Scotty, I need more power!

[kevzep]

All this gushing about the 2505 has a strong basis in truth. Most of us who love this little amp actually have owned one and listened to it for many years. I bought mine new in 1971 after saving up for a year for it and a C-26. It was my main amp for many years until my kids all had made their way in the world and I started having some discretionary funds. I realize that amplification has improved greatly in the years since the 2505 was new. All I care about is that the system is musical and sounds like the recording, warts and all. Over the years I've been on AK I've seen many folks pan different gear. Most that put it down have never owned or spent any time with what they don't like when questioned closely. YMMV.

I have to say, I was more excited about the sound of a MC250 I restored for a customer than I was about my MC2205 purchase.
Just like I feel there is something very special about the sound of the MC452, the MC250/2505 is in the same boat.
They are great little amps and punch well above their weight in sound quality.

 

[TSmith8605]

My view is that with the MC452, you have entered a new realm of amplification, and maybe the pairing of what you had before was a good match for your speakers (tonally), but now you have an imbalance, the amplifier is lightyears ahead and could well be showing some limitations of the speakers you are using.
Its improved your sound, but now the speakers could be holding the MC452 back?
Food for thought?

I agree. However, I spent a few hours this last weekend at the Cal Audio Show in Oakland and spent lots of time listening to many systems and speakers with speaker prices ranging from maybe $6K a pair to $60K a pair. I had some favorites. Focal, Joseph Audio, ML CLX and my favorite two were the Sound Lab full-range 'stats and the completely different Audio Note speakers. Many or most could do things that my Acoustats cannot but I also heard significant flaws in most rooms. But these are quick setups in hotel rooms with electronics with which I am not familiar. So I take the flaws I heard with a grain of salt.

With that experience in mind, I went home and listened to my stuff and, to my surprise, I lost the urge to upgrade the speakers - they were just fine. I did not get the feeling that my system was very far from the stuff I heard and the process of speaker replacement would be hugely daunting and expensive.

OK, I have no expectations on my speakers, I would not recommend them or promote them to others and am not trying to defend my decision (30 years ago) to buy them. I think of them as BOTL speakers. But they just keep being good. And now I am amazed that they keep up with the power output of the MC452.

But I also feel that neither the MX121 nor the C220, both of which are really great, are at the same level as the MC452. So, an upgrade there may be coming. Maybe.

 

[Mike Gibson]

With that experience in mind, I went home and listened to my stuff and, to my surprise, I lost the urge to upgrade the speakers - they were just fine. I did not get the feeling that my system was very far from the stuff I heard and the process of speaker replacement would be hugely daunting and expensive.

OK, I have no expectations on my speakers, I would not recommend them or promote them to others and am not trying to defend my decision (30 years ago) to buy them. I think of them as BOTL speakers. But they just keep being good. And now I am amazed that they keep up with the power output of the MC452.

Now is when you realize it's more about the music than the gear. When you get to the point that a song you really enjoy can draw you into the music while being played on a car radio then you have arrived. Life gets cheaper then as all you need buy is media.

 

[TSmith8605]

Well, the MC452 is not replacing my MC2505, it is replacing my MC275 IV. The MC2505 is normally in my "vintage" system between my C22 and my OL Advents and the MC275 IV is normally running the 'stat panels with the MF SS amp assisting with bass.

A couple of months ago, I switched them just to see what would happen and the MC2505 did very well with the stats. Neither it nor the MC275 have the power really needed for these speakers and in this regard, they were about the same. The MC2505 provided a certain smoothness to the upper midrange that I loved and I think was some kind of synergy or something to do with the complex interaction of highly reactive speakers with autoformers vs MC275 output transformers. Maybe.

The MC275 IV is very nice between the C22 and OL Advents, but that combination is a little too soft - lots of tubes and the Advents are known to have a slight suck-out somewhere in the mid-range and combine that with the C22's softer sound and then the MC275 pushes (only a little) too much further in soft direction. There are a couple of small tubes in the MC275 IV that maybe could be switched out to help but the vintage system is supposed to be vintage and so using a modern amp violates the rules.

Another MC 275 IV with the same output tubes as mine came up on Barter Town a few months ago and I all most bought it. It would have matched mine perfectly for mono-block mode and 3 more dB. But that was only 3 more dB and actually more expensive than MC 452 and I'd have to deal with a lot of tubes.

The MC 275 IV is a lovely, beautiful sounding amp, but it is being displaced here by the MC452. MC2505 will go back into the vintage system when I get to it.

 

[Mike Gibson]

When I went to an active crossover over on my speakers I used my 275 on the horns and 2205 on the woofers. I now use a 2125 on the horns and the 2205 on the woofers. I love being able to dial in the sound just the way I like it. You can spend a few dollars on an ACT crossover as I did or spend thousands on a Marchand. The reason I didn't buy a Marchand wasn't the price it was the flexibility. You have to buy a module for every frequency you want to try. Plus it's not change on the fly.

 

[TSmith8605]

Run the Mc452 stand alone. I think that you may be surprised

I could not find the damping factor spec. on the Musical Fidelity amp but my guess is it higher than 40 (MC452) but regardless I would fully expect improved bass performance full range with MC452.

But, doing so would require too much digging around and moving stuff to get at the wires - the easiest way would be to make up a new set of speaker wires rather than try to dig you the existing wires. Still might be worth the effort for an experiment.

But also, I have a Niles stepped-attunator in the line between the pre and MF amp and that allows me to easily shift the level of the woofer relative to the main panel, something I do a lot and something that would be harder to do with one amp. So if just for that, I like two amps. The MF is about 25 years old and may need repair or replacement at some point and that might be a time to upgrade the woofer amp - unless the speakers fall apart first. The MF is third woofer amp I've had on these speakers replacing an Adcom (now used for rear channels) and and ARC D52B (which broke and could not be repaired.)

Also, using the MC452 on the woofers would renew my fear of overdriving or over-extending the speaker - likely by some loud explosion or other sound effect when watching a movie. This woofer was not designed to be a HT sound-effects woofer. I had a 17" Trinitron when I bought these speakers.

Note I am set up to quickly hook the woofer amp up full range and do (did) that so as not to waste tubes on hours of use for TV sound. This is no longer an issue with the SS amp now on the 'stat panels.

 

[SaturationPt]

Interesting on the cost of the 2nd MC275, that is what has me shopping a new 452 also. I looked at a pair of used Mark Levinsons, price of a used McIntosh, other options and it doesn't make sense to me to buy a used amp for half the price of a new McIntosh amp. In the case of a used ML it's slightly more money for less performance, Krell is more performance for more money, 450 seems like the sweet spot. If it's about money, it would make sense to sell what I have and replace it with the 452, and have money left over.

It seems that the MC452 is a bit of a bargain right now in new hifi, am I looking at this wrong?

 

[TSmith8605]

Interesting on the cost of the 2nd MC275, that is what has me shopping a new 452 also. I looked at a pair of used Mark Levinsons, price of a used McIntosh, other options and it doesn't make sense to me to buy a used amp for half the price of a new McIntosh amp. In the case of a used ML it's slightly more money for less performance, Krell is more performance for more money, 450 seems like the sweet spot. If it's about money, it would make sense to sell what I have and replace it with the 452, and have money left over.

It seems that the MC452 is a bit of a bargain right now in new hifi, am I looking at this wrong?

I have never owned either Krell or ML amps - I did once own a ML JC-2 Preamp - but I've heard them in the past in stores and shows. I recall the Krells hooked to Apogees and Sound Lab A1s and I preferred the A1s. Also, I have no insight into reliability or maintainability of those brands. Can only comment on what I hear with MC452 in my house that seems to be the same as what other owners hear and it does seem to be in a price / performance sweet spot within the McIntosh line.

 

[TSmith8605]

. . .Sounds like a MC 452 would be about perfect by providing about 3 dB headroom above the recommended power for the speakers. And when I do blow up the speakers. . .

Well I was listening and began to notice that the right speaker was down a bit in output and that the right channel tended to clip a lot when the left channel was not. Putting my ear closer to the speaker, I heard some hum. Disconnected the power amp (speaker wire) from the speaker and the hum got louder. I assume this means the high-voltage (5kV) bias supply has failed.

Removed the interface box from the speaker and got a nose full of magic smoke smell.

Pix above show what I guess you would call the high-voltage board within the speaker interface. In the first picture, the large cap is in the signal path after the audio step-up transformer and everything else is the HV bias supply. The 3 resistors in the bottom photo (other side of the same board) are in the signal path after the step-up transformer.

Here's my theory of failure:

The yellow wire brings signal from the audio step-up transformer to the large gray resistor. I think there was a cold or poor solder joint at that connection in the circuit board that caused a voltage drop here. A voltage drop along with the normal current means power is developed in the solder joint causing it to heat up. The resin stain and general mess makes me think the solder actually melted and heated the PC board enough for it to turn into a mess in that corner.

Note that despite this, the big resistor still measures fine (as does the big signal-path cap) and the connection still works - signal still gets through. Also, the DC resistances of the transformers seem to look OK and match with those in the still-good interface.

But I think all this heat on the board caused the adjacent HV bias supply (basically the 5 little caps and the 5 HV diodes) to fail.

I will wire around the mess in the corner of the board and replace the 5 caps and the 5 diodes and I think that will fix it. I did move the good interface box from the left speaker over to the right speaker and it seemed to work meaning that hopefully the stators and diaphragm are fine.

Parts are on the way.

 

[TSmith8605]

I can tell from all the responses to post #110 that you all are on the edge of your seats waiting to hear more news.

I managed to fix the speaker by replacing all the components in the bias supply (except the transformer which is fine) and directly wiring around the burned part of the PC board. Very interesting working with high (5 kV) voltages - you can't really measure much. I did not repair the undamaged speaker (because it's working and I did not want to tear into it) but I have all the parts now for that speaker's bias supply rebuild if needed.

Now both speakers sound and play the same and everything installed and working again and sounding great.

I think I got a little cavalier with these speakers (when using the MC 452) thinking they're old and not worth much and so no big deal. But having spent some time recently at shows listening to very expensive speakers and after having these my 'stats offline for 3 weeks and missing them, I decided that finding replacements would by harder to do than I thought. My new MG 1.7i are very nice and have a bit sweeter midrange but are not going to replace the 'stats. So, I will proceed with more caution in the future - although I believe this failure was caused by a less than perfect solder joint combined more recently with a bunch more current from the MC 452.

 

[Encyc Brown]

My upstairs system is in a 11” x 11” foot room. Dedicated music room. High end ? Na but it all works well for me IMHO

 

[TSmith8605]

My upstairs system is in a 11” x 11” foot room. Dedicated music room. High end ? Na but it all works well for me IMHO. . .

Looks nice but I think you need a couple more cassette decks. What's the R-to-R hiding there?

 

[Encyc Brown]

1891805[/ATTACH]

Looks nice but I think you need a couple more cassette decks. What's the R-to-R hiding there?

Like these in the downstairs system? Lol ya I like Tape. I was one of the ones that depleted the nations last stock of BASF Chrome Tape from National Audio Co, Delta Media and Duplicate.CA along with ATR. However ATR found more pancake tape of the BASF Chrome and have some in stock. Once gone I would say that’s the last of true Chromium Dioxide Type II this country will ever see made as EPA regulations wont allow manufacture anymore. I now have about 2000 new cassette including some new old stock but I only buy new tape from the above mentioned Anyway, behind the Sony TC-399 lurks a BlueDento Bluetooth receiver. I have one downstairs also. I subscribe to premium YouTube and access any LP commercial free with high resolution and dumb it down to analog tape. The results are exquisite especially on the Pioneer CTF-700 as that one is spectacular. All 9 Cassette decks and 2 reel decks have been serviced via new belts and lubrications and whatever else the service tech needed to do to get them all to factory spec in working order

 

[TSmith8605]

Wow!

 

[Encyc Brown]

Wow!

Thanks It is an interesting adventure to put time, effort and money into the one medium that is probably more “dead” than any other. It is a gamble. My goal was to stock up on enough blank new tape to get me through the latter years in life as it may become even more obsolete in time. Right now, there are dedicated companies trying to fill the needs of the niche “tape head” consumers. Unfortunately the gear is gone as no one produces new high quality tape decks. So one must use vintage gear and do what one can to keep it up and running. I don’t work on them, no skills there. I make a 4 hour round trip drive from Bluefield WV to Roanoke VA to Lee Hartman and Sons as they have a very competent service dept. I really enjoy the “art” of recording and find great satisfaction in making the tapes Sound stellar. I use templates for labels when I use the bulk quantity tape purchases as cases and Jcards are purchased separately and hand print tapes that come with all that Jazz. Here are an example of each, cheers

The MAC 6700 has more than enough power to bring these tapes to life! Plus at my age of 59, I will never get the LP’s I want on vinyl. So recording via digital source from the high resolution offered by premium subscription to YouTube affords the ability to dial up any LP I want and get a copy to tape to build a “physical collection” as opposed to just storing on a computer.

 

[damacman]

Thanks It is an interesting adventure to put time, effort and money into the one medium that is probably more “dead” than any other. It is a gamble. My goal was to stock up on enough blank new tape to get me through the latter years in life as it may become even more obsolete in time. Right now, there are dedicated companies trying to fill the needs of the niche “tape head” consumers. Unfortunately the gear is gone as no one produces new high quality tape decks. So one must use vintage gear and do what one can to keep it up and running. I don’t work on them, no skills there. I make a 4 hour round trip drive from Bluefield WV to Roanoke VA to Lee Hartman and Sons as they have a very competent service dept. I really enjoy the “art” of recording and find great satisfaction in making the tapes Sound stellar. I use templates for labels when I use the bulk quantity tape purchases as cases and Jcards are purchased separately and hand print tapes that come with all that Jazz. Here are an example of each, cheers

The MAC 6700 has more than enough power to bring these tapes to life! Plus at my age of 59, I will never get the LP’s I want on vinyl. So recording via digital source from the high resolution offered by premium subscription to YouTube affords the ability to dial up any LP I want and get a copy to tape to build a “physical collection” as opposed to just storing on a computer.
View attachment 1892909
View attachment 1892910 View attachment 1892911 View attachment 1892917 View attachment 1892915 View attachment 1892916

You are without question dedicated to the cause! I'd like to hear one of your tapes on my Nak 505.

 

[Encyc Brown]

You are without question dedicated to the cause! I'd like to hear one of your tapes on my Nak 505.

I would like to hear that also! Naks are the McIntosh of the Tape world with no doubt!

 

[Robvolz]

Wow, this thread has it all,
New amps,
obscure speakers
some drama
cassette hoarders (nothing wrong with that, I admire your passion)

 

[damacman]

Wow, this thread has it all,
New amps,
obscure speakers
some drama
cassette hoarders (nothing wrong with that, I admire your passion)

right?