Hi, I bought this very rare 110v A88 for spares to repair a broken 240v one. Because of it's voltage, it had not , I think, been used much. The nextel was all gloopy and it looked terrible. I converted it to 240 volts, according to helpful instructions from Sugden. Unused for many years, it worked beautifully first-time (after passing the light-bulb test)! A tribute to Sugden build quality! The sound is sublime- clearly Sugden, but also very fast, a bit like Naim! It's a slightly odd design, I think, with 2 transformers (in series?), and puts out 80w into 8 ohms and 150w into 4 ohms. Patrick Miller at Sugden told me that they had been specially made for export to Nigeria, but the buyer was fraudulent, so they were sold in the UK and US markets for a brief period instead. Sonically it is just excellent! I am working from an A44 schematic, which is similar, but with only one transformer. I have 2 amps to make one out of, one working nicely (though with a slightly quiet left channel) and one very battered and intermittent. I am not brilliant at electronics, but really want to restore one to perfection. I have 4 questions, firstly does anyone have any recommendations about capacitor make to preserve the sonic signature? Secondly, does anyone know where one could get small bits re-coated with nextel (or should I just go with paint or powder coating?), thirdly, how do you re-label the dials on the front after re-surfacing the coating? I could just try to re-case it all, but that seems wrong really! I have included some pictures! Thanks for any help or comments
Jo
Jo
Attachments
Hi
I have a Sugden A44 which was damaged in moving house and I have not got around to repairing it. I am unsure about your quoted power outputs. I believe the A44 is around 25 watts with some 5 watts in class A.. The A44 is a Class AB design whereas most of the better known Sugden amps are single ended class A.
For capacitors it would help if you posted a schematic as some of the electrolytic capacitors on the pcb could either be replaced by or paralled by polypropylene capacitors. Otherwise I would replace all electrolytics on the pcb with Elna 105 degree electrolytics. The power supply electrolytics could be Kendeil or another good make such as Elna.
I am not familiar with the coatings you mention for the front panel.
Don
I have a Sugden A44 which was damaged in moving house and I have not got around to repairing it. I am unsure about your quoted power outputs. I believe the A44 is around 25 watts with some 5 watts in class A.. The A44 is a Class AB design whereas most of the better known Sugden amps are single ended class A.
For capacitors it would help if you posted a schematic as some of the electrolytic capacitors on the pcb could either be replaced by or paralled by polypropylene capacitors. Otherwise I would replace all electrolytics on the pcb with Elna 105 degree electrolytics. The power supply electrolytics could be Kendeil or another good make such as Elna.
I am not familiar with the coatings you mention for the front panel.
Don
Don,
Thanks so much for replying. Thanks also for the advice about the capacitors- I will definitely follow that. The A88 is also AB, and apparently is based on the A44. According to Sugden (I think that I spoke with either Mr Tony Miller or Patrick Miller on the phone), they were asked to modify the A44 to 80wpc rms for the special order to Nigeria. How this was done, is lost in time sadly! I tried Sugden for the schematic. They were brilliantly helpful, as always, but it seems that the original circuit diagram was kept as a copy made with ink that has faded to illegibility. I am trying (!) to reverse engineer the circuit from the diagram of the A44 and the actual amplifier, but it is hard going! I also don't have an A44 to compare the physical differences. A number of changes were made, including the addition of the second transformer. Apparently it was more powerful than the later models of A48. It certainly is a different thing to my previous A21a, but shares a similar sound. If the a44 schematic would help, I would be happy to post that? Thanks so much again,
best wishes,
Jo
Thanks so much for replying. Thanks also for the advice about the capacitors- I will definitely follow that. The A88 is also AB, and apparently is based on the A44. According to Sugden (I think that I spoke with either Mr Tony Miller or Patrick Miller on the phone), they were asked to modify the A44 to 80wpc rms for the special order to Nigeria. How this was done, is lost in time sadly! I tried Sugden for the schematic. They were brilliantly helpful, as always, but it seems that the original circuit diagram was kept as a copy made with ink that has faded to illegibility. I am trying (!) to reverse engineer the circuit from the diagram of the A44 and the actual amplifier, but it is hard going! I also don't have an A44 to compare the physical differences. A number of changes were made, including the addition of the second transformer. Apparently it was more powerful than the later models of A48. It certainly is a different thing to my previous A21a, but shares a similar sound. If the a44 schematic would help, I would be happy to post that? Thanks so much again,
best wishes,
Jo
Hi
It would help if you could post the A44 schematic and indicate if you can where you believe changes where made. For example I would guess that there are more output devices per channel; probably twice as many. It would also help if you measure the working + and - voltages and how the two transformers are wired together. Possibly the amplifier uses one amplifier per channel whereas the A44 uses a common transformer to supply both channels.
I am not sure how familiar you are with revamping an amplifier. However if you are not familiar here is a quick summary of the main steps. Transistors and resistors should still be ok unless damaged by heat. Clean all contacts and switch wipers and check the integrity of all solder joints especially those in the power supply and in circuit with the output devices. Change all electrolytic caps as in my earlier post. When you start up again I would use a variac if you have one otherwise start with a 100watt light bulb in series with the amplifier to lower the voltage going into the amplifier. Check for any dc voltage on the output of either channel and if ok start up normally. Then sit back and start playing music.
Don
It would help if you could post the A44 schematic and indicate if you can where you believe changes where made. For example I would guess that there are more output devices per channel; probably twice as many. It would also help if you measure the working + and - voltages and how the two transformers are wired together. Possibly the amplifier uses one amplifier per channel whereas the A44 uses a common transformer to supply both channels.
I am not sure how familiar you are with revamping an amplifier. However if you are not familiar here is a quick summary of the main steps. Transistors and resistors should still be ok unless damaged by heat. Clean all contacts and switch wipers and check the integrity of all solder joints especially those in the power supply and in circuit with the output devices. Change all electrolytic caps as in my earlier post. When you start up again I would use a variac if you have one otherwise start with a 100watt light bulb in series with the amplifier to lower the voltage going into the amplifier. Check for any dc voltage on the output of either channel and if ok start up normally. Then sit back and start playing music.
Don
Don, thanks very much again! My electronics CV is such that advice is always welcome! It reads a bit as follows: OA in electronics when such things existed (!), but working long hours as a medic now. One Marantz CD-80 re-capped, clocked and op-amps replaced based on what I have read on the net and electronics books (all Lego stuff really!)- but great result; One technics amp recapped and PSU capacitors replaced with bigger ones. This sounded great till I blew all the transistors in one channel setting the bias current (after replacing the potentiometers with sealed ones). This was due to a faulty £10 multimeter (lesson learnt!). It was a 'practise' amp, so not so awful, though it felt it at the time! My wife thought I was setting the house on fire.....
I will try to upload the schematic and what I think the main changes are with some photos at the weekend, if you can bear to glance at them. Best wishes,
Jo
I will try to upload the schematic and what I think the main changes are with some photos at the weekend, if you can bear to glance at them. Best wishes,
Jo
Hello Jo and Don,
If still interested I do have the Sugden A88 service manual in electronic format and can send it if needed.
I also have a bunch of boxed A88 lying in my basement and if my memory is good one of them was in pretty good shape last time I looked. I also have a stock of brand new knobs and possibly other parts.
Cheers,
Michel
If still interested I do have the Sugden A88 service manual in electronic format and can send it if needed.
I also have a bunch of boxed A88 lying in my basement and if my memory is good one of them was in pretty good shape last time I looked. I also have a stock of brand new knobs and possibly other parts.
Cheers,
Michel
Hi Michel,
I would love a copy of the service manual- I'm still trying to guess the correct bias current! I would be very interested in the knobs or any other parts that you have -would you be willing to sell them?
Many thanks,
best wishes,
Jo
I would love a copy of the service manual- I'm still trying to guess the correct bias current! I would be very interested in the knobs or any other parts that you have -would you be willing to sell them?
Many thanks,
best wishes,
Jo
Hello Jo,
Sorry for the delay, for some reason I was not notified of your reply...
Send me your email address and I will send you the file I have on the A88.
Some notes are in French so let me know if you need any help translating.
As for the parts let me know what you need, I am pretty sure I will be able to help you.
Cheers,
Michel
Sorry for the delay, for some reason I was not notified of your reply...
Send me your email address and I will send you the file I have on the A88.
Some notes are in French so let me know if you need any help translating.
As for the parts let me know what you need, I am pretty sure I will be able to help you.
Cheers,
Michel
Hi Michel, yes a schematic would be brilliant! The finished amp looks like this, with third party buttons. I guessed the DC offset from an A48 schematic (not ideal!).
The front was hard, but a Rotring stencil on matt primer followed by clear lacquer seemed to work! I missed out the A88 bit though! The new PSU caps are a bit oversized, but it is what I had left over from another project. I used elna for the pre, and some Nichicon for the power amp. It sounds really great, but a bit modern for the vintage! I'm working on a very old sugden preamp now, and I think that vishay sprague capacitors suit the original sound better. I'd be happy to buy genuine buttons, but the nextel coating tends to go all gloopy with time?
My teenagers are so keen on the amp they have temporarily stolen it for the bass, despite the slightly more modern sound! Shall I post my email address here for the schematic?
The front was hard, but a Rotring stencil on matt primer followed by clear lacquer seemed to work! I missed out the A88 bit though! The new PSU caps are a bit oversized, but it is what I had left over from another project. I used elna for the pre, and some Nichicon for the power amp. It sounds really great, but a bit modern for the vintage! I'm working on a very old sugden preamp now, and I think that vishay sprague capacitors suit the original sound better. I'd be happy to buy genuine buttons, but the nextel coating tends to go all gloopy with time?
My teenagers are so keen on the amp they have temporarily stolen it for the bass, despite the slightly more modern sound! Shall I post my email address here for the schematic?
Attachments
I have just checked my old emails from Sugden and found that the current should be set @ 160 mA measured through the fuse and the mid point should be set @ 46V.They suggest checking at 20 mins after setting as they can drift. I posted this just in case someone else is renovating an A88!
Hi Jo,
Send me your email address and I will send you the file I have on the A88.
The buttons I have are as new and not gloopy as they have been stored individually in hermetic bags all their life. I may not have all the models you need.
You should use the Vishay/BC Components capacitors if you want to stay as close to the original as possible. They are available at Digi-Key.
What very old Sugden preamp are you working on?
Cheers,
Michel
Send me your email address and I will send you the file I have on the A88.
The buttons I have are as new and not gloopy as they have been stored individually in hermetic bags all their life. I may not have all the models you need.
You should use the Vishay/BC Components capacitors if you want to stay as close to the original as possible. They are available at Digi-Key.
What very old Sugden preamp are you working on?
Cheers,
Michel
Hello Jo90, I am going to get my Sugden A88 overhauled at AmpLabs in Worcester. I have stripped off all the sticky Nextel painted sides, top and front trim to get them stripped and resprayed. I only need to get the knobs off, but they seem very difficult to budge, do I just keep pulling?
Do you still have any A88 spares including knobs and buttons?
I am restoring my A88 after 30 years of owning it from new and refinishing the case is included in the overhaul.
My restored Sugden A88
I have restored my Sugden A88. It has to be the best one left operating on a daily basis – unless you know better? See it here:
Search - My Photo Gallery
I have restored my Sugden A88. It has to be the best one left operating on a daily basis – unless you know better? See it here:
Search - My Photo Gallery
you should only restore to original what has value.
take that Sugden and put a honey badger amp in it. huge improvement
eg.
pioneer SX-780
1. 300 VA transformer
2. regulated VAS stage for Amp with separate transformer winding
3. amp very close to Honey Badger design
4. 7.5 v for display lamps can run 6922 heater
5. A very good looking unit to display
** A sx 780 can be had on ebay for $200 ( less then a blank case & heat sink)
add 6922 tube preamp for TA7136P ( really can't explain why this is sooo good )
add 22000/50v main filter caps
add 1000/63 v for VAS stage
boost VAS stage regulator voltage from 40 to 45v for mosfets
add double zener regulation to +- 24 volt supplies
add 18v regulator where resistor is mounted on heat sink
Add IRFP9240 & IRFP240 mosfet outputs instead of STK0050II
use phono section to equalize and smooth ipod signal level
properly done the Amp s/n > 100db amp THD 0.003 % bias at 100MA
measured from amp input. Tube distortion .6 - 1.5%
should cause a run on SX 780's as this unit is really easy to work on
take that Sugden and put a honey badger amp in it. huge improvement
eg.
pioneer SX-780
1. 300 VA transformer
2. regulated VAS stage for Amp with separate transformer winding
3. amp very close to Honey Badger design
4. 7.5 v for display lamps can run 6922 heater
5. A very good looking unit to display
** A sx 780 can be had on ebay for $200 ( less then a blank case & heat sink)
add 6922 tube preamp for TA7136P ( really can't explain why this is sooo good )
add 22000/50v main filter caps
add 1000/63 v for VAS stage
boost VAS stage regulator voltage from 40 to 45v for mosfets
add double zener regulation to +- 24 volt supplies
add 18v regulator where resistor is mounted on heat sink
Add IRFP9240 & IRFP240 mosfet outputs instead of STK0050II
use phono section to equalize and smooth ipod signal level
properly done the Amp s/n > 100db amp THD 0.003 % bias at 100MA
measured from amp input. Tube distortion .6 - 1.5%
should cause a run on SX 780's as this unit is really easy to work on
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Hi Michel,
I would really appreciate if you could send me the schematics of the A88 and lt me know what spare parts you still have left.
Thanks
Hi Vuthy,
Send me your email address and I will send you the file I have on the A88.
I don't have much A88 parts left, if at all.
Let me know what you need, I'll look into it but do have high hope.
Regards,
Michel
Send me your email address and I will send you the file I have on the A88.
I don't have much A88 parts left, if at all.
Let me know what you need, I'll look into it but do have high hope.
Regards,
Michel
Sugden a48mk3
Hi Michel, Mario from Montreal here
Sorry to highjack this thread although I think it could help others. I just wanted to catch you in a more recent venue. I have read many times the 10 pages thread on Sudden P28 etc… Good man.
I’m not a technician, but I rebuilt an entire 303 (with instructions)
But this is about the Sudden a48mk3 and I have the schematics, which I can't read fast.
Purchased it used and it seemed fine, recognized the Sudden sound which I seek, but set up wouldn’t allow image evaluation. At home I still enjoyed it but at critical listening, not much of an image… Right side of heatsink is hotter (not much), left side is cold. I dig in to measure voltage at 4.7k pot, got some on right Chanel, nothing on left. Idle current on fuse holders (w/o fuse) shows about 200, adjustable with pot 220k, but left Chanel starts at about 100ma and fall to 60ma before stabilizing.
I get a short between heatsink and left 2sb776 metal plate. I got all output transistors out and all tested fine. I got them back in and destroyed them all but one. Smoke! (yes, isolator pads where the milky type after all). I ordered those 896/776 from eBay, (fingers crossed) https://www.ebay.ca/itm/383630556261asI spent a day searching for replacements for these to no definite avail. Anyone found replacements for those in this day in age?
I also ordered:
2- BD140
4- BD139g
4- BC549b (in case)
2- 470uf 10v
2- 470uf 25v
2- 220uf 100v
(RUBYCON)
AND mica pads
BUT HERE IS WHAT I NEED (Ithink)
Looking at the print side, I suspect signal was redirected (in mono?) to be driven by the right side amplifier, in order to sell the unit (I’m not calling him back)…. Some suspicious black wiring and one print cut off job can be seen on my picture.
Now I could spend days to years figuring out the circuit and fix this, or maybe you could help.
I also call to any member who could just happen to have a pic of the a48mk3 print side which would put me out of my misery in no time. I have one for the a28, but that doesn’t help me
Thank you for any help (je suis prêt a te dedomager)
Hi Michel, Mario from Montreal here
Sorry to highjack this thread although I think it could help others. I just wanted to catch you in a more recent venue. I have read many times the 10 pages thread on Sudden P28 etc… Good man.
I’m not a technician, but I rebuilt an entire 303 (with instructions)
But this is about the Sudden a48mk3 and I have the schematics, which I can't read fast.
Purchased it used and it seemed fine, recognized the Sudden sound which I seek, but set up wouldn’t allow image evaluation. At home I still enjoyed it but at critical listening, not much of an image… Right side of heatsink is hotter (not much), left side is cold. I dig in to measure voltage at 4.7k pot, got some on right Chanel, nothing on left. Idle current on fuse holders (w/o fuse) shows about 200, adjustable with pot 220k, but left Chanel starts at about 100ma and fall to 60ma before stabilizing.
I get a short between heatsink and left 2sb776 metal plate. I got all output transistors out and all tested fine. I got them back in and destroyed them all but one. Smoke! (yes, isolator pads where the milky type after all). I ordered those 896/776 from eBay, (fingers crossed) https://www.ebay.ca/itm/383630556261asI spent a day searching for replacements for these to no definite avail. Anyone found replacements for those in this day in age?
I also ordered:
2- BD140
4- BD139g
4- BC549b (in case)
2- 470uf 10v
2- 470uf 25v
2- 220uf 100v
(RUBYCON)
AND mica pads
BUT HERE IS WHAT I NEED (Ithink)
Looking at the print side, I suspect signal was redirected (in mono?) to be driven by the right side amplifier, in order to sell the unit (I’m not calling him back)…. Some suspicious black wiring and one print cut off job can be seen on my picture.
Now I could spend days to years figuring out the circuit and fix this, or maybe you could help.
I also call to any member who could just happen to have a pic of the a48mk3 print side which would put me out of my misery in no time. I have one for the a28, but that doesn’t help me
Thank you for any help (je suis prêt a te dedomager)
Attachments
After further investigation…
1- the stereo/bridge mono switch was on bridge mono (please tell me that’s not it)… would that allow sound coming from both speakers if connected normally, but cutting voltage on the left amp at the measuring point?… and give 60ma to the idle current on left?
2-the two bottom right parallel wires (photo) are connected on the right to two resistors of which ends are not connected to anything else. Seems in the original design
3- For similar reasons, the top long wire and the lifted two tracks with a small z shape wire seem legit as well.
still would like confirmation
looks like left 2sd776 was short, and switching to bridge mode magically made the amp play on left so it could be sold (?) Or it was acquired from a bridge mono set up and everybody was ignorant of that fact… ? I would really appreciate your help on this before I install components and fire it up.
cheers to everyone
1- the stereo/bridge mono switch was on bridge mono (please tell me that’s not it)… would that allow sound coming from both speakers if connected normally, but cutting voltage on the left amp at the measuring point?… and give 60ma to the idle current on left?
2-the two bottom right parallel wires (photo) are connected on the right to two resistors of which ends are not connected to anything else. Seems in the original design
3- For similar reasons, the top long wire and the lifted two tracks with a small z shape wire seem legit as well.
still would like confirmation
looks like left 2sd776 was short, and switching to bridge mode magically made the amp play on left so it could be sold (?) Or it was acquired from a bridge mono set up and everybody was ignorant of that fact… ? I would really appreciate your help on this before I install components and fire it up.
cheers to everyone
Hi Michel. Please look at the thread, I think I answered the thread instead of answering you. I need your help