jjasniew say
" OK, maybe I could drive the 18" assists with it, but, what a waste of a gorgeous amp like that for a <100Hz job."
Well, I didn't ask the price of the mammoths, (for what?) But surely the class D amplifiers that guys use for PA will do their homework and maybe better if they have DSP, in fact I feed two 18 "subwoofers with Bheringer NX3000D , and I have saved some good money ........😉
Is it the same to travel in a Rolls Royce as in a VW "beetle"? The two fulfill their task fully, they transfer you from one place to another, but there are people who can pay some extras while the trip lasts .....
" OK, maybe I could drive the 18" assists with it, but, what a waste of a gorgeous amp like that for a <100Hz job."
Well, I didn't ask the price of the mammoths, (for what?) But surely the class D amplifiers that guys use for PA will do their homework and maybe better if they have DSP, in fact I feed two 18 "subwoofers with Bheringer NX3000D , and I have saved some good money ........😉
Is it the same to travel in a Rolls Royce as in a VW "beetle"? The two fulfill their task fully, they transfer you from one place to another, but there are people who can pay some extras while the trip lasts .....
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This video was recorded by me 😱 , it is easy to perceive that the microphone of the smartphone is saturated when I approach the right sector, it can be clearly distortion.
As always, appreciating the real sound recording audio with YT is impossible, but in this case it is worse from what I tell you, I assure you that they sound very, very good!
On the next visit I will use a tripod located in the sweet spot !
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The MC Intosh solution is called "Autoformer"
It is known that on the web there are all kinds of information, very good and very bad, going through intermediate points.
This article is very simplistic and with technical errors.
McIntosh transformers – PS Audio
And in this forum we find an excellent and highly recommended link to read in full, and a summary that I copy below:
Autotransformers - why does McIntosh use them? | Audiokarma Home Audio Stereo Discussion Forums
(See post 10)
" This is from the Roger Russell web site.
McIntosh Laboratory Part 1
The McIntosh Autoformer
Transistor power output circuits can match 8-ohm loads directly. This eliminates the need for the output transformer for most manufacturers. However, output stages that are designed to operate into an optimum load of 8 ohms can double or quadruple heat dissipation when operating into 4 or 2 ohm loads. At some frequencies, speakers rated at 8 ohms can dip as low as 4 ohms. Some 4-ohm systems can dip even lower. This mismatch can cause the amplifier to exceed its thermal dissipation limits.
On the other hand, if an amplifier is designed for an optimum load of one or two ohms, a low impedance load would be no problem. However, less power would be available for a speaker having 4 or 8 ohms impedance.
The unique McIntosh output autoformer was the answer. Since McIntosh output stages were connected in a single ended push-pull circuit, one side of the output was always connected to ground. They were typically designed to work into an optimum load of 2.1 ohms. The matching autoformer was connected directly to the output. In the MC2505 amplifier, the matching output was for 4, 8 and 16 ohms. Other impedances became available in later amplifiers. Full continuous amplifier power could be delivered to each of these loads. There qas no danger of exceeding safe limits or overheating.
The autoformer also protected the speakers from damage in the event of amplifier failure. Should a direct current component appear at the amplifier output, it was shunted by the low DC resistance of the autoformer, instead of passing through the speaker voice coil, which could damage the speaker or even cause a fire.
McIntosh autoformers continued to be used in the "top-of-the-line" amplifiers. They were all designed and manufactured by McIntosh. Although the autoformers added extra cost, weight and took up extra space, they assured a safe, optimum match to a variety of speakers and speaker hook-ups. They were constructed and performed in the McIntosh tradition of excellence. "
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The MC1500 has the same output transformer "type" as the MC275, the one with the cathode windings. I've seen articles where you can change the output tubes and get more power, but I'm not going to molest the unit to do that. I think the output tubes are along the lines of 7591, but more power is achieved than would be usual via the transformer design. It's fine by me as-is ;')
I see you have an output transformer with windings for 4-8-16 Ohms. If they are the famous "autoformers" the power delivered in any connection should be the same, as the specs of the Mc275.
Yes, the tubes output are 7591, not KT 88 as I thought.
Yes, the tubes output are 7591, not KT 88 as I thought.
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