Blend Resistors?

[sootywooty]

Hi All! My 9001 sounds great! at lest as good as my modern 7.1 system, which is amazing really for something made all those years ago, and my modern amp is considered a very good amp.

I have been reading about even more seperation by removing the blend resistors, has anybody done this by themselves, i know ss9001 said he has somebody in the usa to do this, but the postage back forth would be high with the price of the mod as well, plus i am not all that good at waiting.

Thanks for Any Help!!

 

[w.a.reid]

my blend resistors are gone - quadbob did that as part of the rebuild - if you got good sound out of your machine....leave it alone. there will be a time when it needs something - THEN have a go at the resistors.

as a note - i wish there was a way to turn the resistors off and on. when i had my speakers - pioneer cs99a x 4 - spread way apart i noticed that when i listen to the BBC news or NPR or other talk radio i did not like how the word - as an example - "Frederic" would get decoded and the "ic" part of the word would appear in one speaker and other part of the word in other speaker - sure in music thats what you want - but try a movie or any kind of dialogue and it got weird. so now i use front and rear left speakers are stacked on each other and right front and rear are stacked on each other in "a" speaker setting - and i do the same with 4 of the same speakers on the opposite wall - when i play both a and b speaker sets - whew ! that sounds great. i sit in the middle of all that on a chair that spins and i just soak it in - -- -and right when things usually get great - - kids come in - wife bitches - phone rings - - neighbors knock. ho hum.

w.a.reid

 

[sootywooty]

Thanks Again w.a. reid!! you sure know your stuff, i need some more cables yet and another member i will be buying an 8 track quad player from. My other rg-700 is coming by boat from australia, it takes awhile so as he has told me, i wish i knew he was sending it this way i would of paid the extra for the plane.

The 700 has a control to really spread the sound out, so i cant wait to rig that up with it, i use the other one on my acram av and it really sounds great.

All the best, Paul.

 

[sootywooty]

Sorry a double post could a mod delete it please!

 

[xoaphexox]

I have removed blend resistors in several Sansui QRX-7001 and QRX-777. The issue would be recalibrating them afterward. It would be neat if there was just a 'switch' for disabling the blending.'

Attached are pics of the boards from the 9001 with the blending resistors removed and the signal path capacitors upgraded to polypropylenes, all new electrolytics, and the rest of the mylars replaced with 1% poly caps.

 

[sootywooty]

Thanks for the reply! btw where abouts were the blend resistors in those pics please, also is it easy to re-calibrate them QuadBob said he could, i just wonder if he did it now with all the talk about him not doing all the work on one members 9001. Also is it very important to re-calibrate does it make alot of difference.

Also funny i was just reading this thread a momment ago and then a reply i have not read it for weeks. lol!

All the best, Paul.

 

[w.a.reid]

I have removed blend resistors in several Sansui QRX-7001 and QRX-777. The issue would be recalibrating them afterward. It would be neat if there was just a 'switch' for disabling the blending.'

Attached are pics of the boards from the 9001 with the blending resistors removed and the signal path capacitors upgraded to polypropylenes, all new electrolytics, and the rest of the mylars replaced with 1% poly caps.

nice job - is this your work?

im always open to a new sansui tech - my stuff is stacking up!

william a reid

 

[xoaphexox]

It is my work; thanks! The blending resistor locations can be spotted if you look closely at the boards. One missing resistor on F-2088 (R601) and two on F-2087 (R39, R40).

To recalibrate you need a signal generator capable of two independent signals (you will need one out-of-phase with the other - I use free software on my PC) and an oscilloscope. Other than that it's just following instructions.

The biggest pain in the butt is that you need to take the faceplate off to dial in the 25V supply voltage. The pot is in a weird place.

 

[xoaphexox]

Edit - deleted duplicate post - good golly this website is s.l.o.w.

 

[sootywooty]

It is my work; thanks! The blending resistor locations can be spotted if you look closely at the boards. One missing resistor on F-2088 (R601) and two on F-2087 (R39, R40).

To recalibrate you need a signal generator capable of two independent signals (you will need one out-of-phase with the other - I use free software on my PC) and an oscilloscope. Other than that it's just following instructions.

The biggest pain in the butt is that you need to take the faceplate off to dial in the 25V supply voltage. The pot is in a weird place.

Thanks for the reply xoaphexox! my 9001 seems to play well but this is a mod i would not mind trying, so do you just have to pull them out i can see the hole were they use to sit in.

Where is the free sw and the instructions btw.

All the best, Paul.

 

[xoaphexox]

You have to unsolder them. You need a signal generator, there are several out there on the internet that are sufficient to produce the 1khz sine waves used for calibration. You also need some nonconductive alignment tools for turning the pots and a digital voltmeter to take the readings. You need 25V from pin 5 on F2088.

Adjustment

1. First, play a LEFT only 1khz tone into the Sansui in QS mode and adjust VR4 until the output on the RIGHT front and back channels are low, but equal. The Right Front and Back channels are always out of phase with each other. When they are equal in volume, that is known as "strict imbalance".

2. Now, play the RIGHT only 1khz tone. Adjust VR3 so that the LEFT front and back channels are low and equal.

3. Now play the mono tone (equal in both channels and in phase) into the Sansui. Adjust VR2 so that the REAR channels are low and equal in level.

4. And finally, play a 1khz tone to both left and right channels that is 180 degrees out of phase into the receiver. Adjust VR1 until the FRONT channels are low and equal in power.

 

[sootywooty]

That re/cal part seems hard i dont think i could do that, and alot of tools needed as well. Thanks for all the info and time btw.

All the best, Paul.

 

[xoaphexox]

Understandable! Take care

 

[sootywooty]

Understandable! Take care

I had idea i see from the pictures their the two circuit board are taken out from a 9001, would it be possible say for me to send you my two so you can modify anything you consider may need doing and take out the blend resistor and do it that way.

Are the boards easy to remove, also as you know i was considering biding on your modded 7001 could the boards be swaped from that onto my 9001 btw.

Also any idea of the postage cost if i won it on the 7001 to the uk yet please.

All the best, Paul.

 

[xoaphexox]

Paul, unfortunately the calibration can only be accurate if the boards are aligned while in the unit, so taking them from the 7001 and putting them in your 9001 could be a gamble. Will it sound good? Probably... but will it really be calibrated? Probably not...

I am waiting to hear back from my shipper, I left him the message after hours. Can you PM or email me your address or zip code? Thanks

 

[MidiMagic]

If you want more than minimal front-back separation on SQ, do not remove the blend resistors. They steer the signals to the proper speakers when logic is not used.

They were used to trade some left-right separation on SQ for some front-back separation.

Without the blend resistors:

- left front to right front: at least 20 dB
- left back to right back: at least 20 dB
- any front to any back: 3 dB
- center front to center back: 0 (no separation at all)

With the blend resistors:

- left front to right front: at least 14 dB
- left back to right back: at least 5 dB
- any front to any back: 4 dB
- center front to center back: 8dB

I put a switch on mine, so I could switch them in and out.

 

[xoaphexox]

I put a switch on mine, so I could switch them in and out.

Good idea - I thought about using sockets for the blending resistors in mine - would you share where you mount the switch? A pic would be awesome!

Still using my QRX-777 & Marantz 4400

 

[Trnsfmr]

Here's a post I did a couple years ago on the fine points of the holy grail alignment on the 9001. I like the idea of the switches. I also found that with the blend resistors removed it's easy to lose separation on the fronts. A little tweeking takes care of that.

http://www.audiokarma.org/forums/showthread.php?t=222680&highlight=holy+grail

Since then I've had a couple more 9001's and am recapping/restoring one right now.