Canuck Audio Mart Hifi and Audio ForumCanuck Audio Mart Hifi and Audio Forum
It is currently Mon Oct 23, 2017 8:18 pm

All times are UTC - 8 hours




Post new topic Reply to topic  [ 30 posts ]  Go to page Previous  1, 2
Author Message
PostPosted: Thu Jan 05, 2017 8:57 pm 
Offline

Joined: Sun Mar 18, 2007 2:01 pm
Posts: 980
Location: Calgary, AB, CA
zon001 wrote:
I add a nikko gamma 5 and for sound quality, it as NOTHING to do with best off any list.


But the Nikko Gamma V is one of his favorite. As the matter of fact it was one of his top 10 pick for a long time until some other tuners came into view. BTW, I still have the Nikko Gamma V, AKAI AT V04, Sherwood and Sony tuners in my collections. And every now and then I resurrect the Nikko Gamma V just for nostalgic moments as it was my reference tuner for 10 years until the Philips tuner came along. Surprisingly enough it still sounds good after all these years. My McIntosh component is being fixed right now hopefully I'd able to listen to it soon.


Top
 Profile  
Reply with quote  
PostPosted: Fri Jan 06, 2017 4:07 am 
Offline

Joined: Sun Apr 05, 2009 7:06 pm
Posts: 947
Location: hawkesbury, ON, CA
I add that tuner with a beta 50 and a delay unit, that I never used. the pre amp was so bad. it was one of the worst pre amp I own. it was so bad that you could play a cd on one input , then you change input while the cd would keep playing, and you could still hear that cd still playing in the background while switch to another input.
and the op like McIntosh tuner, he just want to know witch one to choose.
every time somebody talk tuner. that tuner showdown list keep coming up .
internet is nice, but you cannot believe everything you read.


Top
 Profile  
Reply with quote  
PostPosted: Mon Jan 23, 2017 3:33 pm 
Offline

Joined: Thu Jun 10, 2010 5:10 pm
Posts: 13
Location: Vancouver, BC, CA
tsearay wrote:
Things to consider, I have a MR74 that has been in the shop for over a year as the offending part is unobtanium hence my purchase of the latest magnum dynalab. FWIW T.


Hey there.

Sorry to hear that you are having trouble finding a certain part for your MR 74; this is the same model that I just bought.

Fortunately, the owner (also a fine CAM member) found me with his MR 74 in marvelous cosmetic and operational condition,
so I took the opportunity and bought it.

So that I can know for the future - what is this offending MR 74 part that is not available?

Thank you.


Top
 Profile  
Reply with quote  
PostPosted: Mon Jan 23, 2017 6:00 pm 
Offline
Dealer/Sponsor

Joined: Tue Jun 14, 2016 8:33 am
Posts: 1051
Location: Kingston, ON, CA
libor wrote:
agree the MX110 is essentially MR 67, both tube units...but from what OP is looking at...maybe the MR 78 is the best now.



I had a mint MR78 in the mid 90's. It was VERY good. the feel and look is beyond reproach. It was great to use, every time.

I sold it to keep my HK F250, which had the stereo multiplexer option.

_________________
(Ken Hotte, of) Teo Audio


Top
 Profile  
Reply with quote  
PostPosted: Tue Mar 28, 2017 9:02 am 
Offline

Joined: Sun Oct 02, 2011 3:20 pm
Posts: 42
Location: Port Coquitlam, BC, CA
BCMBDK wrote:
tsearay wrote:
Things to consider, I have a MR74 that has been in the shop for over a year as the offending part is unobtanium hence my purchase of the latest magnum dynalab. FWIW T.

Hey there.
<SNIP>
So that I can know for the future - what is this offending MR 74 part that is not available?
Thank you.


Alll the transformers and inductors of the MR74 except the power transformer. When they are adjusted during alignment, there is high probability that it will break and disintegrate as all the ferrite cores are hollow, unlike the older Mac tuners which uses mostly the solid core. A wrong sized adjustment tool is one factor as the core is normally seized into place.

I did this when rebuilding and aligning an MR74. I ended up using a transformer from an older Mac tuner and making it work with the MR74. This was back in the days when one can still see the winner's name on an eBay auction. I managed to track down the winner of the US eBay auction from Switzerland who didn't need the part. I shared this mod on the Yahoo high end FM tuner group.

My experience with Mac tuners is that they defy what most audiophiles and DIY audio folks think about what parts should not be used on a high end audio gear. I currently have an MR71 on my bench right now and it uses plenty of Z5U and X5F ceramic capacitors in the audio chain. These dielectrics are highly microphonic and change in value over temperature and voltage. The MR74 is actually guilty of this too and likely their other siblings. Some of the electrolytic capacitors on the MR71 are actually underrated. The MR71 has 150V capacitors being subjected to 170V for several seconds during power on. Now to me that is a poor engineering , design and safety issue. Nobody is perfect but the MR71 had plenty of Mac tube predecessors, one would think Mac engineers should have learned after several design iterations.

Then there is the Mac stereo decoder. The MR78 and models before it used a very similar stereo decoder topology. They all have the same "fault" and probably the sound that people like. The MR77 and older models doesn't have 19kHz and 38kHz notch filter on their audio outputs. So if you are one of those who likes to set the treble to maximum and loudness engaged, you are roasting your tweeters with the ultrasonic energy from the Mac tuner. The MR78 has a 19kHz filter and MR80 has both 19kHz and 38kHz filter.

The MR80. A tuner upon closer inspection is not exactly a high end tuner. It employs 4 ceramic filters in normal mode which is actually narrow in the real world of FM tuners that is why not high end in my books. There is no form of group delay equalization in between the 4 ceramic IF filters, a practice that Marantz does on some of its tuners too. This design doesn't translate into good audio quality. You end up with a demodulated audio that has plenty of high order harmonics. The MR80 IF filter topology closely mimics the MR 78 but the MR78 has the RIMO LC filters which have better group delay characteristic. The MR80 is a departure of the long tradition of that old Mac stereo decoder, this time around McIntosh used the TCA4500A/LM4500A. This part they got it right but a bit too late as the IF filter on the MR80 is not a good design choice.


Top
 Profile  
Reply with quote  
PostPosted: Wed Mar 29, 2017 7:39 am 
Offline
User avatar

Joined: Tue Apr 05, 2005 2:43 pm
Posts: 1516
Location: *, ON, CA
BCMBDK wrote:
tsearay wrote:
Things to consider, I have a MR74 that has been in the shop for over a year as the offending part is unobtanium hence my purchase of the latest magnum dynalab. FWIW T.


Hey there.

Sorry to hear that you are having trouble finding a certain part for your MR 74; this is the same model that I just bought.

Fortunately, the owner (also a fine CAM member) found me with his MR 74 in marvelous cosmetic and operational condition,
so I took the opportunity and bought it.

So that I can know for the future - what is this offending MR 74 part that is not available?

The MPX filters 4 of mine were damaged by someone (qualified) trying to align the tuner, which I don't believe was necessary as I took it in to resolve a power issue. My advice never realign a tuner that is receiving as designed. A lot of misinformation out there regarding tuners needing realignment, if it is working it doesn't. T

Thank you.


Top
 Profile  
Reply with quote  
PostPosted: Wed Mar 29, 2017 11:58 am 
Offline
User avatar

Joined: Sun Dec 04, 2005 3:16 pm
Posts: 1034
Location: Georgetown, ON, CA
Hi ej251awd,
Quote:
there is high probability that it will break and disintegrate as all the ferrite cores are hollow, unlike the older Mac tuners which uses mostly the solid core. A wrong sized adjustment tool is one factor as the core is normally seized into place.

About the only thing I can agree with you on in this statement is that the wrong tool will most often crack the core. Generally, they can get pretty stiff over time, and it takes some effort to get them moving without breaking the core, but it can be done.

The only core problems I have had with any tuner have been when a bad technician has been in there first. In the case of tsearay's tuner, I have it here. I am waiting to find the cores for two inductors. They were completely missing when the tuner arrived here. One inductor uses two cores. I sincerely doubt that they were all "broken and disintegrated" when that first well known tech (to CAM's membership) got it.

When I first looked into this tuner, can you believe that the entire IF strip had been tuned to 10 MHz (close to, but not exact)?? ! This McIntosh certified technician doesn't even know what the standard IF frequency is for FM tuners. Anyway, I am also McIntosh certified and I'm trying to save this tuner. It is the second nightmare from this same technician who works out of Micron Electronics, and I would love to see him gone.

ej251awd, you might be in a position to really help with this problem. All I need to know is the length of the cores used in the 19 KHz transformer (T401, 162-055) and the 19 KHz filter (L402, 122-094). I have discovered I have some cores that will fit these locations. If you get one of these tuners in, or another that uses the same inductors in the MPX circuit, would it be possible to measure the core lengths? I have some response out of them with cores I guessed at for length, but I really need the proper length. Also, could you count the number of cores in these inductors? As I mentioned, there is no dust, no core fragments. Both are as clean as a whistle. I'm going to bet that that other technician has the cores sitting on his bench. Even if they were cracked, they would have been useful, and repairable.

Any other technician who has a tuner in, please help by measuring those cores. I've aligned the tuner and all I need is this information.

Best regards, Chris


Top
 Profile  
Reply with quote  
PostPosted: Wed Mar 29, 2017 1:19 pm 
Offline

Joined: Sat Sep 20, 2008 4:55 am
Posts: 115
Location: London, ON, CA
Go to:

http://www.biline.ca/audio_critic/audio_critic_down.htm

and download issues 23,24 and 26 for articles by Dr. David Rich on tuners....you will learn a lot


Top
 Profile  
Reply with quote  
PostPosted: Wed Mar 29, 2017 1:22 pm 
Offline

Joined: Sun Oct 02, 2011 3:20 pm
Posts: 42
Location: Port Coquitlam, BC, CA
Chris,

I don't have the measurements of the cores. Sorry.

My long term plan if I get another MR74 with the same problem that you have is design and build a drop in replacement MPX board using the newer MPX ICs with IBOC, pilot and subcarrier filters. I need a unit too so I can match the muting characteristic of the old tuner. Right now I have other priorities :)

Try the Yahoo high end FM tuner group.


Top
 Profile  
Reply with quote  
PostPosted: Wed Mar 29, 2017 1:30 pm 
Offline
User avatar

Joined: Sun Dec 04, 2005 3:16 pm
Posts: 1034
Location: Georgetown, ON, CA
Hi ej251awd,
Thanks, I didn't expect you would have those off hand. But, if you don't ask, you'll never get an answer or help. I sure wish I could drop in a new MPX board! I could design one and adapt it, but that would cost several hundred dollars at least with the engineering that goes into it - as you know.

I hear you on other priorities!

If you wanted measurements for your long term goals, what would they be? I will be back into this tuner again and can take them for you. It's the 19 KHz pilot amp and filter that doesn't work, everything else is working well.

Best, Chris


Top
 Profile  
Reply with quote  
PostPosted: Wed Mar 29, 2017 6:42 pm 
Offline
User avatar

Joined: Sun Dec 04, 2005 3:16 pm
Posts: 1034
Location: Georgetown, ON, CA
Hi gnickers,
I looked at the articles you posted (I don't know if they were for me), but didn't see anything helpful in there. I do thank you for taking the time to post the link and identify which downloads to look at. I know this took you some time to do.

-Chris


Top
 Profile  
Reply with quote  
PostPosted: Thu Mar 30, 2017 6:57 am 
Offline

Joined: Sun Oct 02, 2011 3:20 pm
Posts: 42
Location: Port Coquitlam, BC, CA
anatech wrote:
Hi ej251awd,

If you wanted measurements for your long term goals, what would they be? I will be back into this tuner again and can take them for you. It's the 19 KHz pilot amp and filter that doesn't work, everything else is working well.

Best, Chris


Chris,

Even with the measurements, I still need a unit to try it with and do some optimization. I have some of the measurements already somewhere on my notes. I was just making an excuse and you got me.

If there is significant demand and people are willing to pay for the MR74 specific MPX board, I can make it go. Search for ej25awd on Google and you will find me. We've "talked" before :)

Right now, doing some other electronics-related work. Not audio stuff so not that exciting.


Top
 Profile  
Reply with quote  
PostPosted: Thu Mar 30, 2017 7:42 am 
Offline
User avatar

Joined: Sun Dec 04, 2005 3:16 pm
Posts: 1034
Location: Georgetown, ON, CA
Hi ej25awd,
I don't know how to find vendors on Ebay, but I'll give it another whirl. I hope our contact was a positive one!

I hear you on the MPX board replacement. It would probably be an upgrade over what they were using in the factory configuration. I'm thinking on doing something like that for my Marantz 150 and 2120. If that part was available, I would certainly suggest it to customers who either had problems like this one (Technician Induced Malfunction), TIM was here. I'd have a hard time offering it just to upgrade a tuner that didn't need it.

Good luck on your non-audio endeavors!

Best, Chris


Top
 Profile  
Reply with quote  
PostPosted: Thu Mar 30, 2017 8:29 am 
Offline

Joined: Sun Oct 02, 2011 3:20 pm
Posts: 42
Location: Port Coquitlam, BC, CA
anatech wrote:
Hi ej25awd,
I don't know how to find vendors on Ebay, but I'll give it another whirl. I hope our contact was a positive one!

Good luck on your non-audio endeavors!

Best, Chris


eBay changed a lot and you can not go deep into previous sales and have the ability to contact the winner. That was taken away long time ago. I just checked eBay for the parts you need, negative. The fact that McIntosh no longer stock it , means people like me broke one at one point in their career :mrgreen:

If you do find the dimensions of the core, I might be able to help as I have recently acquired a box full of ferrite cores for IF and RF stages. Thread count and length will help me narrow it down.

One our last contact, you help me remove pictures of the Tek AA501 on an ad I did for test equipment at the site you are moderating :)


Top
 Profile  
Reply with quote  
PostPosted: Thu Mar 30, 2017 4:13 pm 
Offline
User avatar

Joined: Sun Dec 04, 2005 3:16 pm
Posts: 1034
Location: Georgetown, ON, CA
Ahhh, I vaguely remember that. It was no problem at all.

I'll try to get you that information. The one problem I have is there is no way to determine what the thread count would have been. Not even core fragments exist.

-Chris


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 30 posts ]  Go to page Previous  1, 2

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group