New to Bose 901 IV - needed amp and equalizer help!

[kayes]

I have a few questions regarding Bose 901 IV and a Technics SU- V4K stereo integratesd amplifier. I was gifted these items from my father. They have been stored in a cool dry basement for quite some time.

The amplifier has what appears to be a crackly input selector switch. Sometimes it doesn’t even work (just the most faint sound coming out of the left channel. It’s very inconsistent. One minute the right speaker works and sometimes it doesn’t.

Now for the speakers and equalizer. I recently had the speakers refoamed. I got them back and it sounds like the right speaker has a flappy crackly sound on one side of the cabinet. One song that I tried (Blackbird) the sound was very distorted in the right speaker.

A big issue I’m having is the equalizer doesn’t seem to effect the sound. I have set up everything just like the instructions (I’m pretty sure I did but now I’m wondering). Is it possible it’s the equalizer that’s messed up? If anyone has experience with the Technics SU-V4K amp some insight would be awesome!

I will attach some pictures of my setup.

Please, any help is greatly appreciated! These speakers have been the family most of my life and have always wanted to use them. Thank you so much!

EDIT - I just talked to my dad and he said the sales person who sold him the Technics amp many years ago said it wasn’t necessary for the equalizer with the new amp technology. Is that correct?

 

[leesonic]

I think you have to have the record selector set to the source you are using (eg. CD) and the input selector to tape 1.

Lee.

 

[kayes]

I think you have to have the record selector set to the source you are using (eg. CD) and the input selector to tape 1.

Lee.

Hi Lee, thanks for your reply. I did try that with no effect unfortunately. I tried,what seemed like, every combination with no luck.

 

[kayes]

Also, I guess I should ask if this amp is compatible to the equalizer? I just talked to my dad and he said the sales person who sold him the Technics amp many years ago said it wasn’t necessary for the equalizer with the new amp technology. Is that correct?

 

[faber12]

The EQ is compatible, and required.

 

[faber12]

Sounds like you need a different amp/speaker to test. Try swapping the leads from the speaker that is distorting with the other one at the back of the amp. If the symptom follows the speaker then the problem is in the speaker. If the problem is the amp channel then the problem will switch speakers when you swap wires.

Without known good equipment to use for testing it can be hard to diagnose.

What is your location? If you are close to me, I would help you in person.

 

[kayes]

Sounds like you need a different amp/speaker to test. Try swapping the leads from the speaker that is distorting with the other one at the back of the amp. If the symptom follows the speaker then the problem is in the speaker. If the problem is the amp channel then the problem will switch speakers when you swap wires.

Without known good equipment to use for testing it can be hard to diagnose.

What is your location? If you are close to me, I would help you in person.

Thanks for the offer of help but I am in Saskatoon Saskatchewan Canada. I used his old Pioneer SA-5200 amp and the equalizer works and the right speaker still doesn’t work correctly. I do think the Technics amp input switch is messed, hopefully only needs cleaning or soldering.

 

[kayes]

The EQ is compatible, and required.

Are you aware of how I would properly setup the equalizer on the Technics so it works?

 

[faber12]

Are you aware of how I would properly setup the equalizer on the Technics so it works?

Leesonic is correct in how it is to be connected.

The record out from the amp should be connected to the input of the EQ, and the output of the EQ should be connected to the 'playback' input of the amp.

The input selector should then be set to the tape loop that has the EQ and the Rec Selector should be used to select listening source.

 

[faber12]

If the speakers work without distortion without the EQ, the EQ may be faulty. You can try switching the left/right at the EQ and see if the symptom follows an EQ channel.

 

[toxcrusadr]

Crackly switch is likely just dirty and needs cleaning. A shop can do this for you or if you're willing look up the DeOxit for Dummies thread. (I'll post a link in a minute)

Who did the refoam? If it was a pro shop hopefully they played them to make sure all is well. If a driver was refoamed off center, the voice coil can rub on the magnet structure and cause crackly distorted noises. If you narrow this down to the speaker (not amp etc.), try to identify which driver. Use a paper towel tube to listen to each one if you have to. If you find one that's doing it, gently press on each side, top and bottom of the cone while playing at low volume. See if it gets worse or goes away. If so it's an off center refoam job. This can kill the driver so don't play it any more till you get it fixed.

The EQ is there to correct the terrible looking frequency response curve of the 901 (which results from other design features of the speaker) to make it sound right. Which amp you drive it with has no effect on that and the EQ will still be necessary.