Adding a selectable line input to valve radiogram - Page 6 - UK Vintage Radio Repair and Restoration Discussion Forum

Station X · 2nd Nov 2020, 7:29 pm

Let's not forget that there were autochangers that only played 78's. If breakage had been problem they wouldn't have been popular.

Rich400 · 3rd Nov 2020, 11:59 am

Quote:

Originally Posted by regentone001

I have 1000s of 78s and regularly play them on auto changers and have never had one break, even cracked ones have survived the drop though often it causes the crack to be more obvious with one side ending up higher than the other. I suspect that unfortunately the record was already cracked and the drop finished it off. I bought a copy of Moonlight Serenade off eBay last year so you should be able to get another copy
Steve

Thanks Steve
It played fine before but it’s possible that there was a fault.
I think I will fit a thin layer (2 to 3mm) of cushioning under the mat just in case.
They do tend to fall hard!

Edward Huggins · 3rd Nov 2020, 2:42 pm

You can add more Cushioning if you feel the need, but this is only going to be "effective" on the first record on the stack. I think it might be that you are just not used to seeing a stack of 78s play automatically? They do make a racket when they land and the auto mechanism (except on Collaro decks) does rattle its way through the cycle. I have never damaged a stacked up 78 in over 65 years!

Rich400 · 3rd Nov 2020, 4:24 pm

Hi Edward
Thanks for your comment but more than happy to auto change 78's that's what lead to the catastrophic failure of my copy of Moonlight Serenade. It has been suggested that this may had had a crack in it, but I didn't notice anything. This platter is quite small and I suspect any air cushion effect is not happening here, certainly not on LP's. I think I will try the cushioning, as I will mainly be playing one or two on auto and there should still be some compressibility at that number. I was wondering if there was any 'tilt' adjustment on the spindle to increase some drag on the way down.

Edward Huggins · 3rd Nov 2020, 4:47 pm

Well, your turntable is 10" in diameter and that's the size of most 78s....
I think you have become far too overly concerned. Just pile 'em high and play 'em!
It's most likely that you will never damage/weaken another 78 ever again.
Do not attempt to alter/adjust the stacking spindle on your BSR UA12/14, leave well alone. Indeed, you may be thinking of the unique tilted spindle to be found on many early Garrard autochangers.

Rich400 · 3rd Nov 2020, 9:28 pm

Quote:

Originally Posted by Edward Huggins

Well, your turntable is 10" in diameter and that's the size of most 78s....
I think you have become far too overly concerned. Just pile 'em high and play 'em!
It's most likely that you will never damage/weaken another 78 ever again.
Do not attempt to alter/adjust the stacking spindle on your BSR UA12/14, leave well alone. Indeed, you may be thinking of the unique tilted spindle to be found on many early Garrard autochangers.

Hi Edward
My deck is an early garrard 121 Mk 2
So it mey have an adjustment?

Edward Huggins · 4th Nov 2020, 10:09 am

Well, that has a wide enough 10" platter and again there is no adjustment available, or needed, to the stacking spindle.

lazythread · 4th Nov 2020, 12:21 pm

The RC121/2 has an 8 inch turntable and if the mat has solidified, it could well be a hard drop for the first record. I remember a copy of Richard Tauber's "Song of Songs" shattering on my parents' RC120/2 ca. 1972. The outside edge of the mat was starting to develop hard spots. I had just been given the record and hadn't noticed a crack.

However, I play 78s on a Garrard SL65 changer without problems and you shouldn't worry in principle.

New remanufactured rubber mats for the RC121/2 appear on eBay regularly so salvation is at hand. In the meantime just a keep a record on the platter all the time to act as a mat.

I'm not aware of any adjustment available for the spindle, my service sheet is, er, put in a safe place.

Edward Huggins · 4th Nov 2020, 1:35 pm

The Garrard "Autoslim" is the Garrard with an 8" platter, but the Garrard RC121/2 does have a 10" platter. Just check out the photos of these. It will give ample support to any 10" 78.

Rich400 · 4th Nov 2020, 1:49 pm

Quote:

Originally Posted by lazythread

The RC121/2 has an 8 inch turntable and if the mat has solidified, it could well be a hard drop for the first record. I remember a copy of Richard Tauber's "Song of Songs" shattering on my parents' RC120/2 ca. 1972. The outside edge of the mat was starting to develop hard spots. I had just been given the record and hadn't noticed a crack.

However, I play 78s on a Garrard SL65 changer without problems and you shouldn't worry in principle.

New remanufactured rubber mats for the RC121/2 appear on eBay regularly so salvation is at hand. In the meantime just a keep a record on the platter all the time to act as a mat.

I'm not aware of any adjustment available for the spindle, my service sheet is, er, put in a safe place.

Hi that’s great advice, the mat has certainly hardened, and as I took delivery of a new stylus for my Ronette BF-40, I thought I would try a 45.
Unfortunately the mat is so hard the disc starts to slip.
I gave it a wipe over with alcohol but to no avail, looks like a new mat!
Excellent advice thanks very much
Richard

Edward Huggins · 4th Nov 2020, 2:13 pm

If this is the case then make a 10" mat out of a large Pizza tray. Use a 10" record as a template.

lazythread · 5th Nov 2020, 10:57 am

Quote:

Originally Posted by Edward Huggins

The Garrard "Autoslim" is the Garrard with an 8" platter, but the Garrard RC121/2 does have a 10" platter. Just check out the photos of these. It will give ample support to any 10" 78.

Edward, we're both wrong

I just measured the platters on my turntables

RC121/2 = 9" over the platter, 8¾"over the mat (which has probably shrunk as it is rock hard I certainly wouldn't play 78s on it until I get a new mat)
Autoslim = 8"
SL65 = 10⅜"

Best wishes

Edward Huggins · 5th Nov 2020, 11:11 am

Many thanks for correcting me with the specifics above. Even so, a 9" platter is surely bound to give adequate support to a 10" disc. Most of the early BSRs, Collaros, Garrards and those troublesome Plessey/EMI decks had platters between 9" and 10" in diameter and these were principally designed for stacking 78s. Now, I know we are getting into some fine detail here, but I am trying to re-assure the OP about the inherent safety of stacking shellacs (unless they are already damaged) on to an autochanger.

Rich400 · 5th Nov 2020, 6:46 pm

Quote:

Originally Posted by Edward Huggins

Many thanks for correcting me with the specifics above. Even so, a 9" platter is surely bound to give adequate support to a 10" disc. Most of the early BSRs, Collaros, Garrards and those troublesome Plessey/EMI decks had platters between 9" and 10" in diameter and these were principally designed for stacking 78s. Now, I know we are getting into some fine detail here, but I am trying to re-assure the OP about the inherent safety of stacking shellacs (unless they are already damaged) on to an autochanger.

Hi Edward
Many thanks for your reassurance but I have no issue stacking the 78’s. As it broke a perfectly good one I think we can safely say it’s down to the mat.
The new one should be here tomorrow.

Rich400 · 7th Nov 2020, 12:01 pm

Now making time to sit down and put together a schematic for this mod so I can order the bits, but meantime I thought I would post a pic of the new mat, it’s amazing what you can get hold of, thanks for the advice gents hopefully no more breakages!
Ps I think I will up grade the head shell with the stereo input, to MM. the Ronette BF40 sounds flat as a pancake, the GC8 head shell on 78’s even sounds better!
(Of course the 78’s help there...)
So I need to integrate a pre amp into my modification circuitry, not to much of a problem there but as the tracking weight in this deck seems to be high I thought of using the Ortofon Pro S. this fits straight into my head shell and I can put together a pre amp to suit. I’ll wire this as an option on my new rotary switch so I can still switch between cartridges.
Unless someone knows of a more appropriate cartridge?

Edward Huggins · 7th Nov 2020, 12:28 pm

It's unlikely you'll hear any appreciable difference by adding a MM cartridge and a pre-amp - but you might hear more hum and noise. Anf then there's the question of correct tracking. After 115 posts and counting, I think we've covered some of this earlier?
Just go get an BSR SC11M, 12M or 12H and it will sound well matched to the Decca.
If not that, then a cheapo Chinese with LPS/78 flipunder stylus on a standard 1/2" mount. As I say, and short of trawling back throgh all these many Posts, surely we've discussed all this before.....?

Rich400 · 7th Nov 2020, 1:55 pm

Quote:

Originally Posted by Edward Huggins

It's unlikely you'll hear any appreciable difference by adding a MM cartridge and a pre-amp - but you might hear more hum and noise. Anf then there's the question of correct tracking. After 115 posts and counting, I think we've covered some of this earlier?
Just go get an BSR SC11M, 12M or 12H and it will sound well matched to the Decca.
If not that, then a cheapo Chinese with LPS/78 flipunder stylus on a standard 1/2" mount. As I say, and short of trawling back throgh all these many Posts, surely we've discussed all this before.....?

Hi Edward
Thanks for your post.
I’ve seen most of these posts and I’m still getting a benefit.
To my knowledge I can’t remember discussing a pre amp and requesting a recommendation for a mm cartridge. This is important as I need to design a circuit that integrates a pre amp and the potential to adjust the RIAA curve with my selectable ext input. Knowing the right cartridge is a cornerstone of this.
I do note your preference for cheapo Chinese cartridges though. I am still leaning to something a little better for myself however, but your advice is appreciated.
I now note these Ortofon OM pro S carts are a good upgrade for this deck as they work well with the higher tracking weight (I think that’s one thing I mentioned before though...) I just picked this up from another post on this site, well buried though.
Thanks again for the input.

Edward Huggins · 7th Nov 2020, 2:58 pm

You may need to read up a bit more on pre-amps. You can't ADJUST an RIAA curve as this is fixed. The pre-amp provides the RIAA curve.
As to fitting an Ortofon MM, well you already have my view on this.
However, other Members may have a different opinion.
But again, I think this has all been well covered earlier...

Rich400 · 7th Nov 2020, 6:14 pm

Quote:

Originally Posted by Edward Huggins

You may need to read up a bit more on pre-amps. You can't ADJUST an RIAA curve as this is fixed. The pre-amp provides the RIAA curve.
As to fitting an Ortofon MM, well you already have my view on this.
However, other Members may have a different opinion.
But again, I think this has all been well covered earlier...

Hi Edward thanks again

To clarify the RIAA curve just describes the non linear relationship of bass in the output of the cartridge. By building in an adjustable low pass filter into the circuitry Of my modification I can either increase or reduce the bass level. This will adjust graphically the RIAA curve.
Sorry for not being clearer on this point.

Rich400 · 14th Nov 2020, 6:09 pm

Hi
Looking for a bit of advice...
I have the mod working ( selectable input to this amp) now and I am very surprised with the excellent sound quality!
My question is that while I am doing this I would like to trim the final line output to the amp (a small amplification) with a panel mounted potentiometer controlling a pre amp to trim between the varying input levels found between cd outputs (actually from the server via WiFi but this just replicates the original cd output levels).
A simple pot won’t do as the higher levels seen from discs are the correct level for my amp. So I have to marginally lift these lower levels.
I tried a board I had kicking around which was a cheap Chinese preamp with tone pots on board but the line input level to this was too high. I don’t actually know it’s specs but sounds like a phono preamp as it was seriously clipping.
Besides I just need a single panel mounted stereo pot/amp for this.
Can anyone advise something that will do? I have 12vac next door powering the new VU meters so it would be handy if the new board was also 12vac.
Thanks in advance.

2nd Nov 2020, 7:29 pm	#101
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Adding a selectable line input to valve radiogram Let's not forget that there were autochangers that only played 78's. If breakage had been problem they wouldn't have been popular. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

3rd Nov 2020, 2:42 pm	#103
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram You can add more Cushioning if you feel the need, but this is only going to be "effective" on the first record on the stack. I think it might be that you are just not used to seeing a stack of 78s play automatically? They do make a racket when they land and the auto mechanism (except on Collaro decks) does rattle its way through the cycle. I have never damaged a stacked up 78 in over 65 years! __________________ Edward.

3rd Nov 2020, 4:24 pm	#104
Rich400 Tetrode Join Date: Oct 2020 Location: Lowestoft, Suffolk, UK. Posts: 71	Re: Adding a selectable line input to valve radiogram Hi Edward Thanks for your comment but more than happy to auto change 78's that's what lead to the catastrophic failure of my copy of Moonlight Serenade. It has been suggested that this may had had a crack in it, but I didn't notice anything. This platter is quite small and I suspect any air cushion effect is not happening here, certainly not on LP's. I think I will try the cushioning, as I will mainly be playing one or two on auto and there should still be some compressibility at that number. I was wondering if there was any 'tilt' adjustment on the spindle to increase some drag on the way down.

3rd Nov 2020, 4:47 pm	#105
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram Well, your turntable is 10" in diameter and that's the size of most 78s.... I think you have become far too overly concerned. Just pile 'em high and play 'em! It's most likely that you will never damage/weaken another 78 ever again. Do not attempt to alter/adjust the stacking spindle on your BSR UA12/14, leave well alone. Indeed, you may be thinking of the unique tilted spindle to be found on many early Garrard autochangers. __________________ Edward.

4th Nov 2020, 10:09 am	#107
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram Well, that has a wide enough 10" platter and again there is no adjustment available, or needed, to the stacking spindle. __________________ Edward.

4th Nov 2020, 12:21 pm	#108
lazythread Pentode Join Date: Jun 2011 Location: Berkshire, UK. Posts: 124	Re: Adding a selectable line input to valve radiogram The RC121/2 has an 8 inch turntable and if the mat has solidified, it could well be a hard drop for the first record. I remember a copy of Richard Tauber's "Song of Songs" shattering on my parents' RC120/2 ca. 1972. The outside edge of the mat was starting to develop hard spots. I had just been given the record and hadn't noticed a crack. However, I play 78s on a Garrard SL65 changer without problems and you shouldn't worry in principle. New remanufactured rubber mats for the RC121/2 appear on eBay regularly so salvation is at hand. In the meantime just a keep a record on the platter all the time to act as a mat. I'm not aware of any adjustment available for the spindle, my service sheet is, er, put in a safe place. __________________ Richard It's great when it goes around to make a sound. Last edited by lazythread; 4th Nov 2020 at 12:27 pm.

4th Nov 2020, 1:35 pm	#109
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram The Garrard "Autoslim" is the Garrard with an 8" platter, but the Garrard RC121/2 does have a 10" platter. Just check out the photos of these. It will give ample support to any 10" 78. __________________ Edward.

4th Nov 2020, 2:13 pm	#111
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram If this is the case then make a 10" mat out of a large Pizza tray. Use a 10" record as a template. __________________ Edward.

5th Nov 2020, 11:11 am	#113
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram Many thanks for correcting me with the specifics above. Even so, a 9" platter is surely bound to give adequate support to a 10" disc. Most of the early BSRs, Collaros, Garrards and those troublesome Plessey/EMI decks had platters between 9" and 10" in diameter and these were principally designed for stacking 78s. Now, I know we are getting into some fine detail here, but I am trying to re-assure the OP about the inherent safety of stacking shellacs (unless they are already damaged) on to an autochanger. __________________ Edward.

7th Nov 2020, 12:01 pm	#115
Rich400 Tetrode Join Date: Oct 2020 Location: Lowestoft, Suffolk, UK. Posts: 71	Re: Adding a selectable line input to valve radiogram Now making time to sit down and put together a schematic for this mod so I can order the bits, but meantime I thought I would post a pic of the new mat, it’s amazing what you can get hold of, thanks for the advice gents hopefully no more breakages! Ps I think I will up grade the head shell with the stereo input, to MM. the Ronette BF40 sounds flat as a pancake, the GC8 head shell on 78’s even sounds better! (Of course the 78’s help there...) So I need to integrate a pre amp into my modification circuitry, not to much of a problem there but as the tracking weight in this deck seems to be high I thought of using the Ortofon Pro S. this fits straight into my head shell and I can put together a pre amp to suit. I’ll wire this as an option on my new rotary switch so I can still switch between cartridges. Unless someone knows of a more appropriate cartridge? Attached Thumbnails

7th Nov 2020, 12:28 pm	#116
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram It's unlikely you'll hear any appreciable difference by adding a MM cartridge and a pre-amp - but you might hear more hum and noise. Anf then there's the question of correct tracking. After 115 posts and counting, I think we've covered some of this earlier? Just go get an BSR SC11M, 12M or 12H and it will sound well matched to the Decca. If not that, then a cheapo Chinese with LPS/78 flipunder stylus on a standard 1/2" mount. As I say, and short of trawling back throgh all these many Posts, surely we've discussed all this before.....? __________________ Edward.

7th Nov 2020, 2:58 pm	#118
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,328	Re: Adding a selectable line input to valve radiogram You may need to read up a bit more on pre-amps. You can't ADJUST an RIAA curve as this is fixed. The pre-amp provides the RIAA curve. As to fitting an Ortofon MM, well you already have my view on this. However, other Members may have a different opinion. But again, I think this has all been well covered earlier... __________________ Edward.

14th Nov 2020, 6:09 pm	#120
Rich400 Tetrode Join Date: Oct 2020 Location: Lowestoft, Suffolk, UK. Posts: 71	Re: Adding a selectable line input to valve radiogram Hi Looking for a bit of advice... I have the mod working ( selectable input to this amp) now and I am very surprised with the excellent sound quality! My question is that while I am doing this I would like to trim the final line output to the amp (a small amplification) with a panel mounted potentiometer controlling a pre amp to trim between the varying input levels found between cd outputs (actually from the server via WiFi but this just replicates the original cd output levels). A simple pot won’t do as the higher levels seen from discs are the correct level for my amp. So I have to marginally lift these lower levels. I tried a board I had kicking around which was a cheap Chinese preamp with tone pots on board but the line input level to this was too high. I don’t actually know it’s specs but sounds like a phono preamp as it was seriously clipping. Besides I just need a single panel mounted stereo pot/amp for this. Can anyone advise something that will do? I have 12vac next door powering the new VU meters so it would be handy if the new board was also 12vac. Thanks in advance.