Subject: JBL4320 Studio Monitor, year 1972 serial number 5188, 16 ohm - Amp ss (8ohm

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01-22-2018, 07:15 AM
anconi

Subject: JBL4320 Studio Monitor, year 1972 serial number 5188, 16 ohm - Amp ss (8ohm

Subject: JBL4320 Studio Monitor, year 1972 serial number 5188, 16 ohm - Amp ss (8ohm max) MacIntosh MC601 or MC275 tube (16 ohm 2 channels)
Buongiorn. I apologize for using the electronic translator. And also because I do not know if this is the place and the exact way to ask questions.
My father gave me this pair of speakers that I piloted with a 16 ohm vintage amp and are in perfect condition and original.
I would like to drive the "4320" with two MacIntosh MC601s or an MC275 tube in stereo.
Currently I have a MacIntosh M2500 tube Preamp. The length of the power cables is 12 meters; 450 cubic meters around the listening room.
- Questions: Has anyone listened to the "4320" (16 ohm) coupling with MacIntosh SS MC601 (8 ohms max) or with a CM 275tube? What impressions did you have?
Questions:
1) What changes in tone or quality can I expect with the coupling of an 8ohm MacIntosh output amp with JBL 4320 speakers at 16ohm?
2) The use of an amp tube 275 MacIntosh, which has outputs in stereo at 16ohm would solve the q.n ° "1", but I worry about the length of the cables and the little current supplied by the 275tube and less control of the woofer.
Many thanks to everyone.
01-22-2018, 12:53 PM
Ian Mackenzie

Welcome to the Lansing forums

In reference to the MC275 below is the user manual
Are you sure it only has 8 ohm output?

You may have an early model ?

I have also shown a link to a test report

https://content.abt.com/documents/81...nersmanual.pdf

https://www.stereophile.com/content/...r-measurements
http://www.mcintoshlabs.com/us/Produ...oductId=MC275B

Question 1

The main difference is you will only have 1/2 the power or 37.5 Watts
This amp has a low output impedance 8ohm tap so a variation in loudspeaker impedance won’t cause too much change in output voltage (see test report)

The Jbl 4320 has a minimum impedance of 12 ohms @175 hertz

Question 2

Refer to user manual link for instructions of connection for stereo 16 ohm load

In the case of the MC601 product specifications
http://www.mcintoshlabs.com/us/Produ...roductId=MC601

There are McIntosh users on the forums here
McIntosh also have a customer enquirers Portal in their website should you require more clarity

I am envious of your 4320’s and amplifiers.

Are you able to post a picture of the 4320’s?
01-23-2018, 01:06 PM
Mctwins

Quote:

Originally Posted by anconi

Subject: JBL4320 Studio Monitor, year 1972 serial number 5188, 16 ohm - Amp ss (8ohm max) MacIntosh MC601 or MC275 tube (16 ohm 2 channels)
Buongiorn. I apologize for using the electronic translator. And also because I do not know if this is the place and the exact way to ask questions.
My father gave me this pair of speakers that I piloted with a 16 ohm vintage amp and are in perfect condition and original.
I would like to drive the "4320" with two MacIntosh MC601s or an MC275 tube in stereo.
Currently I have a MacIntosh M2500 tube Preamp. The length of the power cables is 12 meters; 450 cubic meters around the listening room.
- Questions: Has anyone listened to the "4320" (16 ohm) coupling with MacIntosh SS MC601 (8 ohms max) or with a CM 275tube? What impressions did you have?
Questions:
1) What changes in tone or quality can I expect with the coupling of an 8ohm MacIntosh output amp with JBL 4320 speakers at 16ohm?
2) The use of an amp tube 275 MacIntosh, which has outputs in stereo at 16ohm would solve the q.n ° "1", but I worry about the length of the cables and the little current supplied by the 275tube and less control of the woofer.
Many thanks to everyone.

Hallo!

I don't have listening to that particular speaker but to me one MC275 in stereo mode connected to 16ohm tap is more than enough to drive the jbl 4320.

A MC601 is "overkill" for those speakers, my opinion.

According to specs for jbl 4320 is 60 Watts(RMS), program 120 Watts.
01-23-2018, 01:39 PM
speakerdave

Quote:

Originally Posted by Mctwins

Hallo!

I don't have listening to that particular speaker but to me one MC275 in stereo mode connected to 16ohm tap is more than enough to drive the jbl 4320.

A MC601 is "overkill" for those speakers, my opinion.

According to specs for jbl 4320 is 60 Watts(RMS), program 120 Watts.

+1

In my experience 200 solid state watts carefully used can harmlessly liven up a very efficient vintage speaker--in my case an Altec 604-8G--over what a 60 watt tube amp does, but 600 watts could be dangerous. One mistake could shred the woofer, and authentic recone kits for the LE15A are no longer available.
01-23-2018, 04:44 PM
Ian Mackenzie

+1

That MC601 reminds me of the movie The Forbidden Planet...Lol
01-24-2018, 03:57 AM
anconi

Dear Ian Mackenzie, thank you very much for your answer. Thanks also to Mctwins
I gladly send the "4320" hole, with the newly reconstructed woofers. Let me know, please which address.
I apologize, but I have probably misunderstood the questions and I have not understood the answers well, and I thank you again for the answers you want to give me.
I already have the Mac M2500tube, but I still have to choose the final power between MC601 or MC275 and ask for advice for the best coupling with the 4320. To those who listen to them, or for comparable experiences, I ask for an opinion on these couplings for these speakers .
1) At your answer n1 you speak of a halving of power. I am obliged by the absence of outputs in the MC601 at 16 ohms, and then I expect about a halving of the power, even if it has the output transformers, connecting it to 8ohm output. I do not understand when you say for the "601" 37.5watt. Did you mean 375 watts. ?
Please refer to "This amp has a low output impedance 8ohm tap a variation in loudspeaker" But the test for the MC 275, or I did not find that of the 601? I misunderstood?
This made me think I was referring to 275; that in any case I would eventually use two channels, but from the 16 ohm output.
2) I turned to you and the forum to ask if anyone has had direct listening experiences with these 4320 and the indicated electronics; or comparable experiences comparable to those I have exhibited. I understand that it is not easy, and for this I also thank you.
3) You suggest me to ask MacIntosch users in the portal. I did not find the forum in the MacIntosh portal
Your opinion like that of others will be very welcome
Thanks again and best regards,
01-24-2018, 04:04 AM
anconi

I apologize, my writing was also addressed to speakerdave, which I had not seen. Greetings and thanks for him too.
01-25-2018, 11:22 AM
anconi

Dear Ian Mackenzie, I re-read your post yesterday. Can you please tell me what your sentence means "That MC601 reminds me of the movie The Forbidden Planet ... Lol".
Thanks and good job.
01-25-2018, 11:38 AM
Ian Mackenzie

http://www.tcm.com/tcmdb/title/1114/...et/videos.html

It’s a sci fi movie. Lots of big meters demonstration unlimited power
01-25-2018, 11:42 AM
Ian Mackenzie

It’s lost in the translation

Try the MC275
The MC275 is 75 Watts into 8 ohms
The MC275 is 37.5 Watts into 16 ohms.

Can you post a pic of the MC275 do we can see the speaker connections?
01-27-2018, 08:19 AM
anconi

5 Attachment(s)

Quote:

Originally Posted by Ian Mackenzie

It’s lost in the translation

Try the MC275
The MC275 is 75 Watts into 8 ohms
The MC275 is 37.5 Watts into 16 ohms.

Can you post a pic of the MC275 do we can see the speaker connections?

Dear Ian Mackenzie and all the others,
Thank you for your availability; I repeat, I have not yet bought the power amplifiers, either MC275 or MC601. My problem is not how to connect the 4320 to the faucets.
I have listened to many pairs, of these electronics and those of other high-level producers, but never with the "4320" I restricted the field to MacIntosh, but I could not listen to them together with my sneakers. The already present M2500 tube pre I like a lot in the audio chain.
I am looking for someone who has listened to them together "JBL4320 and MC601" or "JBL4320 and MC275tube" and, please, if he has to give me his impressions of listening. their opinions, even on similar situations. I thank you all.
* JBL4320: 2x SS MC601 "or" 1 MC275tube stereo 16ohm "?
I make purely theoretical considerations, which I hope are correct, ready to correct me.
I understand that the doubts you have reported to me are probably due to the following reasons, in addition to the excessive power: JBL woofers in AlNiCo and in ferrite (the 2215 of the 4320 is in AlNiCo) and tend to generate a non-negligible back-EMF , like all more or less, and this voltage generated by the movement of the magnetic group during operation, which returns to the amplifier must be controlled. The phenomenon is more noticeable as the power supplied by the amplifier increases.
For this problem, it seems to me, that there are two factors to the advantage and others against in my case.
I'm:
a) The wofers are of large diameter, therefore less sensitive than smaller cones with the same SPL; to deliver EMF to the amplifier.
b) The large power of the MC601 (compared to 4320) and their efficiency would lead to a very high SPL even at relatively low power delivery, for example 25/30% of the maximum assuming that the power that can be delivered by the 8 "faucets" 601 is "only" 300w. This, in theory, should still reduce the problem of woofer control. The power reserve could benefit from dynamics and instantaneous peaks of a large orchestra.
On the other hand it seems to me that there is a general problem due to the low output impedance of the final power amplifier, a consequence, in particular, of the autotransformers, both solid and even more so on the MC275 valve, perhaps also due to the "linearity" 16ohm, I'm wondering ???
I have listened with other speakers, but I have not found a great problem such a presence of the autotransformer, especially with Solid State amp, compensated perhaps by the great music, scene plans and silentness of the MAC. This is my impression with many installations heard, even from other brands.
What is yours?
This is what MAC declares: DAMPING FACTOR: MC601:> 40 Wideband; MC275:> 22.
 Any McIntosh transistor amplifier including MC601 will work fine on 16 Ohms if you use the 8 ohm output.
This will reduce the power of the MC601 to around 400 watts since the MC601 "
Thanks to everyone and have a good weekend.
01-29-2018, 04:27 AM
anconi

I also added photos of the "4320". I'm sorry for the orientation error of two photos.
You like them? What do you think and what suggestions do you have?
Best regards to everyone
01-29-2018, 05:00 AM
Ian Mackenzie

Very nice photos
The 4320 is nice

Can l make a suggestion

(This is not an advertisement)

There is a way to solve your concerns

Yes different brand
l use this brand for over 17 years.

I have tried numerous brands and l personally prefer the Pass labs amplifiers with JBL loudspeakers.

Why?
Vintage Jbl systems take on a new lease of life with Pass amplifiers.
Simply put these amplifiers operate in class A at low power levels and l feel this is very important with efficient loudspeakers using horn compression drivers.

Due to the dynamic behaviour of horns and the piston operation of the metal diaphragm in the compression driver the horn can be be very revealing or analytical.

Some people find the slant plate lens magnifies this characteristic.

At low levels this is a problem and people blame the horn and lens.

With the Pass Labs amplifiers at low levels there is no switching distortion, glare or electronic haze with the compression driver and slant plate lens.

My Jbls have been compared to Quad electrostatic loudspeakers by visiting listeners.

In the end you have to make your own decision.

https://www.passlabs.com/amplifier/x260.8

Or
https://www.passlabs.com/amplifier/int-250

http://www.theabsolutesound.com/arti...ted-amplifier/

It will do about 130 Watts into 16 ohms
High damping factor
Very hi fidelity
01-30-2018, 10:22 AM
anconi

Quote:

Originally Posted by Ian Mackenzie

Very nice photos
The 4320 is nice

Can l make a suggestion

(This is not an advertisement)

There is a way to solve your concerns

Yes different brand
l use this brand for over 17 years.

I have tried numerous brands and l personally prefer the Pass labs amplifiers with JBL loudspeakers.

Why?
Vintage Jbl systems take on a new lease of life with Pass amplifiers.
Simply put these amplifiers operate in class A at low power levels and l feel this is very important with efficient loudspeakers using horn compression drivers.

Due to the dynamic behaviour of horns and the piston operation of the metal diaphragm in the compression driver the horn can be be very revealing or analytical.

Some people find the slant plate lens magnifies this characteristic.

At low levels this is a problem and people blame the horn and lens.

With the Pass Labs amplifiers at low levels there is no switching distortion, glare or electronic haze with the compression driver and slant plate lens.

My Jbls have been compared to Quad electrostatic loudspeakers by visiting listeners.

In the end you have to make your own decision.

https://www.passlabs.com/amplifier/x260.8

Or
https://www.passlabs.com/amplifier/int-250

http://www.theabsolutesound.com/arti...ted-amplifier/

It will do about 130 Watts into 16 ohms
High damping factor
Very hi fidelity

Thank you very much for the advice and the motivations you wrote. I hope to have the possibility of a comparison of these electronics.
You gave me a good reason to reflect on some doubts I had.
You will have noticed in the photos the conditions of the "4320" and the environment in which they sound: the speakers seem like new; the listening environment could definitely improve. I do not know your opinion.
A cordial greeting and good work.
01-30-2018, 01:10 PM
Ian Mackenzie

It all looks very nice.

I would take your time. See if you can borrow amplifier for a trial at home?