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I have one stock pair that is refurbished and another one that is modded in a way that appears to be based on Roy's design... It has the recommended Hi Vi tweeter and a large copper coil on the back.

Thinking about stacking them ala Advent. Tweeters together in the middle.

Roy's on top or bottom?

Anyone done this and have recommendations?

Would love to hear from you, Roy... Glenn?

And anyone, Mr. Kent.

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I don't think it much matters which is on top, but the original is supposed to have better dispersion than the Hi-Vi so maybe factor that in.

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The most important in addition to proper room placement and high-quality input sources is to use two separate power amps that are matched.

Two amplifiers that are equal in power and ideally the same manufacturer.

See example below.

https://community.classicspeakerpages.net/topic/10649-do-ar-speakers-really-sound-that-good-more-new-video/

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I haven't stacked 2ax's yet but have stacked AR5's on top of AR2ax's. While two identical power amps receiving the same signal might be preferable, I just used the speaker A and B outputs on a receiver. Since both speakers are 8 ohm that would be the same as wiring them in parallel. Just make sure the amp has enough power and can handle 4 ohm loads. Not being identical speakers the dome midranges of the 5's were quite prominent, but the overall voicing was close.

fr0mOw5m.jpg4ESxADfm.jpg 

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I'd advise caution as Larybody suggests. Neither the 2aX nor Advent has a particularly flat impedence curve, unlike the Dynaco A25, which does, relatively speaking. 

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1 hour ago, Jim Pearce said:

I don't understand. There is a risk that you are warning me about I think. What is it?

Yes.

On 8/29/2020 at 9:50 PM, lARrybody said:

make sure the amp has enough power and can handle 4 ohm loads.

Make sure the amp is rated by the manufacturer for 4 ohm loads.

 

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8-31-2020

Far be it from me to be a proponent of the use of receivers, much less of ever having owned one in my long time history in the world of high-fidelity since 1967. At 17 years old, I learned at an early stage of my hi-fi travels that the best way to go was with separate individual components.

Having a separate pre-amp and amplifier offers more service dependability and reliability but, also offer the ability to change either or both amp and pre-amp in-order to upgrade whenever one chooses to. It’s like either buying your own home where you can change anything you want at anytime or by using a receiver it’s akin to renting a furnished monthly apartment that you simply occupy and have minimal options of change. In my early investigations in the world of high-fidelity, I chose early on that the separate components offered the most flexibility.

The casual listener or person who choses not to delve the furthest they could venture to, opts to purchase a receiver, admittedly, I was not that sort of person. I wanted to grow with the hobby in my quest to get the best sound I possibility could according to what level my finances and knowledge afforded me so, I took the path of separate components.

If the ‘OP’ is simply experimenting or thinking of options in the future, it is best to be cautious with how you hook-up the components and be watchful of temperatures and performance of the receiver being used because when stressing especially an amplifier, the ‘end’ of the experimentation can rear its ugly head in a split-second or quicker than an unexpected rogue fart.

See my short post here: https://community.classicspeakerpages.net/topic/11312-ar-58s-rebuild/page/3/?tab=comments#comment-131209

This link may be of use: http://forums.audioreview.com/vintage-gear/what-vintage-receivers-handle-4-ohm-speakers-35724.html

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Hi Jim, I had a ST-120 also, in 1972.  I built it in kit form. I think it cost me $89. or $129. I don't recall. Although I would imagine other's had good service from it and I truly had great faith in the Dynaco brand as did "AR" but, my experience was one of the bad ones. This doesn't mean it's not a good amp but, when I used it with my AR-3a's in 1972, when deep bass was in a recording, I had to tell myself I was hearing it although,  I was probably diluting myself because it was always very faint and slight in volume.

I still have another one I bought used so I still have some faith in it though.  I haven't used it since early 1983 and I won't take a chance unless I used a variac first.

Personally, pushing that amp with 4 speakers might be a high risk. I believe others who may have had a better time at using it than I did might assist you and have a more positive reply.

Here's another  ST-120 link: https://community.classicspeakerpages.net/topic/12086-dyna-stereo-one-twenty/

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Jim

The ST-120 is, I believe only rated for 8 ohms. And it’s old. Good amp for one pair of speakers IF it has been checked out. Maybe add another ST-120?

Kent

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I've said it numerous times. I didn't fully realize what the AR-3a 12" woofer could do in terms of phenomenal bass response until I first hooked up a new Phase Linear PL-400 amplifier in mid 1974. It offered 210 watts RMS @ 8 ohms per-side, double that at 4 ohms.It had opened up a whole new world of high-quality with a new crispness in the highs, intense depth, strong solid bass, separation of tonal qualities of each instrument, and an amazing sense of 'real' to my system. All of those who insist on using anything less are short-sighted. And gee, that was 46 years ago, ""C'mon man"". With-in a short time I was further made to understand what a hardy, strong and powerful performer the AR-3a midrange speaker was in handling all of those watts. Before that I also used the ST-120 to drive my 3as and it sounded basically lackluster. When I approached moderately 'loud-ish' volume levels 'acoustic-feedback' would show its ugly face. Not fun and I started saving for something else and in that period the 'muscle-amp-era' was just becoming popular. But that ST-120  amplifier made me suffer and chomp at the bit about wanting to own the recent developments of the 'super-power' amps as they were referred to. 

Now, I push 16 tweeters at one time and those mids are simply amazing as they are able to soak up and output gobs of power with-out flinching in the slightest. The sole biggest difference between the AR-2ax and the AR-5 is the AR-5 has the better midrange speaker.

And Jim, at the risk of discouraging you, you can receive all kinds of replies here and elsewhere combined but, you won't be fully convinced or let down until you try things on your own but, no, I personally would not recommend pushing that amp as Jkent has indicated and for all of bad experiences I had with it.

 

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23 hours ago, JKent said:

Jim

The ST-120 is, I believe only rated for 8 ohms. And it’s old. Good amp for one pair of speakers IF it has been checked out. Maybe add another ST-120?

Kent

Not sure what you mean.

Are you suggesting that I run two systems, one on the top of the other, stacked, that I patch the two amps together and in effect make one amp?

In any case, I have no idea how to go about wiring two amps except to biamp.

I could figure out how to biamp, running one amp to the tweeters and another to the woofers, is that what you're suggesting?

 

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On 8/29/2020 at 11:40 AM, JKent said:

I don't think it much matters which is on top, but the original is supposed to have better dispersion than the Hi-Vi so maybe factor that in.

I guess I will put the superior tweeter in a position at the same level at which I spend most of my eartime.

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On 8/30/2020 at 7:45 PM, Martin said:

I'd advise caution as Larybody suggests. Neither the 2aX nor Advent has a particularly flat impedence curve, unlike the Dynaco A25, which does, relatively speaking. 

Not sure what the ramifications this arrangement are, what the caveats are.

Why is caution needed?

What are the risks?

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On 8/29/2020 at 8:50 PM, lARrybody said:

I haven't stacked 2ax's yet but have stacked AR5's on top of AR2ax's. While two identical power amps receiving the same signal might be preferable, I just used the speaker A and B outputs on a receiver. Since both speakers are 8 ohm that would be the same as wiring them in parallel. Just make sure the amp has enough power and can handle 4 ohm loads. Not being identical speakers the dome midranges of the 5's were quite prominent, but the overall voicing was close.

fr0mOw5m.jpg4ESxADfm.jpg 

Aha, here is the post I was looking for...how can I tell how much power is enough?

I hope there is something measurable and not subjective.

 

Also, someone said something about needing a variac.

I have always thought that it was only needed for tube gear.

This st120 is the first solid state made by this outfit.

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23 minutes ago, Jim Pearce said:

Not sure what you mean.

Are you suggesting that I run two systems, one on the top of the other, stacked, that I patch the two amps together and in effect make one amp?

In any case, I have no idea how to go about wiring two amps except to biamp.

I could figure out how to biamp, running one amp to the tweeters and another to the woofers, is that what you're suggesting?

 

the pat-4 has outs to two amps. connect one pair of speakers to each amp

using a variac couldn’t hurt. if the amp has not been used in a while it will re-form the caps slowly but with something that old i recommend a real technician check it out 

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Unless I'm misremembering, the original Absolute Sound article was about vertically stacking Large Advent speakers, tweeter-to-tweeter. This turned out to be the best alignment. 

A stock Dynaco Stereo 120 isn't comfortable with low-impedance loads, especially when trying to reproduce a low frequency signal at volume; running 4 AR-2ax speakers from a single ST-120 could be a problem for the amplifier.

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@ Jim P. Show us a photo of what you're using in room used so we'll all have a better idea.

And as I suggested early on, use a 'variac' or the 'light-bulb switch' method which is actually better. With that amp I would think an 8 or 10 AMP variac would be sufficient.  Ultimately, if your experience is limited or non-existent, do as others have said,  seek qualified help.

 

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4 hours ago, JKent said:

the pat-4 has outs to two amps. connect one pair of speakers to each amp

using a variac couldn’t hurt. if the amp has not been used in a while it will re-form the caps slowly but with something that old i recommend a real technician check it out 

Oh and oh .

Thanks and thanks.

Next duty would be to research the reform thing .

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Thanks for all of your help, all of you.

And yes, my knowledge and abilities are limited.

There are, fortunately, two local people that are far more knowledgeable that I could ever hope to be.

Yesterday I happened to come by a pair of University 315c series 200 triaxials in original cabinets for 60 bucks. Cabinets extremely rough, pulled a back and interior seems pristine.

Probably not appropriate to discuss these here but would definitely welcome comments on them. Private messages welcomed.

They're pristine and appear to be a classic, that's for sure.

Admin, thanks for your tolerance.

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  • 2 weeks later...

Your University speakers are a nice find. Highly efficient and therefore,  the opposite in so many ways of the New England speakers we love. I have a lone University 6303 which is a cheap version of yours and it sounds fantastic.   BTW, I like JKent's idea to use 2 stereo amps to power your stacked 2aXs. That solves the impedance problem nicely. 

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