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Mac 1500 vs Fisher 500c.

97.95.43.235
Posted on November 28, 2016 at 22:42:53
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005






"
The 500c and the Mac 1500 are two interesting units.I have six of the 500c and one 800c. The 500c and 800c are all tube units including preamp section while the mac 1500 has a discrete solid state preamp,but the tuner and amplifier stage are tube other than the tuner output stage which has four discrete transistors.
All in all,I much prefer the 1500 as it does everything better IMHO.
Some of the reasons for this is the superior iron,the 12AU7 drivers as opposed to a 12AX7 which are weak by comparison.I say this because on the 500c,there is a slope that develops as you get past 12 o-clock on the volume control and distortion rises dramatically.The 1500 I can take all the way to 4 o-clock on the volume pot and I'm still not clipping and the 1500 is making more power. It also has separate bias pots for the 7591s.
The tuner in the 500c is very good but it also very good in the 1500.What I really love about the 1500 is the fact that it's quiet and that allows you to hear more detail and little nuances that would otherwise over look.
Now keep in the mind that I rebuilt that this unit with new filter caps going up 2.5 times the original values.I also uses Schottkys in the power supply and I did change transistors in the phono section to ones that were more quiet.I changed all coupling caps to k40s and Solen Film and tin foil.Muse caps all thru the bias and emitter circuits.
The main problem with Mac 1500 is the high impedance 10v supply.There is a filter cap that shorts and that will kill the preamp.

Now before you go off on a tangent thinking I'm crazy,I'm working on a circuit for the 500c that will help dramatically..I'm changing the 12AX7 driver to a 7247 or a 6U8a.The feedback also needs tweaking in the 500c because the Sherwood S-8000 runs well with a 12AX7 driving the 7868s but,the iron and feedback are different.When I feel better,I will do more testing on the 500c preamp. Right now tho,this 1500 just gets it in every way.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

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Those transformers, posted on November 28, 2016 at 23:49:12
FenderLover
 Mike, how have you been? Hope back is healing.

Those trannies have EIA code = 159. I have this as DX Radio Products, Chicago. Never heard of this manufacturer.

Do you know anything about their relationship with McIntosh?

Thanks!

 

RE: Mac 1500 vs Fisher 500c., posted on November 28, 2016 at 23:53:43
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Mike, you may want to borrow the idea in the below post. It really helped transform my late model 400. I believe most of the Fisher integrated/receiver volume/preamp output sections would benefit from this. I know it's adding silicon but it's worth it in my opinion.

http://www.audiokarma.org/forums/index.php?threads/improving-the-fisher-400.511867/page-2#post-6672509

http://www.audiokarma.org/forums/index.php?threads/improving-the-fisher-400.511867/page-3#post-6674188

While you're at it also fix the phono stage's RIAA curve

http://www.audiokarma.org/forums/index.php?threads/the-fisher-phono-preamp-and-riaa.600690/

 

RE: Those transformers, posted on November 29, 2016 at 00:00:47
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 FenderLover, speaking of transformers, is it worth it to replace a large box silver faced Bandmaster's output transformer with a Bassman reproduction?

 

Bandmaster OPT, posted on November 29, 2016 at 06:08:57
FenderLover
 Nope. The Bandmaster (esp the Bandmaster Reverb) has one of the heavier duty OPT, of all dual 6L6GC output Fenders. And it's spec'ed for guitar use. Very clean tone, to super loud.

If you are going to use a bass through the amp --- I'd look for a good bass amp. Like vintage Ampeg Portaflex. Or more modern SVT.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 06:29:11
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 Rebuilding Mac 1500s now - OK Mike it looks like we are going to have to get you a second job now!!!!

I had two of them in the past and always felt some serious corners were cut to get these to market at a price point. After all they were intended for the "mid level" buyer and not the high end buyers.

It is interesting how you are fixing up some of the ills of that stereo. I always felt it had good bones but as I just mentioned - they were engineered with some serious short cuts and it showed.

There was this zener diode that would always blow - on both of them. Was that the filter cap you were referring too?

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 09:10:12
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 LOL
It's funny you say that because I just had two of my auto tech students ask me about the Fisher X202 in the trunk of my old Town Car which I can't lift out right now.Anyway, I have them doing a fuel filter change and FI flush for an exercise and you have to put the car in the air but before you do that,you have to shut off the air suspension in the trunk.That's when they asked me about that old funny looking tube amp that they so were so intrigued with.
I told them I rebuild this stuff and that's when said,does it pay better than teaching.LOL
We have one day a month where I allow them to bring their vehicles in and work on them and I grade the exercise but these two didn't have a car to work on so I let them change the fuel filter and flush the fuel system injectors on my car. Now I don't have to do it.

"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Bandmaster OPT, posted on November 29, 2016 at 10:03:44
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Hmm. the Bandmaster Reverb's transformer seems small for it's class. Much smaller than the Bandmaster non reverb or bassman. Maybe it's a good thing.

It's for guitar. For bass it wouldn't be much fun outside of a practice amp. I have to swap out a mid pot that was changed sometime to 25k and figure out why it thumps when the vibrato is engaged even if it's all the way down. All the electrolytic caps have been swapped and I tried a new LDR.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 10:48:33
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 I did not think that the 7591 was all that tough to drive. I thought the 12AX7 while weak was up to the job. Many that is why my Scott 222D and Dynaco SCA35 use pentodes for drivers.

Dave

 

RE: Bandmaster OPT, posted on November 29, 2016 at 10:52:33
FenderLover
 Unless there is something wrong with that tranny, I'd let it be. Potential buyers will check for trannies made within the time frame of the amp.

As for that thump... could be the foot switch. Contacts can get dirty. Sometimes, a little Deoxit fixes the problem.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 11:53:28
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 Full pentode mode "finals" are easy enough to drive. It's the "fixed" bias grid to ground resistance limit of the 7591 that's the sticking point. Fisher used 330 Kohm parts that have drifted upwards, over time. The data sheet gives 300 Kohms as max. From the beginning, Fisher was "out on a limb". :>( Current production 7591s are intolerant of the liberties Fisher took.

Mikey is on the right track in thinking 12DW7/7247. AAMOF, Fisher used the 7247 in the X-100. Then, "bean counting" set in. Reduce inventorying costs by stocking "only" 12AX7s. Never mind the fact that the high RP 'X7 triode must work into a high net AC impedance.

I'll upload the relevant X-100 schematic fragment, later today.


Eli D.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 13:08:48
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 I never owned a Mac 1500, but a few Fisher 400s & 500s. The Fishers are nothing special in stock form. A little muddy IMO. But, after some simple mods & tube upgrades, the Fishers are great & very musical. They sound like a live performance. They are better than a modded Scott 340B too.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 16:09:20
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Sony, have you ever tried any of the below tweaks that I put a link to in my below post? I still have to order the stuff to fix the riaa curve but the buffer after the volume really was a positive.

 

RE: Bandmaster OPT, posted on November 29, 2016 at 16:22:20
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 I was using a shorted rca plug to test:(. Just one of those odd issues.

 

Those Opt. transformers also say 352...= Magnetic Windings, posted on November 29, 2016 at 16:41:07
Interstage Tranny
Audiophile

Posts: 3063
Location: Eastern
Joined: October 4, 2006
 Magnetic Windings of Easton, PA made some of the finest trannies for many vintage HiFi manufacturers.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 17:19:58
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000



Fisher phono sections are notorious for poor bass extension. Reworking the phono section to use the tweaked RCA setup deals with that and allows the recording O/Ps to have respectable drive level.


Eli D.

 

Schematic Fragment, posted on November 29, 2016 at 17:23:15
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000






Eli D.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 17:28:35
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 They are better than a modded Scott 340B too."

I would love to see the mods you used because I haven't found that to be the case at all. I agree that they are muddy and distorted but I would love to try Danny's mods or ones you used. The 340A I really like and the 340B is good as well with proper upgrades.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Danny........., posted on November 29, 2016 at 17:45:16
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 I do not see your link for Fisher mods, but I will share exactly what I performed.

First I built a new RIAA with discrete components plus the fix for better low end. Frankly, I heard no difference from the stock RIAA.

I replaced all coupling capacitors with K40Y-9 including the phono section. I lowered the 7868 or 7591 with 220K grid resistors and changed the .047uF to .068uF at the power tube grid.

The power supply doubler changed to 2x 680uF 400 volt capacitors. Added a poly type 10uF capacitor on the doubler output. Change rectifiers to UF4007. Kept screen at 40uF, all others at 50uF.

Added two 3500uF for the bias supply & changed bias bridge rectifier to UF4007;

Used short plate Westinghouse 12AX7 or Brimar CV4004 in phono section. These tubes greatly clean up the phono section. Preamp section used RCA 12AX7 tall plate. Either black or grey are good with no noise issues like some black plates. Used vintage Tung Sol 12AX7s at phase inverters. RCA or Sylvania 7858 or 7591 finishes the tubes. Should mention a 12AT7 was used in the multiplexer output regardless if marked 12AX7.

After these mods, the clarity was greatly improved. The phono section was stunning- such a difference. It had a little chime in the audio that made it so musical sounding. Chime being like a church bell ringing if that makes sense.

 

Fender amp tremolo problem, posted on November 29, 2016 at 18:06:18
FenderLover
 So the amp "thumps" when the RCA shorting jack is in? But, doesn't if you remove this plug?

The Vibrato/Tremolo in the Bandmaster, the anode voltage seems to come from point "B." The only filtering prior to this point is the choke (which is prolly ok) and the first filter stage (series 70mfd caps).

Did you change the leveling 220k-ohm resistors, in this first stage? May have some imbalance between those two caps. Not enough filtering for the VIBRATO portion?

I like using 220k-ohm 2-watt metal oxide or 5-watt wire-wound Mills.

 

RE: Mac 1500 vs Fisher 500c., posted on November 29, 2016 at 18:20:16
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 Michael, see my post above.

 

@#$_&*!.... Shhhhhh-nT, posted on November 29, 2016 at 23:41:07
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 !
The Mind has No Firewall~ U.S. Army War College.

 

352 = Magnetic Windings, posted on November 30, 2016 at 06:16:17
FenderLover
 Is company also know as Essex? That's the EIA info I have for 352.

Anyhow, makes more sense. Entire code = 352529.

529 = 1965, 29th week. So Mike's receiver is an early production model.

Thanks!


8^)

 

Service manual, posted on November 30, 2016 at 06:23:47
FenderLover
 Schematics start on page 7.

 

As always, Excellent info! (nt), posted on November 30, 2016 at 10:01:33
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001

 

RE: Danny........., posted on November 30, 2016 at 14:26:18
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Sony, thank you. I have to open mine again to see what I used for the doubler etc. I know that I increased it but I can't remember to how much. I forsure did not add the poly cap.

Here's a link to my post with the links to Dave Gilespie tweaks.

http://audioasylum.com/forums/vintage/messages/23/237783.html

Believe it or not I actually liked Cornell Dubilier DMT caps in the output stage more so than the russian PIO's. They are polyester film/foil. It could have been that I didn't give the k40's enough time to run in etc but I've liked them in other rebuilds. I had the DMT's installed first so I may also have grew use to their sound.

http://www.mouser.com/ds/2/88/DMT-12545.pdf

http://www.mouser.com/ds/2/88/DMT-12545.pdf

 

RE: Fender amp tremolo problem, posted on November 30, 2016 at 18:45:57
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Thank you for the reply and ideas. I appreciate it and they are a great help.

I'll have to open the amp again and see if I changed out the 220k's. It's been years. If not I'll try that. I'll also see what's installed cap wise. I believe stock that the Bandmaster TFL5005D had a 5uf. I may have went to 10uf but probably not 25uf.

 

RE: Mac 1500 vs Fisher 500c., posted on November 30, 2016 at 21:44:24
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 I just remembered that my grandpa had a 1500 in his den when I was a kid. I would really love to hear one again. How much do they go for?

Thinking about the Fisher. It suffers from the miller effect without a buffer after it's volume pot before the power amp section. I think that is more of the issue than the driver tubes but I could be mistaken.

Dan

 

RE: Mac 1500 vs Fisher 500c., posted on November 30, 2016 at 22:29:28
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Look on Ebay because it can vary.What happened to the one gramps had?
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Mac 1500 vs Fisher 500c., posted on November 30, 2016 at 22:53:13
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 It probably got tossed when he passed:(. It was in the early 90's. I recall that he wasn't found of transistor amps probably partly because he could fix a tube setup himself. If I ever run across one and have the extra cash I'd love to pick one up for nestalgia.

 

For that tremolo drive 12AX7 in TFL 5005d, posted on December 1, 2016 at 00:07:17
FenderLover
 I'd had some 5mfd/50VDC caps a long, long time ago. Used 10mfd/50VDC and even 25mfd/50VDC. No difference in the tremolo tone, that I can tell.

An 8mfd/150VDC Sprague ATOM will fit, in that position. AES now stocks 5mfd/50VDC ATOMs.

 

RE: Fender amp tremolo problem, posted on December 1, 2016 at 04:53:07
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 220K on the power tube grids does not change the sonic signature. It keeps the power tubes from running away.

 

RE: Fender amp tremolo problem, posted on December 1, 2016 at 04:54:15
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 K40Y-9 take 50 hours to sound good and 200 hours to fully break in.

 

Very interesting post and follow ups. I have both, posted on December 1, 2016 at 14:05:24
gonzo
Audiophile

Posts: 2512
Location: new england
Joined: November 28, 2002
 a Fisher 500c and a Mac 1500 in stock form ( i.e., they need work) Is the mac the one to have restored rather than the 500c? Thanks Norm

 

RE: Very interesting post and follow ups. I have both, posted on December 1, 2016 at 19:50:36
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Norm
I think so absolutely. I'm awe struck by the 1500 with the mods I put in it and the other receiver I find to have really articulate balance as is the HK TA-260.The Mac 1500 just does it right.It doesn't behave like it's compromised like so many receivers are.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Mac 1500 vs Fisher 500c., posted on December 1, 2016 at 19:53:38
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 The only part of the 1500 is SS is the preamp section but they did it so well that you would never guess it have any solid state components in them.
If you think about it,CD players and DACs have SS output stages,most of them.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Mac 1500 vs Fisher 500c., posted on December 1, 2016 at 23:14:24
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Dude, totally. My favorite preamp is a recapped Apt Holman with my tube amps. it just seems to mesh perfectly. As long as the output stage is tube it sounds tube to me.

To be honest I never really cared for the tube preamp with a solid state amp.

 

RE: Very interesting post and follow ups. I have both, posted on December 1, 2016 at 23:22:03
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Mike, is the 260 that good? I sadly acquired one after my best friend suddenly passed away. I There isn't a day that goes by that I don't miss him.

Anyway, he had it on ice and was more into the 70's solid state stuff. I remember telling you about it when he got it from some tall guy in San Francisco among other details that escape me and you actually knew the guy he bought it from haha. Small world.

Dan

 

RE: For that tremolo drive 12AX7 in TFL 5005d, posted on December 1, 2016 at 23:23:47
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 I wonder if I have the wrong tube in the spot. I'll have to check on it.

 

RE: Phase Splitter Tubes, posted on December 2, 2016 at 14:20:51
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 I am not sure I would go with 6U8 or 12DW7 phase splitters. Any 12AU7 as in 1/2 of the 12DW7 are not good sounding tubes. I know a phase splitter is not as critical as preamp circuits, but every tube counts. 6U8s are ok, but still not an audio tube.

The best 12DW7 by a long shot were CBS 12DW7s. They are very rare now. It may take over a year just for one to show up on ebay.

 

RE: Very interesting post and follow ups. I have both, posted on December 2, 2016 at 22:05:25
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005









I got forgot to mention the Sherwood S-8000s are phenomenal as well.Even tho they have a 12AX7 driver,they also have a copper classes chassis.Yes,I like the HK 260 a lot because of the brilliant layout and circuitry,and overall execution.Even the controls are mounted on a separate chassis,away from anything that may cause issues.The iron is hefty as well.The quality of the controls are first rate,at least for the time and still for today.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Very interesting post and follow ups. I have both, posted on December 3, 2016 at 16:40:26
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 Mike, thanks for the reply. I really wanted a 8000 but I didn't pull the trigger when I should have. One was cheapish that needed some work here on craigslist but I was deep into a Fisher 400 at the time.

I'll drag the ta260 out. It's already partially rebuilt. I even have a extra set of output tubes for it.


 

RE: Mac 1500 vs Fisher 500c., posted on December 3, 2016 at 19:30:24
rickl
Audiophile

Posts: 583
Location: Twin Cities
Joined: February 7, 2002
 It is interesting to see the love for the McIntosh 1500. The C26 pre which is the basis of the 1500 doesn't get much love.

I've recapped my c26 per Terry Dewick and others on AudioKarma and it is fine (not my favorite pre but is sure is pretty).

looking for some jazz and a little libations - js

 

RE: Mac 1500 vs Fisher 500c., posted on December 3, 2016 at 19:36:36
rickl
Audiophile

Posts: 583
Location: Twin Cities
Joined: February 7, 2002


here is a pic
looking for some jazz and a little libations - js

 

RE: Mac 1500 vs Fisher 500c., posted on December 3, 2016 at 20:53:13
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 That sure looks nice. Where does the sound fall short for you?

 

RE: Mac 1500 vs Fisher 500c., posted on December 3, 2016 at 21:07:53
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Keep in mind that the preamp of the 1500 is going thru a tube amp and driver stage which helps a lot.Put Schotky diodes and PME-271 paper in wax caps in the audio path and you will really like you C26 much more. The C28 and C32 are much better but,you can do much more to your C26.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Mac 1500 vs Fisher 500c., posted on December 3, 2016 at 21:45:48
rickl
Audiophile

Posts: 583
Location: Twin Cities
Joined: February 7, 2002
 Thanks Mike. We might have chatted about these kemet caps in the past.

I'll put them on my next mouser order. I did not change out the coupling caps, only the electrolytics.

looking for some jazz and a little libations - js

 

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