Connecting a CD recorder to my SP/PH10

I use the tape outlet PAS preamplifier (original) to the computer and saturates the signal. To avoid this problem I interject in a potentiometer signal cable 500 K.

If the cassette deck input impedance is low like the other devices the same problem will exist. I think your best option is to use the MK4 buffer amp on ebay that was posted previously. It has a 1Meg ohm input impedance which would provide minimal loading, maybe use this only when you want to record. A listening test will tell you if leaving it connected will alter the sound quality during normal use. The other option would be if you wanted to try your hand at tech stuff. I don't know if there's enough reserve power in your preamp to provide enough power for one 12AU7 tube. This tube is ideal for a dual cathode follower amp which is practically the simplest amplifier, a cathode follower is used to do exactly what you need (high input impedance and low output impedance). The 12AU7 has two sections so you only need one. The power supply filament winding would need to supply either 150ma/300ma current and also about 15mA current from B+. Each amp (for R and L) would need approximately two capacitors and 4 resistors. I'm looking at page 50 of "Design and Construction of Tube Guitar Amplifiers", but I'm sure there are other circuits around. If you were willing to try this I'm sure we can get additional help from some of the users here. I envision a simple vector board with these components on it and mounted inside your chassis.

I share your desire to keep all things "tube".
Good luck...

bluerondo wrote:If the cassette deck input impedance is low like the other devices the same problem will exist. I think your best option is to use the MK4 buffer amp on ebay that was posted previously. It has a 1Meg ohm input impedance which would provide minimal loading, maybe use this only when you want to record. A listening test will tell you if leaving it connected will alter the sound quality during normal use. The other option would be if you wanted to try your hand at tech stuff. I don't know if there's enough reserve power in your preamp to provide enough power for one 12AU7 tube. This tube is ideal for a dual cathode follower amp which is practically the simplest amplifier, a cathode follower is used to do exactly what you need (high input impedance and low output impedance). The 12AU7 has two sections so you only need one. The power supply filament winding would need to supply either 150ma/300ma current and also about 15mA current from B+. Each amp (for R and L) would need approximately two capacitors and 4 resistors. I'm looking at page 50 of "Design and Construction of Tube Guitar Amplifiers", but I'm sure there are other circuits around. If you were willing to try this I'm sure we can get additional help from some of the users here. I envision a simple vector board with these components on it and mounted inside your chassis.

I share your desire to keep all things "tube".
Good luck...

I did my buffer with 12au7 and the schematics from http://www.valvewizard.co.uk/accf.html
( close to bottom). It uses 1/2 of 12au7 per channel, one tube is enough for stereo.

Now to make life easier, ebay sells zillions of buffers, one example :
http://www.ebay.com/itm/1x-6N3-Tube-HIFI-Buffer-Audio-pre-amplifier-amp-board-with-Transformer-/321511473902?pt=LH_DefaultDomain_0&hash=item4adb93c2ee
app. usd 55 . Needs some assembly.

TurboToy and PeterH are correct, the problem is that the SP10/PH10 does NOT have an output buffer, and anything connected to the TAPE OUT jacks should have an input impedance of greater than 100K. Even that will load the phono output down enough to cause a serious change in the RIAA EQ.

So, out of curiosity, is the "Tape out" just for a tube reel to reel deck?
Not bitchin', I LOVE my ST-70 and SP/PH 10 (both of which continue to work perfectly...thank you Troy and Sal).

you can use the TAPE OUT jacks for anything, but it had better have a very high input impedance, or it will load down the phono stage.
Best to add a buffer (either solid state or tube).

Any reason this is not a viable solution ? I hope so . As Bob may attest, it looks like a long winter indoors.

I have added a Hagerman Bugle2 solid state phono preamp to my zmod PAS3 as follows

TT to outboard phono preamp input
Phono preamp output to burner input
Burner output to preamp line level input.

The cd burner can now be used with no harm to the phono board.

When I get an urge to record,i just swap the cables at the turntable, and set my PAS to the input my burner uses.
It seems to work great, Takes about ten seconds to swap the cables, acts as a tape loop, and has the added benefit allowing me to monitor the recording levels.

For daily listening i use the zmod phono stage.
I do like it better, but the Bugle is also very good.
I have used a Yaquin buffer but it attenuates the signal too much for the burner to compensate for.
http://www.ebay.com/itm/YAQIN-CD1-Upgrade-6992-Tube-Buffer-Processor-For-CD-DVD-make-TRANS-sound-nice-/170482642516

I'm thinking again about trying this with the TASCAM CD-RW900 mkII. I like dmags' idea but I don't like having to plug and unplug my turntable mostly because of a space problem and the difficulty of getting behind the gear (and no room to slide components out for access).

Would a simple switcher degrade the signal to my SP10/PH10? Should I use anything special for this switch? I really, really don't want to degrade the sound in my living room. Keep in mind, my use for burnt CDs will only be in the decidedly low-fi Dodge caravan.

Also I have an old Pioneer SA 520 (with a phono input and plenty of line outs) that's only hooked up to a Sirius radio that I suppose would work as well as a new buffer/pre-amp. Right, wrong?

Remember, I'm a non-tech.



Actually I guess "B" should go to the Pioneer (or buffer/preamp) and then to the burner.

Sorry to resurrect an older thread but I just pulled the trigger on the TASCAM CD-RW900mkII Professional CD Recorder. (See first post for URL).

One poster said it might work, one said he had had zero luck getting this to work but most thought it would work with one of those eBay Chinese buffer amps. So I'm prepared to have to buy one of those gizmos.

Since I originally posted, I picked up an Audio Control 520B EQ unit (old early '80's stuff recommended by deepee99) that I have between my SP10/PH10 and my VTA ST70. (It works perfectly on the rare occasion I need to tweak a freq. on an old record).

The Audio control has a "tape out" that I'm hoping will work with the Tascam. If it doesn't, my next step would be to buy this…

http://www.ebay.com/itm/NEW-MK4-Indeed-Class-A-Valve-Buffer-Amp-Amplifier-electro-harmonix-ECC82EH-12AU7-/290827407364?pt=Vintage_Electronics_R2&hash=item43b6aa1004

…………which was recommended by PeterH.

Is there anyway that I can damage my SP10/PH10 buy trying out the Tascam both directly out of the "tape" out" or if that doesn't work, going out of the "tape out" of the Audio Control EQ box?

Here's a description of the Audio Control (takes a minute to load…)

https://ia700400.us.archive.org/25/items/Audio_Control_520B_Equalizer_/IA_Audio_Control_520B_Equalizer.pdf

Thanks in advance. I just don't want to chance screwing up my gorgeous sounding stereo.
Dave

The audio control has an input impedance of 100k ( p.29 ) so it's a border case, according to post #19
it will load down the riaa stage.
It wont hurt anything but sound will not be optimal.

A high impedace ( on input ) buffer is what you need, connected to the "tape-out" of the preamp.
The buffers output should have low impedance ( < 100k, but most buffers are in the <10k region)

I don't understand about the Audio Control's input impedance. I've been using it as an occasional EQ tweak and my system sounds great either with the Audio Control on or off.
Thanks for the help.

Dave_in_Va wrote:I don't understand about the Audio Control's input impedance. I've been using it as an occasional EQ tweak and my system sounds great either with the Audio Control on or off.

That 100kΩ input impedance may not be critical depending on what equipment you are using upstream. With just about anything solid state it will be OK. If it's tube equipment feeding it, it will still be OK if the tube gear's output is a cathode follower or an impedance-isolating buffer. Even if it's a Dynaco PAS whose phono stage sees the Audio Control directly through a selector switch, it won't cause THAT much of a problem, only a bass roll-off that you may not notice with a lot of recordings.

Where people run into problems is with input impedances of 10kΩ or so, when fed by tube equipment.

that's a really nice tube amp buffer you linked to on ebay, but it's about double the price that it should be!!
Here's one nearly identical for half the price . .. . http://www.ebay.com/itm/New-version-12AU7-tube-Class-A-tube-headphone-amplifier-preamplifier-w-psu/141093135880?
Yes, the point that myself and Peter and GP49 have been making is that alot of SS gear has a very low input impedance (under 10K) whereas almost all tube gear has a very high input impedance (more than 200K) and that anything under 100K is going to load down your PAS preamp tape output and also mess up the phono RIAA EQ,
so likely you will wind up needing a tube preamp/buffer staqe like the one you linked or the one I linked.
If you don't need a chassis I've got a new unstuffed AIKIDO buffer board for $30 that would need about $30 worth of parts to stuff, plus a $35 power transformer,
but your ebay link and mine are both ready to use as is so more convenient.

I appreciate the help. I'm not too sure exactly what the PAS is (an older Dynaco preamp?). I have a SP10 with the PH10 built in. VTA 70 power amp.
Just trying to be clear.

(Do you think there is any chance that running out of the EQ tape out instead of the SP/PH10 will make a difference?)

Dave_in_Va wrote:I appreciate the help. I'm not too sure exactly what the PAS is (an older Dynaco preamp?). I have a SP10...

The PAS is the old Dynaco stereo tube preamp.

For your SP10, either Ray or Bob will be able to advise (if either of you is reading, chime in!).  It depends on where you are connecting your Audio Control (which circuit is feeding it) and how tolerant is is of a 100KΩ input impedance.

The main out of the SP10 which normally goes to the VTA ST70 goes to the Audio Control EQ input, that output goes to the ST70.
Nothing currently is coming/going to any tape ins/outs.
(The CD burner arrives Tuesday.)

Dave_in_Va wrote:The main out of the SP10 which normally goes to the VTA ST70 goes to the Audio Control EQ input, that output goes to the ST70.
Nothing currently is coming/going to any tape ins/outs.
(The CD burner arrives Tuesday.)

Ahh, thats another way. Then it won't load the riaa. ( but it will be affected by the volume control)
Yes, you could connect the out to the cd-burner. No problem.

The "classical way" of introducing a EQ is to feed the eq from "tape out" and channel the
EQ output to "tape in" ,ans using the "after tape" switch on the amp. Commonly called "tape loop".
Connected this way the signal is tapped before any volume/tonecontrols. I do not know
if your SP10 is equipped with a "after tape" switch.

But by all means test. You won't damage anything.

Thanks Peter.
Yes, I have the in/out loop and in fact the Audio Control manual recommends hooking it up this way.
I'm going to leave it as it is, as it seems to work fine on the rare occasions I use it.

The CD burner will be here in two days and I'll try it connected to the "tape out" of the Audio Control. It'll be great if it works. If not I'll be picking out a tube buffer.

For what it's worth, the main reason I decided to go with a burner is that recently I've been buying and really enjoying a load of LPs by Popul Vuh. By the time I pay the shipping these things cost about $40 a pop. I want to have some available for a 1600 mile drive coming up this April and simply don't want to start duplicating them with $15.00 CD's.

(Also, as far as I can tell, my SP10 is just an SP9 with no tone controls, and yes, it has the "Source/Tape" switch.)

going back to the beginning of the thread, Troy's suggestion on using the $35 amp/buffer from MCM is probably your best way to go for no fuss.
Connect it to the TAPE OUT on your SP10. Then to the EQ. Then the EQ out to the recorder and/or amplifier.

The MCM amp has to low input impedance ( 47k)

Here is one that should have > 500k ( at least if it follows the x-10D schematic) This is a ready-built
device with builtin powersupply, just connect the rca cables and off you go :
http://www.ebay.com/itm/Finished-Tube-6N11-X-10D-Buffer-Pre-AMP-preamplifier-Base-on-Musical-Fidelity-/141093091305?hash=item20d9cdb7e9:g:-mQAAOxyg7xSYAQs

An suggestion : as this is not the first time a simple buffer is needed, why don't
Roy make one, boxed with PSU ? And also sell the cathode-follower board as a kit ?

How's this one look? I didn't see the impedance but it appears to be hand wired (and ships from Canada).
I'm not familiar with these tubes (6J1).

http://www.ebay.com/itm/YAQIN-SD-CD2-Stereo-Audio-Processor-Tube-Buffer-/141890400874?hash=item210953b26a:g:uA8AAOSwrklVc26d

Looks like I'm getting two different opinions. I'm hoping the recorder will work coming out of the EQ's "tape out" as discussed earlier.

Thanks again for all of the help.

(And Roy, as long as you're here, does my SP10/PH10 use a 12X4 or 6X 4 rectifier? Thanks.)

Dave_in_Va wrote:How's this one look? I didn't see the impedance but it appears to be hand wired (and ships from Canada).
I'm not familiar with these tubes (6J1).

http://www.ebay.com/itm/YAQIN-SD-CD2-Stereo-Audio-Processor-Tube-Buffer-/141890400874?hash=item210953b26a:g:uA8AAOSwrklVc26d

Looks like I'm getting two different opinions. I'm hoping the recorder will work coming out of the EQ's "tape out" as discussed earlier.

Thanks again for all of the help.

(And Roy, as long as you're here, does my SP10/PH10 use a 12X4 or 6X 4 rectifier? Thanks.)

This amp is spot on ! ( it mentions cathode follower, and as suck it use to have high input
impedance. If not there is nothing a solder cannot fix ). Go for it !

Well, I tried it directly out of the "tape out" of the SP10/Ph10 and also out of the "tape out" of the Audio Control.

Both worked. Probably better directly out of the preamp but it's kind of a moot point. I got a decent CD recorded but it definitely loaded the system down. I unplugged the connects from the "tape out" as it was playing and the audio quality increased greatly. It was very noticeable.

So I guess the buffer between the SP10/PH10 and the Tascam burner is the answer.

Do you guys all think this one is the ticket? I don't see any listing for the input/output impedance.

http://www.ebay.com/itm/131717897994?_trksid=p2055119.m1438.l2661&ssPageName=STRK%3AMEBIDX%3AIT

(It looks cool, it's tube, it's point to point hand wired, the tubes seems to be readily available as cheap NOS, and it ships from Canada.)

Thanks again for all of the help.
Come hell or high water I'm going to be listening to my expensive Krautrock psych LP collection on the Pa./Ohio/Indiana Turnpike this Spring!

Yes, it's your choice.
A guy in audiokarma made a schematic :
http://audiokarma.org/forums/index.php?attachments/cd2-schematics-jpg.367394/

It has input impedance in the meg region.

It appears to be a little nicer than this one...

http://www.ebay.com/itm/290827407364?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT