Hi All
Just picked up a pair of Celestion Ditton 551 (1979)and managed to repair a tweeter and replace both blown 500mA
fuses. I have listened to them a bit using my Sansui 250 which is not a very high power tube amp. (10-15W a side?)
They sound great turned up about 1/2 way, but the bass response is not as powerful as I would imagine.
I have no previous experience with these speakers and wonder if it's just a characteristic of them
when not driven very hard or the crossovers need recapping for optimum bass?
I visually checked 1 cross-over and it looked original with no swelling caps and resistors measured almost within tolerance.
I really wanted to avoid recapping at this stage as:
They sound pretty good to my ears except bass a little underwhelming.
I am refinishing cabs and grille cloth (hands are full)
It's a real pain to pop out the woofers to get at crossovers and risk damaging something else.
So I was hoping some people who are familiar with these speakers may shed some light.
Would be much appreciated.
Thanks Rich
Just picked up a pair of Celestion Ditton 551 (1979)and managed to repair a tweeter and replace both blown 500mA
fuses. I have listened to them a bit using my Sansui 250 which is not a very high power tube amp. (10-15W a side?)
They sound great turned up about 1/2 way, but the bass response is not as powerful as I would imagine.
I have no previous experience with these speakers and wonder if it's just a characteristic of them
when not driven very hard or the crossovers need recapping for optimum bass?
I visually checked 1 cross-over and it looked original with no swelling caps and resistors measured almost within tolerance.
I really wanted to avoid recapping at this stage as:
They sound pretty good to my ears except bass a little underwhelming.
I am refinishing cabs and grille cloth (hands are full)
It's a real pain to pop out the woofers to get at crossovers and risk damaging something else.
So I was hoping some people who are familiar with these speakers may shed some light.
Would be much appreciated.
Thanks Rich
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Have you tried both the 16 ohm and 8 ohm output connections?
Also make sure the speakers are both in phase.
Also make sure the speakers are both in phase.
Hey there ...
It's great to see old classic speakers made of good materials still alive.
I would say there are two main issues to be addressed.
Given the age of the speakers, re-capping the crossovers is basically essential.
If memory serves me correctly, these speakers were built with about 60W per Ch. amps in mind.
It is my opinion that you do actually need a more powerful amplifier to properly drive these speakers.
Also, the age of your amp. could give rise to multiple capacitor & noise issues.
Ebay is full of wonderful amplifier bargains. (today good sound doesn't only come from tubes)
I'm sure you'll get some more good info. to come 🙂
PS.
I would love some smart member to post a schematic of the XO network.
It's great to see old classic speakers made of good materials still alive.
I would say there are two main issues to be addressed.
Given the age of the speakers, re-capping the crossovers is basically essential.
If memory serves me correctly, these speakers were built with about 60W per Ch. amps in mind.
It is my opinion that you do actually need a more powerful amplifier to properly drive these speakers.
Also, the age of your amp. could give rise to multiple capacitor & noise issues.
Ebay is full of wonderful amplifier bargains. (today good sound doesn't only come from tubes)
I'm sure you'll get some more good info. to come 🙂
PS.
I would love some smart member to post a schematic of the XO network.
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I experienced once that a previous owner opened the box and did not take care about reconnecting the wire phase of the bass drivers correctly.
So a measurement shows if frequency response is OK or not.
It could be that both bass drivers are out of phase and you have a suck out between mid and bass driver.
So a measurement shows if frequency response is OK or not.
It could be that both bass drivers are out of phase and you have a suck out between mid and bass driver.
Heres a couple of videos by Mr Haycross on his refurbishment of a pair, the electros used in that era are notorious for going out of spec:
This is all great fun for people who look in the second-hand shops for an interesting restoration project!
I had a terrible time with some Ditton 44. But could they go LOUD! Real party speakers. Everything was broken! Sent them to the dump eventually. 🙂
From @rayma's PDF:
Nice decor. A Classic dome mid 3 Way. Doesn't look like a 12" bass though.You tell me.
http://www.troelsgravesen.dk/SP38.htm
Dome mid is always complicated on crossover. Cone mid simpler.
http://www.troelsgravesen.dk/SEAS-3-Way-Classic-mkII.htm
Lots of stuff about positioning, which is very Roy Allison:
Valve amps are not good with controlling reflex, lacking damping factor. Closed box can work better, so you might stuff socks in the ports.
Or use solid state amplification.
Simple test for correct bass polarity is to face the two speakers directly close together. The bass will disappear if wired wrong.
I think bass is a matter of taste, and maybe the bass control on an amp is a better option. And room positioning. These are 2 Pi speakers apparently.
Anyway, my 2 cents. Watching with interest. Best, Steve.
I had a terrible time with some Ditton 44. But could they go LOUD! Real party speakers. Everything was broken! Sent them to the dump eventually. 🙂
From @rayma's PDF:
Nice decor. A Classic dome mid 3 Way. Doesn't look like a 12" bass though.You tell me.
http://www.troelsgravesen.dk/SP38.htm
Dome mid is always complicated on crossover. Cone mid simpler.
http://www.troelsgravesen.dk/SEAS-3-Way-Classic-mkII.htm
Lots of stuff about positioning, which is very Roy Allison:
Valve amps are not good with controlling reflex, lacking damping factor. Closed box can work better, so you might stuff socks in the ports.
Or use solid state amplification.
Simple test for correct bass polarity is to face the two speakers directly close together. The bass will disappear if wired wrong.
I think bass is a matter of taste, and maybe the bass control on an amp is a better option. And room positioning. These are 2 Pi speakers apparently.
Anyway, my 2 cents. Watching with interest. Best, Steve.
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Wow. Thanks for all the info.
That brochure is great to have.
I never would have thought that grille cloth was original.
I will post a pic when they are finished.
That brochure is great to have.
I never would have thought that grille cloth was original.
I will post a pic when they are finished.
Replacing the electrolytic capacitors in the bass section (two 30 uF in parallel = 60 uF) will almost certainly improve the bass reproduction.
Electrolytics elsewhere should also be replaced.
I would replace the old electrolytics with new electrolytics in order to approach the manufacturer's original intended voicing of the speaker.
That was good work, Galu!
Henceforth you shall be known as "Galu the Googler", which sounds like a magician from a Jack Vance novel.
My bookmark for guessing coil values, and thus modifying bafflestep bass boost, should the need arise...
And we know how to do that.
http://www.troelsgravesen.dk/3WClassic.htm
Looks pretty similar to me, except for the middle cone section. Seen one three way, you seen 'em all. 😎
Henceforth you shall be known as "Galu the Googler", which sounds like a magician from a Jack Vance novel.
My bookmark for guessing coil values, and thus modifying bafflestep bass boost, should the need arise...
And we know how to do that.
http://www.troelsgravesen.dk/3WClassic.htm
Looks pretty similar to me, except for the middle cone section. Seen one three way, you seen 'em all. 😎
Hey there Galu ...
I'm a tad confused by the '3 input' diagram and the R1>L4 circuit.
I can't quite decipher the 'word writing' (?)
Could you enlighten me 😕
Saugkreis is German for LCR, so refers to the LCR on the mid, and Masse means bulk literally, but also the ground plane of the circuit board AFAIK.
http://www.hifi-forum.de/viewthread-185-10150.html#46
I'd trust the official Celestion schematic in post 8.
Here is a picture of the original crossover:
There is also a control panel for tweeter and mid level with a red fault indicator LED for the tweeter. A couple of people have recapped this crossover in quite strange ways.
I didn't watch all of the Mr. Haycross videos, but he seems a very top man. Replaced all the electrolytics with new identical electrolytic 50V Alcaps, cleaned the potentiometers on the level adjusts with, presumably, aerosol switch cleaner. And redid some of the wiring.
He did say it is a very good speaker. But after 40 years capacitors get tired and out of spec. If it was me, I would change the electrolytics and that little MKT or MKP capacitor and clean the pots. I'd not try his rewiring. Too much work!
I am not sure if there are capacitors on the level adjust circuit. That would need checking.
He has the same inductance multimeter as me! But coils are tough as old boots IMO. Rarely go wrong,
Soldering iron, solder, capacitors and switch spray shouldn't cost too much. I don't know what that rubbery tape he used was, but seems a good idea to control vibration of components. Snippers, longnose pliers also required I think. Excellent speakers, those old Celestions. My nephew has some old Ditton 22, and they are superb.
http://www.hifi-forum.de/viewthread-185-10150.html#46
I'd trust the official Celestion schematic in post 8.
Here is a picture of the original crossover:
There is also a control panel for tweeter and mid level with a red fault indicator LED for the tweeter. A couple of people have recapped this crossover in quite strange ways.
I didn't watch all of the Mr. Haycross videos, but he seems a very top man. Replaced all the electrolytics with new identical electrolytic 50V Alcaps, cleaned the potentiometers on the level adjusts with, presumably, aerosol switch cleaner. And redid some of the wiring.
He did say it is a very good speaker. But after 40 years capacitors get tired and out of spec. If it was me, I would change the electrolytics and that little MKT or MKP capacitor and clean the pots. I'd not try his rewiring. Too much work!
I am not sure if there are capacitors on the level adjust circuit. That would need checking.
He has the same inductance multimeter as me! But coils are tough as old boots IMO. Rarely go wrong,
Soldering iron, solder, capacitors and switch spray shouldn't cost too much. I don't know what that rubbery tape he used was, but seems a good idea to control vibration of components. Snippers, longnose pliers also required I think. Excellent speakers, those old Celestions. My nephew has some old Ditton 22, and they are superb.
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"Saugkreis" translates as "suction circuit" and refers to the series notch filter (R1, C5, L4) on the midrange driver as shown on the official schematic.
The "SA 5830" board contains the two L-pads and an overload protection circuit which incorporates a quick-acting fuse with LED failure indicator.
Those non-polar ELCAP electrolytic capacitors don't age well, and I would replace them with modern equivalents as a matter of course.
Some, if not all, of the capacitance values stamped on the ELCAPS are no longer available as standard values.
In that case, it is necessary to connect two or more capacitors in parallel to achieve the required capacitance (as has been the case in Steve's final image).
For example, 10 uF in parallel with 2 uF would give the required 12 uF.
https://wilmslowaudio.co.uk/mundorf-electrolytic-ecap-capacitors
This Haycross video is worth watching, it is the one linked above:
I hadn't really thought about availability of Alcaps. But the restoration is only 6 months old.
In fact Mr. Haycross fitted Polypropylenes to the tweeter section. 3.3uF/0.14mH/7uF. Look in about 10 minutes.
That's a very standard Celestion filter. And Mr. Haycross knows Celestion. I am sure 6.8uF would do.
The contact cleaner he used is called DeoxIT, and he does replace stuff on the level adjust board.
I hadn't really thought about availability of Alcaps. But the restoration is only 6 months old.
In fact Mr. Haycross fitted Polypropylenes to the tweeter section. 3.3uF/0.14mH/7uF. Look in about 10 minutes.
That's a very standard Celestion filter. And Mr. Haycross knows Celestion. I am sure 6.8uF would do.
The contact cleaner he used is called DeoxIT, and he does replace stuff on the level adjust board.
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One should not confuse ELCAP with ALCAP, the latter type being very reliable in my experience.
Falcon Acoustics says that where ALCAP are replacing original black ELCAP capacitors the voicing will remain true to the designer's intended sound character:
https://www.falconacoustics.co.uk/l...citors/alcap-electrolytic-capacitors-50v.html
Other NP electrolytic capacitor makes are equally suitable, like the Mundorf E-Cap I linked to earlier.
The electrolytics he measures are dried out, as they have a higher capacity than they should. Good idea to replace them all, measureing capacity does not show the other parameter that are far off. If I found such dried caps inside a speaker, the distortion was audible higher. How audible it was depended on the position in the crossover.
Replacing the resistors and foil caps is questionable, if they measure as new you can use them for ever.
Replacing the L-pads with fixed resistors after measuring for a linear value could have an positive audible impact IMO, such a variable in line with a mid or tweeter is not the best idea. When the speakers were new, it may have been an advantage to adjust for response problems of the source, even if I don't think so. More some kind of useless gimmik from the sales departement.
What he mentioned about MKP caps sounding harsh, if used instead of electrolitics is very questionable. May be more profitable for him to use the cheaper version, but MKP or any foil type of cap sounding worse than electrolitc is 100% BS. Makes a good job look worse, without real need. In the end he want's to make money with his video and sell speaker restorations. High value caps are expensive...
Replacing the resistors and foil caps is questionable, if they measure as new you can use them for ever.
Replacing the L-pads with fixed resistors after measuring for a linear value could have an positive audible impact IMO, such a variable in line with a mid or tweeter is not the best idea. When the speakers were new, it may have been an advantage to adjust for response problems of the source, even if I don't think so. More some kind of useless gimmik from the sales departement.
What he mentioned about MKP caps sounding harsh, if used instead of electrolitics is very questionable. May be more profitable for him to use the cheaper version, but MKP or any foil type of cap sounding worse than electrolitc is 100% BS. Makes a good job look worse, without real need. In the end he want's to make money with his video and sell speaker restorations. High value caps are expensive...