Setup Question - Dynaco Quadaptor

[Jackal]

Hey guys,

I'm trying to figure out how I'm going to set up my stereo & speakers. I'm currently running my pair of MK IV's with a PAS-3 and FM-3. To "complete" the set, I purchased a Quadaptor. I know it's not the best at developing a "true" quadraphonic sound (I hear it's better to do it at the line in level), but I love how it fits will the rest of the set.

I have two questions over implementation:

1). The instruction manual recommends the two mono blocks share a common ground. Is this something that can be accomplished by simply tying the two amp grounds together? I feel this will be difficult due to the size and small spacing of the terminal posts. Could I just ground them together by running a wire between chassis screws instead?

2). I am planning on running my AR-3a's for the front and AR-2ax's for the rear (thank you Roy for both!!!). Are the 2ax's overkill? I have a pair of AR-4x's that are also available for this application.

I'm working on designing a cabinet that should nicely incorporate each component, including the two digital voltmeters I use to monitor bias

Thanks,

-Jack

[dynaco_dan]

Hey guys,

I'm trying to figure out how I'm going to set up my stereo & speakers. I'm currently running my pair of MK IV's with a PAS-3 and FM-3. To "complete" the set, I purchased a Quadaptor. I know it's not the best at developing a "true" quadraphonic sound (I hear it's better to do it at the line in level), but I love how it fits will the rest of the set.

I have two questions over implementation:

1). The instruction manual recommends the two mono blocks share a common ground. Is this something that can be accomplished by simply tying the two amp grounds together? I feel this will be difficult due to the size and small spacing of the terminal posts. Could I just ground them together by running a wire between chassis screws instead?

2). I am planning on running my AR-3a's for the front and AR-2ax's for the rear (thank you Roy for both!!!). Are the 2ax's overkill? I have a pair of AR-4x's that are also available for this application.

I'm working on designing a cabinet that should nicely incorporate each component, including the two digital voltmeters I use to monitor bias

Thanks,

-Jack

Hi there

The Quadaptor does not distort the signal and can, if recorded, playback the recording studio ambience.

The Dynaco pre-amp, if a PAS-3X, and FM-3 tuner, are very suitable with a lot of stereo equipment, if working

properly.

The PAS-3X has a very high acceptance factor with tube followers.

The amps unfortunately are at the low end of power output for the 3A's and maybe even the 2AX's.

That is just driving them individually, at low levels, not together.

The 4X's would likely shine if used by themselves in stereo at moderate levels.

The Dynaco MK iV's are very stable but only have a low output into 8 ohms, never mind 4 ohms or lower.

A second pair of 4X's would make for a very good amplifier Quad match, I feel.

To think about using the 3A's and 2AX's with the Quadaptor, maybe lean towards a 50 watts or higher per

channel stereo amplifier or two mono amplifiers.

If you had more amplifier power the 3A's in front and the 2AX's in rear would sound excellent.

Be cautious with the thumbscrew connectors on the quadaptor, they are very close and a short is a possible

unless the leads are tinned.

If the FM-3 tuner ever requires shipping, DON'T, it may well be damaged beyond repair, visit AVA.COM, re

Frank's FM-3 shipping story.

Any wooden sleave, metal preferred, will need a large ventilation opening top and bottom because of the tube heat.

[Jackal]

Hi Dan,

I haven't yet had any problems driving the AR-3a's at moderate volume; the 40 wpc RMS seems to be holding up ok. That may be due to the size and setup of the room, though.

I have heard of people driving the 3a's with much less (although I can't imagine them working too well).

Any comment on the common ground issue?

Thanks,

-Jack

[dynaco_dan]

Hi Dan,

I haven't yet had any problems driving the AR-3a's at moderate volume; the 40 wpc RMS seems to be holding up ok. That may be due to the size and setup of the room, though.

I have heard of people driving the 3a's with much less (although I can't imagine them working too well).

Any comment on the common ground issue?

Thanks,

-Jack

Hi again

You will be able to drive those speakers at a much reduced volume level than with a larger amp i was suggesting.

After the FTC committee formed a written policy for, pre-conditioning, hifi manufactureres to follow, the only Dyna amp that met their standard, un-

altered amp that is, was the Dyna 400.

Their other models were derated to meet the, maybe unfair and very out to lunch, test requirements and methods, rather than the usual world

we,live in.

Some lesser other hifi equipment was re-advertised at a different lower rating and re-introduced as a new model, rather than scrapping them.

The Mark 4 is likely a very clean 20 - 25 watts continuous, not 40 watts RMS, at 8 ohms, at perhaps even 20 - 20,000 Hz.

I do not have the amps 4 or 16 ohm output numbers or if there is any that we can discus here.

The AR-3A has tremendous demands on an amplifier, any amplifier, with it's low efficiency and woofer and tweeter high and low impedance

loads.

AR recommended 25 watts per channel for the AR-3A's and less for the 2AX's and AR-4X's.

These were very conservative minimum figures and 2 - 4 times or more is much better.

With moderate usuage of the volume control you should enjoy each pair of speakers but I certainly would not suggest using the quadaptor

and either other speaker pair.

Your amps will not blow up or anything crazy, just they will be over-taxed.

As I mentioned earlier, I feel that the amps would sound great with the AR-2AX's 8 ohm load and even happpier with just a pair of AR-4X's or add

another pair of AR-4X's to keep the Quadaptor sound quality and load within reason.

Your electronic equipment with a pair of AR-4X's or 2 pair with a Quadaptor, would have been a dream system and a best buy, back then and even

now.

You can tye both DYNACO, and most all other amps, ground connections together or separate but be certain they are both the ground

connections and not one hot ( + positive ) and one ground ( - negative ).

I used to sometimes strip about an inch of insulation off both leads, form a small circle and wrap the end over and solder, sort of a fabricated loop to

slip over the screw post or thumb screws.

Solder terminals are also great if soldered.

I had an idea, too many ideas, not enough time or money, I was going to buy 8/32 brass threaded standoffs and cut them in half and drill out one

end to accomodate a banana plug.

I was then going to remove the machine screws from the Quadaptor and from the inside screw out brass 8/32 machine screw with lock washers

and thread the 1/2 standoffs and then used use banana plugs.

If you do not solder the wires at least twist them tightly and form a half circle plus and place the wires so that when you tighten the nuts ot thumb

screws the insulated side will be on the left so when you make a tight connection the wire will tend to tighten rather than loosen.

Touching, even briefly, the hot and ground wires can cause the amplifiers to have a mild heart attack, tube amps to a lesser degree.

With some cheap or older solid state amplifiers that error could cause the output stages to go up in smoke.

The better solid state amps have electronic or fuse protection which may help.

[Jackal]

Hey Dan,

I wasn't aware of the FTC committee rule (for others who had no idea, check http://en.wikipedia.org/wiki/Audio_power#Continuous_power, second paragraph). Thanks for that news. 20-25 watts is lower than I thought, but still seems to be more than enough for the 3a's. I don't ever have to turn it too high to get a good volume level out of the amps, maybe the Tung-Sol EL-34B's really do eek out a few extra watts? I'll try the 2ax with the 4x's when I experiment with the Quadaptor.

Do many tube amps get higher than that? I have seen solid state get to rediculous numbers, but never see high numbers with tube amps, unless they have a large number of output tubes.

-Jack

[dynaco_dan]

Hey Dan,

I wasn't aware of the FTC committee rule (for others who had no idea, check http://en.wikipedia....ontinuous_power, second paragraph). Thanks for that news. 20-25 watts is lower than I thought, but still seems to be more than enough for the 3a's. I don't ever have to turn it too high to get a good volume level out of the amps, maybe the Tung-Sol EL-34B's really do eek out a few extra watts? I'll try the 2ax with the 4x's when I experiment with the Quadaptor.

Do many tube amps get higher than that? I have seen solid state get to rediculous numbers, but never see high numbers with tube amps, unless they have a large number of output tubes.

-Jack

Hi again

Somehow i wrote to that commitee around 1974, I was then registered to receive the results.

Recently I came across their reply to me and an original copy of the final printed results.

Being a federal copyrighted document I cannot post it here and also there is a lot of pages.

Perhaps others here have more knowledge than I but I felt that there was a move in an honest direction at least.

Apparently there was still ways to work around with numbers after the report was published.

Dynaco Mark 3, a mono amp, and St 70, stereo amp, tube amps are highly sought after today and the supply is much less than the demand.

The Mark 3's, slightly more output, were used a lot by musicians and the ST-70 can be changed to mono for increased output.

They also are only 20 +/- continuous watts greater than the Mark 4's, basicly hardly audible improvement but perhaps cleaner sounding..

There was and is other tube equipment suppliers but they are even much more money and with little more in return.

Typically a 60 watt or more continuos per channel s/s amp is more appropriate but if you are happy continue to enjoy.

I just wanted to make you aware of the limitations of your using the Quadaptor and very inefficient AR-3A speakers.

You may well enjoy your original Quadaptor idea but at least you are a little more aware of it's limitations.

I do not use the RMS descriptor here as this is not valid in our description.

[pvk-also]

I used a QD-1 for years. I absolutely loved it. Then, for years, I had no system. Now that I've finally put together another system, I'll be damned if I can find my old Quadapter. I don't mind using the QD-1, even if it controls speakers instead of line level. As to 5-1 surround and its afficionados, I ask them how many ears they have. Personally, I only have two, and

I can still tell where someone is in relation to me, front or back, side to side, and I don't need to see them to know. Our minds are very good at picking out sound sources out of a group of sounds. Our brains decode the ambiance for us. All recording equipment can record this ambiance, and most all playback equipment can reproduce it, except, of course, for the front speakers, given that you're really asking them to do two different things at the same time. Reflections off the walls of a studio or, better yet, a concert hall, all get recorded, and just need to be extracted from the main signals via the Quadapter. What the quadapter does is provide a stable impedance to the amp. Personally, I use a separate amp and preamp for the rear. Right now, without my Quadapter, I simply ran the positive speaker cables to the amp, and just tied the negatives together, behind the amp, without attaching them to the amp. This works quite fine, but without the Quadapter, you basically have 3.2 ohms, so your amp better be at least 2 ohm stable. Again, this setup works well for me. I just wish I could find my old Quadapter. :-)

[dynaco_dan]

I used a QD-1 for years. I absolutely loved it. Then, for years, I had no system. Now that I've finally put together another system, I'll be damned if I can find my old Quadapter. I don't mind using the QD-1, even if it controls speakers instead of line level. As to 5-1 surround and its afficionados, I ask them how many ears they have. Personally, I only have two, and

I can still tell where someone is in relation to me, front or back, side to side, and I don't need to see them to know. Our minds are very good at picking out sound sources out of a group of sounds. Our brains decode the ambiance for us. All recording equipment can record this ambiance, and most all playback equipment can reproduce it, except, of course, for the front speakers, given that you're really asking them to do two different things at the same time. Reflections off the walls of a studio or, better yet, a concert hall, all get recorded, and just need to be extracted from the main signals via the Quadapter. What the quadapter does is provide a stable impedance to the amp. Personally, I use a separate amp and preamp for the rear. Right now, without my Quadapter, I simply ran the positive speaker cables to the amp, and just tied the negatives together, behind the amp, without attaching them to the amp. This works quite fine, but without the Quadapter, you basically have 3.2 ohms, so your amp better be at least 2 ohm stable. Again, this setup works well for me. I just wish I could find my old Quadapter. :-)

Hi there

The Dynaco QD-1 Quadaptor is a very reasonable system enhancer at a very affordable price, either in kit form or factory wired.

It is always nice to read of someones use in their system.

There was at least one inquiry here about someone building one recently from scratch.

I mentioned that they usually go for around $40.00 on ebuy.

There is not a lot of parts to the kit but the switch is special and the 3 level pots are non-existant today.

If one was to attempt to duplicate function, the switch may still be one of those few models produced by Electroswitch.

The 3 section w-w pot can be duplicated in function with 3 Ohmite or equal w-w pots and a stacking bracket kit.

In all likely-hood it will cost well over $100.00 plus case, etc.