Tresham DR-102 Power amplifier with no Power Supply...HELP!!!

[donmarrese]

Hi all
Hope not breaking any rules (re: banned name) if so, Moderators please remove this post asap.

I've come across, in my quest to find and Tresham equipment, a DR-102 power amplifier. Unfortunately it did not come with a power supply.
I've spoken to the guy who developed these units in the 80's, (not banned name) and as far as he's concerned, all schematics went to Tannoy. He remembers certain values, but I don't want to invest in a supply that might propel the amp 20ft into the sky!

Does anyone out there have a copy of the schematic/Component sheet + Values, so that 'll be able to resurrect this beautiful amplifier from the flames of hell? (Sorry for the Drama...) or is anyone willing to build one for me, who knows what it takes to build one?

Distributed information system head banging required here...

thank in advance for your thoughts.

Regards
Don

[Primalsea]

I am in the exactly the same position as you. I also have a DR102 but no power supply. I did strip mine down and worked out how to make a power supply, but have not got round to it yet. I can dig out the info in a few days; it's in the loft somewhere. I am 99% sure I have go it correct.

It will take either multiple transformers or a custom wound unit, so will be quite expensive to make.

[Firebottle]

Judging from the photos I can see on t'web I am guessing that the power supply is just a transformer in a box.

It doesn't help that the 'power out' and corresponding 'power in' sockets aren't marked with more info than that :doh:

Can you take some close up pictures of the inner wiring of the power amp, it looks like there a two large reservoir capacitors in there, really need to know if the wires from the 'power in' go to a rectifier or just directly to these capacitors.

Wouldn't be too onerous to knock up a power supply either way.

:cool:

[shane]

[Banned name] may be persona non grata round here, but he’s not hard to get in touch with. Why not email him? I promise I won’t tell anyone if you do...

[donmarrese]

[Banned name] may be persona non grata round here, but he’s not hard to get in touch with. Why not email him? I promise I won’t tell anyone if you do...

I did as a matter of fact, and got the most negative response...
Anyway, he was only a sales man at Tresham, Mark and Geoff were the technical guys..

Regards

[donmarrese]

I am in the exactly the same position as you. I also have a DR102 but no power supply. I did strip mine down and worked out how to make a power supply, but have not got round to it yet. I can dig out the info in a few days; it's in the loft somewhere. I am 99% sure I have go it correct.

It will take either multiple transformers or a custom wound unit, so will be quite expensive to make.

Your right, I have the list of components, and one of them is a Toroidal hand wound jobby that costs £80

All in, it's gonna cost £300...I have the component list, but the values are a bit vague....
I've since made some enquiries and share the results with you...

[donmarrese]

Judging from the photos I can see on t'web I am guessing that the power supply is just a transformer in a box.

It doesn't help that the 'power out' and corresponding 'power in' sockets aren't marked with more info than that :doh:

Can you take some close up pictures of the inner wiring of the power amp, it looks like there a two large reservoir capacitors in there, really need to know if the wires from the 'power in' go to a rectifier or just directly to these capacitors.

Wouldn't be too onerous to knock up a power supply either way.

:cool:

Hi Alan,
The rectifiers are within the amplifier, the external box supplies power to 3 separate bridges (me thinks)..Oh yes, the previous owner decided to Burr 4 of the screws on the lid, so I'll get lid off first then take some pics...I've gotta dash now, but will post components required soon....
Regards

[Primalsea]

Very roughly off the top of my head so dont quote me its something like 65-0-65 AC for the low power section of the amp and 42-0-42 AC for the high current section, plus 24DC for the timer and relay circuit. I dont think there is a rectifier on the relay board, so you need one and some filter caps in the PSU for this. I think you still can get get hold of the plugs in order to make a lead up, or if not you can buy new sockets and plugs that will fit the hole in the chassis.

Does anyone know what the rms watts into 8 ohms is? Would be a bit easier to confirm the volatges if so.

[guy]

Very roughly off the top of my head so dont quote me its something like 65-0-65 AC for the low power section of the amp and 42-0-42 AC for the high current section, plus 24DC for the timer and relay circuit. I dont think there is a rectifier on the relay board, so you need one and some filter caps in the PSU for this. I think you still can get get hold of the plugs in order to make a lead up, or if not you can buy new sockets and plugs that will fit the hole in the chassis.

Does anyone know what the rms watts into 8 ohms is? Would be a bit easier to confirm the volatges if so.


http://www.audioasylumtrader.com/ca/listing/Amplifier-SS/TANNOY-Tresham/DR-102/Reference-amplifier/61863

has some details on the power, also has the name of the founder of the company - he may be worth trying to find.

[Light Dependant Resistor]

An image here of the Preamp , power supply and power amps rear panel.
https://www.ebay.com/itm/TRESHAM-DR1-DR102-PS-102-PRE-amp-POWER-AMP-POWER-SUPPLY-USED-RARE-/253040347731?rmvSB=true&nma=true&si=CAKXjEoZOyTw1p%252FtPqM8ABdmGVc%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

I think in the circumstance a letter or email to Tannoy might provide answer. A clue in the image above shows the connectors may be stocked by Radio Spares.

Other power amps of similar vintage in the UK rarely exceeded 100w per channel, which can be achieved with 35v 0v 35v secondaries.
Quad's 405 for instance just achieved 100w per channel into 8 ohms, whereas the Naim 250 was 80w per channel.
My guess is there are two possibly three toroidal transformers internally in the power supply casework, nothing too fancy just laid out with fusing
and connection to the connector block. As I say, I doubt any voltage from these exceeds 35v 0v 35v, and may include as suggested a relay designated output. A image or two internally of the power amp would assist to assist, for instance the DC specification on power supply capacitors, if they are 63v you can be fairly sure the DC rails are 50v, or slightly lower.

[Primalsea]

The 2 massive caps are rated at 80v and the smaller caps fornthe low current section 100v. The output devices are J50 and J135, 2 of each in parallel for each channel. These are rated at 160v and 7 amps each. There was a picture on the web showing 50v dc for the high current section and 80v dc for the low current section. This would seem to be about right if the amp was rated at 300 watts (312 peak, roughly 150 RMS) into 8 ohms. I believe that the orignal intention for these amps were for PA systems and designed to be robust.

[donmarrese]

http://www.audioasylumtrader.com/ca/listing/Amplifier-SS/TANNOY-Tresham/DR-102/Reference-amplifier/61863

has some details on the power, also has the name of the founder of the company - he may be worth trying to find.

Hi Guy, that dialogue from that forum/website isn't exactly true...because of the restrictions imposed, and rightly so, on mentioning a certain Twat, I cannot elaborate..
although it was the bigger amp Tannoy's were interested in not the DR-102...DR-102 is a scaled down version of the SR-404...SR-404 was the only decent amp that could drive their Larger Tannoy's at the time..Tresham tamed the Mosfet amp!

[donmarrese]

The 2 massive caps are rated at 80v and the smaller caps fornthe low current section 100v. The output devices are J50 and J135, 2 of each in parallel for each channel. These are rated at 160v and 7 amps each. There was a picture on the web showing 50v dc for the high current section and 80v dc for the low current section. This would seem to be about right if the amp was rated at 300 watts (312 peak, roughly 150 RMS) into 8 ohms. I believe that the orignal intention for these amps were for PA systems and designed to be robust.

Hi Paul
We're making some progress here...
2 things, if you look at that ebay Tresham kit for sale right now, (Over priced BTW) you'll notice the power supply going to the amp is made by Avondale...See the sticker..:-)
I've send Avondale an email..waiting for a reply re. the elusive power supply...

also, here is a list of components we need...not sure if the values are correct...

Toroidal 35V x 2 300VA RS 123-4029
Toroidal 18V x 2 120VA (3.33A) RS 223-8033
2A 200V Bridge rectifier RS 629-3728
2 x 4700uF 50V capacitors RS 711-1526 (Twin pack)
Toroidal 67V x 2 1A (120VA)
Case
IEC chassis mount plug
20mm fuse holder
Neon indicator RS 786-4384

Put that in yer pipe and smoke it!
We might be able to resurect the holy grail with this thread!

All the best
Don

[donmarrese]

The 2 massive caps are rated at 80v and the smaller caps fornthe low current section 100v. The output devices are J50 and J135, 2 of each in parallel for each channel. These are rated at 160v and 7 amps each. There was a picture on the web showing 50v dc for the high current section and 80v dc for the low current section. This would seem to be about right if the amp was rated at 300 watts (312 peak, roughly 150 RMS) into 8 ohms. I believe that the orignal intention for these amps were for PA systems and designed to be robust.

Ah Paul, the earlier kit was designed specifically for Studio use...but yes, ur right, they where and still are bullet proof!

[Primalsea]

Hi Paul
We're making some progress here...
2 things, if you look at that ebay Tresham kit for sale right now, (Over priced BTW) you'll notice the power supply going to the amp is made by Avondale...See the sticker..:-)
I've send Avondale an email..waiting for a reply re. the elusive power supply...

also, here is a list of components we need...not sure if the values are correct...

Toroidal 35V x 2 300VA RS 123-4029
Toroidal 18V x 2 120VA (3.33A) RS 223-8033
2A 200V Bridge rectifier RS 629-3728
2 x 4700uF 50V capacitors RS 711-1526 (Twin pack)
Toroidal 67V x 2 1A (120VA)
Case
IEC chassis mount plug
20mm fuse holder
Neon indicator RS 786-4384

Put that in yer pipe and smoke it!
We might be able to resurect the holy grail with this thread!

All the best
Don

I suspect that you may not need the 18v transformer, 4700uf caps and rectifier as these are just fed through the power amp and into the matching preamp. If you dont have the preamp, or you have the separate preamp psu these are not needed I think. It is possible that the pre amp supply also fed the relay and protection board, meaning that i was wrong about needing 24v dc. I need to did my DR102 out the loft and read my notes from when I stripped it down.

Stay tuned.

[guy]

Hi Guy, that dialogue from that forum/website isn't exactly true...because of the restrictions imposed, and rightly so, on mentioning a certain Twat, I cannot elaborate..
although it was the bigger amp Tannoy's were interested in not the DR-102...DR-102 is a scaled down version of the SR-404...SR-404 was the only decent amp that could drive their Larger Tannoy's at the time..Tresham tamed the Mosfet amp!

Hi Donmarrese,

Primalsea wanted to know the power output of the amp, the site that I linked to contains that information.

This site:
http://audiotools.com/en_dead_to.html
seems to confirm that Tresham was founded by (and sold to Tannoy by) the person that you so obviously have an axe to grind with.

Also, I don't think that it is particularly good form to use such insulting terms - not least because it reflects on yourself.

Guy.

[donmarrese]

Guy, I speak to the other founder member on a regular basis, and if you knew what I know, you'd agree with me.
I'll pm my mob and I will enlighten you further,
No axe to grind...

Sent from my ONE A2003 using Tapatalk

[Primalsea]

Quite a few years ago Tannoy emailed me the schematics for the amp, bit I lost them. I asked again recently but apprently now it is not their policy to provide such sensitive technical data on their products - A amp they not made for decades!

One thing did occur to me is that it may be the case that the low current section regulator outputs 80 volts, so the peak voltage of the transformer will have to be higher than this. The output voltage of the regulator should be established first before buying the transformer.

[DSJR]

Guy, I speak to the other founder member on a regular basis, and if you knew what I know, you'd agree with me.
I'll pm my mob and I will enlighten you further,
No axe to grind...

Sent from my ONE A2003 using Tapatalk


Ignoring personalities - and one in particular - I understand Tresham was sold totally to Tannoy and this included all documentation, drawings and so on. This individual wasn't with Tannoy for very long my dealer-pal tells me and, apart from a generally very good review in one of the 'Choice amp books, Tannoy quietly abandoned production a short while later I understand.

Maybe it's too much bother for Tannoy for someone to look through old files thirty five years on, but if they hold the schematics and so on, they should be willing to help surely? Maybe they've also destroyed all the old paperwork and designs for units that they didn't continue with?

[Beobloke]

This may well be the case - namely that whilst people at Tannoy may be more than willing to help, they simply cannot because the information is no longer avaiable.

I still remember the number of emails we received when I was at Goodmans, asking for circuit diagrams for old Module 90 receivers and the like. We'd have loved to have helped, but the information had been binned years previously.

[donmarrese]

Ignoring personalities - and one in particular - I understand Tresham was sold totally to Tannoy and this included all documentation, drawings and so on. This individual wasn't with Tannoy for very long my dealer-pal tells me and, apart from a generally very good review in one of the 'Choice amp books, Tannoy quietly abandoned production a short while later I understand.

Maybe it's too much bother for Tannoy for someone to look through old files thirty five years on, but if they hold the schematics and so on, they should be willing to help surely? Maybe they've also destroyed all the old paperwork and designs for units that they didn't continue with?

Spot on, yes Tannoy's bought the brains as well as the documentation et al.

about 7 years ago, I came across a DR-1 Tresham pre amp, with no power supply...1st call = Tannoy. I spoke to customer services; Can't help you Sir point blank.
2nd Call to Schweppes (You know who): totally negative response, didn't want to know, why don't you try one of my plastic boxes with earthing problems?

There's load more, but this thread is all about re creating a power supply, and whose got the schematics...

[Primalsea]

I also suspect that the published power output of these amps were very conservative. I found a data sheet and the figures seem to be what the designer considered maximum power while still retaining good performance, not what the amp is actually capable of. The key is to find out the output of the low current regulator. For this I think it is a case of tracing out the circuit and running it through a simulator.

[Audioflyer]

Not sure if this will help!

21935

[Firebottle]

Well that certainly helps a lot.

With a bit of creative rectification you could do that with 2 off the shelf transformers.

[Primalsea]

I think I may have cracked it.

Toroidal 35V x 2 300VA RS 123-4029. This is rectified and filtered in the DR102 to provide +/- 50 VDC for the output MOSFETS.

Toroidal 67V x 2 1A (120VA). This is rectified and filtered in the DR102 to provide +/- 100 VDC which is then dropped to +/- 80 VDC for the driver stage. A 65V X 2 toroidal may work; is is a more commonly available item.

Toroidal 18V x 2 120VA (3.33A) RS 223-8033
2A 200V Bridge rectifier RS 629-3728
2 x 4700uF 50V capacitors RS 711-1526 (Twin pack)

These last three items are required because the relay and sensing board needs +/ 24VDC. I haven't checked the but this may also be the power supply for the preamp as well. Not sure yet. Very over specified components just to power a relay board.

From Farnell:

Connector Housing, Mini Universal MATE-N-LOK Series, Plug, 9 Ways, 4.14 mm
Manufacturer: AMP - TE CONNECTIVITY
172169-1

Connector Housing, Mini Universal MATE-N-LOK Series, Receptacle, 9 Ways, 4.14 mm
Manufacturer: AMP - TE CONNECTIVITY
172161-1

The connector & plug are to replace the BICC Burndy 12 way connectors that are no longer available as far as I can tell. Only 7 pins are actually used, so a 9 way connector will be fine. This is a 14mm x 14mm connector and some modification to the case may be required.

Rocker Switch, Non Illuminated, DPDT, On-On, Black, Panel, 20 A
Manufacturer: ARCOLECTRIC
C1560VQAAA

Fuse, Cartridge, Slow Blow, 5 A, 250 V, 5mm x 20mm, 0.2" x 0.79", 218 Series
Manufacturer: LITTELFUSE
0218005.MXP

Fuseholder, Base Mount, 250V, 6.3A, 5 x 20mm, Solder Tags
Manufacturer: BULGIN
FX0360

Power Entry Connector, 6600.3, Receptacle, 250 V, 10 A, Panel Mount, Quick Connect
Manufacturer: SCHURTER
6600.4320

LED Panel Mount Indicator, Amber, 240 VAC, 6.4 mm, 1 mA
Manufacturer: CAMDENBOSS
IND515205-LED2-T/AMB

Metal Enclosure, NEMA, IP66, Wall Mount, Steel, IP66, NEMA 4, 12, 200 mm, 300 mm
Manufacturer: HOFFMAN ENCLOSURES
MSC20030080E

the case is white and not exactly a stunner, but it is relatively cheap.

[donmarrese]

Well done Paul..

Sent from my ONE A2003 using Tapatalk

[DSJR]

I do wish you all the best, as I hate to see old decent gear be chucked out because nothing can be done with them. Even the Goodmans Module 90, of which shedloads were sold (and the chassis used in other label music-centres too, the deck mounted on top) wasn't a bad unit when new I recall.

[donmarrese]

Well, we've come this far...but we are looking at £100 alone in transformers for this power supply...this could be one costly power supply, unless anyone has any ideas or access to cheaper components, Transformers from a trade source maybe? (not sacrificing quality, of course...)

Comments welcome...