Buy new or revise and modify 30 year old class A amp and speakers?

[Raycoupe]

I would suggest starting with DSP room measurements before deciding on revisions or replacements.

And again we’re wasting time on silly electronics, while 90% of the sound quality is determined by the speaker and the room interactions. Focus on that, it will be much more rewarding and will actually make a massive difference.

Today I did some listening tests and measured the direct output of the speaker (was linear) AND the sound at my listening position (Not linear). Ears and db measurement agree, it's the room causing the bass drop off between 40 and 50 hz and spikes at 36! When my house was renovated a lot of things changed and moved, but I didn't take into account the effect on sound.

The new dac/pre-amp arrives within two hours, allowing me to directly connect pc to dac to poweramp, cutting out that low budget, 25+ yo Harman Kardon middle man. I'm very curious what that will do for the high frequencies.

It looks more and more in favor to revise the MA220 and having the ferro liquid in the tweeters replaced.

I will look into both phase and DA conversion techniques before getting on with discussion about that. The ears will eventually decide any decision I make.

Thank you all for pointing me in the right direction and please forgive me for sometimes being stubborn once on a roll. After a good nights sleep I've seen the light.

 

[voodooless]

You might have been better off ordering something with some room correction DSP inside to fix some of the bass issues. Also, a subwoofer may help with the bass issues. Also, for that, you'd need something with proper bass management. What DAC/pre did you get?

 

[Raycoupe]

You might have been better off ordering something with some room correction DSP inside to fix some of the bass issues. Also, a subwoofer may help with the bass issues. Also, for that, you'd need something with proper bass management. What DAC/pre did you get?

SMSL raw-mda1, just to get an idea of current state of technique for only 280 euro's. Without DSP, but I hope it will at least beat my PC onboard dac/opamps and provide a new pre-amp.

DSP is completely new to me, I never listened to a system with and without DSP correction enabled. Another subject to get into.
I'll start with speaker position and room corrections, but resolving bass interference will be just as challenging as in the old days.

The big problem is my room setup. It's 5,5 meters (18 feet) by 4,5m (14,75ft) and the speakers are along the longest wall. I could place them at the short wall but I don't like sitting with my back towards the window/garden.

After the renovation I never bothered to account for sound and just placed them conveniently. So the speakers are currently spaced roughly 3 ft off the wall, spaced close to 7ft and my ears are at 6 ft. The wall behind me is at less that 5 ft. And while there is furnature in the room, those are all hard surfaces. The heavy curtains are the only thing preventing refelctions currently. So it's a big mess and I will have to experiment to get the best result without DSP or subwoofers for now. Step by step. Fortunately I don't have a wife, so I can do as I please.

 

[voodooless]

The SMSL is perfectly fine. SOTA performance for a reasonable price!

You can still experiment with EQ via your PC. There are lots of options:

'EQ Software for Windows, Linux, macOS, iOS/iPadOS and Android.'

Dec 16, 2020

Any suggestions are welcome. Post suggestions here. I will gather the details and add them. Thanks. This will be organized as results come in.
@sweetchaos made a guide for PEQ filter data input and operation.
For crossover software go here.

Windows:
AutoEQ four easy steps to make your headphones sound better, requires EQ APO and or Peace EQ.
GG with parametric EQ, mixer and mic control.
Equalizer APO is a parametric / graphic equalizer for Windows.
Equalizer APO multichannel peakmeter.
EACS - Equalizer APO Config...

• Doodski
• Replies: 784
• Forum: Home Music Servers, Computers and Streamers

• 

You said you did some measurements? If so, is your equipment good enough to measure the KEF tweeters? They may just be functioning fine and you don’t need ferrofluid replacement. Some types do not wear out over time. I don’t know what KEF used back then, but nowadays I think they use stuff that lasts a very long time.

 

[Raycoupe]

The SMSL is perfectly fine. SOTA performance for a reasonable price!

You can still experiment with EQ via your PC. There are lots of options:

'EQ Software for Windows, Linux, macOS, iOS/iPadOS and Android.'

Dec 16, 2020

Any suggestions are welcome. Post suggestions here. I will gather the details and add them. Thanks. This will be organized as results come in.
@sweetchaos made a guide for PEQ filter data input and operation.
For crossover software go here.

Windows:
AutoEQ four easy steps to make your headphones sound better, requires EQ APO and or Peace EQ.
GG with parametric EQ, mixer and mic control.
Equalizer APO is a parametric / graphic equalizer for Windows.
Equalizer APO multichannel peakmeter.
EACS - Equalizer APO Config...

• Doodski
• Replies: 784
• Forum: Home Music Servers, Computers and Streamers

• 

You said you did some measurements? If so, is your equipment good enough to measure the KEF tweeters? They may just be functioning fine and you don’t need ferrofluid replacement. Some types do not wear out over time. I don’t know what KEF used back then, but nowadays I think they use stuff that lasts a very long time.

Thanks for the list, very useful stuff. I'm using Linux and great that OS is included. Just using the build in EQ in VLC mediaplayer does sound awful.

For that quick measurement I just used an old mic I had lying around. I would trust it's linearity in the high frequencies anymore. My ears will tell me is high frequencies will improve, with the new dac/preamp that old Harman Kardon can be ditched from the signal path. It will simplify evaluating the MA220 and Kef's.

 

[voodooless]

For Linux CamillaDSP should be gold standard.

 

[voodooless]

For that quick measurement I just used an old mic I had lying around. I would trust it's linearity in the high frequencies anymore.

That’s probably mostly okay. It would still show severe issues with the tweeters. Just measure like 10 cm from the tweeter, but not straight on. A 20 to 40 deg angle should be good. There the tweeter should be most linear. A sweep van 500 Hz to 20 kHz should be enough.

 

[antcollinet]

and please forgive me for sometimes being stubborn once on a roll

We've all been there. Or at least I have - multiple times.

 

[Raycoupe]

The dac has arrived. Unfortunately I didn't realize that bluetooth is reception only, but I'll live with it, once I get a small to large headphone jack adapter.
Also picked up a cheap new microphone and thanks for pointing me toward s EQ/DSP software Camilla @voodooless , because that software list is quite extensive!

I need to move a large and heavy cabinet (and some smaller items) so I can improve my speaker placement and have some room to adjust placement.
Working out a plan to move that bulky thing, to make it complicated, it's part display cabinet with glass panes.

 

[Steven van Rooijen]

I'm having trouble finding experiences of people who have their old class A amps revised/modified. What to expect in sound quality?

I have a van Medevoort integrated class A amplifier MA220 I bought new in 1992. Due to circumstances it has been kept in storage 20 years and only used for 10 years. Revision and modification would cost nearly 600 euro's. Would it bring back original sound quality?

Since I do not own may other components at the moment, it's hard to determine the remaining sound quality of the amp. It's currently hooked up to a 25 year old harman kardon used as a pre-amp. It's sounds better than using the power amp of the Harman Kardon, but I realize it's pre-amp is probably not well suited for pairing with the van Medevoort. The lows are terribly abscent with the pre-amps bass setting on full blast.

The same goes for my Kef UniQ 90's speakers. Don't know how much soundquality is left, can't test it with a decent amp and don't know if it's worth replacing ferrofluid and revision of the cross over filter.

Perhaps soundquality has improved dramatically over 30 years and it's a now brainer to throw everything in the trash an buy new. But I simply don't know. Somehow I expect more progress is made on speakers than amps, but that is just a hunch.

I do now I was not very happy with the sound of a second hand 1,5 years old Yamaha r-n2000a, with a cheap S303 Yamaha CD-player and a pair of Dynaudio Evoke 50 speakers. It could be that the sellers room was the problem, not the equipment, but placement of instruments and vocals where all over the place. If this is what 30 years of devellopment has brought (although it's a class A/B amp) I would be very dissappointed.

Revision/mods of the MA220 would cost almost 600 euro's. Replacement 3000. (I know a 2 x 250 class D hypes ncore chinese amp would also cost 600, but that's a big gamble to buy without listening session)
Revision/mods of the Kef's would cost +/- 500. Replacement with i.e. Kef R3 Meta's 2200 euro's.

I could easily afford the revision/mods, buying new would be would be achievable, but not all at once.

I would suggest to bring your MA220 to Van Medevoort for inspection and/or upgrade. That should be OK and no other pre-amp is necessary. Or trade-in for at least the separate combination of vM CA220 and vM PA220 if they have them available. Or use the vM MA220 pre-out to connect to any vM PAxxx.

 

[Timcognito]

My AR CA-50 sat for 15 years gathering dust and except for spontaneous dust ignition upon startup and abrupt shut down, sounded great after cleaning everything with electronic cleaning spray. What specifically needs 600 euros of repair? I would clean and try.

 

[levimax]

My AR CA-50 sat for 15 years gathering dust and except for spontaneous dust ignition upon startup and abrupt shut down, sounded great after cleaning everything with electronic cleaning spray. What specifically needs 600 euros of repair? I would clean and try.

^THIS. If amp is working and does not have audible buzz or hum it is most likely fine.