as it does!)

bose-802-curve

 

Isn’t that crazy??  At the very least, it explains why these Bose 802 speakers are not known for being very loud and why there is less headroom than other speaker systems.  It also explains how 8 tiny speakers can sound soooooooo good!

I needed to find a way to get close to equalizing to these levels without the Bose EQ module and listening for the hiss.  The quick answer came with a cheap old equalizer that I have owned for 35 years (or more!).

rack-3

I tested it out and some of the switches were not working properly… it needed a little TLC, so opening it up and spraying switches and sliders with contact cleaner and moving the sliders around for a bit, then doing a quick test, wiped it down and it was back to looking and working as good as new!

Unfortunately it only goes to + and – 12db, a far cry from the +18db that the Bose 802-E equalizer does and that’s needed for the 802 speakers to achieve their signature sound, so I found a small fairly good functioning work-around.  My trick was to lower the starting point (-8db on the EQ), treating it as the zero starting point with all settings and to compensate, raise the gain to maximum.  This brought all levels a bit closer to what the Bose EQ did… but without any hiss!

Now, my solution isn’t 100% effective but I noticed that it was ever so slightly not quite as good sounding and punchy as with the Bose EQ and for sure the volume dropped a little, proof that the EQ also raises gain overall (which really means little, as I never have the amp past the #3 position anyway), but it was dead quiet and that was the important part in that first test.

For now, I’m deciding to keep it.  To accommodate it, things had to be moved around on my music rack a touch, to make access a bit better.  Here is how it looked before:

20160512_204642

Here is how it looks now:

rack-1

rack-6

With the MPTube Studio preamp in place.  This is what it looks like in it’s most recent iteration:

tubemp-7

I’m satisfied with how it works, looks and is accessed now.

I would love to get the EQ fixed, but local queries tell me that it is a $550+tax job to address.  As a free solution using my EQ, this works 90% as well.

This is part of the fun I am having with my system.  More to come soon!

Addendum October 25, 2016:

I found out that there are places that can fix the Bose 802-E equalizer without me needing to sell the car, house and have me vend my services as a gigolo on the street for 10 years to be able to afford a repaired EQ solution!

1 – This guy from a US located Ebay Account (or here is his WEBSITE), includes free return shipping in the USA, seems very comprehensive.  We’ve exchanged a couple of emails, and I like the way this guy works (via his reviews from others), and communicates.  He is in the $150US range, but he does so much more than just do a minor overall repair, he future-proofs it!

So what does he do?
– Base Recap and Maintenance Service ($82.95)
– Elna Silmic II Audiophile Grade Capacitors (+$10.00)
– Replace four Dual Operating Amps (+$24.00)
– Voltage regulator pairs (+$7.50 per pair)
– Transformer (+$30.00)
Grand Total: $154.45US plus whatever shipping from me to him costs.

2 – This place on the web that do a more basic repair, but cost more ($159.95US), it also includes free shipping to the USA too, but they are a but less comprehensive.

I didn’t expect it to be cheap, but it is less than if I wanted to replace the entire speaker setup.  If I could keep it all under $250, I would be pleased, and that’s what it looks like I will more than likely do in the future… we shall see!

My advice?  If you plan on keeping your 802’s for a while, yes, definitely, get it done!



5:32 PM 4/10/2016