double the neg ?

[craig]

Hi, recently had my dynaco A'25s restored at "vanlspeakerworks" chicago, he called me tonight to tell me they are ready for pick up so i will be picking them up tomorrow. He replaced the capacitor above normal and the max capacitor I decided to keep the switch. He went on to tell me he replaced the tweeter wires and doubled the negative on the woofer something, i don't remember the exact terminology he used, i'm a little worried to spite his good reputation, will that hurt or help? He says they sound tighter and sweeter, just a little worried about the "double the negative". What does that mean ? i don't mind strong bass but i don't want to ruin the roll over, i have a spare pair in case i don't like the restoration but maybe i'm just paranoid. I'm attached to both pairs the other pair i own have never been restored. I pick them up tomorrow.

[dynaco_dan]

Hi, recently had my dynaco A'25s restored at "vanlspeakerworks" chicago, he called me tonight to tell me they are ready for pick up so i will be picking them up tomorrow. He replaced the capacitor above normal and the max capacitor I decided to keep the switch. He went on to tell me he replaced the tweeter wires and doubled the negative on the woofer something, i don't remember the exact terminology he used, i'm a little worried to spite his good reputation, will that hurt or help? He says they sound tighter and sweeter, just a little worried about the "double the negative". What does that mean ? i don't mind strong bass but i don't want to ruin the roll over, i have a spare pair in case i don't like the restoration but maybe i'm just paranoid. I'm attached to both pairs the other pair i own have never been restored. I pick them up tomorrow.

Hi Craig

If there is any mods available for any of the speakers here on CSP that improve stability, sound or longevity I would be the first to support them.

For the Dynaco brand A-10, A-25, A-35 and A-50 classic speaker series there has been none.

Now that I have said that, there is changes that some owners will do.

Most every change will be inaudible to most listeners.

Increasing wire guage is an improvement but for over a million sold not necessary.

As long as good quality copper wire is used as replacement.

I mention this only as since I started in the sheet metal trade recycling has appeared and there is variablity of the final product.

Bypassing the switch is another change that if you have absolutely decided at which output level you prefer.

Changing the resistor that is not fried or out of value is not necessary but if you feel better about it, why not.

Changing the woofer and tweeter cabinet sealing compound on A-35 and A-50's may slightly improve bass.

Replacing the caps and with what has been debated since the very beginning of time.

Which brand and model of capacitor has been debated with no carved in stone answer, yet.

I personally have not heard of a failed Dynaco resistor or cap but have replaced one broken switch on my A-50.

As Kent and others will verify, the KLH Twelve, and possibly KLH Five crossovers have several resistors and capacitors that dramatically fail.

I hope you receive an itemized receipt which we can see to translate what you actually had done, "double the negative" is interesting.

I certainly can't knock today's interesting terminology.

Update 20110805 9:20 PM

The woofers are the weak link, in my experience, particularly the A-25's, the greatest number.

Under warantee I replaced over 200 A-25 woofers and maybe 2 tweeters, in less than 2 years.

Perhaps 10% were due to actual defective voice coil assembly.

There was a number of woofers that the voice coil was glued to the form and the bond became undone.

Our instructions from Dynaco were, if the voice coil was burned and loose, to cover it under warantee.

Also if the voice coil wire insulation is bubbled, cover it under warantee, burnt form or not.

It is amazing the amount of heat that a woofer can take before the voice coil form paper chars, similar to a toaster element.

Mild incidences of the above would be an obvious but slight buzz when testing them with a test tone.

[Horswispr]

The only change I've ever done to Dynacos that improved their sound (aside from replacing broken drivers) was to replace old capacitors. I've used Solens and Daytons with values ranging from 5.1 to 6.2 mfd. Most Dynacos I've opened up came with 5.1s, though I've seen a couple of pair of red fronts with 4.7s. If he used a higher value capacitor, in theory the result should be slightly more upper midrange energy (near the bottom of the tweeter's output). In real life, the difference between the sound of 5.1s and 6.2s is very slight. If by higher values he means voltage ratings, then it's moot. It seems all contemporary capacitors have higher voltage ratings (250 or 500, I think) relative to the older ones. I would simply ask him exactly what the capacitor values are, and what he means by double negative. In my experience, newer capacitors generally do improve the sound slightly: more smoothness and clarity.

[dynaco_dan]

The only change I've ever done to Dynacos that improved their sound (aside from replacing broken drivers) was to replace old capacitors. I've used Solens and Daytons with values ranging from 5.1 to 6.2 mfd. Most Dynacos I've opened up came with 5.1s, though I've seen a couple of pair of red fronts with 4.7s. If he used a higher value capacitor, in theory the result should be slightly more upper midrange energy (near the bottom of the tweeter's output). In real life, the difference between the sound of 5.1s and 6.2s is very slight. If by higher values he means voltage ratings, then it's moot. It seems all contemporary capacitors have higher voltage ratings (250 or 500, I think) relative to the older ones. I would simply ask him exactly what the capacitor values are, and what he means by double negative. In my experience, newer capacitors generally do improve the sound slightly: more smoothness and clarity.

Hi there

Thank you for your insight.

[craig]

bla well he replaced the speaker wire with some exotic then wire with cotton dialect not sure maybe i should give up on these things

[craig]

i keep thinking if he doubled the negative on the return from the woofer, it seems like the bass got too tight and confined when it used to be more fluid, i keep thinking about the tweeter wire ( thin exotic ) and the double the negative thing. i wonder how hard those 2 things would be to reverse or weather i should reverse them ?