Hello,
I am looking for this kind of amp to use in a bi amped system to connect to my Altec voice of the theatre bass bins.
There will be a 12 db passive filter placed at its entrance that works best with high input impedance. The mc2505 is 200K so that will be ok.
The Altec 515 woofers are 16 ohm and the mc 2505 autotransformer has a 16 ohm tap so perfect as well.
Some of the models like the mc2200 dont have a 16 ohm tap.
Are there any pitfalls buying these old amps?
I guess it will be wise to replace the caps in the power supply. Todays caps are smaller and better . Maybe recifiers too?
Dont wanna stasrt changing active parts but will be easy to find a replacements for the transistors once they are going downhill?
Greetrings, Eduard
I am looking for this kind of amp to use in a bi amped system to connect to my Altec voice of the theatre bass bins.
There will be a 12 db passive filter placed at its entrance that works best with high input impedance. The mc2505 is 200K so that will be ok.
The Altec 515 woofers are 16 ohm and the mc 2505 autotransformer has a 16 ohm tap so perfect as well.
Some of the models like the mc2200 dont have a 16 ohm tap.
Are there any pitfalls buying these old amps?
I guess it will be wise to replace the caps in the power supply. Todays caps are smaller and better . Maybe recifiers too?
Dont wanna stasrt changing active parts but will be easy to find a replacements for the transistors once they are going downhill?
Greetrings, Eduard
As it looks 16ohms 75W, any 150W/8ohms amplifier will be OK to use. You don't need output transformer.
Sajti
Sajti
Hello,
The impedance curve of this Altec system is one that is difficult to '' drive '' well. The Hiraga 20/30 watts can do it . Using an output transformer will give the amp an easy load to control. But because these 515 units are not made anymore i want something with an output transformer and a little bit of power. A well designed 30 watt will do.
There are some Nelson Pass design with output transformer but they lack a bit of power. I will hear one in Vietnam in dercember maybe it will change my mind.
Greetings, eduard
The impedance curve of this Altec system is one that is difficult to '' drive '' well. The Hiraga 20/30 watts can do it . Using an output transformer will give the amp an easy load to control. But because these 515 units are not made anymore i want something with an output transformer and a little bit of power. A well designed 30 watt will do.
There are some Nelson Pass design with output transformer but they lack a bit of power. I will hear one in Vietnam in dercember maybe it will change my mind.
Greetings, eduard
A 120W McIntosh MC2120 or MC2125 (metered version) has a 16Ω tap, and after changing a few old caps sounds phenomenal on horn-loaded studio monitors.
It will not hurt the older fragile studio monitors either.
My friend seldom runs over 1.2W in his studio on his JBL monitors (unless I am doing the final mix).
I used my MC2120 to drive the HF in a tri-amp PA, still have two MC2120.
It will not hurt the older fragile studio monitors either.
My friend seldom runs over 1.2W in his studio on his JBL monitors (unless I am doing the final mix).
I used my MC2120 to drive the HF in a tri-amp PA, still have two MC2120.
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Hi Guys
Why is the small-signal crossover passive?
You could expand the range of possible PAs simply by adding a buffer to the crossover output. Of course, if you are doing that it would be even more sensible to make an active crossover: 12dB only requires one opamp filter preferably driven by a buffer itself.
To drive the 16R load to 30W would require a conventional amp rated at 60W into 8R, which is not expensive to buy nor difficult to build. Unless you want the specific sound and distortion of the McIntosh, there are much simpler ways to go that will result in more accurate sound.
djk: I don't see how you can get a good mix listening to it that loud. My studio monitors produce 90dB with 1W input and I cannot sty in the room if it is that loud. It is much easier to hear everything 10-20dB quieter. But to each his own...
Have fun
Why is the small-signal crossover passive?
You could expand the range of possible PAs simply by adding a buffer to the crossover output. Of course, if you are doing that it would be even more sensible to make an active crossover: 12dB only requires one opamp filter preferably driven by a buffer itself.
To drive the 16R load to 30W would require a conventional amp rated at 60W into 8R, which is not expensive to buy nor difficult to build. Unless you want the specific sound and distortion of the McIntosh, there are much simpler ways to go that will result in more accurate sound.
djk: I don't see how you can get a good mix listening to it that loud. My studio monitors produce 90dB with 1W input and I cannot sty in the room if it is that loud. It is much easier to hear everything 10-20dB quieter. But to each his own...
Have fun
Hello,
The original Altec Lansing A7 with 8 ohm woofers does have two peaks in its impedance that makes them hard to drive by ''traditional amplifiers''. One of the few that is doing well is the Hiraga 20 and 30 watts and most tube gear do well because of the output transformers.
I did built mine with the 515 16G, which is a 16 ohm woofer because my present amp has an output transformer designed for that load.
I have the design of a passive cross over that can be inserted bewteen a low output impedance pre amp and a high input impedance power amp.
There are some Mcintosh on ebay but getting them to eorope will make them rather expensive. I have to be sure they are working ok. The only thing i will probably do is change some capacitors.
I know there are models with 16 ohm taps and ones with only 2/4 and 8 ohm. I really want a 16 ohm tap.
Greetings, Eduard
The original Altec Lansing A7 with 8 ohm woofers does have two peaks in its impedance that makes them hard to drive by ''traditional amplifiers''. One of the few that is doing well is the Hiraga 20 and 30 watts and most tube gear do well because of the output transformers.
I did built mine with the 515 16G, which is a 16 ohm woofer because my present amp has an output transformer designed for that load.
I have the design of a passive cross over that can be inserted bewteen a low output impedance pre amp and a high input impedance power amp.
There are some Mcintosh on ebay but getting them to eorope will make them rather expensive. I have to be sure they are working ok. The only thing i will probably do is change some capacitors.
I know there are models with 16 ohm taps and ones with only 2/4 and 8 ohm. I really want a 16 ohm tap.
Greetings, Eduard
" I don't see how you can get a good mix listening to it that loud. "
It's simple, the music has real drums in the mix, sometimes violin too.
A friend (violin) player had five different instruments for different venues. When he played in a Country and Western band the pedal steel player (with a 500W amp on 101dB/W/1M speakers) complained the violin (un-amplified, not even his loudest violin) was too loud on stage (even with a mute on it).
It's simple, the music has real drums in the mix, sometimes violin too.
A friend (violin) player had five different instruments for different venues. When he played in a Country and Western band the pedal steel player (with a 500W amp on 101dB/W/1M speakers) complained the violin (un-amplified, not even his loudest violin) was too loud on stage (even with a mute on it).
Hello,
I did buy a Mcintosh mc2505 on ebay in the usa. With track and trace i can see it is already arrived in my country. So now have to wait for taxes to be added and the bill to be presented during delivery.
Did read a bit on this device. It did cost 549$ at introduction which is more than 3000 hamburger at that age. What kind of people did buy these amps in those days?
I will have to find the copy of articles i have about passive crossover networks for bi-amplifier systems. I have one from Sound Practices must have another one published in another Americain magazine in the sixties? using adjustable? Peerless inductors.
Any additional info is welcome!
The french did start using this topology in the eighties but you did need pre amp with low impedance output . I HAVE. And power amps with high impedance input.
Maybe as a start i will just '' feed '' the full frequency range to the mc2505 and use 12 db filter at its output. I think the signal above 600 cycles will not present much of an extra load? I dont wanna start adding parts inside the mc2505 right from the start.
Any ideas welcome.
Greetings, Eduard
I did buy a Mcintosh mc2505 on ebay in the usa. With track and trace i can see it is already arrived in my country. So now have to wait for taxes to be added and the bill to be presented during delivery.
Did read a bit on this device. It did cost 549$ at introduction which is more than 3000 hamburger at that age. What kind of people did buy these amps in those days?
I will have to find the copy of articles i have about passive crossover networks for bi-amplifier systems. I have one from Sound Practices must have another one published in another Americain magazine in the sixties? using adjustable? Peerless inductors.
Any additional info is welcome!
The french did start using this topology in the eighties but you did need pre amp with low impedance output . I HAVE. And power amps with high impedance input.
Maybe as a start i will just '' feed '' the full frequency range to the mc2505 and use 12 db filter at its output. I think the signal above 600 cycles will not present much of an extra load? I dont wanna start adding parts inside the mc2505 right from the start.
Any ideas welcome.
Greetings, Eduard
Hello,
Got my MC2505 yesterday. I love the looks of it.
Maybe i wanna add a regulator for the input stage. Transformer is specified for 110 ma and the dc supplied to the circuit is 90 volts. I already asked Belleson in the USA if they can make a single rail regulator.
The output stage has a double rail supply with 40 volts output. The current rating of the transformer is 3.1 A so the output stage will be class AB or B.
I am thinking about adding an extra filter in its power supply. Now it is just a single 10000 µF cap for each rail and i wanna try CLC with same value cap and a few hundred mH choke from Lundahl. What current rating would i need?
I might even add a regulator from Belleson there too because they give good results in my DDDAC too.
Greetings, Eduard
Got my MC2505 yesterday. I love the looks of it.
Maybe i wanna add a regulator for the input stage. Transformer is specified for 110 ma and the dc supplied to the circuit is 90 volts. I already asked Belleson in the USA if they can make a single rail regulator.
The output stage has a double rail supply with 40 volts output. The current rating of the transformer is 3.1 A so the output stage will be class AB or B.
I am thinking about adding an extra filter in its power supply. Now it is just a single 10000 µF cap for each rail and i wanna try CLC with same value cap and a few hundred mH choke from Lundahl. What current rating would i need?
I might even add a regulator from Belleson there too because they give good results in my DDDAC too.
Greetings, Eduard
Hello,
Decided to change the power supply from one 9300 µF on the + and one on the - side to a CLC one with 8200 µF 100 mH and a final 22000 µF mundorf 63 volts caps.
One could say if the original caps are ok why replace them. BUT this amplifier is old and one day it might go wrong.
I will replace the smaller caps used for the input stage power supply as well.
Maybe the ones on the circuit boards. They cost peanuts.
Because i will have to reposition the caps i might as well replace the resistors in the power supply too to assure good soldering using new parts.
Anything else to replace in the Mcintosh mc2505?
Installing new bindingpost and bypassing the speaker on/off switch would be benificial but not sure if i will go this far.....
Greetings, Eduard
Decided to change the power supply from one 9300 µF on the + and one on the - side to a CLC one with 8200 µF 100 mH and a final 22000 µF mundorf 63 volts caps.
One could say if the original caps are ok why replace them. BUT this amplifier is old and one day it might go wrong.
I will replace the smaller caps used for the input stage power supply as well.
Maybe the ones on the circuit boards. They cost peanuts.
Because i will have to reposition the caps i might as well replace the resistors in the power supply too to assure good soldering using new parts.
Anything else to replace in the Mcintosh mc2505?
Installing new bindingpost and bypassing the speaker on/off switch would be benificial but not sure if i will go this far.....
Greetings, Eduard
Hello,
Anyone has the right information needed to order the hardware( screws) needed for attaching the bottom plate to the main chassis. I know it isnt metric.
Greetings, Eduard
Anyone has the right information needed to order the hardware( screws) needed for attaching the bottom plate to the main chassis. I know it isnt metric.
Greetings, Eduard
Hello,
The USA must be hibernating.
Because i am in the proces of replacing the two smaller caps mounted on the chassis i can use the hardware that was used to mount these 2 caps.
Greetings, Eduard
The USA must be hibernating.
Because i am in the proces of replacing the two smaller caps mounted on the chassis i can use the hardware that was used to mount these 2 caps.
Greetings, Eduard
Hybernating? 😱
Did you consider than between March 30 when you asked and today there is a weekend involved?
Plus it being Easter Holiday
I know anxious people but you must be near the top of the list 🙄
Hello,
Usually i am online during weekend.
Easter is for people who like chocolate, i dont
Religion may be an excellent means of taming and training the pervers, obtuse and wicked biped race: but in the eyes of the friend of truth every fraud, however pious, is still a fraud. ( Arthur Schopenhauer)
Greeting, Eduard
Usually i am online during weekend.
Easter is for people who like chocolate, i dont
Religion may be an excellent means of taming and training the pervers, obtuse and wicked biped race: but in the eyes of the friend of truth every fraud, however pious, is still a fraud. ( Arthur Schopenhauer)
Greeting, Eduard
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