Arcam Delta 90 Amp - UK Vintage Radio Repair and Restoration Discussion Forum

James B · 2nd Oct 2007, 10:33 pm

Not sure if this quite qualifies as 'vintage' (1986!) but I've acquired this amp today. I haven't powered it up yet as it's now a bit late to be doing so, but tomorrow I'll try it. Very sturdy build; the transformer is like a tractor wheel and weighs as much I'm sure...

I downloaded the manual from the Arcam website but there doesn't seem to be much other info on this amp about. Does anyone have one? Are they any good for Arcam stuff?

paulsherwin · 2nd Oct 2007, 10:47 pm

I've never owned or even heard one of these but it's an upper mid range amp. Arcam launched the Delta range in the mid 80s (85?) to replace the very well regarded Arcam Alpha. I think the Delta 90 was 3 models up in the range (there was a 60 and 70, though I don't think there was an 80). There was also a Delta 120 which had separate pre and power amps.

Should be a good amp anyway - useful if you want to annoy the neighbours

Paul

James B · 2nd Oct 2007, 11:41 pm

Hmm yes... it seems to be rated at 70 watts stereo into 8 ohms!! My current studio amp is a slightly more modest Rotel 25 watt affair!

paulsherwin · 2nd Oct 2007, 11:59 pm

Quote:

Originally Posted by James B

Hmm yes... it seems to be rated at 70 watts stereo into 8 ohms!! My current studio amp is a slightly more modest Rotel 25 watt affair!

That probably means it is 70W RMS both channels driven. Quality hifi amps are normally rated in this way (none of your 'peak music power output' nonsense

).

It's quite a lot of noise, but of course you need the power if you're using inefficient speakers or listening to material with a very wide dynamic range. Amps of this quality (I would guess around £400 new) would be expected to produce this sort of output.

Paul

James B · 3rd Oct 2007, 2:15 am

You would be right, Paul. The manual claims:

Both channels (8 ohms) 70w
(20Hz-20kHz, 0.5% THD)

Single Channel 8 ohms 85w
Single Channel 4 ohms 130w

Peak Current Delivery ±16A

Bit of a powerhouse then! I have been eyeing up floorstanding speakers on ebay....

mhennessy · 3rd Oct 2007, 11:07 am

Should you need a service manual, email Arcam and they will send you a pdf by return. Which is great service IMO - most hi-fi manufacturers are very protective of their IP.

You're dead right to bring together power and speaker efficiency. After all, 70W is only 4.5dB more than 25W. If I might be allowed to take some examples from that era, consider that Rogers/BBC LS3/5A's are 82.5dB/2.83V, and Rogers LS7's are 88dB/2.83V. Therefore, your Rotel coupled with the LS7's will actually sound louder than the Arcam with the LS3/5A's. Needless to say, the Arcam driving the LS7's will reach insane levels! Modern speakers vary just as much, of course...

Also, as both these amps have unregulated power supplies, their "dynamic power" will be considerably greater than their "average" or "continuous sine wave" (not RMS!) power ratings. This is quite "legit" BTW; unlike PMPO!

If possible, I'd interested in seeing pictures of the insides, plus the service manual if you decide to get it.

Mark

James B · 3rd Oct 2007, 12:44 pm

Thanks for that, I will get in touch with Arcam for a service manual and pass it on if anyone wants one. I have taken some pictures of the Delta 90 guts, but they are a bit big to put on the thread itself. I could scale them down but then you'll lose the ability to zoom in to see what's there. If anyone wants 5 pics, just PM me

rovereab · 5th Oct 2007, 11:51 pm

My set-up is a Delta 90.2 amplifier, Delta 80 tuner, Dual 505-4 record deck, Micromega Stage 1 CD player and Mission 753 speakers.

I wonder if my amplifier is much different?

I chose the components carefully at the time and in particular the combination of the amplifier and speakers. The amplifier being a bit "flat" and the speakers a bit "bright" seemed to suit our lounge. I was lucky to be able to audition several pairs of speakers in our lunge before I bought the 753s.

I rate Arcam components highly and would buy from them again. Nice solid feeling to them.

Regards.

Eamonn

James B · 6th Oct 2007, 12:14 am

Update: It does work! I finally got hold of a spare bit of speaker cable to try them. It was only with a naff spare pair of 6-ohm Sony hi-fi speakers, but even on those, there was a lot of depth and power to the sound. It is indeed loud: 9 o'clock on the volume was plenty for average listening!

Arcam sent me the service and operation manuals as mhennessy suggested. If anyone would like them, just PM me. The only cosmetic differences I have seen between the 90 and 90.2, from looking on the net, are a scale on the volume control and two lines on the top of the fascia. Other than that I have no idea

dtm1962 · 15th Jan 2008, 4:38 am

Quote:

Originally Posted by James B

Update: It does work! I finally got hold of a spare bit of speaker cable to try them. It was only with a naff spare pair of 6-ohm Sony hi-fi speakers, but even on those, there was a lot of depth and power to the sound. It is indeed loud: 9 o'clock on the volume was plenty for average listening!

Arcam sent me the service and operation manuals as mhennessy suggested. If anyone would like them, just PM me. The only cosmetic differences I have seen between the 90 and 90.2, from looking on the net, are a scale on the volume control and two lines on the top of the fascia. Other than that I have no idea

Please can you forward Arcam Delta 90 schematic to me as I picked up one of these amps myself and I like to have the service manual as well.

Thanks in advance,

Dan

2nd Oct 2007, 10:33 pm	#1
James B Retired Dormant Member Join Date: Mar 2007 Location: Retford, Nottinghamshire, UK. Posts: 181	Arcam Delta 90 Amp Not sure if this quite qualifies as 'vintage' (1986!) but I've acquired this amp today. I haven't powered it up yet as it's now a bit late to be doing so, but tomorrow I'll try it. Very sturdy build; the transformer is like a tractor wheel and weighs as much I'm sure... I downloaded the manual from the Arcam website but there doesn't seem to be much other info on this amp about. Does anyone have one? Are they any good for Arcam stuff?

2nd Oct 2007, 10:47 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Arcam Delta 90 Amp I've never owned or even heard one of these but it's an upper mid range amp. Arcam launched the Delta range in the mid 80s (85?) to replace the very well regarded Arcam Alpha. I think the Delta 90 was 3 models up in the range (there was a 60 and 70, though I don't think there was an 80). There was also a Delta 120 which had separate pre and power amps. Should be a good amp anyway - useful if you want to annoy the neighbours Paul

2nd Oct 2007, 11:41 pm	#3
James B Retired Dormant Member Join Date: Mar 2007 Location: Retford, Nottinghamshire, UK. Posts: 181	Re: Arcam Delta 90 Amp Hmm yes... it seems to be rated at 70 watts stereo into 8 ohms!! My current studio amp is a slightly more modest Rotel 25 watt affair!

3rd Oct 2007, 2:15 am	#5
James B Retired Dormant Member Join Date: Mar 2007 Location: Retford, Nottinghamshire, UK. Posts: 181	Re: Arcam Delta 90 Amp You would be right, Paul. The manual claims: Both channels (8 ohms) 70w (20Hz-20kHz, 0.5% THD) Single Channel 8 ohms 85w Single Channel 4 ohms 130w Peak Current Delivery ±16A Bit of a powerhouse then! I have been eyeing up floorstanding speakers on ebay....

3rd Oct 2007, 11:07 am	#6
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Arcam Delta 90 Amp Should you need a service manual, email Arcam and they will send you a pdf by return. Which is great service IMO - most hi-fi manufacturers are very protective of their IP. You're dead right to bring together power and speaker efficiency. After all, 70W is only 4.5dB more than 25W. If I might be allowed to take some examples from that era, consider that Rogers/BBC LS3/5A's are 82.5dB/2.83V, and Rogers LS7's are 88dB/2.83V. Therefore, your Rotel coupled with the LS7's will actually sound louder than the Arcam with the LS3/5A's. Needless to say, the Arcam driving the LS7's will reach insane levels! Modern speakers vary just as much, of course... Also, as both these amps have unregulated power supplies, their "dynamic power" will be considerably greater than their "average" or "continuous sine wave" (not RMS!) power ratings. This is quite "legit" BTW; unlike PMPO! If possible, I'd interested in seeing pictures of the insides, plus the service manual if you decide to get it. Mark

3rd Oct 2007, 12:44 pm	#7
James B Retired Dormant Member Join Date: Mar 2007 Location: Retford, Nottinghamshire, UK. Posts: 181	Re: Arcam Delta 90 Amp Thanks for that, I will get in touch with Arcam for a service manual and pass it on if anyone wants one. I have taken some pictures of the Delta 90 guts, but they are a bit big to put on the thread itself. I could scale them down but then you'll lose the ability to zoom in to see what's there. If anyone wants 5 pics, just PM me Last edited by arjoll; 4th Oct 2007 at 8:53 am. Reason: Removed email address - please refer to forum rule G2

5th Oct 2007, 11:51 pm	#8
rovereab Tetrode Join Date: Mar 2005 Location: Chelmsford, Essex, UK. Posts: 86	Re: Arcam Delta 90 Amp My set-up is a Delta 90.2 amplifier, Delta 80 tuner, Dual 505-4 record deck, Micromega Stage 1 CD player and Mission 753 speakers. I wonder if my amplifier is much different? I chose the components carefully at the time and in particular the combination of the amplifier and speakers. The amplifier being a bit "flat" and the speakers a bit "bright" seemed to suit our lounge. I was lucky to be able to audition several pairs of speakers in our lunge before I bought the 753s. I rate Arcam components highly and would buy from them again. Nice solid feeling to them. Regards. Eamonn

6th Oct 2007, 12:14 am	#9
James B Retired Dormant Member Join Date: Mar 2007 Location: Retford, Nottinghamshire, UK. Posts: 181	Re: Arcam Delta 90 Amp Update: It does work! I finally got hold of a spare bit of speaker cable to try them. It was only with a naff spare pair of 6-ohm Sony hi-fi speakers, but even on those, there was a lot of depth and power to the sound. It is indeed loud: 9 o'clock on the volume was plenty for average listening! Arcam sent me the service and operation manuals as mhennessy suggested. If anyone would like them, just PM me. The only cosmetic differences I have seen between the 90 and 90.2, from looking on the net, are a scale on the volume control and two lines on the top of the fascia. Other than that I have no idea