One last question about A25's

[craig]

The person at van l speakerworks chicago says my dynaco A25's would sound better if i bypass the switch, He is replacing the caps and resisters on them for me. I'm afraid if i bypass the switch i will miss the max setting on them. I called him back,he's still waiting for the parts, he said he could replace both the one below setting and the max setting, but doing it that way he would have to use the switch and he doesn't recommend it. He swears it will sound cleaner if i bypass the switch but i wont beable to max it out then, he will replace it with the value one below max. What route is better ? whats the best solution out of the 2 ? I'm torn

[Martin]

As the longtime owner of many pairs of A-25s and A-35s (as well as several A-25XLs and A-40XLs with the 3-position switch) I can tell you that the tweeter controls are very useful just as Dynaco originally intended and IMHO, should not be limited. As you know, the tweeter control position you choose depends on your room environment and placement more than anything else, so it's difficult to provide you with a meaningful answer. I have successfully used each of the 5 positions in different rooms over the years and would not want to have fewer choices than what Dynaco originally provided. Given your dilemma, why not bypass the switch and see how they sound in your listening room. If you like what you hear, your problem is solved. If you don't, you can go back to plan "B".

[craig]

As the longtime owner of many pairs of A-25s and A-35s (as well as several A-25XLs and A-40XLs with the 3-position switch) I can tell you that the tweeter controls are very useful just as Dynaco originally intended and IMHO, should not be limited. As you know, the tweeter control position you choose depends on your room environment and placement more than anything else, so it's difficult to provide you with a meaningful answer. I have successfully used each of the 5 positions in different rooms over the years and would not want to have fewer choices than what Dynaco originally provided. Given your dilemma, why not bypass the switch and see how they sound in your listening room. If you like what you hear, your problem is solved. If you don't, you can go back to plan "B".

well im having a speaker shop do it for me, they seem to think i should bypass it, everytime i argue against bypassing they tell me it's silly not to bypass it. i don't use all 5 positions but i do use normal one above normal and max positions. whats imho stand for ? they havn't started it yet maybe i should call them and just take them back and pay for the parts decide later.

[dynaco_dan]

well im having a speaker shop do it for me, they seem to think i should bypass it, everytime i argue against bypassing they tell me it's silly not to bypass it. i don't use all 5 positions but i do use normal one above normal and max positions. whats imho stand for ?

they havn't started it yet maybe i should call them and just take them back and pay for the parts decide later.

Hi there

If the capacitor is a dud, it will definitely need to be replaced.

Replacing it with what brand and model is not carved in stone, yet.

Solen makes a decent and reasonable cap and they are readily available.

Definitely if you were to spend about $100.00 for each cap you will hear a difference, Murphy's Law.

The value can be close to the OEM cap, as they do not make an exact value, plus tolerances.

Unless the switch is broken or the resistors are blown, just leave the speakers as stock.

After all this, they may also charge you an estimate fee plus the parts.

[craig]

Hi there

If the capacitor is a dud, it will definitely need to be replaced.

Replacing it with what brand and model is not carved in stone, yet.

Solen makes a decent and reasonable cap and they are readily available.

Definitely if you were to spend about $100.00 for each cap you will hear a difference, Murphy's Law.

The value can be close to the OEM cap, as they do not make an exact value, plus tolerances.

Unless the switch is broken or the resistors are blown, just leave the speakers as stock.

After all this, they may also charge you an estimate fee plus the parts.

Thanks, I made a decision and decided to keep the switch, he's going to replace the max value and the one above max. I'm not sure how bad the cap was to begin with but i figure after 40 years its time to replace it. they sounded pretty damn good, i orginally took them in for a buzzing problem wich he has already repaired. He said he's going to use calarity brand cap's so not quite as expensive as your suggestion but i hope they sound even better or at least just as good. I'm taking a chance with them i guess. They should be done next tues or weds, ill let you know what i think of the results. I have another pair that have no work done to them so i can compare.

[Robert S]

Thanks, I made a decision and decided to keep the switch, he's going to replace the max value and the one above max. I'm not sure how bad the cap was to begin with but i figure after 40 years its time to replace it. they sounded pretty damn good, i orginally took them in for a buzzing problem wich he has already repaired. He said he's going to use calarity brand cap's so not quite as expensive as your suggestion but i hope they sound even better or at least just as good. I'm taking a chance with them i guess. They should be done next tues or weds, ill let you know what i think of the results. I have another pair that have no work done to them so i can compare.

Dear Friend: I had a pair of A-25's for a few years until they were stolen, replaced by A-35's - same drivers & crossover in a larger cabinet. Good for you for keeping the switch! Not sure why you should 'replace the max value' etc. The switch selects a series of 2 ohm resistors, which are in turn with a series 6 uF (?) capacitor with the tweeter - the resistors are ceramic wire-wound units, very reliable. Hey, the switch bypasses itself in one position -- perhaps you just need to squirt it with a good contact cleaner.

Always worth replacing the capacitor, but do NOT get sucked in to 'high-end' stuff, a cunsumer rip-off even worse than ink-jet cartridges! And forget electrolytics, and 'bipolar'. There are good film capacitors out there, Solen was mentioned, 50 volts or more is plenty. One source for those and equally good ones might be Parts Express, catalog pages 159 - 161. For example, a 6.2 uF propoplyene 250V film capacitor, about right for your speakers, is $2.68. [[Disclaimer: I have no association with Parts Express]]

Good luck with restoring your A-25s! Best speakers I've ever heard, but that was many years ago.

[craig]

Dear Friend: I had a pair of A-25's for a few years until they were stolen, replaced by A-35's - same drivers & crossover in a larger cabinet. Good for you for keeping the switch! Not sure why you should 'replace the max value' etc. The switch selects a series of 2 ohm resistors, which are in turn with a series 6 uF (?) capacitor with the tweeter - the resistors are ceramic wire-wound units, very reliable. Hey, the switch bypasses itself in one position -- perhaps you just need to squirt it with a good contact cleaner.

Always worth replacing the capacitor, but do NOT get sucked in to 'high-end' stuff, a cunsumer rip-off even worse than ink-jet cartridges! And forget electrolytics, and 'bipolar'. There are good film capacitors out there, Solen was mentioned, 50 volts or more is plenty. One source for those and equally good ones might be Parts Express, catalog pages 159 - 161. For example, a 6.2 uF propoplyene 250V film capacitor, about right for your speakers, is $2.68. [[Disclaimer: I have no association with Parts Express]]

Good luck with restoring your A-25s! Best speakers I've ever heard, but that was many years ago.

I men't to say one above normal and the max position, i rarely use the max but but i rarely use normal (usually use one above). I'm actually a little worried they will be changed too much but i have a spare pair in case i don't like the restoration. He mentioned he doubled the neg on the something and rewired the tweeter on top of replacing 2 caps and all the resistors i didn't ask him to double the neg or whatever he did but he says they sound tighter and deeper and sweeter. i'm a little worried because i don't know double the neg means , but he does have a good reputation, ill find out how they sound tomorrow when i go to pick them up.

[Horswispr]

What's your verdict about the restored Dynaco A-25s? I have found that the 5-position switches on Dynacos are NOT problematic and should just be left alone. They don't tend to get scratchy or "go out" like those on AR-2axs, etc. As far as capacitors go, I just use the 5.1 mfd 5% tolerance caps from Solen or Dayton (between about $3 and $6 each at Parts Express) and they sound fine. Sometimes there's a bit of improvement; sometimes the old caps were OK and I'm not even sure I hear any improvement.

[craig]

the verdict was i had a mixed reaction .... after many tests i found out one of them sounded distorted even after rehab the other sounded good more air to the highs and less mids getting to the highs but a tiny bit less smooth at very loud volumes, even that is hard to judge knowing my pre amp is the weak part of my system. something about the rehabbed ones i still didn't like so i took them down for a month put them back up only to find something was weird about them, then with same channel i tested both on same song and realized one of them was distorted, i called him he took them back and im awaiting repair on them now, he said he would fix the problem for free, i already had to take them back once because some hot glue got on something and caused the pot tweet not to work on one side, he fixed that but they still seem distorted compared to other side. he told me he started working on them today and to give him 3 or 4 days and he will fix it. im hoping for the best

[Mark Korda]

Hi Craig,I just joined the forum.I'm rebuilding and finishing a couple pairs of A-25's.When i opened 1 pair up I noticed the 5 position switch contacts looked brand new,very shiny bright.I don't think contact cleaner would have made any difference.It showed they didn't scrimp and went with a high quality switch.I'm also rebuilding a Dynaco A-25 Mark2 speaker's.This was the best Dyna speaker I ever heard besides the A-30XL.They came out in 1977-78 and were beautifully finished.The Mark2 does not have any resistors or a position switch.Instead they used a high quality 8 ohm L-pad for proper tweeter leveling control and a 50v Bi-polar 8.2 uf cap and a coil which an employee of Van AlStine's,Wayne said was .75mh.I can't read any thing on it.The tweeter is the same as the A-25XL which is the Seas H-86,the A-25 used the H-87.I'll send a picture tomorrow once I figure out my digital camera.The Mark 2 had brown grill cloth and the tweeter was not to the right of the woofer but symetrically lined up over the woofer.One thing where Dyna (scrimped on cost) was the foam woofer gasket which is next to nothing and could barely de-couple the woofer from the cabinet.I use modeling clay for gasket replacement and even easier is Mortite insulation.It's like modeling clay on a stringed roll,even though for some reason Wayne warned against it.I read on a lengthy forum other builders have loved it.It's way better than Parts Express speaker gasket tape.Take care....Mark Korda

[craig]

Well i finally heard back from him, He said there was nothing wrong with the A25's, but ! one side has a 2db difference in mid range. He also said it was nothing in the crossover and im kinda wondering if thats really true, the fancy tweeter wire the double the negative on the return, i'm a little disappointed. First i took them back after the rehab because of a hot glue problem that hindered the tweeter on one side from its full output, he fixed that but says this new problem with the slightly cleaner bass and mids in one channel is not the crossover he worked on, should i get rid of the double neg ? i remember them sounding even before the original problem of one woofer going out. i have another pair that need caps i think this time ill just do the caps myself with daytons or solens. I go to pick up the nice looking pair tomorrow but he didn't do anything to them, any ideas ?

[Horswispr]

I've restored many pairs of Dynacos and never had exactly that problem. Was the output even before he started working on them? I'd think the double negative would make no difference as far as output level goes. Can you ask if the 2 db difference is in the woofers, the tweetes, or both? A drop in tweeter output level is usually a capacitor's fault. A drop in woofer output...I'm not sure, since there are no coils or anything else before the woofer in the Dynaco crossover. A slightly rubbing woofer? In that case I'd just replace the woofer.

[dynaco_dan]

Well i finally heard back from him, He said there was nothing wrong with the A25's, but ! one side has a 2db difference in mid range. He also said it was nothing in the crossover and im kinda wondering if thats really true, the fancy tweeter wire the double the negative on the return, i'm a little disappointed. First i took them back after the rehab because of a hot glue problem that hindered the tweeter on one side from its full output, he fixed that but says this new problem with the slightly cleaner bass and mids in one channel is not the crossover he worked on, should i get rid of the double neg ? i remember them sounding even before the original problem of one woofer going out. i have another pair that need caps i think this time ill just do the caps myself with daytons or solens. I go to pick up the nice looking pair tomorrow but he didn't do anything to them, any ideas ?

Hi again

You mentioned back in July 30, 2011 that you had a buzz which was repaired.

If you can tell us what was diagnosed and the repair done it will help.

The tweeter switch inserts a resistor at each step when turning the level down.

A nother resistor is added to the previous one until there is about 10 ohms in line with the tweeter ant the lowest setting.

The maximum setting is basicly no resistance in the tweeters path.

For some reason the switches just keep working and working and working without a problem.

They are not a high end switch just very reliable and durable.

I've had one 5 position switch that broke out of hundreds and it may have been forced beyond the switches stop position.