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CR800 poor bass performance

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damian911

New Member
Hello all,

I have a CR800 that I've owned for the last two years but haven't used it in quite a while. So with some trepidation I connected it up to some old speakers and switched it on, the relay clicked and sound came out of the speakers. The volume and tone pots were silent and smooth, a little crackle on the switches but all looking positive.

I decided to connect it to a pair of Neat Petite 3s and give it a decent source but no matter what source I gave it there was an absence of low bass. So I set about sorting out the following:

1) Recapped the power board (Panasonic, Nichicon etc)
2) Checked and ended up replacing the main filter caps (upgrade to 10000uf)
3) Recapped the main amp board (Panasonic, Silmic and some BP Muse)
4) Cleaned the pots and selectors
5) Cleaned the fascia/buttons/dials etc
6) Replaced the bulbs with some modern super-bright yellow LEDs

I biased and set the idle of the amp to within factory tolerances but still the same!

I've even bypassed the pre-amp using the coupler and used a separate pre-amp to check if it was the tone board (a recap I'm not looking forward to!).

Any thoughts or suggestions?
 
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Has anyone any ideas? Should I try with a set of more sensitive speakers rather than the 85-86db Neats as I've read that the Yamaha is a little sensitive to the speakers.

edit: The service manual I have is difficult to read the transistor voltages, could some list what the voltages should be for the following:

TR701, TR703, TR705, TR707, TR709, TR711, TR713, TR715, TR717, TR719, TR721/722/723/724/725

Alternatively if there is a better quality scan of the Main NA06408 section of the service manual that might be better.

Thanks in advance!
 
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You might need to recap the whole unit. I know mine doesnt have any problem with bass if its in the music. Could be the speakers, also if you're used to listening to Sansuis, Marantz and such the yamaha will sound a bit thin.
 
Mymamiya said:
You might need to recap the whole unit. I know mine doesnt have any problem with bass if its in the music. Could be the speakers, also if you're used to listening to Sansuis, Marantz and such the yamaha will sound a bit thin.
Click to expand...

Thanks, I've pretty much recapped all the main amp board, need to replace two on the power board but they are supplying a different circuit so not affecting the Aux to Main route.

You are right regarding the 'bass' response from the Marantz, that is warm compared to many. Even with compensating for that, the bass turned to 9-10 it still doesn't have the weight of the Marantz.
 
It's pretty typical for a Yamaha amp to sound weak, lacking grunt. It's probably because they've traditionally always been cheaping out on the transformers. Compare any Yamaha to a similarly powerful any-other-brand-amp. The transformer size difference will be significant.
 
The pre amp section sounds tired. That is a very important part of the amp chain. I would say mine sounds much like a modern amp. Just clean and clear, not the thick vintage sound. If i turn the bass up two notches it really thumps. I really doubt any transistors are your problem.
 
Mymamiya said:
The pre amp section sounds tired. That is a very important part of the amp chain. I would say mine sounds much like a modern amp. Just clean and clear, not the thick vintage sound. If i turn the bass up two notches it really thumps. I really doubt any transistors are your problem.
Click to expand...

Thanks again. I'll give that a re-cap next, any suggestions on how far or what to re-cap with?
 
The obvious question is did you confirm the speakers are not out of phase?
 
I didnt think of the ol' backwards speaker wires. That will certainly kill the bass. Maybe you are expecting more than it can deliver. Your original post said you bypassed the preamp. If you do recap the preamp board dont bother silmics, they are too fat. Any good audio cap will do.
 
w1jim said:
The obvious question is did you confirm the speakers are not out of phase?
Click to expand...

That was my first check!

Mymamiya said:
I didnt think of the ol' backwards speaker wires. That will certainly kill the bass. Maybe you are expecting more than it can deliver. Your original post said you bypassed the preamp. If you do recap the preamp board dont bother silmics, they are too fat. Any good audio cap will do.
Click to expand...

Perhaps, I'm not usually one for heavy bass, just warmth. Thanks for the advice on the fat Silmics.
 
ZOOM said:
It's pretty typical for a Yamaha amp to sound weak, lacking grunt. It's probably because they've traditionally always been cheaping out on the transformers. Compare any Yamaha to a similarly powerful any-other-brand-amp. The transformer size difference will be significant.
Click to expand...
Your so FOS.
 
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